To identify the factors controlling the distribution of dissolved organic carbon (DOC) in the northern Ariake Sea (Japan), we measured DOC, salinity and chlorophyll a (Chl. a) along transect lines from the largest river discharging into the Ariake Sea (the Chikugo River) to the opposite shore. The DOC concentration was significantly correlated with salinity, although no correlation was found between the Chl. a concentration and DOC. Thus, river inflow is the primary source of DOC. However, the expected concentration of riverine DOC, represented by the y-intercept of the regression curve between salinity and DOC, was much higher than the DOC concentration of the Chikugo River, suggesting the presence of additional DOC sources to the Ariake Sea. We conducted particulate organic matter (POM) decomposition experiments and observed DOC production after incubation. Thus, microbial POM decomposition may be a source of excess DOC. This study is the first to show that river inflow and microbial decomposition of POM affect the DOC distribution in the northern Ariake Sea.
{"title":"Influence of River Inflow and Microbial Activity on Distribution of Dissolved Organic Carbon in the Northern Part of Ariake Sea, Kyushu, Japan","authors":"K. Uchino, K. Mori, Natsumi Fukushima, H. Takasu","doi":"10.2965/JWET.20-174","DOIUrl":"https://doi.org/10.2965/JWET.20-174","url":null,"abstract":"To identify the factors controlling the distribution of dissolved organic carbon (DOC) in the northern Ariake Sea (Japan), we measured DOC, salinity and chlorophyll a (Chl. a) along transect lines from the largest river discharging into the Ariake Sea (the Chikugo River) to the opposite shore. The DOC concentration was significantly correlated with salinity, although no correlation was found between the Chl. a concentration and DOC. Thus, river inflow is the primary source of DOC. However, the expected concentration of riverine DOC, represented by the y-intercept of the regression curve between salinity and DOC, was much higher than the DOC concentration of the Chikugo River, suggesting the presence of additional DOC sources to the Ariake Sea. We conducted particulate organic matter (POM) decomposition experiments and observed DOC production after incubation. Thus, microbial POM decomposition may be a source of excess DOC. This study is the first to show that river inflow and microbial decomposition of POM affect the DOC distribution in the northern Ariake Sea.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69271080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, a field survey of fecal contamination indicators and Clostridium perfringens cpe(+) in river environments was conducted to verify the effectiveness of C. perfringens cpe(+) as a microbial source tracking indicator in public water bodies. In the Saijo River, which serves as a model of point source contamination from human sewage effluents, the concentrations of Escherichia coli, enterococci and C. perfringens increased after the inflow of sewage effluents, with the cpe-positive prevalence rate of C. perfringens isolates increasing from 13.3 to 21.5%. In the Nagaike River, contaminated with household sewage effluents from non-point sources, high concentrations of E. coli, enterococci, and C. perfringens cpe(+) were detected, with high cpe-positive prevalence rates of 27.6 and 26.4%. Contrarily, in the Koayu River, which is contaminated with treated wastewater from a large swine farm, an increase in the concentration of fecal contamination indicators and C. perfringens was observed; however, the cpe-positive prevalence rate of C. perfringens isolates remained unchanged, ranging as low as 3.6 and 3.9%. Altogether, our results revealed that the concentration and pollution load of C. perfringens cpe(+) is an effective microbial source tracking indicator of human fecal contamination in freshwater environments.
{"title":"Evaluation of C. perfringens cpe-positive Strain as a Source Tracking Indicator of Human Contamination in Freshwater Environments","authors":"Hiroyuki Suzuki, K. Oonaka, A. Hashimoto","doi":"10.2965/JWET.20-089","DOIUrl":"https://doi.org/10.2965/JWET.20-089","url":null,"abstract":"In this study, a field survey of fecal contamination indicators and Clostridium perfringens cpe(+) in river environments was conducted to verify the effectiveness of C. perfringens cpe(+) as a microbial source tracking indicator in public water bodies. In the Saijo River, which serves as a model of point source contamination from human sewage effluents, the concentrations of Escherichia coli, enterococci and C. perfringens increased after the inflow of sewage effluents, with the cpe-positive prevalence rate of C. perfringens isolates increasing from 13.3 to 21.5%. In the Nagaike River, contaminated with household sewage effluents from non-point sources, high concentrations of E. coli, enterococci, and C. perfringens cpe(+) were detected, with high cpe-positive prevalence rates of 27.6 and 26.4%. Contrarily, in the Koayu River, which is contaminated with treated wastewater from a large swine farm, an increase in the concentration of fecal contamination indicators and C. perfringens was observed; however, the cpe-positive prevalence rate of C. perfringens isolates remained unchanged, ranging as low as 3.6 and 3.9%. Altogether, our results revealed that the concentration and pollution load of C. perfringens cpe(+) is an effective microbial source tracking indicator of human fecal contamination in freshwater environments.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69266053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Nakai, A. Das, Yuya Maeda, N. Humaidah, Masaki Ohno, W. Nishijima, Takehiko Gotoh, T. Okuda
Thraustochytrids such as Aurantiochytrium are heterotrophic and produce valuable fatty acids (FAs) and therefore expected as a tool for removal of organic compounds in wastewater and simultaneous production of FAs. The four strains of Aurantiochytrium sp. were isolated from the mangrove leaf samples, and among these the strain L3W showed the high specific growth rate of 0.27 1/h at 25°C. In addition, this strain grew at the ranges of temperature from 15°C to 35°C, pH from 3 to 9, and salinity from 0.3 to 70 PSU. Under the optimal condition of 25°C, 30 PSU, and pH7, the strain L3W produced 270 mg/g of FAs including 135 mg/g of docosahexaenoic acid, 11 mg/g of pentadecanoic acid and 9.3 mg/g of margaric acid. Furthermore, the strain L3W produced these FAs at pH3 and pH9. The pH and salinity tolerance of the strain L3W might be advantageous in its application for production of valuable FAs under competition with other microorganisms in unsterile wastewater.
{"title":"A Novel Strain of Aurantiochytrium sp. Strain L3W and Its Characteristics of Biomass and Lipid Production Including Valuable Fatty Acids","authors":"S. Nakai, A. Das, Yuya Maeda, N. Humaidah, Masaki Ohno, W. Nishijima, Takehiko Gotoh, T. Okuda","doi":"10.2965/JWET.20-087","DOIUrl":"https://doi.org/10.2965/JWET.20-087","url":null,"abstract":"Thraustochytrids such as Aurantiochytrium are heterotrophic and produce valuable fatty acids (FAs) and therefore expected as a tool for removal of organic compounds in wastewater and simultaneous production of FAs. The four strains of Aurantiochytrium sp. were isolated from the mangrove leaf samples, and among these the strain L3W showed the high specific growth rate of 0.27 1/h at 25°C. In addition, this strain grew at the ranges of temperature from 15°C to 35°C, pH from 3 to 9, and salinity from 0.3 to 70 PSU. Under the optimal condition of 25°C, 30 PSU, and pH7, the strain L3W produced 270 mg/g of FAs including 135 mg/g of docosahexaenoic acid, 11 mg/g of pentadecanoic acid and 9.3 mg/g of margaric acid. Furthermore, the strain L3W produced these FAs at pH3 and pH9. The pH and salinity tolerance of the strain L3W might be advantageous in its application for production of valuable FAs under competition with other microorganisms in unsterile wastewater.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69265952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shumona Akther, Wenzhao Sun, P. Pokhrel, Jumpei Suzuki, M. Fujita
We assessed the photosynthetic efficiency of the lab-cultured large benthic foraminifers (LBFs), Calcarina gaudichaudii and Baculogypsina sphaerulata, by means of a pulse-amplitude-modulated (PAM) fluorometer for representative photosynthetic activity; and identified an optimal light intensity and water temperature for the lab-scale cultivation. It is known that in the actual environment, the convex side of LBFs exhibit higher photosynthetic efficiency [Y(II)] than concave one. However, our experimental results from the lab setting showed that Y(II) values apparently did not differ on the basis of their having convex and concave sides. This was due to the condition between the position of the LBFs within the glass vial and light irradiation. The LBFs were exposed to eleven different light conditions for a period of 72 h. The LBFs exhibited relatively higher Y(II) at 40−120 and 240 lum/ft2, compared with that at 1150−1800 lum/ft2. Using a light intensity of 80 lum/ft2 and water temperature of 20°C to inhibit epiphyte infestation due to the growth of suspended microalgae released by the LBF hosts, LBFs were able to be cultured for 120 d under laboratory conditions, while B. sphaerulata could be cultured for 57 d under the on-site conditions in a previous study.
{"title":"An Assessment of Photosynthetic Activity in Large Benthic Foraminifers and the Optimization of Light Intensity for Lab-scale Cultivation","authors":"Shumona Akther, Wenzhao Sun, P. Pokhrel, Jumpei Suzuki, M. Fujita","doi":"10.2965/JWET.20-136","DOIUrl":"https://doi.org/10.2965/JWET.20-136","url":null,"abstract":"We assessed the photosynthetic efficiency of the lab-cultured large benthic foraminifers (LBFs), Calcarina gaudichaudii and Baculogypsina sphaerulata, by means of a pulse-amplitude-modulated (PAM) fluorometer for representative photosynthetic activity; and identified an optimal light intensity and water temperature for the lab-scale cultivation. It is known that in the actual environment, the convex side of LBFs exhibit higher photosynthetic efficiency [Y(II)] than concave one. However, our experimental results from the lab setting showed that Y(II) values apparently did not differ on the basis of their having convex and concave sides. This was due to the condition between the position of the LBFs within the glass vial and light irradiation. The LBFs were exposed to eleven different light conditions for a period of 72 h. The LBFs exhibited relatively higher Y(II) at 40−120 and 240 lum/ft2, compared with that at 1150−1800 lum/ft2. Using a light intensity of 80 lum/ft2 and water temperature of 20°C to inhibit epiphyte infestation due to the growth of suspended microalgae released by the LBF hosts, LBFs were able to be cultured for 120 d under laboratory conditions, while B. sphaerulata could be cultured for 57 d under the on-site conditions in a previous study.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69269320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Otomo, A. Terada, Yuyou Li, Kazuya Nishitoba, F. Takakai, K. Okano, N. Miyata, S. Masuda
In full-scale sewage treatment plants, long-term and high-frequency monitoring is required to mitigate nitrous oxide (N2O) emissions. In this study, the profile of the dissolved N2O concentration in a full-scale oxidation ditch reactor was investigated to determine the variation of the N2O emission factor. It was found that the concentration of dissolved N2O depended on microbial activity, which is affected by water temperature, dissolved oxygen concentration, and the dimensional relationship between the rotator and the inflow point. In the reactor, higher transcription levels of amoA mRNA and lower transcription levels of clade II type nosZ mRNA may be associated with N2O production. The emission factor for removed dissolved inorganic nitrogen presented a mean value of 0.86% and a median of 0.19%. When N2O production was promoted, gasification from the water surface was the most significant emission source, accounting for 52% of the total N2O emitted, on average. The N2O emission factor was often lower than 0.01% during stable operation; however, this factor was subject to sudden increases caused by nitrite accumulation.
{"title":"Long-term Assessment of N2O Emission Factor in Full-scale Oxidation Ditch Reactor Considering Spatiotemporal Distribution","authors":"S. Otomo, A. Terada, Yuyou Li, Kazuya Nishitoba, F. Takakai, K. Okano, N. Miyata, S. Masuda","doi":"10.2965/JWET.20-145","DOIUrl":"https://doi.org/10.2965/JWET.20-145","url":null,"abstract":"In full-scale sewage treatment plants, long-term and high-frequency monitoring is required to mitigate nitrous oxide (N2O) emissions. In this study, the profile of the dissolved N2O concentration in a full-scale oxidation ditch reactor was investigated to determine the variation of the N2O emission factor. It was found that the concentration of dissolved N2O depended on microbial activity, which is affected by water temperature, dissolved oxygen concentration, and the dimensional relationship between the rotator and the inflow point. In the reactor, higher transcription levels of amoA mRNA and lower transcription levels of clade II type nosZ mRNA may be associated with N2O production. The emission factor for removed dissolved inorganic nitrogen presented a mean value of 0.86% and a median of 0.19%. When N2O production was promoted, gasification from the water surface was the most significant emission source, accounting for 52% of the total N2O emitted, on average. The N2O emission factor was often lower than 0.01% during stable operation; however, this factor was subject to sudden increases caused by nitrite accumulation.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69269779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study reports the availability of seawater as an economical chloride (Cl−) source for the UV/ electro-chlorine process from the viewpoints of advanced oxidation performance and unwanted byproduct formation of chlorate ion (ClO3) and bromate ion (BrO3). In the electrochemical oxidant production stage, the oxidant production rate in diluted seawater containing 30 mM Cl− was 21% lower than that in the NaCl solution due to coexisting electrolytes in the seawater. The ClO3 formation during electrolysis was successfully inhibited under acidic conditions and BrO3 formation was not detected in the diluted seawater. However, ClO3 and BrO3 were steadily formed in the undiluted seawater electrolysis, even when the initial pH value was set to 3. The oxidant utilization efficiency for 1,4-dioxane removal during UV irradiation was not deteriorated in the diluted seawater but decreased under basic conditions due to the radical scavenging effect of electrochemically produced free bromine and free chlorine. As a result, the formation of BrO3 and ClO3 was enhanced under basic conditions, whereas BrO3 formation was completely inhibited at an initial pH ≤ 5. Consequently, the diluted seawater was thought to be available as a Cl− source for the UV/electro-chlorine process if an acidic condition was maintained throughout the operation.
本研究从高级氧化性能和氯酸盐离子(ClO3)和溴酸盐离子(BrO3)的有害副产物形成的角度报道了海水作为UV/电氯工艺经济氯化物(Cl−)源的可行性。在电化学氧化剂生成阶段，由于海水中电解质共存，在含有30 mM Cl−的稀释海水中，氧化剂的生成速率比在NaCl溶液中低21%。在酸性条件下，电解过程中ClO3的生成被成功抑制，而在稀释后的海水中没有检测到BrO3的生成。而在未稀释的海水电解过程中，即使初始pH值为3,ClO3和BrO3也能稳定生成。在稀释后的海水中，由于电化学产生的游离溴和游离氯对自由基的清除作用，紫外线照射去除1,4-二恶烷的氧化剂利用效率没有下降，但在碱性条件下则有所下降。结果表明，碱性条件下促进了BrO3和ClO3的生成，而初始pH≤5时则完全抑制了BrO3的生成。因此，如果在整个操作过程中保持酸性条件，则认为稀释后的海水可作为UV/电氯工艺的Cl -源。
{"title":"Availability of Seawater as A Chloride Source for UV/electro-chlorine Advanced Oxidation Process","authors":"N. Kishimoto, Koki Hara","doi":"10.2965/jwet.21-080","DOIUrl":"https://doi.org/10.2965/jwet.21-080","url":null,"abstract":"This study reports the availability of seawater as an economical chloride (Cl−) source for the UV/ electro-chlorine process from the viewpoints of advanced oxidation performance and unwanted byproduct formation of chlorate ion (ClO3) and bromate ion (BrO3). In the electrochemical oxidant production stage, the oxidant production rate in diluted seawater containing 30 mM Cl− was 21% lower than that in the NaCl solution due to coexisting electrolytes in the seawater. The ClO3 formation during electrolysis was successfully inhibited under acidic conditions and BrO3 formation was not detected in the diluted seawater. However, ClO3 and BrO3 were steadily formed in the undiluted seawater electrolysis, even when the initial pH value was set to 3. The oxidant utilization efficiency for 1,4-dioxane removal during UV irradiation was not deteriorated in the diluted seawater but decreased under basic conditions due to the radical scavenging effect of electrochemically produced free bromine and free chlorine. As a result, the formation of BrO3 and ClO3 was enhanced under basic conditions, whereas BrO3 formation was completely inhibited at an initial pH ≤ 5. Consequently, the diluted seawater was thought to be available as a Cl− source for the UV/electro-chlorine process if an acidic condition was maintained throughout the operation.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69270706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. D. A. Purba, N. Abdullah, A. Yuzir, A. Zamyadi, K. Shimizu, J. Hermana
Recently, the symbiosis between microalgae and bacteria for wastewater treatment system receives more attention as microalgae and bacteria coexist symbiotically under suitable environmental condition. Moreover, the microalgae and bacteria interaction in granular form had been considered as an environmental friendly alternatives due to the synergistic cooperation between microalgae and bacteria in treating wastewater. This study aims to develop microalgae-bacteria aerobic granular sludge using low-strength domestic wastewater. A mixture of Scenedesmus obliquus and activated sludge at ratio of 17% microalgae to 83% activated sludge (v/v) was used as the seed sludge to develop microalgaebacteria aerobic granular sludge. Upon 30 days of experimental period, granular sludge was successfully developed with largest granular diameter of 6 mm. The developed granules exhibited excellent settling properties with 62.8 m/h settling velocity. Better granular settleability indicated by low sludge volume index (SVI30) was detected at 8 mL/g. Observation using field-emission scanning electron microscope (FESEM) showed the attachment of microalgae cells on the outer layer of granular sludge. Moreover, microalgae-bacteria aerobic granular sludge demonstrated good COD and ammoniacal nitrogen removal at 72% removal efficiency.
{"title":"Rapid Development of Microalgae-Bacteria Granular Sludge Using Low-Strength Domestic Wastewater","authors":"L. D. A. Purba, N. Abdullah, A. Yuzir, A. Zamyadi, K. Shimizu, J. Hermana","doi":"10.2965/JWET.20-132","DOIUrl":"https://doi.org/10.2965/JWET.20-132","url":null,"abstract":"Recently, the symbiosis between microalgae and bacteria for wastewater treatment system receives more attention as microalgae and bacteria coexist symbiotically under suitable environmental condition. Moreover, the microalgae and bacteria interaction in granular form had been considered as an environmental friendly alternatives due to the synergistic cooperation between microalgae and bacteria in treating wastewater. This study aims to develop microalgae-bacteria aerobic granular sludge using low-strength domestic wastewater. A mixture of Scenedesmus obliquus and activated sludge at ratio of 17% microalgae to 83% activated sludge (v/v) was used as the seed sludge to develop microalgaebacteria aerobic granular sludge. Upon 30 days of experimental period, granular sludge was successfully developed with largest granular diameter of 6 mm. The developed granules exhibited excellent settling properties with 62.8 m/h settling velocity. Better granular settleability indicated by low sludge volume index (SVI30) was detected at 8 mL/g. Observation using field-emission scanning electron microscope (FESEM) showed the attachment of microalgae cells on the outer layer of granular sludge. Moreover, microalgae-bacteria aerobic granular sludge demonstrated good COD and ammoniacal nitrogen removal at 72% removal efficiency.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69269228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Sugawara, Megumu Fujibayashi, K. Okano, Y. Enda, Shintaro Ichinoseki, Yoshimitsu Taniguchi, N. Miyata
In this study, we conducted long-term laboratory and field feeding experiments to investigate the ability of a freshwater bivalve, Nodularia douglasiae (recently renamed to N. nipponensis) to utilize cyanobacterial cells as food. In the laboratory experiment, N. douglasiae which was fed with 15Nlabeled Microcystis aeruginosa cells over 80 days showed an assimilation efficiency of 47%. The fatty acid compositions in bivalves reflected a slight but apparent increase in the relative ratio of two cyanobacterial fatty acids, linoleic acid (LA) and α-linolenic acid (ALA), to eicosapentaenoic acid (EPA). In the field-feeding experiment, N. douglasiae was fed natural seston in the littoral area of the eutrophic Lake Hachiro (Akita, Japan) during the summers of 2017 and 2018 when cyanobacterial blooms occurred. The ratios of LA and ALA to EPA in bivalves increased from 0.45 to 0.70 and from 0.40 to 0.77 during the summers; the final values were consistent with those obtained in the laboratory feeding experiment. The results indicated that N. douglasiae can utilize cyanobacterial cells as food and maintain assimilation activity at least over several months, and the species may serve as a useful biomanipulation tool for controlling cyanobacterial blooms in freshwater lakes.
{"title":"Assimilation of Cyanobacteria by the Freshwater Bivalve Nodularia douglasiae: Insights from Long-Term Laboratory and Field Feeding Experiments","authors":"K. Sugawara, Megumu Fujibayashi, K. Okano, Y. Enda, Shintaro Ichinoseki, Yoshimitsu Taniguchi, N. Miyata","doi":"10.2965/JWET.20-148","DOIUrl":"https://doi.org/10.2965/JWET.20-148","url":null,"abstract":"In this study, we conducted long-term laboratory and field feeding experiments to investigate the ability of a freshwater bivalve, Nodularia douglasiae (recently renamed to N. nipponensis) to utilize cyanobacterial cells as food. In the laboratory experiment, N. douglasiae which was fed with 15Nlabeled Microcystis aeruginosa cells over 80 days showed an assimilation efficiency of 47%. The fatty acid compositions in bivalves reflected a slight but apparent increase in the relative ratio of two cyanobacterial fatty acids, linoleic acid (LA) and α-linolenic acid (ALA), to eicosapentaenoic acid (EPA). In the field-feeding experiment, N. douglasiae was fed natural seston in the littoral area of the eutrophic Lake Hachiro (Akita, Japan) during the summers of 2017 and 2018 when cyanobacterial blooms occurred. The ratios of LA and ALA to EPA in bivalves increased from 0.45 to 0.70 and from 0.40 to 0.77 during the summers; the final values were consistent with those obtained in the laboratory feeding experiment. The results indicated that N. douglasiae can utilize cyanobacterial cells as food and maintain assimilation activity at least over several months, and the species may serve as a useful biomanipulation tool for controlling cyanobacterial blooms in freshwater lakes.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69269813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. K. Maharjan, T. Kamei, K. Mori, K. Nishida, T. Toyama
Ammonium (NH 4+ ) contamination makes groundwater undrinkable. The dropping nitrification unit, a simple and low-cost biological unit, has been found to be effective for NH 4+ -removal from con taminated groundwater at a near-neutral pH. However, the pH of groundwater varies widely and is highly alkaline (pH 8.7−10) in some areas of the world, which could negatively affect the biological nitrification process. The objectives of this study were to investigate the NH 4+ -removal from alkaline groundwater using dropping nitrification units with sponge or biofringe material, compare their re moval efficiencies, and characterize the effect of alkaline groundwater on the growth and activity of nitrifying bacteria. Synthetic alkaline groundwater (50 mg-NH 4+ -N L −1 ; pH 9.4 ± 0.1) was dropped from the top of 1-m long hanging units at 3 mL min −1 for 56 days. The NH 4+ -removal efficiency of sponge units (> 88%) was significantly higher than that of biofringe units (56−89%). The abundance of amoA gene of ammonia-oxidizing bacteria increased significantly over 56 days and was significantly higher in sponge units than in biofringe units, resulting in higher NH 4+ -removal in sponge units than that in biofringe units. This study demonstrated that dropping nitrification units can be used effec tively for NH 4+ -removal from groundwater having a neutral to alkaline pH.
{"title":"Ammonium Removal from Alkaline Groundwater Using A Dropping Nitrification Unit with Sponge or Biofringe Material","authors":"A. K. Maharjan, T. Kamei, K. Mori, K. Nishida, T. Toyama","doi":"10.2965/jwet.21-084","DOIUrl":"https://doi.org/10.2965/jwet.21-084","url":null,"abstract":"Ammonium (NH 4+ ) contamination makes groundwater undrinkable. The dropping nitrification unit, a simple and low-cost biological unit, has been found to be effective for NH 4+ -removal from con taminated groundwater at a near-neutral pH. However, the pH of groundwater varies widely and is highly alkaline (pH 8.7−10) in some areas of the world, which could negatively affect the biological nitrification process. The objectives of this study were to investigate the NH 4+ -removal from alkaline groundwater using dropping nitrification units with sponge or biofringe material, compare their re moval efficiencies, and characterize the effect of alkaline groundwater on the growth and activity of nitrifying bacteria. Synthetic alkaline groundwater (50 mg-NH 4+ -N L −1 ; pH 9.4 ± 0.1) was dropped from the top of 1-m long hanging units at 3 mL min −1 for 56 days. The NH 4+ -removal efficiency of sponge units (> 88%) was significantly higher than that of biofringe units (56−89%). The abundance of amoA gene of ammonia-oxidizing bacteria increased significantly over 56 days and was significantly higher in sponge units than in biofringe units, resulting in higher NH 4+ -removal in sponge units than that in biofringe units. This study demonstrated that dropping nitrification units can be used effec tively for NH 4+ -removal from groundwater having a neutral to alkaline pH.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69270713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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