| Takahiro KUBA | Last modified date：2024.04.21 |
Professor /
Water and Material Cycles System /
Faculty of Engineering
Papers
| 1. | Jahidul Hassan,Md. Mijanur Rahman Rajib,Md. Noor-E-Azam Khan,Shahjalal Khandaker,Md. Zubayer,Kazi Raghib Ashab,Takahiro Kuba,Hadi M. Marwani,Abdullah M. Asiri,Md. Munjur Hasan,Aminul Islam,Mohammed M. Rahman,Md. Rabiul Awual, Assessment of heavy metals accumulation by vegetables irrigated with different stages of textile wastewater for evaluation of food and health risk, Journal of Environmental Management, https://doi.org/10.1016/j.jenvman.2024.120206, 353, 120206-1-120206-12, 2024.02, [URL], Wastewater irrigation for vegetable cultivation is greatly concerned about the presence of toxic metals in irrigated soil and vegetables which causes possible threats to human health. This study aimed to ascertain the accumulation of heavy metals (HMs) in edible parts of vegetables irrigated with different stages of textile dyeing wastewater (TDW). Bio-concentration factor (BCF), Estimated daily intake (EDI), and target hazard quotient (THQ) were computed to estimate human health risks and speculate the hazard index (HI) of adults and children with the consumption of HMs contaminated vegetables at recommended doses. Five vegetables (red amaranth, Indian spinach, cauliflower, tomato, and radish) in a pot experiment were irrigated with groundwater (T1) and seven stages of TDW (T2∼T8) following a randomized complete block design (RCBD) with three replications. Among the TDW stages, T8, T7, T4, and T5 exhibited elevated BCF, EDI, THQ, and HI due to a rising trend in the accumulation of Pb, Cd, Cr, and Ni heavy metals in the edible portion of the red amaranth, followed by radish, Indian spinach, cauliflower, and tomato. The general patterns of heavy metal (HM) accumulation, regarded as vital nutrients for plants, were detected in the following sequence: Zn > Mn/Cu > Fe. Conversely, toxic metals were found to be Cd/Cr > Ni > Pb, regardless of the type of vegetables. Principal Component Analysis (PCA) identified T8, T7, and T4 of TDW as the primary contributors to the accumulation of heavy metals in the vegetables examined. Furthermore, the analysis of the heavy metals revealed that the BCF, THQ, and HI values for all studied metals were below 1, except for Pb. This suggests that the present consumption rates of different leafy and non-leafy vegetables, whether consumed individually or together, provide a low risk in terms of heavy metal exposure. Nevertheless, the consumption of T8, T7, and T4 irrigated vegetables, specifically Indian spinach alone or in combination with red amaranth and radish, by both adults and children, at the recommended rate, was found to pose potential health risks. On the other hand, T2, T3, and T6 irrigated vegetables were deemed safe for consumption. These findings indicated that the practice of irrigating the vegetables with T8, T7, and T4 stages of TDW has resulted in a significant buildup of heavy metals in the soils and edible parts of vegetables which are posing health risks to adults and children. Hence, it is imperative to discharge the T8, T7, and T4 stages of TDW after ETP to prevent the contamination of vegetables and mitigate potential health risks. Keywords Textile wastewater, Heavy metals, Health hazard index, Bioconcentration factor, Leafy vegetables, Target hazard. |
| 2. | Shahjalal Khandaker,Diloara Akter,Mahmudul Hasan,Abu Saifullah,Hadi M. Marwani,Aminul Islam,Abdullah M. Asiri,Mohammed M. Rahman,Md. Munjur Hasan, Takahiro Kuba,Md. Rabiul Awual,Forkan Sarker, From industrial jute fibre spinning wastes to biofibre-reinforced plastics, Materials Chemistry and Physics, https://doi.org/10.1016/j.matchemphys.2023.128586, 313, 128586-1-128586-10, 2024.02, A huge amount of jute caddies is generated as a by-product in jute spinning industries solid waste is generally disposed of either in landfilling or burned as boiler fuel triggers environmental pollution. Owing to their higher fibre length and moderate single fibre tensile properties, the waste fibres in jute caddies can be transformed into dry fibre preform which in turn could be used in the production of composites. In this work, jute caddies were cleaned by compressed air before being pressed into dry fibre preform in order to increase the fibre packing capacity in the composites. Thermoplastic composites were manufactured by combining 40 % fibre with 60 % polypropylene (PP) matrix (by weight) using a hot press machine. The effect of chemical treatments (alkali and benzoyl chloride) on jute fibre was characterized by FTIR, TGA, and SEM. Tensile and flexural properties were evaluated to see the performance of composites. The findings of this study demonstrated that this newly developed dry short fibre jute caddies-based thermoplastic composites possess improved flexural properties by ⁓42.75 % if they are chemically modified with binders. Polyvinyl alcohol (PVA) can react with the functional groups of jute fibre to form strong hydrogen bonding that may result in enhanced bending properties of the composites. Therefore, the proposed composite made from jute caddies waste could be ideally used in semi-structural composite applications leading to a sustainable approach to disposing of jute industry solid waste through a circular economy. Keywords: Jute caddies, Fibre preform, Chemical treatment, Thermoplastic composite, Mechanical properties. |
| 3. | Diatoms play the main role as primary producer, in tidal flat ecosystems, which have high biological production. Diatoms requires silicon as essential nutrient. Since diatoms in tidal flats mainly obtain dissolved silicon (DSi) loading from a river, it is important to accumurate information about DSi dynamics. In this study, we conducted fieldworks on the basin of Zuibaiji river and evaluated the DSi supply into Imazu tital flat(S0), DSi traping or supply by a reservoir and a sewage treatment plant(T1, S1, respectively). S0 and T1 were estimated as 10.4 ton, and 0.57 ton in December 2022, respectively. It is considered that diatom production and sedimentation to bottom layer in the reservoir was main factor for DSi traping. S1 was also estimated that 2.7 ton of DSi were supplied in December 2022. It is indicated that the reservoirs and the sewage treatment plants have non-regligible influence to DSi supply into tital flats.. |
| 4. | Md.TofazzalHossain,ShahjalalKhandaker,M Mahbubul Bashar,Aminul Islam,Minhaz Ahmed,Rabeya Akter,Abdulmohsen K.D. Alsukaibi,Md. Munjur Hasan,Hamed M. Alshammari,TakahiroKuba,Md. RabiulAwualhj, Simultaneous toxic Cd(II) and Pb(II) encapsulation from contaminated water using Mg/Al-LDH composite materials, Journal of Molecular Liquids, https://doi.org/10.1016/j.molliq.2022.120810, 368, Part B, 120810-1-120810-13, 2022.12, A huge amount of jute caddies is generated as a by-product in jute spinning industries being considered solid waste are generally disposed of either in landfilling or burned as boiler fuel that triggers environmental pollution. Owing to their higher fibre length and moderate single fibre tensile properties, the waste fibres in jute caddies can be transformed into dry fibre preform which in turn could be used in the production of composites. In this work, jute caddies were cleaned by compressed air prior to being pressed into dry fibre preform in order to increase the fibre packing capacity in the composites. Thermoplastic composites were manufactured by combining 40% fiber with 60% polypropylene matrix (by weight) using a hot press machine. The effect of chemical treatments (alkali and benzoyl chloride) on jute fibre was characterized by FTIR, TGA, and SEM. Tensile and flexural properties were evaluated to see the performance of composites. The findings of this study demonstrated that this newly developed dry short fibre jute caddies-based thermoplastic composites possess improved flexural properties by ⁓42.75 % if they are chemically modified with binders. Polyvinyl alcohol (PVA) can react with the functional groups of jute fibre to form strong hydrogen bonding that may result in enhanced bending properties of the composites. Therefore, composite made from jute caddies waste could be ideally used in semi-structural composite applications leading to a sustainable approach to disposing of jute industry solid waste through a circular economy.. |
| 5. | This study is investigated to the competition between cyanobacterium Microcystis aeruginosa and diatom Nitzschia palea that can increase their cell number in a favorable environment for the occurrence of water bloom. We particularly focused on the temperature and pH effects on the inhibition effects of M. aeruginosa by N. palea. The maximum cell yield of M. aeruginosa reduced by approximately 50 % in the co-culture with N. palea at 15–30 ℃ as compared to that in the monoculture. N. palea also reduced the maximum cell yield of M. aeruginosa by 33, 54 and 66 % at pH 7.0, 8.0 and 9.0, respectively. N. palea reduced M. aeruginosa growth in the culture condition where water bloom is likely to occur. However, M. aeruginosa remained the dominant species in co-culture at 20–30 ℃ or pH 7.0–8.0. It is necessary to artificially increase the relative abundance of N. palea for enhancing the inhibition effect of M. aeruginosa.. |
| 6. | Shunsuke Watanabe,Naoki Matsunami,Ikki Okuma,Takahiro Kuba,Megumu Fujibayashi, Effect of the substrate surface and nutrient adsorption and elution on the growth of benthic diatom Nitzschia palea, Ecological Engineering, https://doi.org/10.1016/j.ecoleng.2022.106743, 183, 106743-1-106743-7, Volume 183, October 2022, 106743, 2022.10, [URL], Benthic diatoms are beneficial organisms whose activity supports ecosystems and improves water quality. The pennate diatom Nitzschia palea is an important diatom species, as it has a potential to control cyanobacterial blooms. Several studies have attempted to restore lakes by using artificially produced substrates that remove nutrients or harmful substances. Although substrates provide attachment sites, they may adversely affect the growth of diatoms by removing nutrients. In this study, we investigated a suitable substrate for N. palea growth. Substrates such as glass beads, activated carbon, and oyster shells, which can be used for lake water or ecosystem restoration, were selected. The most suitable substrate was determined from the perspective of nutrient adsorption, elution, and availability of adhesion sites. N. palea was cultivated with substrates until the stationary growth phase was attained, and N. palea growth and the change in nutrient content of the medium were investigated. Silicate eluted from small glass beads considerably increased the maximum cell yield of N. palea (7.03 × 106 cells mL 1). Activated carbon absorbed nitrate from the medium and decreased the specific growth rate of N. palea from 0.47 d 1 (without substrate) to 0.24 d 1 while providing attachment sites and increasing the maximum cell yield compared to the control (1.49 × 106 and 1.01 × 106 cells mL 1 under activated carbon and control treatments, respectively). Oyster shells absorbed phosphate and did not increase the maximum cell yield. Our results suggest that submerged substrates that absorb nutrients may negatively affect the growth of attached diatoms. Therefore, when using the substrates for lake water restoration, attention must be paid to the growth of attached diatoms.. |
| 7. | Yasushi Iseri,Aimin Hao,Tomokazu Haraguchi,Tetsuya Oishi,Takahiro Kuba,Koji Asai,Sohei Kobayashi, Improvement of Water Quality by Light-Emitting Diode Illumination at the Bottom of a Field Experimental Pond, https://doi.org/10.3390/w14152310, 14, 2310-1-2310-16, 2022.07, Remediation of water quality by stimulating algal photosynthesis using light-emitting diodes (LEDs) has attracted attention, but few studies have examined this in outdoor freshwater environments. To understand the effects of LED illumination on water quality, the dissolved oxygen (DO), temperature, pH, and electric conductivity were monitored over 5 months in three depressions with or without a red/blue LED light at the bottom of an experimental pond. The effects of the blue LED on water quality were evident in the period with less rainfall after the change of water quality to an equilibrium state; DO and pH were higher, and EC was lower for the blue LED than for the control. The diel changes of these variables were also lower for the blue LED. The effects of the red LED on DO and pH were also evident, but to a lesser extent compared to those of the blue LED. A vertical mixing of water associated with a nighttime cooling of the surface water was suggested by a rapid DO increase after a temperature decrease in the control. Such internal water circulation and an inflow of water after rainfall might have obscured the LED effects in the rainy period. The bottom water of the blue LED had a higher density and species richness of phytoplankton than that of the control at the end of the experiment. A lower density of phytoplankton and higher nutrient concentrations in the red LED might have been due to a higher density and feeding activity by zooplankton. Our results confirmed the applicability of LED illumination in stimulating algal photosynthesis, and in improving the oxygen condition of the bottom water in freshwater ponds.. |
| 8. | Shunsuke Watanabe,Naoki Matsunami,Ikki Okuma,Podiapen Tannen Naythen,Megumu Fujibayashi,Yasushi Iseri,Aimin Hao,Takahiro Kuba, Blue light irradiation increases the relative abundance of the diatom Nitzschia palea in co-culture with cyanobacterium Microcystis aeruginosa, Water Environment Research, https://doi.org/10.1002/wer.10707, 94, 4, 1-8, e10707, 2022.03, Lake eutrophication is associated with cyanobacterial blooms. The pennate diatom Nitzschia palea (N. palea) inhibits the growth of the cyanobacterium Microcystis aeruginosa (M. aeruginosa); therefore, increasing the relative abundance of N. palea may contribute to the inhibition of Microcystis blooms. Several studies have demonstrated that blue light irradiation promotes diatom growth and inhibits cyanobacterial growth. In this study, we evaluated the effects of blue light irradiation on N. palea and M. aeruginosa abundance. Monocultures and co-cultures of N. palea and M. aeruginosa were exposed to blue light and fluorescent light at 32 μmol photons m2 s1. The relative abundance of N. palea under fluorescent light decreased gradually, whereas the abundance under blue light was relatively higher (approximately 74% and 98% under fluorescent light and blue light, respectively, at the end of the experiment). The inhibition efficiency of blue light on the growth rate of M. aeruginosa was related to the light intensity. The optimal light intensity was considered 20 μmol photons m2 s1 based on the inhibition efficiency of 100%. Blue light irradiation can be used to increase the abundance of N. palea to control Microcystis blooms..  |
| 9. | Cs Adsorption Capability of Activated Charcoal and its Incineration Volume Reduction Ratio and Cs Recovery Ratio. |
| 10. | Effect of Atmospheric Pressure Non Equilibrium Plasma Treatment for Activated Carbon and Bamboo Charcoal on Cesium Adsorption. |
| 11. | Shahjalal Khandaker, Mir Ferdous Chowdhury, Md Rabiul Awual, Aminul Islam, Takahiro Kuba, Efficient cesium encapsulation from contaminated water by cellulosic biomass based activated wood charcoal, Chemosphere, 10.1016/j.chemosphere.2020.127801, 262, 1-13, 2021.01, In this study, cost-effective cellulosic biomass based activated wood charcoal was developed from Japanese Sugi tree (Cryptomeria japonica) by concentrated nitric acid modification for adsorption of Cs from contaminated water. The physicochemical properties of specimens were investigated using N2 adsorption-desorption isotherms (BET method), FESEM, FTIR, and XPS spectra analysis. The experimental results revealed that the surface area of the raw wood charcoal was significantly decreased after boiling nitric acid modification. However, several oxygen-containing acidic function groups (-COOH, -CO) were introduced on the surface. The adsorption study confirmed that the equilibrium contact time was 1 h, the optimum adsorption pH was neutral to alkaline and the suitable adsorbent dose was 1:100 (solid: liquid). The maximum Cs was removed when the concentration of Na and K were lower (5.0 mM) with Cs in solution. The Cs adsorption processes well approved by the Langmuir isotherm and pseudo-second-order kinetic models and the maximum adsorption capacity was 35.46 mgg-1. The Cs adsorption mechanism was clearly described and it was assumed that the adsorption was strongly followed by chemisorptions mechanism based on the adsorbent surface properties, kinetic model and Langmuir isotherm model. Most importantly, about 98% of volume reduction was obtained by burning (500 °C) the Cs adsorbed charcoal, which ensured safe storage and disposal of radioactive waste. Therefore, this study can offer a guideline to produce a functional adsorbent for effective Cs removal and safe radioactive waste disposal.. |
| 12. | Aimin Hao,Tomokazu Haraguchi,Takahiro Kuba,He Kai,Yingchao Lin,Yasushi Iseri, Effect of the microorganism-adherent carrier for Nitzschia palea to control the cyanobacterial blooms, Ecological Engineering, https://doi.org/10.1016/j.ecoleng.2020.106127, 159, 1-8, 2021.01, [URL], To evaluate the effect of microorganism adherent carrier for Nitzschia palea on the control of Cyanobacterial blooms, the changes of phytoplankton population structure and the chlorophyll a concentration after carrier installation were compared with those without carrier installation in field and laboratory experiments. The results showed that the installation of the carrier could control the growth of Microcystis spp., effectively. In the field investigation, the cell number of Microcystis spp. can decrease to 54,800 cells/mL after 5 d treatment comparing to 464,000 cells/mL in water without treatment, but the installation of adherent carrier did not influence the growth of other phytoplanktons including Chlorophyta. Through the observation by a microscope, the adhesion of the Nitzschia palea to this carrier was observed as well as the gliding movement of the Nitzschia palea onto the colonies of Microcystis, indicating that the adhesion, invasion and sliding movement of Nitzschia palea induced the physical destruction and effective control of Microcystis colony. Overall, the installation of this carrier can promote the growth of Nitzschia palea near carrier fiber, and control cyanobacterial blooms by the invasion of Nitzschia palea onto Microcystis colony, which can be used as one of energy-saving and sustainable eco-engineered blue-grass control methods in closed water areas such as lakes and reservoirs.. |
| 13. | Physiological characteristics of diatom Nitzschia palea for ecological engineering countermeasure method of water blooms. |
| 14. | Shahjalal Khandaker, Yusaku Toyohara, Ganesh Chandra Saha, Md Rabiul Awual, Takahiro Kuba, Development of synthetic zeolites from bio-slag for cesium adsorption Kinetic, isotherm and thermodynamic studies, Journal of Water Process Engineering, 10.1016/j.jwpe.2019.101055, 33, 2020.02, This study reported a novel synthetic zeolite based adsorbent developed from the municipal wastewater sludge molten slag (bio-slag) through the hydrothermal modification process for removal of cesium (Cs) from simulated wastewater. The artificial zeolites were produced from the raw bio-slag which was identified by the several physicochemical experimental procedures such as the surface area analysis (the BET technique), the FESEM, the XRF and the XRD. The Cs adsorption process of modified bio-slag was exmined by the linear pseudo-first order, pseudo-second order and intra-particles diffusion models whilst the second order kinetic model confirmed a better agreement with the correlation coefficient, R2 = 0.999-1.000 for 20-400 mg/L Cs solution. The Langmuir, Freundlich and the Temkin isotherm model were investigated using the adsorption isotherm data. A satisfactory correlation coefficient value (R2= >0.980) proved that the isotherm parameters were perfectly fitted to the Langmuir and Freundlich model and the highest Cs adsorption ability of modified bio-slag were 51.02, 51.02 and 49.51 mg/g at 288, 298 and 308 K, respectively. The better agreement of adsorption data with the second order kinetic model and the Langmuir model proved the adsorption mechanism was controlled by the chemical reaction (ion-exchange). Thermodynamic studies under the different temperatures proved that the adsorption reaction was endothermic (ΔH =20.53 kJ/mol) and ΔS = 0.021 kJ/mol/K) and non-spontaneous (ΔG>0). Moreover, the modified bio-slag effectively removed Cs even in the co-existence of Na+ and K+ as competitive ions at their wide range of concentrations (upto 300 mM) although the higher concentration slightly affected the Cs adsorption.. |
| 15. | The competition characteristic of diatom Nitzschia palea and water blooms and the growth inhibition effect of LED Irradiation on cyanobacteria Microcystis aeruginosa. |
| 16. | Shahjalal Khandaker,Yusaku Toyohara,Takahiro Kuba, Development of Functional Synthetic Zeolite from Sewage Sludge Molten Slag, International Symposium on Advanced Materials and Nanotechnology 2019 (iSAMN2019), Proceedings of iSAMN2019, 69-70, 2019.08, [URL], This study reports the production ol synthetic zeolrte from sewage sludge molten slag (bio-slag) by alkali hydrothernral treatment. The bio-slag is treated with 1.0 N NaOH at 140C for 24 hr. The zeolite properties of modified bio-slag were identified by using surface area measurenrent, FESEM observation, XRF, XRD investigation and cation exchange capacity [CEC] analysis. The experimental results exhibit that the sutface area and the pore volume of the modified bio-slag increased almost 10 times. The FESEM obserwations showed that the modified bio-slag is highly porous. The XRF analysis indicates that the ratio of SiO2/Al23 in the slag is improved from 2.52 to 2.96 after the modification process which increases the strength of zeolite structure. The XRD analysis confirms that the zeolite X, zeolite Y, zeolite A, and sodalite were formed on the surface of the modified bio-slag. Importantly, the CEC of the modified bio-slag drastically improved almost 2 times due to the formation of synthetic zeolites. Therefore, the developed synthetic zeolite could be used as an emerging material for wastewater treatment, soil decontamination etc.. |
| 17. | Shahjalal Khandaker, Yusaku Toyohara, Seiya Kamida, Takahiro Kuba, Effective removal of cesium from wastewater solutions using an innovative low-cost adsorbent developed from sewage sludge molten slag, Journal of Environmental Management, 10.1016/j.jenvman.2018.05.059, 222, 304-315, 2018.09, This study investigates the effective removal of cesium (Cs) from aqueous solution using sewage sludge molten (SSM) slag that has undergone the surface modification with alkali (NaOH) hydrothermal treatment. The raw and modified slags were characterised systematically using the BET method, the FESEM, the XRF, the XRD spectroscopy and the CEC analysis to understand the physicochemical changes of the materials, and its sensitivity to Cs ions adsorption. Batch adsorption experiments were carried out to investigate the effects of adsorbent dose, contact time, solution pH, different initial Cs concentrations, temperature and the effect of competitive ions on Cs adsorption. The adsorption isotherm, kinetic and thermodynamic studies were also evaluated based on the experimental results. A higher Cs removal efficiency of almost 100% (for 20–100 mg/L of initial concentration) was achieved by the modified SSM slag, and the maximum adsorption capacity was found to be 52.36 mg/g. Several types of synthetic zeolites such as zeolite X, zeolite Y, zeolite A, and sodalite were formed on surface of the modified slag through the modification process which might be enhanced the Cs adsorption capacity. Kinetic parameters were fitted by the pseudo-second order model. The adsorption isotherms data of modified slag were well-fitted to the Langmuir (R2 = 0.989) and Freundlich isotherms (R2 = 0.988). The thermodynamic studies indicated that the adsorption process by the modified slag was spontaneous and exothermic. In the competitive ions effect, the modified slag effectively captured the Cs ion in the presence of Na+ and K+, especially at their lower concentrations. Moreover, the modified slag was reused for several cycles after the successful elution process with an appropriate eluting agent (0.5 M H2SO4), without deterioration of its original performance. Therefore, the SSM modified slag could be effectively used as a low-cost potential adsorbent for high Cs adsorption from wastewater.. |
| 18. | Shahjalal Khandaker, Yusaku Toyohara, Seiya Kamida, Takahiro Kuba, Adsorptive removal of cesium from aqueous solution using oxidized bamboo charcoal, Water Resources and Industry, 10.1016/j.wri.2018.01.001, 19, 35-46, 2018.06, [URL], In this study, the air oxidized bamboo charcoal (BC) was investigated for cesium (Cs) adsorption from aqueous solution. The physicochemical properties of the adsorbent were evaluated systematically using the different techniques including BET, FESEM, FTIR, XPS and also the pHpzc value. Batch adsorption experiments were conducted to determine the effect of contact time, solution pH, initial Cs concentrations, temperature and also the presence of competitive ions on adsorption. The adsorption kinetic parameters confirmed the better fitting of pseudo-second order kinetic model. The isotherm data could be well described by the Langmuir isotherm model and the maximum monolayer adsorption capacity was 55.25 mg g-1. The high specific surface area and the porous structure with some acidic functional groups on the surface were obviously responsible for high Cs adsorption onto oxidized-BC. Thermodynamic parameters such as standard enthalpy, entropy, and Gibbs free energy were evaluated and it had been found that the adsorption process was favorable, spontaneous and endothermic in nature. In the competitive ions study, the presence of Na and K with their concentrations up to 12mM did not strongly affect the removal of Cs by oxidized-BC. Therefore, the experimental results suggested that the oxidized-BC could be used as an effective adsorbent for significant Cs removal from aqueous solution considering the high adsorption capacity, short adsorption time and selective removal of Cs ions.. |
| 19. | Zhifan Ni, Xiaogang Wu, Lingfang Li, Zhe Lv, Zhenjia Zhang, Aimin Hao, Yasushi Iseri, Takahiro Kuba, Xiaojun Zhang, Wei Min Wu, Chunjie Li, Pollution control and in situ bioremediation for lake aquaculture using an ecological dam, Journal of Cleaner Production, 10.1016/j.jclepro.2017.11.185, 172, 2256-2265, 2018.01, Aquaculture has become one of the major sources of lake eutrophication, due to the lack of direct and efficient technologies for pollution control and remediation. This study proposes a novel ecological dam (Eco-dam) system, which consists of biofilter floating beds and plant floating beds that form an enclosure (the test zone) around the breeding area that allows lake water to pass through. A pilot-scale test was conducted to test pollution control and in situ bioremediation during breeding of Chinese mitten crab (Eriocheir sinensis) in Yangcheng Lake, China. The results showed slight improvement of water quality in the test zone compared with the breeding zone. The biofilm that formed on the biofilter played a major role in removal of organic pollutants and nitrogen (0.609 kg COD/(m2·d), 0.512 kg NH4+-N/(m2·d), 0.482 kg NO2−-N/(m2·d), and 0.112 kg NO3−-N/(m2·d)). Both proteins and volatile suspended solids (VSS) in the Eco-dam biofilm decreased from the water surface towards the lake bottom, especially below 0.5 m depth. The average ratio of VSS to suspended solids in the biofilm was 0.337 ± 0.025 g/g. Analysis with the Illumina MiSeq System confirmed the presence of a diverse microbe population in the biofilm, performing organic carbon removal and nitrification and denitrification, with limited photosynthesis near the lake surface and methane oxidation near the lake bottom.. |
| 20. | S. Khandaker, T. Kuba, Y. Toyohara, S. Kamida, Y. Uchikawa, Development of ion-exchange properties of bamboo charcoal modified with concentrated nitric acid, IOP Conf. Series: Earth and Environmental Science, 82, 2017.09, [URL], The surface chemistry and the structural properties of activated carbon can be altered by the acidic modification. The objective of this study is to investigate the changes occurring in bamboo charcoal (BC) during activation with concentrated nitric acid. Low temperature (500˚C) carbonized BC has been prepared and oxidized with 70% concentrated boiling nitric acid (BC-AC). The porous properties of the BC are analyzed with nitrogen adsorption isotherm at 77 K. The surface structure is observed by Field emission scanning electronic microscope (FESEM) and the surface functional groups are examined by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and the pH of the point of zero charge (pHPZC). The results reveal that severe oxidation with HNO3 considerably decreases the surface area of BC with enhanced pore widening and FESEM observation demonstrates the erosive effect of oxidation. The FTIR analysis detects that some absorption bands are assigned for carboxyl, aldehyde and ketone groups on BC-AC. The XPS analysis also clearly shows that the ratio of oxygen and acidic functional groups has been enriched significantly on the BC-AC. The low pHPZC value of BC-AC confirms that the surface is highly acidic for the fixation of acidic functional groups on surface. In general, the existence of the abundant amount of acidic functional groups on adsorbents enhances the sorption of heavy metals ions in aqueous solution. Therefore, it is strongly expected that the modified BC, activated under the proposed conditions would be a promising ion exchanger in aqueous solution and can be applied for the adsorption of different heavy metal ions and radioactive materials from effluent.. |
| 21. | S. Khandaker, T. Kuba, Y. Toyohara, S. Kamida, Y. Uchikawa, Development of ion-exchange properties of bamboo charcoal modified with concentrated nitric acid, 3rd International Conference on Water Resource and Environment, WRE 2017 IOP Conference Series: Earth and Environmental Science, 10.1088/1755-1315/82/1/012002, 82, 1, 2017.08, The surface chemistry and the structural properties of activated carbon can be altered by the acidic modification. The objective of this study is to investigate the changes occurring in bamboo charcoal (BC) during activation with concentrated nitric acid. Low temperature (500°C) carbonized BC has been prepared and oxidized with 70% concentrated boiling nitric acid (BC-AC). The porous properties of the BC are analyzed with nitrogen adsorption isotherm at 77 K. The surface structure is observed by Field emission scanning electronic microscope (FESEM) and the surface functional groups are examined by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and the pH of the point of zero charge (pHPZC). The results reveal that severe oxidation with HNO3 considerably decreases the surface area of BC with enhanced pore widening and FESEM observation demonstrates the erosive effect of oxidation. The FTIR analysis detects that some absorption bands are assigned for carboxyl, aldehyde and ketone groups on BC-AC. The XPS analysis also clearly shows that the ratio of oxygen and acidic functional groups has been enriched significantly on the BC-AC. The low pHPZC value of BC-AC confirms that the surface is highly acidic for the fixation of acidic functional groups on surface. In general, the existence of the abundant amount of acidic functional groups on adsorbents enhances the sorption of heavy metals ions in aqueous solution. Therefore, it is strongly expected that the modified BC, activated under the proposed conditions would be a promising ion exchanger in aqueous solution and can be applied for the adsorption of different heavy metal ions and radioactive materials from effluent.. |
| 22. | Shahjalal Khandaker, Takahiro KUBA, Seiya Kamida, Yuji Uchikawa, Adsorption of Cesium from Aqueous Solution by Raw and Concentrated Nitric Acid-modified Bamboo Charcoal, Journal of Environmental Chemical Engineering, http://dx.doi.org/10.1016/j.jece.2017.02.014, 5, 2, 1456-1464, 2017.06, [URL], The study is conducted to explore the potential of bamboo charcoal (BC) as an adsorbent to remove cesium from aqueous solution. Low temperature carbonized BC (500°C) is prepared and the surface of the BC is modified with 70% concentrated boiling nitric acid (BC-AC). Specific surface area, field emission scanning electron microscope (FESEM), fourier transform infra-red (FTIR) spectroscopy, and point of zero charge (pHpzc) of BC and BC-AC have been investigated in this study. The results demonstrate that BC-AC is enriched with oxygen-containing functional groups but its porous structure and surface area are decreased when compared with the raw BC. Optimum cesium adsorption conditions onto BC and BC-AC have been determined by investigating the contact time, pH of solution, adsorbent dosage and initial solution concentration in batch adsorption process. It has been observed that maximum cesium adsorption capacity is 0.17 and 45.87 mg/g for BC and BC-AC, respectively. It has also been observed that almost 100% cesium could be removed from water at up to 400 mg/L concentrated cesium solution by BC-AC whereas the removal capacity of cesium by BC is very poor. The experimental adsorption data of both BC and BC-AC follows the pseudo-second-order kinetic. The Freundlich adsorption equilibrium isotherm data is more appropriate than the Langmuir isotherm for adsorption of cesium by BC. However, adsorption isotherm data for BC-AC is a better fit with Langmuir isotherm than the Freundlich isotherm model. Furthermore, the separations factor (RL) and the surface coverage (θ) for Langmuir isotherm confirms that the proposed adsorption process is the most suitable for BC-AC. This study suggests that BC-AC could be effectively used for the removal of cesium from environmental water.. |
| 23. | Shahjalal Khandaker, Takahiro Kuba, Seiya Kamida, Yuji Uchikawa, Adsorption of cesium from aqueous solution by raw and concentrated nitric acid-modified bamboo charcoal, Journal of Environmental Chemical Engineering, 10.1016/j.jece.2017.02.014, 5, 2, 1456-1464, 2017.04, The study is conducted to explore the potential of bamboo charcoal (BC) as an adsorbent to remove cesium from aqueous solution. Low temperature carbonized BC (500 °C) is prepared and the surface of the BC is modified with 70% concentrated boiling nitric acid (BC-AC). Specific surface area, field emission scanning electron microscope (FESEM), fourier transform infra-red (FTIR) spectroscopy, and point of zero charge (pHpzc) of BC and BC-AC have been investigated in this study. The results demonstrate that BC-AC is enriched with oxygen-containing functional groups but its porous structure and surface area are decreased when compared with the raw BC. Optimum cesium adsorption conditions onto BC and BC-AC have been determined by investigating the contact time, pH of solution, adsorbent dosage and initial solution concentration in batch adsorption process. It has been observed that maximum cesium adsorption capacity is 0.17 and 45.87 mg/g for BC and BC-AC, respectively. It has also been observed that almost 100% cesium could be removed from water at up to 400 mg/L concentrated cesium solution by BC-AC whereas the removal capacity of cesium by BC is very poor. The experimental adsorption data of both BC and BC-AC follows the pseudo-second-order kinetic. The Freundlich adsorption equilibrium isotherm data is more appropriate than the Langmuir isotherm for adsorption of cesium by BC. However, adsorption isotherm data for BC-AC is a better fit with Langmuir isotherm than the Freundlich isotherm model. Furthermore, the separations factor (RL) and the surface coverage (θ) for Langmuir isotherm confirms that the proposed adsorption process is the most suitable for BC-AC. This study suggests that BC-AC could be effectively used for the removal of cesium from environmental water.. |
| 24. | WATER PURIFICATION BY LED IRRADIATION IN DECOMPOSING WITHERED MICROCYSTIS . |
| 25. | The purpose of this study is to identify whether the released Poly-P can be crystallized as MAP and to evaluate its forming ability.. |
| 26. | Yuxian LIU, Aimin HAO, Yasushi ISERI, Chunjie LI, Zhenjia ZHANG, Takahiro KUBA, POSSIBLE SURVIVAL MECHANISMS OF SINANODONTA WOODIANA EXPOSED TO MICROCYSTIN, Journal of JSCE, Division G: Environmental Systems and Engineering (土木学会論文集), 3, 259-267, 2015.09, [URL], This study aims to figure out the selective feeding mechanism and to deduce the possible detoxification mechanism to the high concentrations of MCs, based on the phenomena found in the long-term grazing experiment.. |
| 27. | Caixia Kang, Takahiro Kuba, Aimin Hao, Yasushi Iseri, Antioxidant Responses of Vallisneria asiatica to Eutrophic Sediments in Lake Taihu, China, Bulletin of Environmental Contamination and Toxicology, 10.1007/s00128-015-1579-4, 95, 2, 194-199, 2015.08, Abstract Three kinds of representative sediments were obtained from a macrophyte-dominated bay (East Lake Taihu) and two algae-dominated regions (Western Lake Taihu and Meiliang Bay). Physiological responses of Vallisneria asiatica to these sediments were compared. Results from 20 days exposures showed no obvious differences in malondialdehyde (MDA) in roots, while the MDA content in leaves of plants exposed to Western Lake Taihu sediment was significantly (p |
| 28. | Caixia KANG, Takahiro KUBA, Hao AIMIN, Yasushi ISERI, Antioxidant Responses of Vallisneria asiatica to Eutrophic Sediments in Lake Taihu, China, Bulletin of Environmental Contamination and Toxicology, http://dx.doi.org/10.1007/s00128-015-1579-4, 95, 194-199, 2015.06, [URL], Results indicated eutrophic sediment was a contributing factor in the disappearance of V. asiatica in Western Lake Taihu.. |
| 29. | CaiXia KANG, Takahiro KUBA, AiMin HAO, Yasushi ISERI, ChunJie LI, ZhenJia ZHANG, Oxidative stress responses of submerged macrophyte Vallisneria asiatica to different concentrations of cyanobacteria, CHINESE JOURNAL OF OCEANOLOGY AND LIMNOLOGY, 10.1007/s00343-015-4084-z, 33, 2, 364-371, 2015.04, In a 10-day aquarium experiment, this investigation examines macrophyte restoration in eutrophic Lake Taihu, the physiological effects of different plant biomass levels and of increasing natural cyanobacterial concentrations on a submerged macrophyte, Vallisneria asiatica. Cyanobacterial stress suppressed the superoxide dismutase (SOD) activity of the plant’s leaves and induced the catalase (CAT) and peroxidase (POD) activities of its roots. The soluble protein content in V. asiatica decreased with an increase in natural cyanobacterial concentrations, whereas the malonaldehyde (MDA) increased significantly at Chl.a concentrations of 222 and 262 µg·L−1 in water. V. asiatica adapted to the stress caused by cyanobacterial concentrations by adjusting its antioxidant defense system to remove the excessive reactive oxygen species when the algal Chl.a concentration was >109 µg·L−1. Additionally, high biomass of V. asiatica (2,222 g FW·m-2) can inhibit the reproduction of cyanobacteria more significantly than low biomass (1111 g FW·m-2). High biomass of V. asiatica increased the oxidative stress in an individual plant when the initial Chl.a concentration in the water reached 222 and 262 µg·L−1, as expressed by the increased MDA in leaves, compared with low biomass of V. asiatica. This provides a basis for controlling cyanobacterial concentrations and V. asiatica biomass for the recovery of V. asiatica in eutrophic Lake Taihu.. |
| 30. | MingYang ZHANG, JianWei DU, Takahiro KUBA, Yong WEN, Comprehensive Evaluation of Poly-Phosphate Release from Sewage Sludge with Thermal Treatment, Applied Mechanics and Materials, 476-483, 2015.04, [URL], Phosphorus is a necessary nutrient element to all lives in the world. Distribution and phosphate rock reserves in the world disclose shortage crisis of phosphorus. Thus phosphorus recovery has been a research hot spot in the world. Mr.Ohtake’ group [1] recommended a new method to recover phosphorus from sewage sludge during heating process. It seems that nearly 90% of the poly-phosphate (poly-P) and 87% of total phosphate (T-P) can be released from cultivated sludge by heating at 70˚C for 1 hour. Meanwhile, released poly-P can precipitate with Ca in neutral condition without any pH adjustment. Sewage sludge was used in this research to identify its performance during thermal treatment. With the increase of temperature and heating time, release of poly-P and T-P increased obviously. However, poly-P would be hydrolyzed when temperature was higher than 80 ˚C. With addition of EDTA, release of poly-P increased nearly 100%. Migration of metal cations during thermal treatment can provide indirect evidence which kinds of metal cations would make impediment on poly-P release. A novel phenomenon was observed poly-P mixed with ortho-phosphate can precipitate with NH4+ and Mg2+ as struvite at pH 8.5.. |
| 31. | POLYPHOSPHATE RECOVERY FROM SEWAGE SLUDGE AS MAGNESIUM AMMONIUM PHOSPHATE AND ITS FORMING ABILITY. |
| 32. | MingYang ZHANG, JianWei DU, Takahiro KUBA, Yong WEN, Comprehensive Evaluation of Poly-Phosphate Release from Sewage Sludge with Thermal Treatment, The 9th International Conference on Waste Management and Technology, 476-483, 2014.10, Phosphorus is a necessary nutrient element to all lives in the world. Distribution and phosphate rock reserves in the world disclose shortage crisis of phosphorus. Thus phosphorus recovery has been a research hot spot in the world. Mr.Ohtake’ group [1] recommended a new method to recover phosphorus from sewage sludge during heating process. It seems that nearly 90% of the poly-phosphate (poly-P) and 87% of total phosphate (T-P) can be released from cultivated sludge by heating at 70˚C for 1 hour. Meanwhile, released poly-P can precipitate with Ca in neutral condition without any pH adjustment. Sewage sludge was used in this research to identify its performance during thermal treatment. With the increase of temperature and heating time, release of poly-P and T-P increased obviously. However, poly-P would be hydrolyzed when temperature was higher than 80 ˚C. With addition of EDTA, release of poly-P increased nearly 100%. Migration of metal cations during thermal treatment can provide indirect evidence which kinds of metal cations would make impediment on poly-P release. A novel phenomenon was observed poly-P mixed with ortho-phosphate can precipitate with NH4+ and Mg2+ as struvite at pH 8.5.. |
| 33. | CaiXia KANG, AiMin HAO, Tasushi ISERI, Takahiro KUBA, Metabolic and Antioxidant Responses of Vallisneria asiatica to Different Concentrations of Dissolved Inorganic Nitrogen and Phosphorus, 日本水処理生物学会, 50, 3, 105-112, 2014.09, To clarify the mechanism of submerged macrophytes disappearance and supply the necessary theory for the phytoremediation in eutrophic Lake Taihu, effects of the moderate nutrients concentration, high NH4+-N concentration and high PO43--P concentration in the water column on the antioxidant defense system in submerged macrophyte, Vallisneria asiatica, were studied with the 20-day aquarium experiments. The results showed that the moderate concentration of nutrients can promote the metabolism of V. asiatica. Either high concentrations of NH4+-N or PO43--P could cause the oxidative stress to cells of V. asiatica, expressed as decreased contents of chlorophyll a (Chl.a) and protein, and the enhancement of catalase (CAT) activities in leaves of V. asiatica. In addition, 0.6 mg·L-1 of PO43--P caused more oxidative damages to V. asiatica than 3.5 mg·L-1 NH4+-N. The results indicated that the antioxidative protection mechanisms could be activated but still could not prevent the damage of the metabolism system in V. asiatica exposed to either high concentrations of NH4+-N or PO43--P. Therefore, it is necessary to establish a dual control strategy of N and P for the restoration of V. asiatica in eutrophic Lake Taihu.. |
| 34. | Takahiro KUBA, MingYang ZHANG, Inhibitory effect of metal ions on the poly-phosphate release from sewage sludge during thermal treatment, ENVIRONMENTAL TECHNOLOGY, 35, 9, 1157-1164, 2014.05, [URL], The purpose of this study was aimed at identifying the influence of metal cations such as Mg2+, Ca2+, Al3+ and Fe3+ on poly-phosphate (poly-P) and total phosphate (T-P) release from sewage sludge collected from wastewater treatment plant during thermal treatment at 70 degrees C for 80 min. With the addition of chelating reagent such as EDTA, release of poly-P and T-P was improved obviously during thermal treatment. Inhibitory effect of metal cations on phosphorus release was apparent by adding metal cations into sludge sample. Most of Ca, Al and Fe inside of cell could be released into the supernatant, but captured in extracellular polymeric substance (EPS); oppositely, large quantity of Mg could be released into the supernatant directly and not concentrated in EPS. Performance of sewage sludge on phosphorus release in summer and winter was different; different precipitation and temperature possibly result in this phenomenon.. |
| 35. | Ming Yang Zhang, Takahiro Kuba, Inhibitory effect of metal ions on the poly-phosphate release from sewage sludge during thermal treatment, Environmental Technology (United Kingdom), 10.1080/09593330.2013.863980, 35, 9, 1157-1164, 2014.05, The purpose of this study was aimed at identifying the influence of metal cations such as Mg2+, Ca2+, Al3+ and Fe 3+ on poly-phosphate (poly-P) and total phosphate (T-P) release from sewage sludge collected from wastewater treatment plant during thermal treatment at 70°C for 80 min. With the addition of chelating reagent such as EDTA, release of poly-P and T-P was improved obviously during thermal treatment. Inhibitory effect of metal cations on phosphorus release was apparent by adding metal cations into sludge sample. Most of Ca, Al and Fe inside of cell could be released into the supernatant, but captured in extracellular polymeric substance (EPS); oppositely, large quantity of Mg could be released into the supernatant directly and not concentrated in EPS. Performance of sewage sludge on phosphorus release in summer and winter was different; different precipitation and temperature possibly result in this phenomenon.. |
| 36. | Yuxian LIU, Aimin HAO, Yasushi ISERI, Takahiro KUBA, Zhenjia ZHANG, A Comparison of the Mussel Anodonta woodiana’s Acute Physiological Responses to Different Algae Diets, Journal of Clean Energy Technologies (JOCET), 2, 2, 126-131, 2014.04, The bivalve Anodonta woodiana is widely distributed throughout Chinese freshwaters and is an important economic pearl mollusk. Recently, A. woodiana as a biomanipulation tool in Chinese lakes due to its strong suppression of phytoplankton, has been attracted increasingly more attention. In order to examine whether A. woodiana can exert grazing pressure on Microcystis and to evaluate the different effects of each algae diets on mussels’ potential growth, a comparative study was carried out on the acute physiological responses to variable microalgae diets including toxic MC-producing cyanobacteria and non-toxic Scenedesmus obliquus green algae. The values of filtration rate, absorption efficiency, oxygen consumption rate and ammonia excretion rate of A. woodiana were measured and finally the SFG (scope for growth) value as a measure of metabolic energy balance for A. woodiana was calculated and compared. The results showed that the mussel A. woodiana has a higher grazing ability on the toxic Microcystis aeruginosa compared with the green algae S. obliquus; Furthermore, the effects of different algae diets on SFG of A. woodiana demonstrated that the toxic M. aeruginosa may supply more energy for A. woodiana’s potential growth. These results indicated that A. woodiana has strong adaptation ability when they were exposed to toxic Microcystis solution in this study, which implied that there is high application feasibility of A. woodiana as a toxic Microcystis-blooming controller in practice.. |
| 37. | Metabolic and Antioxidant Responses of Vallisneria asiatica to Different Concentrations of Dissolved Inorganic Nitrogen and Phosphorus. |
| 38. | Caixia KANG, Takahiro KUBA, Aimin HAO, Yasushi ISERI, Chunjie LI, Zhenjia ZHANG, Effects of Macrophyte Vallisneria asiatica Biomasses on the Algae Community, World Academy of Science, Engineering and Technology, 7, 12, 217-221, 2013.12, [URL], To improve the water quality of lakes and control algae blooms, the effects of Vallisneria asiatica which is one of aquatic plants spread over Lake Taihu, with different biomasses on the water quality and algae communities were researched. The results indicated that V. asiatica could control an excess of Microcystis spp. when the V. asiatica biomass was larger than 50g in the tank with 30L solution in the laboratory. Planktonic and epiphytic algae responded differently to V. asiatica. The presence of macrophyte V. asiatica in eutrophic waters has a positive effect on algae compositions because of different sensitivities of algae species to allelopathic substances released by macrophyte V. asiatica. That is, V. asiatica could inhibit the growth of Microcystis spp. effectively and was benefited to the diatom on the condition in the laboratory.. |
| 39. | Yuxian LIU, Aimin HAO, Yasushi ISERI, Takahiro KUBA, Chunjie LI, Zhenjia ZHANG, The Evaluation of Sinanodonta woodiana Application Feasibility as a Microcystis-Blooming Removal Tool in Microcosm Experiments, 土木学会論文集G (環境) (環境工学研究論文集 第50巻), 69, 7, III_45-III_53, 2013.11, The bivalve is widely distributed throughout Chinese freshwaters and is an important economic pearl mollusk. Recently, Sinanodonta woodiana as a tool in biomanipulation of lakes in China due to its strong suppression of phytoplankton, has been attracted increasingly more attention. In order to evaluate the application feasibility of Sinanodonta woodiana as a Microcystis-blooming removal tool, microcosm experiments were performed with naturally blooming pond water and the bivalves in laboratory for 6 days. In this experiment, phytoplankton abundances and community structure were analyzed on 0-day and 6-day for both control and treatment microcosms; also, filtration rate, absorption efficiency, oxygen consumption rate and ammonia excretion rate of S. woodiana were measured on the 0-day and 6-day and finally the scope for growth (SFG) value as a measure of metabolic energy balance for S. woodiana was calculated and compared. The results showed that Microcystis spp. of colony and unicell were reduced obviously on the 6-day; meanwhile, after six days’ exposure to Microcystis-blooming pond water, the SFG value as a measure of metabolic energy balance for S. woodiana increased. This phenomenon indicates that Microcystis spp. in natural eutrophic water can be removed greatly by S. woodiana; moreover, the bivalves themselves have strong adaptation ability when they were exposed to natural eutrophic water and could grow well after 6 days’ exposure to this eutrophic water. Therefore, it can be inferred that there is high application feasibility of S. woodiana as a Microcystis-blooming controller in practice.. |
| 40. | Yuxian LIU, Aimin HAO, Yasushi ISERI, Chunjie LI, Zhenjia ZHANG, Takahiro KUBA, Application Feasibility of Anodonta woodiana as a Biomanipulation Tool in Lake Taihu, Proc. of The 7th International Symposium on the East Asian Environmental Problems, 58-67, 2013.11. |
| 41. | Caixic KANG, Aimin HAO, Yasushi ISERI, Chunjie LI, Zhenjia ZHANG, Takahiro KUBA, Restoration Conditions of Submerged Macrophyte Vallisneria asiatica in Eutrophic Lake Taihu, China, Proc. of The 7th International Symposium on the East Asian Environmental Problems, 68-73, 2013.11. |
| 42. | Ming Yang Zhang, Ai Min Hao, Takahiro Kuba, The crystallization of struvite by recycling poly-phosphate released from sewage sludge after thermal treatment, 3rd International Conference on Chemical Engineering and Advanced Materials, CEAM 2013 Advances in Chemical Engineering III, 10.4028/www.scientific.net/AMR.781-784.1963, 1963-1967, 2013.10, Because of the shortage crisis of phosphorus element and environmental problems caused by excess discharge of phosphorus compounds into nature water bodies, phosphorus recovery had been research hotspot. Poly-phosphate (poly-P) released from sewage sludge after thermal treatment could be recovered successfully as magnesium ammonium phosphate hexahydrate (MgNH4PO4·6H2O) commonly known as struvite in present study. This phenomenon was the first time to be found in phosphorus recovery from sewage sludge. The parameters affected struvite formation with poly-P had been tested. Poly-P indicated better characteristics in phosphorus recovery compared with ortho-phosphate (Pi) because it can be precipitated at lower pH condition even neutral condition, with less addition of magnesium element.. |
| 43. | DISTRIBUTION CHARACTERISTICS OF WATER QUALITY AND AQUATIC VEGETATION IN A EUTROPHIC SHALLOW LAKE: TAIHU, CHINA In order to find practical strategy for controlling eutrophication in Lake Taihu, in this study, water quality and biota were investigated in East Lake Taihu, Meiliang Bay and West Lakeshore. Compared with the lower nutrients concentrations in East Lake Taihu, the values of Chl.a, turbidity, T-N and T-P showed significant fluctuations with eutrophication level in different places of Meiliang Bay and West Lakeshore. There was significant positive correlation among each value of Chl.a, T-N and T-P in Meiliang Bay, which indicated that the occurrence of water bloom was related to the concentration of nutrient. According to the result of identification, there were totally twelve species of aquatic macrophytes in the investigated area, of which two species were found in Meiliang Bay, one species was found in the southwest coastal zone, and twelve species were found in East Lake Taihu including six species as dominant submerged plants. There were ten species of Cyanophyta during the water bloom in East Lake Taihu and Meiliang Bay, of which Microcystis aeruginosa was found with large quantities of biomass as dominant species. Apart from the Cyannophyta, 21 species of diatom and 20 species of Chlorophyta were identified in East Lake Taihu and Meiliang Bay, of which 41 species were spread in East Lake Taihu. The relatively richer phytoplankton indicated the higher biodiversity conditions in East Lake Taihu.. |
| 44. | Mingyang Zhang, Takahiro KUBA, Aimin HAO, The Crystallization of Struvite by Recycling Poly-Phosphate Released from Sewage Sludge after Thermal Treatment, Advanced Materials Research, 10.4028, 781-784, 1963-1967, 2013.07, Because of the shortage crisis of phosphorus element and environmental problems caused by excess discharge of phosphorus compounds into nature water bodies, phosphorus recovery had been research hotspot. Poly-phosphate (poly-P) released from sewage sludge after thermal treatment could be recovered successfully as magnesium ammonium phosphate hexahydrate (MgNH4PO4•6H2O) commonly known as struvite in present study. This phenomenon was the first time to be found in phosphorus recovery from sewage sludge. The parameters affected struvite formation with poly-P had been tested. Poly-P indicated better characteristics in phosphorus recovery compared with ortho-phosphate (Pi) because it can be precipitated at lower pH condition even neutral condition, with less addition of magnesium element.. |
| 45. | Hiroshi SAKAI, Aimin HAO, Yasushi ISERI, Song WANG, Takahiro KUBA, Zhenjia ZHANG, Hiroyuki KATAYAMA, Occurrence and Distribution of Microcystins in Lake Taihu, China, The Scientific World Journal, Article ID 838176, 2013, 2013.06. |
| 46. | MingYang ZHANG, HAO AIMIN, Takahiro KUBA, Extraction of Poly-Phosphate from the Activated Sludge with Thermal Treatment for Phosphorus Recovery, Advanced materials research, Vols.610-613, pp.2268-2274, 2013.01, Fast consumption of high quality phosphorus mines and uneven distribution in the world result in the shortage crisis for phosphorus, meanwhile lots of phosphate compounds which are discharged into nature water bodies by human beings have already induced many environmental problems. Because of this situation, phosphorus recovery from sewage sludge working in the aeration tank of wastewater treatment plant (WWTP) has been researched in the present study. Poly-phosphate (poly-P) and total phosphate (T-P) accumulated inside activated sludge could be released by thermal treatment at low temperature, 30% poly-P and 29% T-P could be released from sludge by heating at 70˚C. Different kinds of pretreatments had been tested to improve phosphorus release from activated sludge in thermal treatment; addition of chelating reagent at final concentration of 2 mM before thermal treatment could improve the phosphorus release obviously, 68% poly-P and 53% T-P could be released into liquid phase. Approximately 85% T-P could be precipitated with calcium at pH 11; it was interesting to find precipitation occurred in neutral condition without pH adjustment.. |
| 47. | Ming yang Zhang, Ai min Hao, Takahiro Kuba, Extraction of poly-phosphate from the activated sludge with thermal treatment for phosphorus recovery, 2nd International Conference on Energy, Environment and Sustainable Development, EESD 2012 Progress in Environmental Science and Engineering, 10.4028/www.scientific.net/AMR.610-613.2268, 2268-2274, 2013.01, Fast consumption of high quality phosphorus mines and uneven distribution in the world result in the shortage crisis for phosphorus, meanwhile lots of phosphate compounds which are discharged into nature water bodies by human beings have already induced many environmental problems. Because of this situation, phosphorus recovery from sewage sludge working in the aeration tank of wastewater treatment plant (WWTP) has been researched in the present study. Poly-phosphate (poly-P) and total phosphate (T-P) accumulated inside activated sludge could be released by thermal treatment at low temperature, 30% poly-P and 29% T-P could be released from sludge by heating at 70 °C. Different kinds of pretreatments had been tested to improve phosphorus release from activated sludge in thermal treatment; addition of chelating reagent at final concentration of 2 mM before thermal treatment could improve the phosphorus release obviously, 68% poly-P and 53% T-P could be released into liquid phase. Approximately 85% T-P could be precipitated with calcium at pH 11; it was interesting to find precipitation occurred in neutral condition without pH adjustment.. |
| 48. | Hiroshi Sakai, Aimin Hao, Yasushi Iseri, Song Wang, Takahiro Kuba, Zhenjia Zhang, Hiroyuki Katayama, Occurrence and distribution of microcystins in Lake Taihu, China, The Scientific World Journal, 10.1155/2013/838176, 2013, 2013, The occurrence and distribution of microcystins were investigated in Lake Taihu, the third largest lake in China. An extensive survey, larger and broader in scale than previous studies, was conducted in summer 2010. The highest microcystin concentration was found at southern part of Taihu, which was newly included in this survey. In northern coastal areas, total cellular concentrations of 20 to 44 g/L were observed. In northern offshore waters, levels were up to 4.8 g/L. Microcystin occurrence was highly correlated with chemical oxygen demand, turbidity, and chlorophyll-a. Extracellular/total cellular microcystin (E/T) ratios were calculated and compared to other water quality parameters. A higher correlation was found using E/T ratios than original microcystin values. These results show that algal blooms are having a severe impact on Lake Taihu, and further and extensive monitoring and research are required to suppress blooms effectively.. |
| 49. | Yuxian Liu, Aimin Hao, Yasushi Iseri, Chunjie Li, Zhenjia Zhang, Takahiro Kuba, THE EVALUATION OF SINANODONTA WOODIANA APPLICATION FEASIBILITY AS A MICROCYSTIS-BLOOMING REMOVAL TOOL IN MICROCOSM EXPERIMENTS, 土木学会論文集G（環境）, 10.2208/jscejer.69.III_45, 69, 7, III_45-III_53, 2013, Sinanodonta woodiana is widely distributed throughout Chinese freshwaters and is an important economic pearl mollusk. In order to evaluate the application feasibility of S. woodiana as a Microcystis-blooming removal tool, a series of microcosm experiments were performed. First the 6-day feeding responses experiment was carried out with naturally blooming pond water and the bivalves in laboratory, which was lasted for 6 days. In this experiment, phytoplankton abundances and community structure were analyzed on 0-day and 6-day for both control and treatment microcosms; also, filtration rate, absorption efficiency, oxygen consumption rate and ammonia excretion rate of S. woodiana were measured on 0-day and 6-day and finally the scope for growth (SFG) value as a measure of metabolic energy balance for S. woodiana was calculated and compared. The results showed that Microcystis spp. of colony and unicell were reduced obviously on the 6-day; meanwhile, after six day's exposure to Microcystis-blooming pond water, the SFG value for S. woodiana increased. Furthermore, in the extended long-term grazing experiment, bivalves were fed with highly concentrated toxic Microcystis-blooming water and non-toxic Chlorella at the constant concentration (Chl.a=424.5 mg/m3) in two respective tanks for 12 days. No bivalve mortality was registered on both Chlorella group and blooming water group. In addition, SFGs were significantly higher for the blooming water group, compared with them for Chlorella group on 3-day, 6-day and 12-day. These results indicated that toxic Microcystis spp. in natural eutrophic water can be removed greatly by S. woodiana; moreover, the bivalves themselves have strong adaptation ability when they were exposed to toxic natural eutrophic water. Therefore, it can be inferred that there is high application feasibility of S. woodiana as a Microcystis-blooming controller in practice.. |
| 50. | DISTRIBUTION CHARACTERISTICS OF WATER QUALITY AND AQUATIC VEGETATION IN A EUTROPHIC SHALLOW LAKE. |
| 51. | ChumJie LI, ZhenJia ZHANG, HAO AIMIN, Yasushi ISERI, CaiXia KANG, Takahiro KUBA, In situ Remediation of Contaminated Water of Crab Culture by Ecological Dam in Yang Cheng Lake, Proc. of EAEP2012 (The 6th International Symposium on the East Asian Environmental Problems), pp.90-94, 2012.11, Yang Cheng Lake, which is famous with the crab culture, now faces the deterioration of water quality. Ecological dam is designed for in situ remediation of contaminated water of crab culture. The device of ecological dam consists of ecological floating bed with the dimension of 2m long and 1m wide, and immobilized biological media with about 1.8m long which is fixed on the floating bed with one side and immersed in the lake water with another side. In this study, two in situ demonstration areas with dimension of 20m long and 10m wide are constructed in the crab culture farms to investigate the change of water quality. Each area is surrounded by seine to avoid crabs climbing into. In one demonstration area, 36 devices of ecological dam are connected and laid in surrounding, which are planted with water spinaches. The other demonstration area is established in contrast, in which there is no device of eco-dam. It is concluded that during three months’ operation, ecological dam shows a significant effect on the turbidity improvement. However nutrient removal in eco-dam area is not improved, especially for TN. On the contrary, TN shows an obvious increment because of the release of organic nitrogen from the sediment under the condition of weak water exchange. It needs a long time to observe the remediation effect of ecological dam on the contaminated crab culture water.. |
| 52. | YuXian LIU, HAO AIMIN, Yasushi ISERI, ChumJie LI, ZhenJia ZHANG, Takahiro KUBA, Improvement of Water Quality in Lake Taihu with Aquatic Plants and the Relationship between Cyanobacteria Bloom and Aquatic Plants, Proc. of EAEP2012 (The 6th International Symposium on the East Asian Environmental Problems), pp.96-101, 2012.11, The bivalve Sinanodonta woodiana is widely distributed throughout Chinese freshwaters and is an important economic pearl mollusk. Recently, S. woodiana as a tool in biomanipulation of lakes in China due to its strong suppression of phytoplankton, have been attracted increasingly more attention. In order to evaluate the impact of Microcystis-blooming pond water on the physiological behavior in a bioenergetic method, microcosm experiments were performed with natural eutrophic pond water and bivalves in laboratory for six days. In this experiment, filtration rate, absorption efficiency, oxygen consumption rate and ammonia excretion rate of S. woodiana were measured on the 0-day and 6-day, also the percentage changes of phytoplankton with different size scale were measured every two days for both control and treatment microcosms. The results indicated that after 6 days exposure to Microcystis-blooming pond water, the SFG (scope for growth) value as a measure of metabolic energy balance for S. woodiana increased and microplankton (>20 µm, including colony-forming Microcystis spp.) percentage was reduced obviously on the 6-day. This phenomenon indicates the percentage of phytoplankton with different size scale was obviously changed by the bivalves and meanwhile the bivalves themselves could grow well after six days’ exposure to this eutrophic water. Therefore, it can be concluded that S. woodiana can be used as an effective biomanipulation tool in eutrophic water.. |
| 53. | CaiXia KANG, HAO AIMIN, Yasushi ISERI, ChumJie LI, ZhenJia ZHANG, Takahiro KUBA, Improvement of Water Quality in Lake Taihu with Aquatic Plants and the Relationship between Cyanobacteria Bloom and Aquatic Plants, Proc. of EAEP2012 (The 6th International Symposium on the East Asian Environmental Problems), pp.102-107, 2012.11, Serious eutrophication is appearing in the Lake Taihu which is the third largest freshwater lake in China. Therefore, the water quality in Lake Taihu should be improved immediately. To improve water quality of the lake and control algae bloom, the effect of Vallisneria asiatica which is one of the macrophytes spread over Lake Taihu, with different biomass on water quality and algae was researched. The results showed that in the laboratory experiments, DTN, DTP, and turbidity decreased and the biomass of Microcystis sp. reduced with the increase of biomass of Vallisneria asiatica. Therefore, it was expected that Vallisneria asiatica could control an excess of Microcystis sp. in Lake Taihu. Furthermore, we discovered that during experimental period, lots of diatom (Nitzschia sp.) appeared in the Microcystis sp. community resulting in settling down of algae in case of small quantity of Vallisneria asiatica by microscopy. This may be one of the important reasons which resulted in the sharp decrease of the biomass of Microcystis sp. At the same time, epiphytic Cocconeis sp. appeared while Nitzschia sp. lessened in the tanks with large quantity of Vallisneria asiatica, which indicated that there was competition between epiphytic Cocconeis sp. and Nitzschia sp.. |
| 54. | Influence of Copper Ion on Antioxidant Function of Vallisneria asiatica. |
| 55. | Effects of copper ion on antioxidant function of Vallisneria asiatica. |
| 56. | Yuxian Liu, Aimin Hao, Yasushi Iseri, Shunsuke Kurokawa, Zhenjia Zhang and Takahiro Kuba, PRELIMINARY STUDY ON ECOLOGICAL ENGINEERING METHODS OF WATER QUALITY IMPROVEMENT IN THE LAKE TAIHU, Proc. of EAEP2011 (The 5th International Symposium on the East Asian Environmental Problems), pp.101-106, 2011.11, The results of in situ surveys conducted in our study indicated that eutrophication characterized with cyanobacteria water-bloom coupled with significantly high TP and TN value, is still serious, especially in the Meiliang Bay. Although water quality in the East Lake Taihu is comparatively better, the pen culture of the Chinese mitten crab (Eriocheir sinensis) which covers a large part of the lake surface, results in an increase of the organics and nutrients loading. Aimed to solve the mentioned problems, the laboratory experiments were performed with the macrophyte Vallisneria asiatica and the local economic pearl bivalve species Anodonta woodiana, separately. The results showed that Vallisneria asiatica can absorb the nutrients such as N and P effectively, meanwhile this kind of macrophyte is also the crab’s main food. Furthermore, the bivalve Anodonta woodiana showed an effective role in the water quality improvement through its feeding behavior. As a result, the ecological engineering methods were proposed, using the macrophyte Vallisneria asiatica and the pearl bivalve species Anodonta woodiana inside the Lake Taihu, which can not only bring significant economic value to the local residents but also improve water quality.. |
| 57. | Mingyang Zhang, Aimin Hao and Takahiro Kuba, THE EFFECT OF CHELATING REAGENTS ON THE RELEASE OF PHOSPHORUS FROM SEWAGE SLUDGE DURING HEATING PROCESS, Proc. of EAEP2011 (The 5th International Symposium on the East Asian Environmental Problems), pp.95-100, 2011.11, Activated sludge working in the aeration tank can accumulate large phosphorus mainly as poly-phosphate (poly-P) inside bodies. They can release the phosphorus into liquid phase easily during the heating process at 70˚C for 80 minutes. With the addition of chelating reagents, the performance of phosphorus release from sewage sludge can be improved obviously. Through the comparison, citrate can make the best improvement on the phosphorus release from sewage sludge during heating process in four kinds of chelating reagents. Many kinds of mineral elements such as Mg2+, Fe2+, Al3+ and Ca2+ can be released into liquid phase accompany the phosphorus release during heating process with the addition of chelating reagent. Thus the existence of mineral elements possibly prevents phosphorus release from sewage sludge during heating process.. |
| 58. | Chunjie LI, Hongmei LIU, Zhenjia Zhang, Yasushi ISERI, Takahiro KUBA, Aimin HAO, Phosphorus Removal Ability Intensified by Calcium Silicate Hydrates (CSH) in Ecological Technologies, Proc. of EAEP2011 (The 5th International Symposium on the East Asian Environmental Problems), pp.113-117, 2011.11. |
| 59. | Yuxian LIU, Yaping YE, Takahiro KUBA, Aimin HAO, Multiple Criteria Assessment of Ecosystem Services Sustained by Qinhuai River in Nanjing, Proc. of International Conference on Water Resources Management and Engineering (ICWRME 2011),, pp.158-163, 2011.08. |
| 60. | Z. H. Li, X. C. Wang, T. Kuba, T. Kusuda, Porous structure and spatial characteristics of aerobic granules, International Journal of Environment and Pollution, 10.1504/IJEP.2011.039082, 45, 1-3, 25-35, 2011.03, Cryosectioned granules were observed in microstructure, Extracellur Polymeric Substances (EPS) and metal distribution. Aerobic granules composed of pores and channels that were not plugged by EPS, with rather open structure. Microorganisms proliferated mainly on the surface of granule and on the wall of channels, carbohydrate EPS mainly distributed on the surface of granules, and protein EPS mainly distributed in the interior part of granules. Also, aerobic granules accumulated considerable calcium and phosphorus, which increase the ash solid fraction of granules and thus improve the settleability. Additionally, iron was neither temporally accumulated nor heterogeneously spatially distributed.. |
| 61. | Aimin Hao, Takahiro Kuba, Yasushi Iseri, Zhenjia Zhang, Yuxian Liu, Tomokazu Haraguchi, Effects of copper ion on antioxidant function of Vallisneria asiatica, Ecology and Civil Engineering, 10.3825/ece.14.115, 14, 2, 115-122, 2011.01, The objective of this research is to demonstrate the antioxidant ecological response of Vallisneria asiatica to the heavy metal Cu2+ pollution which is recently a serious problem in the lakes. Batch experiments with five different concentrations of Cu2+ (0, 5, 10, 20, 40, 80 mg·L-1) were carried out. After the 12th day, the roots and leaves of Vallisneria asiatica dipped in the solution with Cu2+ were removed and the physiological and biochemical indexes, chlorophyll, protein and malondialdehyde (MDA) content, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activity were measured. After the experiment; the roots and leaves cultivated in the 0 mg·L-1 of Cu2+ group showed chlorophyll and protein content reduced while the MDA content, POD and SOD activity were increased notoriously. Compared with the 0 mg·L -1 of Cu2+ group, the 5 mg·L-1 of Cu2+ group showed chlorophyll and protein content increase, SOD and POD activity showed also a slight increase, while MDA content decreased. However, for the 10 mg·L-1 of Cu2+ group, the decrease of chlorophyll and protein content and the increase of MDA content were observed. Also a sharp increase of SOD and CAT activity compared with the 5 mg·L-1 group were found; for over 10 mg·L-1 of Cu2+ concentration, chlorophyll content and protein content fell off, whereas increase of MDA became considerable, CAT raised up steadily and POD showed a decrease trend. The results showed that, both insufficiency and overabundance of Cu2+ in water environment can affect the anti-oxidation function of Vallisneria asiatica, which can be observed by the value of SOD, CAT and POD activity. Therefore, the measurement of anti-oxidation activity, protein content and MDA as a forecast and judgment indicator of Cu2+ contaminations in the water environment can be considered in the future.. |
| 62. | YuXian LIU, Takahiro KUBA, Aimin HAO, Yasushi ISERI, ZhenJia ZHANG, Biomanipulation method for aquatic environment conservation in the in Lake Taihu, The 2nd International Symposium on Aquatic Environment and Biodiversity Conservation in the Lake Taihu Basin, Proc. of the 4nd International Symposium on Aquatic Environment and Biodiversity Conservation in the Lake Taihu Basin, 2010.11. |
| 63. | ZhenJia ZHANG, Takahiro KUBA, Yasushi ISERI, Aimin HAO, Introduction of reduction technology with wastewater pollution from electroplating enterprise in the basin of Lake Taihu, The 2nd International Symposium on Aquatic Environment and Biodiversity Conservation in the Lake Taihu Basin, Proc. of the 4nd International Symposium on Aquatic Environment and Biodiversity Conservation in the Lake Taihu Basin, 2010.11. |
| 64. | Aimin HAO, Yasushi ISERI, YuXian LIU, MingYang ZHANG, ZhenJia ZHANG, Takahiro KUBA, Effect of Water Environment on Biota in Lake Taihu, The 2nd International Symposium on Aquatic Environment and Biodiversity Conservation in the Lake Taihu Basin, Proc. of the 4nd International Symposium on Aquatic Environment and Biodiversity Conservation in the Lake Taihu Basin, 2010.11. |
| 65. | Ming-Yang ZHANG, Takahiro KUBA, Aimin HAO, Yu-Xian LIU, Phosphorus Recovery from Sewage Sludge with Heating Method, The 4th International Symposium on the East Asia Environmental Problems (EAEP2010), Proc. of the 4th International Symposium on the East Asia Environmental Problems (EAEP2010), pp.9-14, September 2010, 2010.10. |
| 66. | Yu-Xian LIU, Y. YE, Takahiro KUBA, Aimin HAO, Economic Valuation of Ecosystem Service sustained by Qinhuai River in Nanjing, The 4th International Symposium on the East Asia Environmental Problems (EAEP2010), Proc. of the 4th International Symposium on the East Asia Environmental Problems (EAEP2010), pp.167-171, September 2010, 2010.10. |
| 67. | Yasushi ISERI, Takahiro KUBA, Aimin HAO, Yu-Xian LIU, Ming-Yang ZHANG, Zhen-Jia ZHANG, Control of Freshwater Cyanobacterial Bloom using Eco-Engineering Methods, The 4th International Symposium on the East Asian Environmental Problems (EAEP2010), Proc. of the 4th International Symposium on the East Asia Environmental Problems (EAEP2010), pp.179-184, September 2010, 2010.10. |
| 68. | Aimin HAO, Yasushi ISERI, Yu-Xian LIU, Ming-Yang ZHANG, Zhen-Jia ZHANG, Takahiro KUBA, Interaction of Biota and Water Environment in Lake Taihu, The 4th International Symposium on the East Asian Environmental Problems (EAEP2010), Proc. of the 4th International Symposium on the East Asia Environmental Problems (EAEP2010), pp.173-178, September 2010, 2010.10. |
| 69. | Takahiro KUBA, Masayuki BANNO, Kousuke SANO, Naoya KAWAMURA, Shumpei ICHIKAWA and Yusuke SAKAI, Bamboo Charcoal as an Adsorbent for the Removal of Non-Point Pollutants, The 3rd International Symposium on the East Asian Environmental Problems (EAEP2009), 2009.12. |
| 70. | Capacity and Mechanism of Nitrate Anion Adsorption onto Bamboo Charcoal. |
| 71. | Zhi-Hua Li, Takahiro Kuba, Tetsuya Kusuda, Xiao-Chang Wang, Effect of extended feeding time on aerobic granulation in SBR, Technology and Sustainable Development, 6, 2/3/4, 104-114, 2009.06. |
| 72. | Zhi-Hua LI, KUBA Takahiro, Tetsuya KUSUDA, Xiao-Chang WANG, Effect of Extended Feeding Time on Aerobic Granulation in SBR, World Review of Science, Technology and Sustainable Development, 6, 2/3/4, 104 - 114, 2009.06. |
| 73. | Zhi Hua Li, Takahiro Kuba, Tetsuya Kusuda, Xiao Chang Wang, Effect of extended feeding time on aerobic granulation in SBR, World Review of Science, Technology and Sustainable Development, 10.1504/WRSTSD.2009.031833, 6, 2-4, 104-114, 2009, Two different feeding lengths were applied to control the granule size. It was found that the size of granules was considerably controlled in R2 (60 min for feeding). However, the settleability in R2 was not as good as that in R1 (12 min for feeding). However, this approach of controlling the granule size also loosens the structure concerning on the difference between SVI5 and SVI30, which might lead to instability in the long term. Based on the observation of the ash-solids fraction of biomass, it was confirmed that frequent update of granules mainly happened on the surface of granules.. |
| 74. | V. Torrico, T. Kuba, T. Kusuda, Optimization of Internal Bypass Ratio for Complete Ammonium and Phosphorus Removal in a Dephanox-type Two-Sludge Denitrification System, Journal of Environmental Engineering, ASCE, Vol.134, No.7, pp.536-542, 2008.07. |
| 75. | Vladimir Torrico, Takahiro Kuba, Tetsuya Kusuda, Optimization of internal bypass ratio for complete ammonium and phosphate removal in a dephanox-type two-sludge denitrification system, Journal of Environmental Engineering, 10.1061/(ASCE)0733-9372(2008)134:7(536), 134, 7, 536-542, 2008.06, The capacity of complete simultaneous ammonium and phosphate removal was studied in a laboratory scale Dephanox system in relation to its internal bypass ratio (BPR). In this configuration, most of the ammonium detected in the effluent is ammonium bypassed by the system's internal settler. Therefore, this research studies the possibility of complete simultaneous ammonium and phosphate removal by means of the balance of bypassed ammonium with ammonium requirement for growth of denitrifying phosphorus accumulating organisms in the anoxic tank. During these experiments, ammonium removal was governed by internal BPR and limited by sludge settleability. The predominant anaerobic-anoxic sludge developed a high settleability, allowing the application of drastic low BPRs. The system studied under many BPRs proved to achieve almost complete simultaneous ammonium and phosphate removal for BPRs ranging from 0.08 to 0.13 of the influent. A BPR lower than the inferior limit produced extreme accumulation of sludge into the internal settler, interfering in the distribution of sludge and consequently in removal efficiency. A positive effect of the internal settler was the extension of anaerobic contact time and anaerobic solids retention time. The increased phosphorus release suggests that a higher volatile fatty acids production might have occurred when raw wastewater was used as influent.. |
| 76. | Zhi-Hua LI, KUBA Takahiro, Tetsuya KUSUDA, Xiao-Chang WANG, A Comparative Study on Aerobic Granular Sludge and Effluent Suspended Solids in a Sequence Batch Reactor, Environmental Engineering Science, Vol.134, No.7, pp.577-584, 2008.05. |
| 77. | Z. H. Li, T. Kuba, T. Kusuda, X. C. Wang, A comparative study on aerobic granular sludge and effluent suspended solids in a sequence batch reactor, Environmental Engineering Science, 10.1089/ees.2007.0091, 25, 4, 577-584, 2008.05, Having outstanding settleability, aerobic granular sludge receives increasing attention for wastewater treatment. Washing out undesired sludge (frequently in the form of flocs) is an essential operation condition for developing granules, and thus a high solids concentration is in effluent. However, the properties of effluent solids have not been fully understood. To study the properties of effluent solids could better understand granulation and provide basic information for the followed polish unit design to remove these solids. Results in this study shows that sizes of effluent solids increased with the increase of granule size. The effluent solids exhibited higher EPS (extracellular polymer substances) concentrations but lower fraction of carbohydrate content, and higher fraction of ash solids. The properties of effluent suspended solids and deteriorated granules changed in a similar fashion, suggesting that the effluent solids resulted mainly from the deteriorated granules. It was also found that ash solids buildup was a result of compact structure, which in turn, improved the stability of granules by increasing the settleability.. |
| 78. | Education and Learning Improvement by Introduction of an Evaluation System to Graduation Research. |
| 79. | Education and Learning Improvement by Introduction of an Evaluation System to Graduation Research Work. |
| 80. | Z.H. Li, T. Kuba, T. Kusuda, Effect of Rotifers on the Stability of Aerobic Granules, Environmental Technology, Vol.28, No.2, pp.235-242, 2007.02. |
| 81. | Z. H. Li, T. Kuba, T. Kusuda, X. C. Wang, Effect of rotifers on the stability of aerobic granules, Environmental Technology, 10.1080/09593332808618772, 28, 2, 235-242, 2007.02, The current study evaluated the effect of rotifers on the stability of aerobic granules. Two sequence batch reactors (SBRs) with airflow rates of 4 (R1) and 6 (R2) l min-1, respectively, were used to develop aerobic granules. Granules were well developed with excellent settleability in terms of SVI30 (sludge volume index,) of about 50 ml g-1 in both reactors at the beginning. With the outgrowth of rotifers, granules completely disintegrated in R1 around cycle 500 (a cycle was 3 hours). However, after the rotifers disappeared, i.e. cycle 550, granules re-appeared with a slow settling rate in R1 (SVI30 : 200-300 ml g-1). The rotifers mechanically damaged the structure of granules, resulting in disintegration. However, granules developed under high shear force seem to have strong resistance to rotffers. During re-granulation, a long time lag between the improvements of morphology and settleability suggested that re-granulation resulted from entanglement more than bio-attachment or bio-growth. Additionally, it was confirmed that the ratio of carbohydrate to protein extracellular polymeric substances (EPS) could well indicate the strength of granules. Protein EPS well correlated with the difference between SVI5 and SVI30 in R1, therefore, decreasing protein EPS would increase the compactness of granules.. |
| 82. | V. Torrico, T. Kuba, Effect of Anaerobic SRT on Complete Phosphate Removal in a Post-denitrification System, 環境工学研究論文集, Vol.43、pp.327-332, 2006.11. |
| 83. | Z.H. Li, T. Kuba, T. Kusuda, Aerobic Granular Sludge: A Promising Technology for Decentralized Wastewater Treatment, Future of Urban Wastewater Systems -Decentralisation and Reuse-, Xiaochan C. Wang, Rong Chen (editors), Proceedings of the International Water Association (IWA) Conference 2005, Xi'an. pp.269-275. Xi'an International Center, Xi'an, China, 18-20 May, 2005.5, Proceedings of the International Water Association (IWA) Conference 2005, Xi'an. pp.269-275 Water Science & Technology, Vol.53 (9), pp.79-85, 2006.09. |
| 84. | K. Hamada, T. Kuba, V. Torrico, M. Okazaki, T. Kusuda, Comparison of Nutrient Removal Efficiency between Pre- and Post-denitrification Wastewater Treatment, Future of Urban Wastewater Systems -Decentralisation and Reuse-, Xiaochan C. Wang, Rong Chen (editors), Proceedings of the International Water Association (IWA) Conference 2005, Xi'an. pp.269-275. Xi'an International Center, Xi'an, China, 18-20 May, 2005.5, Proceedings of the International Water Association (IWA) Conference 2005, Xi'an. pp.269-275 Water Science & Technology, Vol.53 (9), pp.169-175, 2006.09. |
| 85. | Z. H. Li, Takahiro Kuba, T. Kusuda, Selective force and mature phase affect the stability of aerobic granule An experimental study by applying different removal methods of sludge, Enzyme and Microbial Technology, 10.1016/j.enzmictec.2006.01.030, 39, 5, 976-981, 2006.09, To evaluate the effect of sludge removal methods on the stability of aerobic granules, three different removal methods of sludge were investigated in sequencing batch reactors (SBR). Results demonstrated that (i) in R1, removing fresh granules effectively maintained granules with sizes of 1-2 mm and SVI of 31-45 ml g-1 for more than 432 cycles (one cycle length was 3 h); (ii) in R3, removing aged granules led to disintegration of granules; (iii) in R2, removing completely mixed sludge resulted in granules with good settleability. However, the morphology of granules in R2 was similar to that of granules in R3 with sizes of about 4-5 mm. It was also found that removing fresh granules built up more ash solids in granules than removing aged granules did and removing aged granules significantly led to lysed granules with void shells. Results suggest that removing fresh granules is an effective approach of selective force for aerobic granulation, and the mature phase plays an important role on the stability of granules by rearranging granule structure (e.g. the buildup of ash solids).. |
| 86. | V. Torrico, T. Kuba, T. Kusuda, Effect of Particulate Biodegradable COD in a Post-denitrification Enhanced Biological Phosphorus Removal System, Journal of Environmental Science and Health, Part A Toxic/Hazardous Substance & Environmental Engineering, Vol.A41 (8), pp.1715-1728, 2006.08. |
| 87. | Vladimir Torrico, Takahiro Kuba, Tetsuya Kusuda, Effect of particulate biodegradable COD in a post-denitrification enhanced biological phosphorus removal system, Journal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering, 10.1080/10934520600754771, 41, 8, 1715-1728, 2006.08, This research studied the effects of the particulate biodegradable fraction (X S ) of chemical oxygen demand (COD) in a post-denitrification configuration. Denitrifying polyphosphate-accumulating organisms (DN-PAOs) and nitrifiers were completely separated in a system also known as Dephanox. It was composed by an anaerobic-anoxic (A 2 ) process coupled with a parallel Nitrification biofilm tank. The results of a long-term operation of the Dephanox continuous-flow lab-scale system as well as results of sludge characterization assays showed that raw wastewater feeding promoted complete phosphorus (P) removal by double via (i) providing complementary volatile fatty acids (VFAs) for a complete P removal by prefermentation of the X S fraction of COD under a long anaerobic SRT, and (ii) assisting the metabolic accumulation and selection of DN-PAOs. Complete P removal was accomplished only when the system was fed with raw wastewater (high X S concentration). When primary effluent was used as influent, lack of VFAs in the anaerobic stage led to an incomplete and instable P removal, suggesting that the use of primary treatment is not only unnecessary but detrimental for simultaneous nutrient removal in a post-denitrification configuration.. |
| 88. | Education and Learning Improvement by Introduction of an Evaluation System to Graduation Research. |
| 89. | Z. H. Li, T. Kuba, T. Kusuda, Aerobic granular sludge A promising technology for decentralised wastewater treatment, Water Science and Technology, 10.2166/wst.2006.278, 53, 9, 79-85, 2006.07, In order to evaluate the characteristics of aerobic granular sludge, a sequencing batch reactor, feeding with synthetic wastewater at the organic loading rate of 8 kg COD/m3 d, was employed on the laboratory scale. Granules occurred in the reactor within 1 week after the inoculation from conventional flocculent sludge. Aerobic granular sludge was characterised by the outstanding settling properties and considerable contaminates removal efficiencies. The SVI30 values were in the range of 20 to 40 ml g-1. However, the sludge volume index of short settling time (e.g. SVI10 - 10 min) is suggested to describe the fast settling properties of aerobic granular sludge. The potential application in the decentralised system is evaluated from the point view of footprint and high bioactivity. The occurrence of sloughing, resulting from the outgrowth of filamentous organisms, would be responsible for the instability of aerobic granules. The starvation phase should therefore be carefully controlled for the maintenance and stability of aerobic granular sludge system.. |
| 90. | K. Hamada, T. Kuba, V. Torrico, M. Okazaki, T. Kusuda, Comparison of nutrient removal efficiency between pre- and post-denitrification wastewater treatments, Water Science and Technology, 10.2166/wst.2006.272, 53, 9, 169-175, 2006.07, A shortage of organic substances (COD) may cause problems for biological nutrient removal, that is, lower influent COD concentration leads to lower nutrient removal rates. Biological phosphorus removal and denitrification are reactions in which COD is indispensable. As for biological simultaneous nitrogen and phosphorus removal systems, a competition problem of COD utilisation between polyphosphate accumulating organisms (PAOs) and non-polyphosphate-accumulating denitrifiers is not avoided. From the viewpoint of effective utilisation of limited influent COD, denitrifying phosphorus-removing organisms (DN-PAOs) can be effective. In this study, DN-PAOs activities in modified UCT (pre-denitrification process) and DEPHANOX (post-denitrification ptocess) wastewater treatments were compared. In conclusion, the post-denitrification systems can use influent COD more effectively and have higher nutrient removal efficiencies than the conventional pre-denitrification systems.. |
| 91. | Z.H. Li, T. Kuba, T. Kusuda, The Influence of Starvation Phase on the Properties and the Development of Aerobic Granules, Enzyme and Microbial Technology, Vol.38(5), pp.670-674, 2006.05. |
| 92. | Z.H. Li, T. Kuba, T. Kusuda, Selective Force and Mature Phase Affect the Stability of Aerobic Granule: An Experimental Study by Applying Different Removal Methods of Sludge, Enzyme and Microbial Technology, Vol.39, pp.976, 2006.05. |
| 93. | Z. H. Li, Takahiro Kuba, T. Kusuda, The influence of starvation phase on the properties and the development of aerobic granules, Enzyme and Microbial Technology, 10.1016/j.enzmictec.2005.07.020, 38, 5, 670-674, 2006.03, The current study was to evaluate the influence of starvation phase on surface negative charge, relative hydrophobicity, extra-cellular polymer substances (EPS) and the formation mechanism of aerobic granules. Granules with encouraging settling properties occurred in the reactor about 7 days after the inoculation. The surface negative charge decreased from 0.203 to 0.023 meq g VSS-1 and the relative hydrophobicity increased from 28.8 to 60.3% during the granulation period. Concentrations of protein and carbohydrate decreased from 18.0 to 7.1 and 7.0 to 2.9 mg g VSS-1, respectively in the first period. And from day 13, those values were observed in the range of 5.8-8.6 and 2.9-5.6 mg g VSS-1, respectively. The EPS especially protein concentrations well correlated with surface charge and relatively hydrophobicity. It was concluded that a reasonable amount of EPS should be controlled to form and maintain aerobic granules. It was proposed that aerobic granulation was initiated by starvation phase and then enhanced by anaerobic metabolism.. |
| 94. | 7-216 Education and Learning Improvement by Introduction of an Evaluation System to Graduation Research. |
| 95. | Vladimir Torrico, Takahiro Kuba, EFFECT OF ANAEROBIC SRT ON COMPLETE PHOSPHATE REMOVAL IN A POST-DENITRIFICATION SYSTEM, ENVIRONMENTAL ENGINEERING RESEARCH, 10.11532/proes1992.43.327, 43, 327-332, 2006, A continuous flow post-denitrification (Dephanox type) lab-scale system fed with raw wastewater was operated in order to investigate the effect of the anaerobic solids retention time (anaerobic SRT) on phosphate removal. The presence of an internal settler just after the anaerobic tank enhanced the anaerobic SRT. Additional enhancement was provided by accumulation of solids into the internal settler under extreme operational conditions that seemed to be optimal for nutrients removal. Batch experiments with Dephanox sludge showed that the particulate COD fraction contributed with an additional 50% of phosphate release, thus an additional VFAs production can be inferred. In the case of the Dephanox sludge, the enhanced anaerobic SRT assisted effectively to achieve complete phosphate removal. As reference, the same batch experiments with AO and A2O sludge from a full scale plant fed with primary effluent were carried out. The results showed that particulate COD fraction did not contribute significantly on the VFAs production. The combination of long SRT and abundant particulate COD apparently promoted fermentative organisms and denitrifying phosphorus accumulating organisms (DN-PAOs) acting in a syntrophic association on phosphorus removal.. |
| 96. | Activities of Enhanced Biological Nutrient Removal by the UCT Process in Low-Temperature Terms. |
| 97. | ACTIVITIES OF ENHANCED BIOLOGICAL NUTRIENT REMOVAL BY THE UCT PROCESS IN LOW-TEMPERATURE TERMS. |
| 98. | T. Kuba, V. Torrico, K. Hamada, T. Kusuda, Recycling Technology of Water -Biological Sewage Treatment and Prevention of Eutrophication-, First International Workshop on Sustainable Habitat Systems -Concept and Technology-, December 10, 2004, ACROS Fukuoka Conference Hall, pp.63-68, 2004.12. |
| 99. | Lin-Jiang Yuan, T. Kusuda, T. Kuba, Promoting Nitrification by Using Functional Gel as Immobilizing Medium under Different Temperature Stimulation Patterns, Proc. of Strong N and Agro 2003. IWA specialty symposium on strong nitrogenous and agro-wastewater Conference, Souel. 2, 621-632. Journal of Environmental Science and Health, Part A., Vol.A39, No.7, pp.1787-1796,2004, 10.1081/ESE-120037877, 39, 7, 1781-1790, Journal of Environmental Science and Health, Part A., Vol.A39, No.7, pp.1787-1796, 2004.01. |
| 100. | Isolation of the Denitrifying Phosphate-Accumulating Organisms Using Alternating Anaerobic-Anoxic Screening Method. |
| 101. | Isolation of the Denitrifying Phosphate-Accumulating Organisms Using Alternating Anaerobic-Anoxic Screening Method. |
| 102. | K. Hamada, T. Kuba, T. Kusuda, Development of an Activated Sludge Model with Denitrifying Dephosphatation, 第3回IWA国際水質会議, Melbourne Convention Centre, 2002, 第3回IWA国際水質会議, Melbourne Convention Centre, 2002 No.e211335a, pp.1-8, Enviro 2002 & IWA 3rd World Water Congress, Australlia, 7-12 April, 2002, 2002.04. |
| 103. | K. Kumabe, M. Etoh, T. Kuba, T. Kusuda, Application of Light-Stimulus-Responsive Gells to Immobilized Media, Proc. of Asian WATERQUAL 2001, First IWA Asia-Pacific Regional Conference, Vol.II, pp.639-644, 2001, Dec., Proc. of Asian WATERQUAL 2001, First IWA Asia-Pacific Regional Conference, Vol.II, pp.639-644, 2001, Dec., 2001.12. |
| 104. | Application of Light-Stimulus-Responsive NIPA-CH Gels to Immobilized Media. |
| 105. | A Possibility of Control and Prevention of Excessive Phytoplankton Growth by Photochromism. |
| 106. | T. Kuba, M.C.M. van Loosdrecht, J.J. Heijnen, Biological Dephosphatation by Activated Sludge under Denitrifying Conditions: pH Influence and Occurrence of Denitrifying Dephosphatation in a Full-scale Waste Water Treatment Plant, Asian Waterqual ヤ97, 6th IAWQ Asia-Pacific Regional Conf. in Seoul, 1997 May)
Wat. Sci. Tech., Vol.36, No.12, pp.75-82, 1997 Dec., 10.1016/S0273-1223(97)00713-0, 36, 12, 75-82, Asian Waterqual ヤ97, 6th IAWQ Asia-Pacific Regional Conf. in Seoul, 1997 May) Wat. Sci. Tech., Vol.36, No.12, pp.75-82, 1997 Dec., 1997.12. |
| 107. | E. Murnleitner, T. Kuba, M.C.M. van Loosdrecht, J.J. Heijnen, An Integrated Metabolic Model for the Aerobic and Denitrifying Biological Phosphorus Removal, Biotechnology and Bioengineering, Vol.54, No.5, pp.434-450, 1997 Jun., Biotechnology and Bioengineering, Vol.54, No.5, pp.434-450, 1997 Jun., 1997.06. |
| 108. | E. Murnleitner, T. Kuba, M. C.M. Van Loosdrecht, J. J. Heijnen, An integrated metabolic model for the aerobic and denitrifying biological phosphorus removal, Biotechnology and Bioengineering, 10.1002/(SICI)1097-0290(19970605)54:53.0.CO;2-F, 54, 5, 434-450, 1997.06, In this work, an integrated metabolic model for biological phosphorus removal is presented. Using a previously proposed mathematical model it was shown to be possible to describe the two known biological phosphorus removal processes, under aerobic and denitrifying conditions, with the same biochemical reactions, where only the difference in electron acceptor (oxygen and nitrate) is taken into account. Though, apart from the ATP/NADH ratio, the stoichiometry in those models is identical, different kinetic parameters were found. Therefore, a new kinetic structure is proposed that adequately describes phosphorus removal under denitrifying and aerobic conditions with the same kinetic equations and parameters. The ATP/NADH ratio (δ) is the only model parameter that is different for aerobic and denitrifying growth. With the new model, simulations of anaerobic/aerobic and anaerobic/denitrifying sequencing batch reactors (A2 SBR and A/O SBR) were made for verification of the model. Not only short-term behavior, but also steady state, was simulated. The results showed very good agreement between model predictions and experimental results for a wide range of dynamic conditions and sludge retention times. Sensitivity analysis shows the influence of the model parameters and the feed substrate concentrations on both systems.. |
| 109. | B. Warinpaisan, T. Kuba, M. Irie, T. Kusuda, Increase in Rate of Biological Nitrification with NIPAAm Gel as Immobilizing Media, Asian Waterqual '97, 6th IAWQ Asia-Pacific Regional Conf. in Seoul, 1997 May, Asian Waterqual '97, 6th IAWQ Asia-Pacific Regional Conf. in Seoul, 1997 May, 1997.05. |
| 110. | T. Kuba, M.C.M. van Loosdrecht, E. Murnleitner, J.J. Heijnen, Kinetics and Stoichiometry in the Biological Phosphorus Removal Process with Short Cycle Times, Water Research, Vol.31, No.4, pp.918-928, 1997 Apr., Water Research, Vol.31, No.4, pp.918-928, 1997 Apr., 1997.04. |
| 111. | T. Kuba, M.C.M. van Loosdrecht, F.A. Brandse, J.J. Heijnen, Occurrence of Denitrifying Phosphorus Removing Bacteria in Modified UCT-type Waste Water Treatment Plants, Water Research, Vol.31, No.4, pp.777-786, 1997 Apr., Water Research, Vol.31, No.4, pp.777-786, 1997 Apr., 1997.04. |
| 112. | T. Kuba, M. C.M. Van Loosdrecht, E. Murnleitner, J. J. Heijnen, Kinetics and stoichiometry in the biological phosphorus removal process with short cycle times, Water Research, 10.1016/S0043-1354(96)00371-5, 31, 4, 918-928, 1997.04, Aerobic or denitrifying biological phosphorus removal in a sequencing batch rector (SBR) with short repetitive anaerobic-aerobic (A/O) or anaerobic-anoxic (A2) cycling has been studied. These conditions resemble processes with large internal recycle flows. Under these conditions the fatty acid dosage per anaerobic phase is low compared to a conventional SBR or plug flow process. It was shown that at the same sludge retention time (SRT) the average poly-β-hydroxybutyrate (PHB) content of the biomass decreased, with increasing the number of A/O or A2 cycles. This had no direct effect on the biological phosphorus removal. In the A2 SBR, however, phosphorus removal was deteriorating due to transfer of nitrate to the anaerobic phase. Most mathematical models for biological phosphorus removal processes show a relation between the biomass growth rate and the PHB content. This research shows that such a unique relation does not exist, since at one SRT different `steady state' PHB levels could be obtained, depending on the cycle number and the use of oxygen or nitrate as an electron acceptor. This indicates the need for an alternative kinetic model.. |
| 113. | T. Kuba, M. C.M. Van Loosdrecht, F. A. Brandse, J. J. Heijnen, Occurrence of denitrifying phosphorus removing bacteria in modified UCT-type wastewater treatment plants, Water Research, 10.1016/S0043-1354(96)00370-3, 31, 4, 777-786, 1997.04, The occurrence of denitrifying phosphorus removing bacteria (DPB) and the contribution of DPB to phosphorus removal in full-scale wastewater treatment plants (WWTPs) has been investigated by batch tests with the activated sludge from two WWTPs (WWTP-Genemuiden and -Holten). Both WWTPs are operated as UCT-type processes. Batch tests to evaluate the biomass composition of the sludges were developed. These batch tests showed a clear difference of denitrifying dephosphatation activity between the WWTP-Genemuiden and -Holten sludge. In the sludge of the WWTP-Genemuiden the (denitrifying) dephosphatation activity was rather low, whereas a high activity was formed in the WWTP-Holten sludge. The following possible reasons for the lower proportion of (denitrifying) dephosphatation activity in the WWTP-Genemuiden sludge in comparison with the WWTP-Holten sludge, were suggested; (a) nitrate/oxygen transfer to the anaerobic/anoxic zone due to the internal recirculation inside the treatment plant, (b) lower amounts of fatty acids in the influent due to shorter retention time of waste water in sewer lines, and (c) lower amount of nitrate recycled to the anoxic zone.. |
| 114. | A. Wachtmeister, T. Kuba, M.C.M. van Loosdrecht, J.J. Heijnen, A Sludge Characterization Assay for Aerobic and Denitrifying Phosphorus Removing Sludge, Water Research, Vol.31, No.3, pp.471-478, 1997 Mar., Water Research, Vol.31, No.3, pp.471-478, 1997 Mar., 1997.03. |
| 115. | A. Wachtmeister, T. Kuba, M. C.M. Van Loosdrecht, J. J. Heijnen, A sludge characterization assay for aerobic and denitrifying phosphorus removing sludge, Water Research, 10.1016/S0043-1354(96)00281-3, 31, 3, 471-478, 1997.03, It was recently recognized that denitrifying bacteria, as well as aerobic bacteria, contribute to the biological phosphorus removal process. For evaluation of the phosphorus removal process it is necessary to have tests enabling a proper characterization of the microbial population in the activated sludge. In this study we evaluated the possibility of anoxic phosphorus release or aerobic/anoxic phosphorus uptake tests for sludge characterization. Hereto we employed sludge mixtures of enrichment cultures from laboratory sequencing batch reactor (SBR) systems operated under aanaerobic-aerobic (A/O) or anaerobic-anoxic (A2) conditions. It is shown that interpretation of phosphorus release tests, with or without nitrate present, is difficult. On the other hand a comparison of phosphorus uptake under aerobic and anoxic conditions leads to a straightforward characterization of the microbial population in the phosphorus removing organisms, with respect to their phosphorus removal activity under aerobic and anoxic conditions.. |
| 116. | M.C.M. van Loosdrecht, G.J. Smolders, T. Kuba, J.J. Heijnen, Metabolism of Micro-organisms Responsible for Enhanced Biological Phosphorus Removal from Wastewater: Use of Dynamic Enrichment Cultures, Antonie van Leeuwenhoek, Vol.71, No.1-2, pp.109-116, 1997 Feb., Antonie van Leeuwenhoek, Vol.71, No.1-2, pp.109-116, 1997 Feb., 1997.02. |
| 117. | M.C.M. van Loosdrecht, T. Kuba, H.M. van Veldhuizen, F.A. Brandse, J.J. Heijnen, Environmental Impacts of Nutrient Removal Process: Case Study, Journal of Environmental Engineering, Vol.123, No.1, pp.33-40, 1997 Jan., Journal of Environmental Engineering, Vol.123, No.1, pp.33-40, 1997 Jan., 1997.01. |
| 118. | Mark C.M. Van Loosdrecht, Takahiro Kuba, Henry M. Van Veldhuizen, Frank A. Brandse, Joseph J. Heijnen, Environmental impacts of nutrient removal processes Case study, Journal of Environmental Engineering, 10.1061/(asce)0733-9372(1997)123:1(33), 123, 1, 33-40, 1997.01, The influence of primary clarification of sewage on nitrogen and phosphorus removal in a modified University of Cape Town (UCT) type wastewater-treatment plant (WWTP) has been studied on a full scale. Before or after the introduction of raw sewage, the sludge was characterized on (denitrifying) phosphorusremoving activities by batch tests. For both situations, mass and energy balances in the WWTP were made in order to evaluate the effect of presettling on the environmental impact of the treatment process. Extra chemical oxygen demand (COD) input due to the introduction of raw sewage improved the overall nitrogen removal, whereas P-removal remained good. However, the improvement of nitrogen removal resulted mainly from increased assimilation into extra sludge production, not from increased denitrification. In fact, results of the batch tests indicated that the denitrification activity after the introduction of raw sewage was almost similar to the sludge with presettled sewage. The introduction of raw sewage resulted in an increase of energy consumption, mainly due to lower methane production in the digester. This research shows that evaluating treatment processes solely on effluent quality can easily lead to overall adverse effects for the environment. The full environmental impact should also be considered for treatment processes.. |
| 119. | M. C M Van Loosdrecht, G. J. Smolders, Takahiro Kuba, J. J. Heijnen, Metabolism of micro-organisms responsible for enhanced biological phosphorus removal from wastewater. Use of dynamic enrichment cultures, Antonie van Leeuwenhoek, 10.1023/A:1000150523030, 71, 1-2, 109-116, 1997, The removal of phosphorus from wastewater is already widely applied. In many cases use is made of micro organisms capable of accumulating phosphorus as polyphosphate inside the cell. The main characteristic providing the competitive advantage to these polyphosphate accumulating bacteria is the capability to use polyphosphate, in the absence of external electron accepters, as energy source for the uptake and storage of acetic acid in the form of polyhydroxybutyrate (PHB). The reduction equivalents for the formation of PHB are derived from the conversion of glycogen to PHB. Despite the widespread use and study of enhanced biological phosphorus removal no pure culture, having the above mentioned characteristics, has been isolated yet. All ecophysiological studies on these type of cultures have therefore been performed by enrichment cultures. This paper reviews the research on these type of organisms, and shows that it is possible to understand a complex microbial process on a metabolic level, both stoichiometrically and kinetically, without the availability of a pure culture.. |
| 120. | T. Kuba, E. Murnleitner, M.C.M. van Loosdrecht, J.J. Heijnen, A Metabolic Model for the Biological Phosphorus Removal by Denitrifying Organisms, Biotechnology and Bioengineering, Vol.52, No.6, pp.685-695, 1996.12. |
| 121. | T. Kuba, E. Murnleitner, M. C.M. Van Loosdrecht, J. J. Heijnen, A metabolic model for biological phosphorus removal by denitrifying organisms, Biotechnology and Bioengineering, 10.1002/(SICI)1097-0290(19961220)52:63.3.CO;2-M, 52, 6, 685-695, 1996.12, A metabolic model for biological phosphorus removal under denitrifying conditions has been established. The model is based on previous work with aerobic phosphorus removal. The form of the kinetic equations used is the same as for the aerobic model. The main difference is the value of P/NADH2 ratio in the electron transport phosphorylation with nitrate (δ(N)). This value was determined independently from batch tests with an enriched culture of denitrifying phosphorus-removing bacteria. The measured δ(N) was approximately 1.0 mol ATP/mol NADH2. This indicates that the energy production efficiency with nitrate compared to oxygen is approximately 40% lower. These batch tests were also used to identify a proper set of kinetic parameters. The obtained model was subsequently applied for the simulation of cyclic behavior in an anaerobic-anoxic sequencing batch reactor at different biomass retention times. The simulation results showed that the metabolic model can be used successfully for the denitrifying dephosphatation process. The obtained kinetic parameters for denitrifying enrichment cultures, however, deviated from those obtained for the aerobic enrichment cultures.. |
| 122. | T. Kuba, M.C.M. van Loosdrecht, J.J. Heijnen, Phosphorus and Nitrogen Removal with Minimal COD Requirement by Integration of Denitrifying Dephosphatation and Nitrification in a Two-Sludge System, Water Research, Vol.30, No.7, pp.1702-1710, 1996.07. |
| 123. | T. Kuba, M. C.M. Van Loosdrecht, J. J. Heijnen, Phosphorus and nitrogen removal with minimal COD requirement by integration of denitrifying dephosphatation and nitrification in a two-sludge system, Water Research, 10.1016/0043-1354(96)00050-4, 30, 7, 1702-1710, 1996.07, Denitrifying dephosphatation enables the removal of phosphorus and nitrogen with minimal use of COD, minimal oxygen consumption and minimal surplus sludge production. Moreover it would make aeration only necessary for nitrification. Therefore we have studied an anaerobic-anoxic (A2) sequencing batch reactor (SBR) coupled to a nitrification SBR. Denitrifying phosphorus removing bacteria (DPB) and nitrifiers were completely separated in two sludges in these two SBRs. The nitrified supernatant was recirculated from the nitrification SBR to the A2 SBR where nitrate was utilized by DPB as an electron acceptor for phosphorus removal. The technical feasibility for simultaneous phosphorus and nitrogen removal in the proposed two-sludge system was evaluated. The benefits of two-sludge systems over single-sludge systems were also discussed. It could be concluded that the separation of the nitrification step leads to an optimal process design for the application of denitrifying dephosphatation. The two-sludge system showed stable phosphorus and nitrogen removal, and enabled the removal of 15 mg-P/1 and 105 mg N/1 at the expense of only 400 mg-COD/1 acetic acid. Stoichiometric calculations showed that, in the two-sludge system the required COD can be up to 50% less than for conventional aerobic phosphorus and nitrogen removal systems. Moreover oxygen requirements and sludge production can be decreased in significant amounts of about 30 and 50%, respectively.. |
| 124. | T. Kuba, M.C.M. van Loosdrecht, J.J. Heijnen, Effect of Cyclic Oxygen Exposure on the Activity of Denitrifying Phosphorus Removing Bacteria, Wat. Sci. Tech., Vol.34, No.1-2, pp.33-40, 1996.01. |
| 125. | T. Kuba, M. C.M. Van Loosdrecht, J. J. Heijnen, Effect of cyclic oxygen exposure on the activity of denitrifying phosphorus removing bacteria, Proceedings of the 1996 18th Biennial Conference of the International Association on Water Quality. Part 1 Water Science and Technology, 10.1016/0273-1223(96)00492-1, 34, 1-2 -2 pt 1, 33-40, 1996.01, The effect of oxygen on the activity of denitrifying phosphorus removing bacteria has been studied. Denitrifying phosphorus removing bacteria were enriched without oxygen in an anaerobic-anoxic SBR (sequencing batch reactor) over a long time, after which an aerobic phase was introduced into the SBR. The performance on phosphorus and nitrogen removal was examined for an anaerobic-aerobic-anoxic SBR. It could be concluded that oxygen has no detrimental effect on the denitrifying dephosphatation activity. The maximum phosphorus uptake rate by the enriched denitrifying sludge was almost equal for anoxic and aerobic conditions, and the anoxic phosphorus removal activity was kept within at least 5 months after the introduction of the aerobic phase. From the experiments it followed that the advantage of applying denitrifying phosphorus removing bacteria can only be obtained in a pre-denitrification process like the UCT-type of process.. |
| 126. | T. Kuba, A. Wachtmeister, M.C.M. van Loosdrecht, J.J. Heijnen, Effect of Nitrate on Phosphorus Release in Biological Phosphorus Removal Systems, Wat. Sci. Tech., Vol.30, No.6, pp.263-269, 1994.06. |
| 127. | T. Kuba, A. Wachtmeister, M. C.M. Van Loosdrecht, J. J. Heijnen, Effect of nitrate on phosphorus release in biological phosphorus removal systems, Proceedings of the 17th Biennial Conference of the International Association on Water Quality. Part 1 Water Science and Technology, 10.2166/wst.1994.0277, 30, 6 pt 6, 263-269, 1994, The effect of nitrate on phosphorus release by biological phosphorus removing organisms has been studied. Denitrifying (PB) or aerobic phosphorus removing bacteria were enriched in an anaerobic-anoxic or anaerobic-aerobic sequencing batch reactor (SBR). The enrichment sludges were used in batch tests, in which the effect of simultaneous presence of substrate (HAc) and nitrate was studied on the phosphorus release. It could be concluded that a reduction of the phosphorus release by nitrate in biological phosphorus removal systems is partly due to the presence of DPB, which utilize HAc for denitrification, not for phosphorus release. PHB (poly-β-hydroxybutyrate) was always produced and phosphorus was released by DPB sludge when nitrate and HAc were simultaneously present. The reducing power (NADH2) and the energy (ATP) for this process seemed to be obtained from HAc oxidation by nitrate as well as from polyphosphate degradation. After removal of the HAc, PHB degradation and phosphorus uptake occurred.. |
| 128. | T. Kuba, G. Smolders, M.C.M. van Loosdrecht, J.J. Heijnen, Biological Phosphorus Removal from Wastewater by Anaerobic-Anoxic Sequencing Batch Reactor, Wat. Sci. Tech., Vol.17, No.5-6, pp.241-252, 1993.09. |
| 129. | T. Kuba, G. Smolders, M. C.M. van Loosdrecht, J. J. Heijnen, Biological phosphorus removal from wastewater by anaerobic-anoxic sequencing batch reactor, Proceedings of the International Conference on Sewage into 2000 Water Science and Technology, 10.2166/wst.1993.0504, 27, 5-6, 241-252, 1993.01, In this study an anaerobic-anoxic SBR(sequencing batch reactor) was used in order to investigate the possibility of phosphorus removal process. Comparison of stoichiometry and kinetics with the conventional anaerobic-aerobic SBR system shows a similar potential for phosphorus removal by denitrifying organisms. Therefore in the design of phosphorus removal processes one should not be afraid of nitrate, but use it.. |
| 130. | H. Furumai, T. Kuba, T. Imai, T. Kusuda, Transient responses of wastewater treatment and biomass development in a methanogenic fluidized bed, Proceedings of the 15th Biennial Conference of the International Association on Water Pollution Research and Control Water Science and Technology, 10.2166/wst.1991.0585, 23, 1327-1336, 1991.01, The objectives of this study are to develop a model which can express the characteristics of anaerobic treatment in a methanogenic fluidized bed reactor in non-steady states, and evaluate the usefulness of the model in which 'active' biomass concentration is used as a index of bacteria concentration instead of traditional ones such as volatile suspended solids. The treatment in the fluidized bed reactor started with biocoated synthetic zeolite as support material. The reactor was supplied with synthetic wastewater, a mixture of volatile fatty acids. An experiment on response was conducted according to changing stepwise the influent concentration. Batch experiments on activity were carried out under several steady state conditions, using a kind of volatile fatty acid as a substrate. Transient responses of water quality are investigated in relation to the growth of bacterial groups which decompose volatile fatty acids. Based on the results, a dynamic model is proposed, in which attached biomass is categorized into 'active' biomass and inert organic matter. The transient response of substrate concentrations was clearly expressed by considering the growth of 'active' biomass. It was impossible to explain the responses when VSS was regarded as the biomass concentration in the model.. |
| 131. | Takahiro KUBA, Hiroaki FURUMAI, Tetsuya KUSUDA, A Kinetic Study on Methanogenesis by Attached Biomass in a Fluidized Bed, Water Research, 10.1016/0043-1354(90)90155-Y, 24, 11, 1365-1372, Vol.23, No.11, pp.1365-1372, 1990.11. |
| 132. | Hiroaki FURUMAI, Takahiro KUBA, Tsuyosi IMAI, Tetsuya KUSUDA, Transient Responses of Wastewater Treatment and Biomass Developement in a Methanogenic Fluidized Bed, Water Science and Technology, 23, 7-9, 1327-1336, Vol.23, Kyoto, pp.1327-1336, 1990.08. |
| 133. | Evaluation of Methanogenic Activity Test using Glass Vials. |
| 134. | An Estimation Method of Active Biomass Concentration of Acetate utilizing Methanogen in Anaerobic Mixed Cultures. |
| 135. | Evaluation of Methanogenic Activity Test Using Glass Vials. |
| 136. | Characteristcs of Volatile Fatty Acid Decomposition in Anaerobic Fluidized Bed. |
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