| Takahiro KUBA | Last modified date：2024.04.21 |
Professor /
Water and Material Cycles System /
Faculty of Engineering
Presentations
| 1. | 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.. |
| 2. | 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.. |
| 3. | Shunsuke WATANABE,PODIAPEN Tannen Naythen,Megumu FUJIBAYASHI,Yasushi ISERI,Aimin HAO,Takahiro KUBA, Growth Characteristics of Diatom Nitzschia palea as Competitors of Water Bloom Forming Cyanobacteria, WET2020-online (Water and Environment Technology Conference Online), 2020.11. |
| 4. | Shunsuke WATANABE,PODIAPEN Tannen Naythen,Megumu FUJIBAYASHI,Takahiro KUBA,Yasushi ISERI,Aimin HAO, Growth Characteristics of Diatom Nitzschia palea as Competitors of Water Bloom Forming Cyanobacteria, 2020 World Young Scientist Summit, International Forum on Health of Aquatic Ecosystem and Environment , 2020.10. |
| 5. | Basic research on the occurrence and growth mechanism of cyanobacteria as well as methods to prevent growth have been studied for many years. However, excessive cyanobacteria growth is still occurring frequently in lakes and reservoirs in various places. In recent years, ecological engineering methods have been considered due to their sustainability and energy saving nature. In this study, the hypothesis of whether diatom Nitzschia palea has the growth inhibitory effect on Microcystis aeruginosa (NIES-102) and the water blooms (Microcystis spp. collected from the pond) will be investigated. Moreover, since the wavelength of the optimal light for algae and cyanobacteria to grow varies depending on the species, investigation of the wavelength which suppresses the growth of M. aeruginosa will also be carried out. This will be done in combination with using the competitive nature of N. palea and by using LED irradiation. The results of the empirical investigation showed that in the high nitrogen concentration conditions, the growth of M. aeruginosa was inhibited by the addition of N. palea. However, despite the addition of N. palea and the silicate nutrient to the water blooms collected from the pond, it was not possible to confirm the growth inhibition of the cyanobacteria bloom. In the monoculture, irradiation of blue LED causes N. palea to grow, while M. aeruginosa had suppressed growth. Also, the growth of M. aeruginosa was suppressed by about 78% when compared to the used of monoculture and by adding N. palea under the condition of irradiating yellow LED at 25°C. . |
| 6. | 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), 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.. |
| 7. | , [URL]. |
| 8. | , [URL]. |
| 9. | , [URL]. |
| 10. | Shahjalal Khandaker, Yusaku Toyohara, Takahiro Kuba, Effective removal of cesium from aqueous solution by modified sewage sludge molten slag as a low-cost adsorbent, 8th International Conference on Environmental and Agriculture Engineering (ICEAE 2018), 2018.07, [URL], In this study, the effective cesium adsorption from aqueous solution was experimented onto the sewage sludge molten (SSM) slag, modified by alkaline (NaOH) hydrothermal treatment. Batch adsorption experiments were carried out to investigate the effect of contact time, solution pH, adsorbent dose, different initial cesium ions concentrations, temperature and the effect of competitive ions on cesium adsorption. The adsorption isotherm, kinetic, and thermodynamic studies were also evaluated following the experimental results to explore the equilibrium conditions and the mechanism of cesium adsorption. A higher cesium removal efficiency of almost 100% (for 20-100 mg/L of initial cesium ions concentration) was achieved by the modified slag and the maximum adsorption capacity was found to be 52.36 mg/g compared with the raw slag. The higher adsorption performance of the modified slag may be due to the formation of artificial zeolites on its surface during the hydrothermal treatment process. In the competitive ions effect on cesium adsorption, the modified slag effectively captured the cesium ions in the presence of Na+ and K+, especially at their lower molar concentrations (1:10). Kinetic parameters were fitted by pseudo-second order model. The adsorption isotherms data of modified slag were well fitted to the Langmuir (R2=0.989) and Freundlich isotherms model (R2=0.988). The thermodynamic studies indicated that the adsorption process by the modified slag was spontaneous and exothermic in nature. Moreover, the modified slag was reused several cycles (adsorption-elution-adsorption) without deterioration of its original adsorption performance. Therefore, it is expected that the SSM modified slag could be effectively used as cost-effective and a potential adsorbent for cesium adsorption from wastewater.. |
| 11. | , [URL]. |
| 12. | S. Khandaker1, T. Kuba, Y. Toyohara, S. Kamida and Y. Uchikawa, Development of ion-exchange properties of bamboo charcoal modified with concentrated nitric acid, The 3rd International Conference on Water Resource and Environment (WRE 2017), 2017.06, [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.. |
| 13. | WATER PURIFICATION BY LED IRRADIATION IN DECOMPOSING WITHERED MICROCYSTIS, [URL]. |
| 14. | Development of cesium ion adsorption material using sewage sludge molten slag ―The effect of component of the slag, surface treatment and coexisting ion ―. |
| 15. | Phosphorus recovery by heating extracted polyphosphate from activated sludge. |
| 16. | Cultivation of useful plants over the water surface receiving treated sewage. |
| 17. | Research of preventing water blooms through destructing Microcystis colonies by diatom. |
| 18. | POLYPHOSPHATE RECOVERY FROM SEWAGE SLUDGE AS MAGNESIUM AMMONIUM PHOSPHATE AND ITS FORMING ABILITY. |
| 19. | MingYang ZHANG, JianWei DU, 久場 隆広, Yong WEN, Comprehensive Evaluation of Poly-Phosphate Release from Sewage Sludge with Thermal Treatment , The 9th International Conference on Waste Management and Technology, 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. Keywords: Thermal treatment; Sewage sludge; Metal ions; Release; Struvite. |
| 20. | 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 Conference, International Science index Issue 84, 2013.12. |
| 21. | 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, 環境フォーラム, 2013.11. |
| 22. | YuXian LIU, HAO AIMIN, Yasushi ISERI, Chunjie LI, Zhenjia ZHANG, Takahiro KUBA, Application Feasibility of Anodonta woodiana as a Biomanipulation Tool in Lake Taihu, EAEP2013, The 7th International Symposium on the East Asian Environmental Problems, 2013.11. |
| 23. | CaiXiaKANG, HAO AIMIN, Yasushi ISERI, Chunjie LI, Zhenjia ZHANG, Takahiro KUBA, Restoration Conditions of Submerged Macrophyte Vallisneria asiatica in Eutrophic Lake Taihu, China, EAEP2013, The 7th International Symposium on the East Asian Environmental Problems, 2013.11. |
| 24. | Chunjie LI, Zhenjia ZHANG, HAO AIMIN, Yasushi ISERI, Caixia KANG, Takahiro KUBA, Ecological Dam for In-situ Remediation of Polluted Aquaculture Water in Yang Chen Lake: Experience and Prospect, EAEP2013, The 7th International Symposium on the East Asian Environmental Problems, 2013.11. |
| 25. | Water Pollution of Lake Taihu and Solutions for Environmental Problems. |
| 26. | 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, 2013 4th International Conference on Environment Engineering and Applications (ICEEA 2013), 2013.08. |
| 27. | ZHANG MingYang, HAO AIMIN, Takahiro KUBA, The Crystallization of Struvite by Recycling Poly-Phosphate Released from Sewage Sludge after Thermal Treatment, 3rd/2013 International Conference on Chemical Engineering and Advanced Materials (ICCEAM 2013), 2013.07. |
| 28. | Impact of Human Activities on the water Environment of Lake Taihu Watershed and Solution for Environmental Problems (Our Lakes: From the Present towards a Future Perspective). |
| 29. | Chunjie 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, EAEP2012, The 6th International Symposium on the East Asian Environmental Problems, 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.. |
| 30. | YuXian LIU, HAO AIMIN, Yasushi ISERI, Chunjie LI, Zhenjia ZHANG, Takahiro KUBA, Impacts of Microcystis-Blooming Pond Water on Feeding Behavior and Metabolic Energy Balance of Sinanodonta woodiana in Microcosm Experiments, EAEP2012, The 6th International Symposium on the East Asian Environmental Problems, 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.. |
| 31. | CaiXiaKANG, HAO AIMIN, Yasushi ISERI, Chunjie LI, Zhenjia ZHANG, Takahiro KUBA, Improvement of Water Quality in Lake Taihu with Aquatic Plants and the Relationship between Cyanobacteria Bloom and Aquatic Plants, EAEP2012, The 6th International Symposium on the East Asian Environmental Problems, 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.. |
| 32. | ZHANG MingYang, Takahiro KUBA, HAO AIMIN, Extraction of Poly-Phosphate from the Activated Sludge with Thermal Treatment for Phosphorus Recovery, 2nd/2012 International Conference on Energy, Environment and Sustainable Development (EESD 2012), 2012.10, 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.. |
| 33. | The Conception of Ecological Dam. |
| 34. | The Conception of Ecological Dam. |
| 35. | Proposal of an Eco-Emgineering Environmental Improvement Strategy in the Lake Taihu, China： A Concept based on the Water Quality and the Biota. |
| 36. | THE EFFECT OF CHELATING REAGENTS ON THE RELEASE OF PHOSPHORUS FROM SEWAGE SLUDGE DURING HEATING PROCESS. |
| 37. | PRELIMINARY STUDY ON ECOLOGICAL ENGINEERING METHODS OF WATER QUALITY IMPROVEMENT IN THE LAKE TAIHU. |
| 38. | Phosphorus Removal Ability Intensified by Calcium Silicate Hydrates (CSH) in Ecological Technologies. |
| 39. | Japanese Society for Agricultural, Biological, and Environmental Engineers and Scientists Annual Meeting 2011 Sapporo (JSABEES) Hokkaido University, September 6-8, 2011 . |
| 40. | Multiple Criteria Assessment of Ecosystem Services Sustained by Qinhuai River in Nanjing. |
| 41. | Present Aquatic environment and the conservation in the Lake Taihu. |
| 42. | Bamboo charcoal was examined to determine the adsorption capacity of nitrate anion and the mechanism in aqueous solution. Added to these, reduction of non-point pollutant load, such as roadway runoff, using the adsorption ability of bamboo charcoal was estimated by a simple one-dimensional laminar model. The bamboo charcoal (BC) was manufactured from Moso bamboo (Phyllostachys heterocycla) at the carbonization temperature of 800°C (BC800). Effect of acid and alkali post-treatment for the BC800 on the nitrate anion adsorption capacity was investigated. The BC800 post-treated with acid (hydrochloric acid) following alkali (sodium hydroxide) had higher adsorption capacity than that post-treated oppositely. It was concluded that the nitrate anion adsorption mechanism onto the bamboo charcoal was ion-exchange chemical adsorption, i.e., the BC800 with partially-substitution of chlorine ion for hydroxide ion easily adsorbed the nitrate anion. From the model estimation with a simple adsorption tank system, the breakthrough time of the BC800 turned out to be more than a year. These results lead to the conclusion that the effective utilization of the bamboo charcoal as an adsorbent could reduce and prevent non-point pollution.. |
| 43. | Education and Learning Improvement by Introduction of an Evaluation System to Graduation Research. |
| 44. | Effect of Microfauna on the Stability of Aerobic Granules. |
| 45. | Aerobic Granular Sludge: A Promising Technology for Decentralized Wastewater Treatment. |
| 46. | Comparison of Nutrient Removal Efficiency between Pre- and Post-denitrification Wastewater Treatment. |
| 47. | Nitrogen and Phosphorus Removal in Two-sludge System 〜Volume Exchange Ratio Effect〜. |
| 48. | Analysis of Microbial Community in an Alternating Anaerobic-Anoxic System by the Method of Fluorescent in situ Hybridization. |
| 49. | Characteristics of Aerobic Granular System. |
| 50. | Recycling Technology of Water 〜Biological Sewage Treatment and Prevention of Eutrophication〜. |
| 51. | Anoxic Phosphorus Removal in a Post-denitrification System. |
| 52. | A Lowering of Phosphate Removal Efficiency and Its Measures in UCT Process. |
| 53. | Mathematical Model of Denitrifying Dephosphatation Based on IWA ASM. |
Unauthorized reprint of the contents of this database is prohibited.