Seventy borehole data were used to appraise the groundwater resources of the sedimentary and Basement Complex rock terrains of Ogun State, Nigeria. Borehole depth, static water level, discharge and drawdown were evaluated to determine the hydrogeological and hydraulic properties of the aquifers. Specific capacity of the boreholes was estimated at one hour using discharge and drawdown values. Most boreholes in the sedimentary terrain explored shallower aquifers of < 100 m, while most boreholes in the Basement Complex rock terrain explored deeper aquifers > 100 m. The sedimentary rock aquifers had thinner groundwater storage of 65.28 m and average borehole yield of 43.51 m 3 hr −1 , while the Basement Complex rock aquifers had thicker groundwater storage of 95.02 m and average borehole yield of 5.53 m 3 hr −1 . The average efficiency of boreholes in the sedimentary and Basement Complex rock terrains were 0.66 and 7.14 m 2 hr −1 , respectively. Boreholes within Basement Complex rocks had higher efficiency than those within sedimentary rocks. Adequate groundwater occurs in the sedimentary and Basement Complex rock terrains for domestic, industrial and agricultural purposes. The groundwater is weakly acidic with small amount of TDS, hence falls within the fresh water category. The groundwater is not potable but could serve domestic and general purposes.
利用70个钻孔资料对尼日利亚奥贡州沉积和基底复杂岩石地形的地下水资源进行了评价。通过评价钻孔深度、静水位、流量和降水来确定含水层的水文地质和水力特性。利用流量和压降值估算了一小时内钻孔的比容。在沉积地形中，大多数钻孔探测的是< 100 m的浅层含水层，而在基底复杂岩石地形中，大多数钻孔探测的是较深的100 m含水层。沉积岩含水层的地下水存储量较薄，为65.28 m，平均井出水量为43.51 m 3 hr−1;基底复合岩含水层的地下水存储量较厚，为95.02 m，平均井出水量为5.53 m 3 hr−1。沉积和基底复杂岩石地形的钻孔平均效率分别为0.66和7.14 m 2 hr−1。基底杂岩内钻孔效率高于沉积岩内钻孔效率。在沉积和基底复杂的岩石地形中有充足的地下水供家庭、工业和农业使用。地下水呈弱酸性，TDS含量少，属于淡水范畴。地下水不能饮用，但可以用于家庭和一般用途。
{"title":"Groundwater Potential Assessment of the Sedimentary and Basement Complex Rocks of Ogun State, Southwestern Nigeria","authors":"O. Ajayi, C. I. Konwea, Patience O. Sodeinde","doi":"10.2965/jwet.21-177","DOIUrl":"https://doi.org/10.2965/jwet.21-177","url":null,"abstract":"Seventy borehole data were used to appraise the groundwater resources of the sedimentary and Basement Complex rock terrains of Ogun State, Nigeria. Borehole depth, static water level, discharge and drawdown were evaluated to determine the hydrogeological and hydraulic properties of the aquifers. Specific capacity of the boreholes was estimated at one hour using discharge and drawdown values. Most boreholes in the sedimentary terrain explored shallower aquifers of < 100 m, while most boreholes in the Basement Complex rock terrain explored deeper aquifers > 100 m. The sedimentary rock aquifers had thinner groundwater storage of 65.28 m and average borehole yield of 43.51 m 3 hr −1 , while the Basement Complex rock aquifers had thicker groundwater storage of 95.02 m and average borehole yield of 5.53 m 3 hr −1 . The average efficiency of boreholes in the sedimentary and Basement Complex rock terrains were 0.66 and 7.14 m 2 hr −1 , respectively. Boreholes within Basement Complex rocks had higher efficiency than those within sedimentary rocks. Adequate groundwater occurs in the sedimentary and Basement Complex rock terrains for domestic, industrial and agricultural purposes. The groundwater is weakly acidic with small amount of TDS, hence falls within the fresh water category. The groundwater is not potable but could serve domestic and general purposes.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69270917","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 an electrolytic water treatment, electrode reactions for pollutant removal can be easily controlled by changing an electrode potential. Thereby, it has a potential to realize an efficient water treatment process. However, its coulombic efficiency, η , strongly depends on reactant concentrations near electrodes. In a continuous electrolysis, the reactant concentrations near an electrode is lower than that in the bulk due to electrolytic consumption of reactant, which gives a negative impact on the η . Therefore, an introduction of intermittent electrolysis instead of the conventional continuous one was discussed in this research, where the reactant concentration near the electrode is recovered during the electrolysis-off stage. The intermittent electrolysis of 1 mM formic acid solution revealed that the η of formic acid removal under electrolysis-on/off time cycle of 1/10 s was 3.3 times higher than that under the continuous electrolysis. A popular technique to keep the reactant concentration near the electrode is an increase in the linear velocity of solution on the electrode. However, the η at a linear velocity of 20 cm/s was only ≤ 25% higher than that at 10 cm/s. Thus, the intermittent electrolysis was very effective in enhancing the energy-efficiency of electrolytic water treatment.
{"title":"Effect of Intermittent Electrolysis on Electrolytic Removal of an Organic Pollutant","authors":"N. Kishimoto, Atsuya Kitamura","doi":"10.2965/jwet.22-053","DOIUrl":"https://doi.org/10.2965/jwet.22-053","url":null,"abstract":"In an electrolytic water treatment, electrode reactions for pollutant removal can be easily controlled by changing an electrode potential. Thereby, it has a potential to realize an efficient water treatment process. However, its coulombic efficiency, η , strongly depends on reactant concentrations near electrodes. In a continuous electrolysis, the reactant concentrations near an electrode is lower than that in the bulk due to electrolytic consumption of reactant, which gives a negative impact on the η . Therefore, an introduction of intermittent electrolysis instead of the conventional continuous one was discussed in this research, where the reactant concentration near the electrode is recovered during the electrolysis-off stage. The intermittent electrolysis of 1 mM formic acid solution revealed that the η of formic acid removal under electrolysis-on/off time cycle of 1/10 s was 3.3 times higher than that under the continuous electrolysis. A popular technique to keep the reactant concentration near the electrode is an increase in the linear velocity of solution on the electrode. However, the η at a linear velocity of 20 cm/s was only ≤ 25% higher than that at 10 cm/s. Thus, the intermittent electrolysis was very effective in enhancing the energy-efficiency of electrolytic water treatment.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69270985","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. Masuda, F. Takakai, K. Okano, Sota Takeda, D. D. Pham, N. Miyata, Toru Watanabe
As the need for sustainable rice cultivation increases, irrigation with treated sewage effluent (TSE) has become a reasonable solution and its impact on the emission of greenhouse gas (GHG), CH 4 and N 2 O, has gained increasing attention. Despite TSE containing dissolved GHGs, previous studies have not focused on the spatiotemporal profile and impact of TSEs on GHG assessments. Therefore, we conducted an experiment with the pilot-scale reactor using TSE irrigation to assess the importance of the dissolved GHG profiles. The TSE originally contained dissolved CH 4 and N 2 O. The results showed that the dissolved CH 4 concentrations in the TSE were higher than those in the paddy fields. Although the TSE contained dissolved N 2 O, it was also produced in the soils. Moreover, microorganisms, such as Candidatus Nitrotoga arctica and Methanospirillum , became dominant species. Our study demonstrates that measuring the spatiotemporal profiles of dissolved GHGs in paddy fields, as well as in TSE, can lead to more reliable GHG monitoring by assessing the dissolved GHGs in the inflow and outflow of paddy fields.
{"title":"Evaluation of Dissolved Greenhouse Gas Profiles in Paddy Fields Irrigated with Treated Sewage Effluent","authors":"S. Masuda, F. Takakai, K. Okano, Sota Takeda, D. D. Pham, N. Miyata, Toru Watanabe","doi":"10.2965/jwet.21-147","DOIUrl":"https://doi.org/10.2965/jwet.21-147","url":null,"abstract":"As the need for sustainable rice cultivation increases, irrigation with treated sewage effluent (TSE) has become a reasonable solution and its impact on the emission of greenhouse gas (GHG), CH 4 and N 2 O, has gained increasing attention. Despite TSE containing dissolved GHGs, previous studies have not focused on the spatiotemporal profile and impact of TSEs on GHG assessments. Therefore, we conducted an experiment with the pilot-scale reactor using TSE irrigation to assess the importance of the dissolved GHG profiles. The TSE originally contained dissolved CH 4 and N 2 O. The results showed that the dissolved CH 4 concentrations in the TSE were higher than those in the paddy fields. Although the TSE contained dissolved N 2 O, it was also produced in the soils. Moreover, microorganisms, such as Candidatus Nitrotoga arctica and Methanospirillum , became dominant species. Our study demonstrates that measuring the spatiotemporal profiles of dissolved GHGs in paddy fields, as well as in TSE, can lead to more reliable GHG monitoring by assessing the dissolved GHGs in the inflow and outflow of paddy fields.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69270852","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}
{"title":"The Impact of COVID-19 Lockdown on People’s Mobility and Water Quality of Siak River, Indonesia","authors":"Saberina Hasibuan, M. Hasibuan, Alana Jakob","doi":"10.2965/jwet.21-178","DOIUrl":"https://doi.org/10.2965/jwet.21-178","url":null,"abstract":"","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69270928","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}
Operating temperature significantly affects biogas output, process stability, and microbial communi ties involved in anaerobic digestion. There are several unanswered questions regarding how microbial communities adapt in correlation with biogas production performance, especially when a digester fails to maintain thermophilic conditions. In this study, long-term lab-scale anaerobic digestion was carried out using two fed-batch reactors at 55°C, with subsequent decreases in temperature to 48°C and 45°C. Within the first month of incubation, methane (CH 4 ) production increased by approximately 11.18% following a reduction in temperature from 55°C to 48°C. However, the methane production decreased by 33% after the temperature was downshifted to 45°C. Despite the difference in methane production, the thermophilic methanogen population in both reactors declined significantly in the first month with a temperature decrease. After two months of incubation, these methanogenic com munities recovered faster at 48°C than at 45°C, which was highlighted by the rapid colonization of Methanosaeta , Methanobacterium, and Methanothermobacter . Notably, Methanosaeta was the most abundant methanogen under all temperature conditions, indicating its thermotolerance.
{"title":"An Investigation of Temperature Downshift Influences on Anaerobic Digestion in the Treatment of Municipal Wastewater Sludge","authors":"G. A. W. Sudiartha, T. Imai","doi":"10.2965/jwet.22-056","DOIUrl":"https://doi.org/10.2965/jwet.22-056","url":null,"abstract":"Operating temperature significantly affects biogas output, process stability, and microbial communi ties involved in anaerobic digestion. There are several unanswered questions regarding how microbial communities adapt in correlation with biogas production performance, especially when a digester fails to maintain thermophilic conditions. In this study, long-term lab-scale anaerobic digestion was carried out using two fed-batch reactors at 55°C, with subsequent decreases in temperature to 48°C and 45°C. Within the first month of incubation, methane (CH 4 ) production increased by approximately 11.18% following a reduction in temperature from 55°C to 48°C. However, the methane production decreased by 33% after the temperature was downshifted to 45°C. Despite the difference in methane production, the thermophilic methanogen population in both reactors declined significantly in the first month with a temperature decrease. After two months of incubation, these methanogenic com munities recovered faster at 48°C than at 45°C, which was highlighted by the rapid colonization of Methanosaeta , Methanobacterium, and Methanothermobacter . Notably, Methanosaeta was the most abundant methanogen under all temperature conditions, indicating its thermotolerance.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69271035","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}
{"title":"Application of Integrated Hydro-Hydraulic Model to Assess the Impact of Infrastructure on Flood Drainage Issue −Case Study for The Downstream of Kone-Ha Thanh River Basin","authors":"C. K. Tran, Duc Anh Do","doi":"10.2965/jwet.21-139","DOIUrl":"https://doi.org/10.2965/jwet.21-139","url":null,"abstract":"","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69270824","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}
Pub Date : 2021-05-19DOI: 10.26434/CHEMRXIV.14608164.V1
K. Noro, Y. Yabuki, J. Ono, S. Nakamura
A polar organic chemical integrative sampler (POCIS) was developed for the detection of linear alkylbenzene sulfonates (LASs), which are one of the most widely used chemicals globally and represent a type of surfactant agent. Owing to natural disasters and accidents, these LASs have a potential risk to leak into aquatic environments at high concentrations, and thus far, passive sampling methods have not yet been applied in their detection as, being a sorptive compound, they do not easily permeate the membrane of passive samplers. In the present study, the LASs were significantly sorbed onto the polyethersulfonate (PES) membrane, suggesting that the less sorptive polytetrafluoroethylene (PTFE) membrane is suitable for application in the POCIS device. Calibration experiments showed that the developed POCIS device with Oasis WAX as the sorbent and PTFE as the membrane filter had linear ranges > 28 d and sampling rates ranging from 0.035 ± 0.007 (tetradecylbenzenesulfonate) to 0.139 ± 0.024 (dodecylbenzenesulfonate) L d–1. Furthermore, this developed POCIS device was validated under non-steady-state conditions via both chamber and field tests. The condition in the chamber test replicated the LAS concentration change in rivers contaminated by LAS-leaked accidents. The time-weighted average concentrations of dodecylbenzenesulfonate measured using the improved POCIS agreed well with those obtained via grab sampling within 21% over the sampling period of 14 d in both the chamber and field tests. Therefore, the developed POCIS can be successfully applied in the detection of LASs in LAS-contaminated aquatic environments owing to chemical leak accidents.
{"title":"Development and Evaluation of the Performance of the Polar Organic Chemical Integrative Sampler for Linear Alkylbenzene Sulfonate","authors":"K. Noro, Y. Yabuki, J. Ono, S. Nakamura","doi":"10.26434/CHEMRXIV.14608164.V1","DOIUrl":"https://doi.org/10.26434/CHEMRXIV.14608164.V1","url":null,"abstract":"A polar organic chemical integrative sampler (POCIS) was developed for the detection of linear alkylbenzene sulfonates (LASs), which are one of the most widely used chemicals globally and represent a type of surfactant agent. Owing to natural disasters and accidents, these LASs have a potential risk to leak into aquatic environments at high concentrations, and thus far, passive sampling methods have not yet been applied in their detection as, being a sorptive compound, they do not easily permeate the membrane of passive samplers. In the present study, the LASs were significantly sorbed onto the polyethersulfonate (PES) membrane, suggesting that the less sorptive polytetrafluoroethylene (PTFE) membrane is suitable for application in the POCIS device. Calibration experiments showed that the developed POCIS device with Oasis WAX as the sorbent and PTFE as the membrane filter had linear ranges > 28 d and sampling rates ranging from 0.035 ± 0.007 (tetradecylbenzenesulfonate) to 0.139 ± 0.024 (dodecylbenzenesulfonate) L d–1. Furthermore, this developed POCIS device was validated under non-steady-state conditions via both chamber and field tests. The condition in the chamber test replicated the LAS concentration change in rivers contaminated by LAS-leaked accidents. The time-weighted average concentrations of dodecylbenzenesulfonate measured using the improved POCIS agreed well with those obtained via grab sampling within 21% over the sampling period of 14 d in both the chamber and field tests. Therefore, the developed POCIS can be successfully applied in the detection of LASs in LAS-contaminated aquatic environments owing to chemical leak accidents.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44036750","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}
V. Nguyen, V. Le, Thi Thu Ha Nguyen, X. H. Nguyen, V. Nguyen, H. Harada, M. Terashima, H. Yasui
Ascertaining peak oxygen demand is crucial for plant designers to determine blower capacities of wastewater treatment plants in planning phase. To obtain this technical information without cumbersome influent sampling and analysis, a set of field-test activated sludge reactors equipped with DO and nitrate-N sensors was installed at 3 sites and continuously operated for a couple of months in each field. Under the controlled aeration and hydraulics of the reactors, the hourly influent oxygen demands were back-calculated as biodegradable constituents using the IWA-Activated Sludge Model #1. The daily maximum concentrations (rounded to last for 1-hour) of biodegradable organics and nitrogen were ranged between 45~258 mg-COD/L and 10.4~32.3 mg-N/L in Site #1; 119~244 mg-COD/L and 28.3~38.7 mg-N/L in Site #2; 194~552 mg-COD/L and 30.2~51.7 mg-N/L in Site #3 respectively. The marginal blower capacities to maintain at least 1.0 mg-O2/L of DO in the daily maximum oxygen demand were estimated based on the datasets using the statistical method, Extreme Value Distribution analysis. To maintain the DO concentration for 99 days out of 100 days of the plant operations, the blower capacity was supposed to be designed as high as 1.4~2.2 times than those of the blower calculated from the daily average concentration.
{"title":"A Novel Method to Determine Blower Capacity of Wastewater Treatment Plants for Dry and Wet Weather Conditions","authors":"V. Nguyen, V. Le, Thi Thu Ha Nguyen, X. H. Nguyen, V. Nguyen, H. Harada, M. Terashima, H. Yasui","doi":"10.2965/jwet.20-138","DOIUrl":"https://doi.org/10.2965/jwet.20-138","url":null,"abstract":"Ascertaining peak oxygen demand is crucial for plant designers to determine blower capacities of wastewater treatment plants in planning phase. To obtain this technical information without cumbersome influent sampling and analysis, a set of field-test activated sludge reactors equipped with DO and nitrate-N sensors was installed at 3 sites and continuously operated for a couple of months in each field. Under the controlled aeration and hydraulics of the reactors, the hourly influent oxygen demands were back-calculated as biodegradable constituents using the IWA-Activated Sludge Model #1. The daily maximum concentrations (rounded to last for 1-hour) of biodegradable organics and nitrogen were ranged between 45~258 mg-COD/L and 10.4~32.3 mg-N/L in Site #1; 119~244 mg-COD/L and 28.3~38.7 mg-N/L in Site #2; 194~552 mg-COD/L and 30.2~51.7 mg-N/L in Site #3 respectively. The marginal blower capacities to maintain at least 1.0 mg-O2/L of DO in the daily maximum oxygen demand were estimated based on the datasets using the statistical method, Extreme Value Distribution analysis. To maintain the DO concentration for 99 days out of 100 days of the plant operations, the blower capacity was supposed to be designed as high as 1.4~2.2 times than those of the blower calculated from the daily average concentration.","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":"69269372","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}
Shuai Zhou, Manae Ninoseki, Asahi Kusaba, Kazuma Nakagawa, T. Urase
Membrane bioreactor-reverse osmosis process (MBR-RO) is widely applied in wastewater treatment, especially when high-quality treated water is needed. Although MBR shows better performances in the removal of pathogens than the conventional activated sludge process, stable operation of RO process in the latter step of MBR-RO depends on residual bacteria in the filtrate of microfiltration membranes. Species and sizes of bacteria found in the filtrate of activated sludge with 0.2 μm pore-size polycarbonate membranes were investigated in this study. Isolated bacterial species grown on R2A agar medium were identified based on the full length 16S rRNA gene sequences. The result showed that approximately 90% of the isolates found in the filtrates were members of phylum Pro teobacteria in which Ralstonia spp., Achromobacter spp., Methylobacterium spp. and Methylorubrum spp. accounted for the largest proportions while other bacteria affiliated with phyla Actinobacteria and Firmicutes. The leakage of Ralstonia and Actinobacteria was probably due to their small sizes judging from microscopic observation, while a longer filtration time is needed for Methylobacterium and Methylorubrum to be detected in the filtrate.
{"title":"Bacterial Species Identified in the Filtrate of Microfiltration Membranes in the Separation of Activated Sludge","authors":"Shuai Zhou, Manae Ninoseki, Asahi Kusaba, Kazuma Nakagawa, T. Urase","doi":"10.2965/jwet.21-086","DOIUrl":"https://doi.org/10.2965/jwet.21-086","url":null,"abstract":"Membrane bioreactor-reverse osmosis process (MBR-RO) is widely applied in wastewater treatment, especially when high-quality treated water is needed. Although MBR shows better performances in the removal of pathogens than the conventional activated sludge process, stable operation of RO process in the latter step of MBR-RO depends on residual bacteria in the filtrate of microfiltration membranes. Species and sizes of bacteria found in the filtrate of activated sludge with 0.2 μm pore-size polycarbonate membranes were investigated in this study. Isolated bacterial species grown on R2A agar medium were identified based on the full length 16S rRNA gene sequences. The result showed that approximately 90% of the isolates found in the filtrates were members of phylum Pro teobacteria in which Ralstonia spp., Achromobacter spp., Methylobacterium spp. and Methylorubrum spp. accounted for the largest proportions while other bacteria affiliated with phyla Actinobacteria and Firmicutes. The leakage of Ralstonia and Actinobacteria was probably due to their small sizes judging from microscopic observation, while a longer filtration time is needed for Methylobacterium and Methylorubrum to be detected in the filtrate.","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":"69270732","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}
The results of acute test on suppression of Daphnia magna filtration activity for one toxicant (K 2 Cr 2 O 7 , ZnSO 4 and MnSO 4 ) were applied to carry out acute binary tests for 3 binary solutions: “Cr-Mn”, “Cr-Zn” and “Cr-Zn”, where the daphnids were exposed for 1, 2, 3, 4 and 5 hs. While the level of toxicity manifested by the “Cr-Mn” binary systems was lower than “additive”, the results that were observed in the binary solution of “Cr-Zn”, especially for the shorter exposure time of 1–3 hours, showed toxicity above “additive”. A nearly “additive effect” was observed in the binary solution of “Zn- Mn”. We supposed that the theory of metals competing for binding to biotic ligands or any yet unidentified physiological interactions of the metals could explain the toxicity effect on filtration activity of D. magna exposed in three binary solutions. So, the more-than-additive effect for the “Cr-Zn” binary system may indicate that Zn (II) demonstrated its high ability building up protein complexes due to competition with Cr (VI). The less-than-additive toxicity for the “Cr-Mn” solution likely revealed the fact that bioavailability of Cr (VI) to D. magna was reduced in the presence of Mn (II).
{"title":"Developing the Acute Bioassay on Suppression of Daphnia magna Filtration by Fluorescence Measurement","authors":"E. Ginatullina, Kohei Yamagata, M. Kamaya","doi":"10.2965/jwet.20-161","DOIUrl":"https://doi.org/10.2965/jwet.20-161","url":null,"abstract":"The results of acute test on suppression of Daphnia magna filtration activity for one toxicant (K 2 Cr 2 O 7 , ZnSO 4 and MnSO 4 ) were applied to carry out acute binary tests for 3 binary solutions: “Cr-Mn”, “Cr-Zn” and “Cr-Zn”, where the daphnids were exposed for 1, 2, 3, 4 and 5 hs. While the level of toxicity manifested by the “Cr-Mn” binary systems was lower than “additive”, the results that were observed in the binary solution of “Cr-Zn”, especially for the shorter exposure time of 1–3 hours, showed toxicity above “additive”. A nearly “additive effect” was observed in the binary solution of “Zn- Mn”. We supposed that the theory of metals competing for binding to biotic ligands or any yet unidentified physiological interactions of the metals could explain the toxicity effect on filtration activity of D. magna exposed in three binary solutions. So, the more-than-additive effect for the “Cr-Zn” binary system may indicate that Zn (II) demonstrated its high ability building up protein complexes due to competition with Cr (VI). The less-than-additive toxicity for the “Cr-Mn” solution likely revealed the fact that bioavailability of Cr (VI) to D. magna was reduced in the presence of Mn (II).","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":"69271019","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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