Disinfection to protect human health occurs at drinking water and wastewater facilities through application of non-selective oxidants including chlorine. Oxidants also transform organic material and form disinfection ...Disinfection to protect human health occurs at drinking water and wastewater facilities through application of non-selective oxidants including chlorine. Oxidants also transform organic material and form disinfection by-products（DBPs）, many of which are halogenated and cyto-and genotoxic. Only a handful of assays have been used to compare DBP toxicity,and researchers are unsure which DBP（s） drive the increased cancer risk associated with drinking chlorinated water. The most extensive data set employs an in vitro model cell,Chinese hamster ovary cells. Traditionally, most DBP research focuses on the threat to human health, but the effects on aquatic species exposed to DBPs in wastewater effluents remain ill defined. We present the developmental toxicity for 15 DBPs and a chlorinated wastewater to a model aquatic vertebrate, zebrafish. Mono-halogenated DBPs followed the in vivo toxicity rank order： acetamides 〉 acetic acids 〉 acetonitriles ~ nitrosamines, which agrees well with previously published mammalian in vitro data. Di-and tri-halogenated acetonitriles were more toxic than their mono-halogenated analogues, and bromine-and iodine-substituted DBPs tended to be more toxic than chlorinated analogues. No zebrafish development effects were observed after exposure to undiluted or non-concentrated,chlorinated wastewater. We find zebrafish development to be a viable in vivo alternative or confirmatory assay to mammalian in vitro cell assays.展开更多
Increasing production and use of carbonaceous nanomaterials （NMs） will increase their release to the sewer system and to municipal wastewater treatment plants. There is little quantitative knowledge on the removal o...Increasing production and use of carbonaceous nanomaterials （NMs） will increase their release to the sewer system and to municipal wastewater treatment plants. There is little quantitative knowledge on the removal of multi-walled carbon nanotubes （MWCNTs）, graphene oxide （GO）, or few-layer graphene （FLG） from wastewater into the wastewater biomass. As such, we investigated the quantification of GO and MWCNTs by UV-Vis spectrophotometry, and FLG using programmable thermal analysis （PTA）, respectively. We further explored the removal of pristine and oxidized MWCNTs （O- MWCNTs）, GO, and FLG in a biomass suspension. At least 96% of pristine and O-MWCNTs were removed from the water phase through aggregation and 30-min settling in presence or absence of biomass with an initial MWCNT concentration of 25mg.L-1. Only 65% of GO was removed with biomass concentration at or above 1,000 mg. L-1 as total suspended solids （TSS） with the initial GO concentration of 25 mg. L-1. As UV-Vis spectrophotometry does not work well on quantification of FLG, we studied the removal of FLG at a lower biomass concentration （50mg TSS-L-1） using PTA, which showed a 16% removal of FLG with an initial concentration of 1 mg ·L-1. The removal data for GO and FLG were fitted using the Freundlich equation （R2 = 0.55, 0.94, respectively）. The data presented in this study for carbonaceous NM removal from wastewater provides quantitative informa- tion for environmental exposure modeling and life cycle assessment.展开更多
基金provided by the US Environmental Protection Agency through the STAR program (RD83558001)provided by the American Water Works Association Abel Wolman Fellowshipthe Water Environment Federation Canham Studies Scholarship
文摘Disinfection to protect human health occurs at drinking water and wastewater facilities through application of non-selective oxidants including chlorine. Oxidants also transform organic material and form disinfection by-products（DBPs）, many of which are halogenated and cyto-and genotoxic. Only a handful of assays have been used to compare DBP toxicity,and researchers are unsure which DBP（s） drive the increased cancer risk associated with drinking chlorinated water. The most extensive data set employs an in vitro model cell,Chinese hamster ovary cells. Traditionally, most DBP research focuses on the threat to human health, but the effects on aquatic species exposed to DBPs in wastewater effluents remain ill defined. We present the developmental toxicity for 15 DBPs and a chlorinated wastewater to a model aquatic vertebrate, zebrafish. Mono-halogenated DBPs followed the in vivo toxicity rank order： acetamides 〉 acetic acids 〉 acetonitriles ~ nitrosamines, which agrees well with previously published mammalian in vitro data. Di-and tri-halogenated acetonitriles were more toxic than their mono-halogenated analogues, and bromine-and iodine-substituted DBPs tended to be more toxic than chlorinated analogues. No zebrafish development effects were observed after exposure to undiluted or non-concentrated,chlorinated wastewater. We find zebrafish development to be a viable in vivo alternative or confirmatory assay to mammalian in vitro cell assays.
文摘Increasing production and use of carbonaceous nanomaterials （NMs） will increase their release to the sewer system and to municipal wastewater treatment plants. There is little quantitative knowledge on the removal of multi-walled carbon nanotubes （MWCNTs）, graphene oxide （GO）, or few-layer graphene （FLG） from wastewater into the wastewater biomass. As such, we investigated the quantification of GO and MWCNTs by UV-Vis spectrophotometry, and FLG using programmable thermal analysis （PTA）, respectively. We further explored the removal of pristine and oxidized MWCNTs （O- MWCNTs）, GO, and FLG in a biomass suspension. At least 96% of pristine and O-MWCNTs were removed from the water phase through aggregation and 30-min settling in presence or absence of biomass with an initial MWCNT concentration of 25mg.L-1. Only 65% of GO was removed with biomass concentration at or above 1,000 mg. L-1 as total suspended solids （TSS） with the initial GO concentration of 25 mg. L-1. As UV-Vis spectrophotometry does not work well on quantification of FLG, we studied the removal of FLG at a lower biomass concentration （50mg TSS-L-1） using PTA, which showed a 16% removal of FLG with an initial concentration of 1 mg ·L-1. The removal data for GO and FLG were fitted using the Freundlich equation （R2 = 0.55, 0.94, respectively）. The data presented in this study for carbonaceous NM removal from wastewater provides quantitative informa- tion for environmental exposure modeling and life cycle assessment.
