We conducted ecological risk assessment of copper in coastal areas of Japan. For risk assessment, we used a method in the initial environmental risk assessment conducted by the Ministry of the Environment, Japan, and several methods considering bioavailability, used for setting water quality criteria in Europe and the United States. The hazard quotient （ HQ ） method was used for risk characterization. Risk assessment was conducted using 1,622 copper concentration values from the Japanese coastal areas over the past 31 years that we were able to collect. As a result, the area with HQ exceeding 1 was 70.2% of the total in the screening level evaluation; considering bioavailability, it was 3.6 to 4.0%, and the risk characterization result changed depending on the hazard assessment method. Also, considering bioavailability, it was clear that there is a difference in the risk characterization result because water quality varies depending on the location even within the same bay. These results suggest that it is important to obtain toxicological data of species inhabiting Japan and copper concentrations in Japanese coastal areas and to examine what kind of evaluation method should be used for risk assessment.
{"title":"Ecological Risk Assessment of Copper in Coastal Areas of Japan: How will Bioavailability Considerations Change the Assessment Results?","authors":"R. Tai, W. Naito, S. Masunaga","doi":"10.2965/JSWE.42.105","DOIUrl":"https://doi.org/10.2965/JSWE.42.105","url":null,"abstract":"We conducted ecological risk assessment of copper in coastal areas of Japan. For risk assessment, we used a method in the initial environmental risk assessment conducted by the Ministry of the Environment, Japan, and several methods considering bioavailability, used for setting water quality criteria in Europe and the United States. The hazard quotient （ HQ ） method was used for risk characterization. Risk assessment was conducted using 1,622 copper concentration values from the Japanese coastal areas over the past 31 years that we were able to collect. As a result, the area with HQ exceeding 1 was 70.2% of the total in the screening level evaluation; considering bioavailability, it was 3.6 to 4.0%, and the risk characterization result changed depending on the hazard assessment method. Also, considering bioavailability, it was clear that there is a difference in the risk characterization result because water quality varies depending on the location even within the same bay. These results suggest that it is important to obtain toxicological data of species inhabiting Japan and copper concentrations in Japanese coastal areas and to examine what kind of evaluation method should be used for risk assessment.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82113270","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}
We investigated the loads of suspended solids （ SS ） , total （ TN ） and dissolved （ DN ） nitrogen during an extreme storm event （ total rainfall, 742 mm ） on 18 and 19 July 2011 in a forested mountain headwater catchment of the Shimanto River in the western part of Kochi Prefecture, Japan. We compared the extreme storm event with the normal event （ total rainfall, below 100 mm ） and the storm event （ total rainfall, 100 – 300 mm ） . The experimental catchment （ 73 ha ） has an underlayer of sandstone and is mainly covered with a secondary forest that comprises evergreen trees. Samples of streamwater were collected every two hours using an automatic water sampler during six events （ total rainfall, 44 – 742 mm ） . The load of TN during the extreme storm event was about 5 kg ha -1 event -1 , which is similar to the domestic average annual TN load （ 4.9 kg ha -1 yr -1 ） . The proportion of DN to TN in the specific cumulative load decreased sharply from 97% – 99% in the normal event and 77% – 97% in the storm event to 5% in the extreme storm event phase. The results clearly show that the load of particulate nitrogen was markedly greater than the load of DN during the extreme storm event.
研究了2011年7月18日和19日在日本高知县西部岛曼托河森林山源集水区发生的一次极端暴雨事件(总降雨量为742 mm)中悬浮固体(SS)、总氮(TN)和溶解氮(DN)的负荷。我们将极端风暴事件与正常事件(总降雨量，低于100毫米)和风暴事件(总降雨量，100 - 300毫米)进行了比较。实验集水区(73公顷)有砂岩的下层，主要覆盖着由常绿树木组成的次生林。在6个事件(总降雨量44 - 742毫米)中，使用自动水采样器每两小时采集一次溪水样本。极端风暴期间全氮负荷约为5 kg ha -1 event -1，与国内年均全氮负荷(4.9 kg ha -1 yr -1)相近。DN / TN在比累积负荷中的比例从正常期的97% ~ 99%和风暴期的77% ~ 97%急剧下降到极端风暴期的5%。结果清楚地表明，在极端风暴事件中，颗粒氮的负荷明显大于DN的负荷。
{"title":"Nutrients Runoff from a Forested Catchment during an Extreme Storm Event: A Case Study of the Headwaters of the Shimanto River in the Western Part of Kochi Prefecture, Japan in July, 2011","authors":"Yoshiki Shinomiya, Yuichi Yokoyama","doi":"10.2965/jswe.42.219","DOIUrl":"https://doi.org/10.2965/jswe.42.219","url":null,"abstract":"We investigated the loads of suspended solids （ SS ） , total （ TN ） and dissolved （ DN ） nitrogen during an extreme storm event （ total rainfall, 742 mm ） on 18 and 19 July 2011 in a forested mountain headwater catchment of the Shimanto River in the western part of Kochi Prefecture, Japan. We compared the extreme storm event with the normal event （ total rainfall, below 100 mm ） and the storm event （ total rainfall, 100 – 300 mm ） . The experimental catchment （ 73 ha ） has an underlayer of sandstone and is mainly covered with a secondary forest that comprises evergreen trees. Samples of streamwater were collected every two hours using an automatic water sampler during six events （ total rainfall, 44 – 742 mm ） . The load of TN during the extreme storm event was about 5 kg ha -1 event -1 , which is similar to the domestic average annual TN load （ 4.9 kg ha -1 yr -1 ） . The proportion of DN to TN in the specific cumulative load decreased sharply from 97% – 99% in the normal event and 77% – 97% in the storm event to 5% in the extreme storm event phase. The results clearly show that the load of particulate nitrogen was markedly greater than the load of DN during the extreme storm event.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80690072","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}
To clarify the origin of lead （ Pb ） in an irrigation reservoir with a shooting range in upstream, sediments of a small stream located in the shooting range, sediments and soil from upstream of the shooting range, sediments in the irrigation reservoir, and river water have been observed. It is well known that the Pb stable isotope ratio has an original value in each Pb mine. The Pb stable isotope ratios in soil and sediment were totally different between the samples from upstream and downstream of the shooting range. On the basis of the composition ratios of Pb and other metals （ zinc and copper ） used in the brass coating of bullets, the distance index （ D.I. ） was calculated and the results were applied for cluster analysis. Both D.I. and cluster analysis results indicated that soil and sediment samples from the upstream and downstream are clearly different. Our results indicate that our integrated approach of using the Pb isotope ratio, D.I. and cluster analysis is a good indicator of the origin of Pb contamination in soil and sediment.
{"title":"Investigation on Cause of Lead Contamination in Irrigation Reservoir under Shooting Range Using Lead Isotope Ratio","authors":"O. Nagafuchi, K. Nakazawa, Ken’ichi Shinozuka","doi":"10.2965/JSWE.42.35","DOIUrl":"https://doi.org/10.2965/JSWE.42.35","url":null,"abstract":"To clarify the origin of lead （ Pb ） in an irrigation reservoir with a shooting range in upstream, sediments of a small stream located in the shooting range, sediments and soil from upstream of the shooting range, sediments in the irrigation reservoir, and river water have been observed. It is well known that the Pb stable isotope ratio has an original value in each Pb mine. The Pb stable isotope ratios in soil and sediment were totally different between the samples from upstream and downstream of the shooting range. On the basis of the composition ratios of Pb and other metals （ zinc and copper ） used in the brass coating of bullets, the distance index （ D.I. ） was calculated and the results were applied for cluster analysis. Both D.I. and cluster analysis results indicated that soil and sediment samples from the upstream and downstream are clearly different. Our results indicate that our integrated approach of using the Pb isotope ratio, D.I. and cluster analysis is a good indicator of the origin of Pb contamination in soil and sediment.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90589708","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. Furukawa, M. Hatamoto, Jun Kusaka, Kawamata Mutsumi, M. Mori, T. Hoaki, Takashi Yamaguchi
The effect of sponge-pore size for a combined downflow hanging sponge (DHS) and upflow sludge blanket (USB) filtering system for the nitrification and denitrification, respectively, of a marine aquaculture system was evaluated. The nitrifying DHS reactor maintained the concentrations of total ammonia nitrogen and NO2 -N of the breeding water at 0.08 mg-N L and 0.05 mg-N L, respectively. The DO concentration in the breeding water was about 6.17 mg L without direct aeration of the tank. Despite the high DO of the denitrifying USB reactor influent, the nitrogen-removal performance was good and the NO3 -N concentration in the breeding water was maintained below the theoretical value. Regarding the effect of sponge-pore size for nitrification by the DHS reactor, the sponge with the smallest pore size, named CFH-30, had the fastest nitrification rate and sludge growth rate. Microbial community analysis of sludge contained in sponge revealed that sponge with the largest pore size had the highest detection rates for ammoniaoxidizing archaea and nitrite-oxidizing bacteria.
{"title":"Evaluation of Nitrification Performance Using Nitrifying-DHS Reactor with Various Sponge-Pore Sizes for Breeding Tank of Marine Aquaria","authors":"A. Furukawa, M. Hatamoto, Jun Kusaka, Kawamata Mutsumi, M. Mori, T. Hoaki, Takashi Yamaguchi","doi":"10.2965/JSWE.42.7","DOIUrl":"https://doi.org/10.2965/JSWE.42.7","url":null,"abstract":"The effect of sponge-pore size for a combined downflow hanging sponge (DHS) and upflow sludge blanket (USB) filtering system for the nitrification and denitrification, respectively, of a marine aquaculture system was evaluated. The nitrifying DHS reactor maintained the concentrations of total ammonia nitrogen and NO2 -N of the breeding water at 0.08 mg-N L and 0.05 mg-N L, respectively. The DO concentration in the breeding water was about 6.17 mg L without direct aeration of the tank. Despite the high DO of the denitrifying USB reactor influent, the nitrogen-removal performance was good and the NO3 -N concentration in the breeding water was maintained below the theoretical value. Regarding the effect of sponge-pore size for nitrification by the DHS reactor, the sponge with the smallest pore size, named CFH-30, had the fastest nitrification rate and sludge growth rate. Microbial community analysis of sludge contained in sponge revealed that sponge with the largest pore size had the highest detection rates for ammoniaoxidizing archaea and nitrite-oxidizing bacteria.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90459332","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}
Y. Iwasaki, H. Honda, Tohru Nishioka, Y. Ishikawa, Masayuki Yamane
Nationwide evaluation of the exceedance of environmental water quality standards （ EQS ） in the water environment plays a key role in establishing EQSs and effluent regulations. To understand the characteristics of river sites with annual mean concentrations of linear alkylbenzene sulfonate （ LAS ） that exceed the EQS, we compared （ 1 ） channel width as an indicator of river size, （ 2 ） surrounding land use, and （ 3 ） biochemical oxygen demand （ BOD ） as an indicator of organic pollution between “LAS-contaminated sites” with annual mean LAS concentrations of > 0.02 mg L -1 and “uncontaminated sites” with concentrations of ≤ 0.02 mg L -1 using water quality monitoring results from 2015-2016. Results indicated that, compared with uncontaminated sites, LAS-contaminated sites were found more frequently （ 1 ） in rivers with smaller and less variable channel width, （ 2 ） in rivers located in urban and residential areas with less forested and agricultural areas, and （ 3 ） in organic-polluted rivers indicated by higher annual mean of BOD. Generally, aquatic organisms in the natural environment are affected by many physicochemical factors including chemicals. Thus, as we demonstrated, the investigation of the physicochemical characteristics of water quality monitoring sites with higher concentrations of the chemicals of concern is valuable for evaluating management options that are substantially effective for protecting aquatic life.
在全国范围内开展水环境水质超标评价是制定环境水质标准和污水排放法规的关键。为了了解线性烷基苯磺酸盐(LAS)年平均浓度超过EQS的河流站点的特征，我们比较了(1)河道宽度(作为河流大小的指标)，(2)周围土地利用，(3)生化需氧量(BOD)作为2015-2016年平均LAS浓度> 0.02 mg L -1的“LAS污染场地”与浓度≤0.02 mg L -1的“未污染场地”的有机污染指标。结果表明，与未污染的河流相比，las污染的河流出现频率更高:(1)河道宽度较小且变化较小的河流，(2)位于城市和居民区的河流，森林和农业区较少，(3)在有机污染的河流中，BOD的年平均值较高。一般来说，自然环境中的水生生物受到包括化学物质在内的许多物理化学因素的影响。因此，正如我们所证明的那样，对关注的化学物质浓度较高的水质监测点的物理化学特征进行调查，对于评估对保护水生生物实质上有效的管理选择是有价值的。
{"title":"Characteristics of River Sites with Elevated Concentrations of Linear Alkylbenzene Sulfonate: Implications for Water Environmental Management for Protection of Aquatic Life","authors":"Y. Iwasaki, H. Honda, Tohru Nishioka, Y. Ishikawa, Masayuki Yamane","doi":"10.2965/jswe.42.201","DOIUrl":"https://doi.org/10.2965/jswe.42.201","url":null,"abstract":"Nationwide evaluation of the exceedance of environmental water quality standards （ EQS ） in the water environment plays a key role in establishing EQSs and effluent regulations. To understand the characteristics of river sites with annual mean concentrations of linear alkylbenzene sulfonate （ LAS ） that exceed the EQS, we compared （ 1 ） channel width as an indicator of river size, （ 2 ） surrounding land use, and （ 3 ） biochemical oxygen demand （ BOD ） as an indicator of organic pollution between “LAS-contaminated sites” with annual mean LAS concentrations of > 0.02 mg L -1 and “uncontaminated sites” with concentrations of ≤ 0.02 mg L -1 using water quality monitoring results from 2015-2016. Results indicated that, compared with uncontaminated sites, LAS-contaminated sites were found more frequently （ 1 ） in rivers with smaller and less variable channel width, （ 2 ） in rivers located in urban and residential areas with less forested and agricultural areas, and （ 3 ） in organic-polluted rivers indicated by higher annual mean of BOD. Generally, aquatic organisms in the natural environment are affected by many physicochemical factors including chemicals. Thus, as we demonstrated, the investigation of the physicochemical characteristics of water quality monitoring sites with higher concentrations of the chemicals of concern is valuable for evaluating management options that are substantially effective for protecting aquatic life.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75941291","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}
It has been pointed out that some waterbodies face “oligotrophication” owing to a decrease in nutrient loads. In this study, we predicted the effect of a change in future nutrient loads on variables such as the biomass of upper-trophic-level species, using the food chain model. The target area is Lake Biwa, where fish catches have fallen in recent years concurrent with a decrease in nutrient loads. Three models with different structures were developed and 100 patterns of parameter sets were selected for each model by the Monte Carlo method. As a result, the change in the biomass of phytoplankton, regardless of the model structure, tended to be roughly proportional to the change in nutrient loads in general. On the other hand, for the fish, differences in model structures and their prey strongly affected the biomass, and although inflow load increased, the biomass decreased in some cases. Considering the uncertainty of the prediction, we suggested that the addition of nutrients with the aim of increasing the fish populations would cause undesirable results in Lake Biwa such as a combination of deteriorating water quality and no increase in the fish populations.
{"title":"Effect of Nutrient Loads on Upper Trophic Level Species in Lake Biwa: Analysis Using Food Chain Model by Monte Carlo Method","authors":"Yuichi Sato, K. Hayakawa","doi":"10.2965/jswe.42.133","DOIUrl":"https://doi.org/10.2965/jswe.42.133","url":null,"abstract":"It has been pointed out that some waterbodies face “oligotrophication” owing to a decrease in nutrient loads. In this study, we predicted the effect of a change in future nutrient loads on variables such as the biomass of upper-trophic-level species, using the food chain model. The target area is Lake Biwa, where fish catches have fallen in recent years concurrent with a decrease in nutrient loads. Three models with different structures were developed and 100 patterns of parameter sets were selected for each model by the Monte Carlo method. As a result, the change in the biomass of phytoplankton, regardless of the model structure, tended to be roughly proportional to the change in nutrient loads in general. On the other hand, for the fish, differences in model structures and their prey strongly affected the biomass, and although inflow load increased, the biomass decreased in some cases. Considering the uncertainty of the prediction, we suggested that the addition of nutrients with the aim of increasing the fish populations would cause undesirable results in Lake Biwa such as a combination of deteriorating water quality and no increase in the fish populations.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76175400","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 was aimed at investigating the influence of a sewage treatment plant’s seasonal operation on the water quality and nutrient transport of a tidal river. Cross-sectional observations were carried out in the Honjoe River, which flows into Ariake Bay in Japan. Field surveys and experiments focusing on the transport of ammonium nitrogen （ NH 4 + -N ） in the tidal river were performed. As a result, suspended solid （ SS ） sediment formation close to the river, including in the vegetation areas, was accelerated and exhibited the potential local accumulation of NH 4 + -N with SS. In addition, some experiments revealed an empirical equation for the removal rate of NH 4 + -N. According to the equation, the NH 4 + -N sedimentation rates tended to be low when the salinity and initial SS were high. Furthermore, the removal rate of NH 4 + -N calculated using the empirical equation agreed qualitatively with the field results.
{"title":"Consideration of Transport of Ammonium Nitrogen in a Tidal River","authors":"H. Yamanishi, Yuka Aoki","doi":"10.2965/JSWE.42.117","DOIUrl":"https://doi.org/10.2965/JSWE.42.117","url":null,"abstract":"This study was aimed at investigating the influence of a sewage treatment plant’s seasonal operation on the water quality and nutrient transport of a tidal river. Cross-sectional observations were carried out in the Honjoe River, which flows into Ariake Bay in Japan. Field surveys and experiments focusing on the transport of ammonium nitrogen （ NH 4 + -N ） in the tidal river were performed. As a result, suspended solid （ SS ） sediment formation close to the river, including in the vegetation areas, was accelerated and exhibited the potential local accumulation of NH 4 + -N with SS. In addition, some experiments revealed an empirical equation for the removal rate of NH 4 + -N. According to the equation, the NH 4 + -N sedimentation rates tended to be low when the salinity and initial SS were high. Furthermore, the removal rate of NH 4 + -N calculated using the empirical equation agreed qualitatively with the field results.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91433744","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}
Kazumasa Kamachi, H. Shinjô, Y. Tsukamoto, T. Tatsuzawa
It is a challenge to maintain the granular sludge during the treatment of wastewater containing methanol by UASB, since few methanogens can utilize methanol as a substrate. In this study, for the treatment of actual wastewater containing methanol, the change in the microbial community and particle distribution of granular sludge were observed during the acclimatization process of seed granular sludge for the continuous operation of an UASB (Up-flow Anaerobic Sludge Blanket) system with sludge returning after solid-liquid separation. Methanosarcina-like methanogens in the granular sludge became dominant during the acclimatization, and the dominant species was found to be Methanomethylovorans. After their DNA exceeded 80%, the collapse of the granular sludge progressed and the particle diameter became less than 0.5 mm. However, stable performance still could be obtained because of sludge returning after solid-liquid separation, even after the collapse of granular sludge.
{"title":"Disaggregation of Granular Sludge during Methane Fermentation Treatment for Methanol-containing Wastewater","authors":"Kazumasa Kamachi, H. Shinjô, Y. Tsukamoto, T. Tatsuzawa","doi":"10.2965/JSWE.42.67","DOIUrl":"https://doi.org/10.2965/JSWE.42.67","url":null,"abstract":"It is a challenge to maintain the granular sludge during the treatment of wastewater containing methanol by UASB, since few methanogens can utilize methanol as a substrate. In this study, for the treatment of actual wastewater containing methanol, the change in the microbial community and particle distribution of granular sludge were observed during the acclimatization process of seed granular sludge for the continuous operation of an UASB (Up-flow Anaerobic Sludge Blanket) system with sludge returning after solid-liquid separation. Methanosarcina-like methanogens in the granular sludge became dominant during the acclimatization, and the dominant species was found to be Methanomethylovorans. After their DNA exceeded 80%, the collapse of the granular sludge progressed and the particle diameter became less than 0.5 mm. However, stable performance still could be obtained because of sludge returning after solid-liquid separation, even after the collapse of granular sludge.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83437715","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}
Concentrations of neonicotinoids and fipronil in river water were investigated in rural areas, the lower reach of the sewage disposal plant and principal rivers in Osaka Prefecture. As a result, pesticides other than nitenpyram and thiacloprid were detected at all sampling sites. Concentrations of imidacloprid increased drastically in June and concentrations of dinotefuran increased drastically from August to September. These periods were contemporaneous with spraying periods of these pesticides in rice fields. It was determined that none of the pesticide concentrations exceeded the water quality standards in Japan or Predicted Environmental Concentrations (PEC), which were calculated by the Ministry of the Environment, in all survey spots. On the other hand, more than 5% of the aquatic organisms are expected to be affected by neonicotinoids in rural area rivers from late May to June according to the calculation from species sensitivity distribution (SSD) of multiple influence of aquatic arthropods.
{"title":"Investigation of Seasonal Changes and Ecological Risk Assessments of Neonicotinoid Pesticides in Rivers in Osaka, Japan","authors":"K. Oyama, Y. Yabuki, A. Banno","doi":"10.2965/jswe.42.227","DOIUrl":"https://doi.org/10.2965/jswe.42.227","url":null,"abstract":"Concentrations of neonicotinoids and fipronil in river water were investigated in rural areas, the lower reach of the sewage disposal plant and principal rivers in Osaka Prefecture. As a result, pesticides other than nitenpyram and thiacloprid were detected at all sampling sites. Concentrations of imidacloprid increased drastically in June and concentrations of dinotefuran increased drastically from August to September. These periods were contemporaneous with spraying periods of these pesticides in rice fields. It was determined that none of the pesticide concentrations exceeded the water quality standards in Japan or Predicted Environmental Concentrations (PEC), which were calculated by the Ministry of the Environment, in all survey spots. On the other hand, more than 5% of the aquatic organisms are expected to be affected by neonicotinoids in rural area rivers from late May to June according to the calculation from species sensitivity distribution (SSD) of multiple influence of aquatic arthropods.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81669335","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 the present study, we investigated the relationship between 11 properties of digested sludge and the optimal dosage ratio of polymer flocculant, assuming a conditioning process for sludge fed into a dewatering centrifuge. Furthermore, the study was focused on the supernatant phase （ mixed phase of colloidal matter and dissolved matter ） obtained by centrifugal separation of sludge, and a list of the properties of the supernatant phase was created. We then attempted to identify the properties that govern the optimal dosage. As a result, no correlation between total solids and the optimal injection ratio was observed. Therefore, the dosage was defined as the absolute quantity of polymer flocculant per 100 grams of sludge （ g/100 g sludge = % per sludge weight ） . As a result of examining its relationship with various properties, the strongest correlation was observed between the anion concentration of the supernatant phase and the optimal quantity of polymer flocculant, with r=0.73. A correlation was also found between the optimal quantity of polymer flocculant and the turbidity of the supernatant phase （ r=0.68 ） . We thus found that the optimal quantity of polymer flocculant can be predicted simply by centrifuging the raw sludge and measuring the turbidity of the supernatant phase.
{"title":"Setting of Optimal Dosage of Polymer Flocculant in Centrifugal Dewatering Process for Digested Sewage Sludge","authors":"Yoshihiro Suzuki, Keigo Endo, Wakana Taiko, K. Nukazawa, Yuichi Furuhashi, Nobuaki Chuganji","doi":"10.2965/jswe.42.269","DOIUrl":"https://doi.org/10.2965/jswe.42.269","url":null,"abstract":"In the present study, we investigated the relationship between 11 properties of digested sludge and the optimal dosage ratio of polymer flocculant, assuming a conditioning process for sludge fed into a dewatering centrifuge. Furthermore, the study was focused on the supernatant phase （ mixed phase of colloidal matter and dissolved matter ） obtained by centrifugal separation of sludge, and a list of the properties of the supernatant phase was created. We then attempted to identify the properties that govern the optimal dosage. As a result, no correlation between total solids and the optimal injection ratio was observed. Therefore, the dosage was defined as the absolute quantity of polymer flocculant per 100 grams of sludge （ g/100 g sludge = % per sludge weight ） . As a result of examining its relationship with various properties, the strongest correlation was observed between the anion concentration of the supernatant phase and the optimal quantity of polymer flocculant, with r=0.73. A correlation was also found between the optimal quantity of polymer flocculant and the turbidity of the supernatant phase （ r=0.68 ） . We thus found that the optimal quantity of polymer flocculant can be predicted simply by centrifuging the raw sludge and measuring the turbidity of the supernatant phase.","PeriodicalId":16300,"journal":{"name":"Journal of Japan Society on Water Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89489778","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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