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Zhu S.,Tongji University | Yin D.,Tongji University | Gao N.,Tongji University | Zhou S.,Tongji University | And 2 more authors.
Desalination and Water Treatment

Microcystins (MCs) are very stable toxins in water bodies and can be poorly removed by traditional drinking water treatment processes. Powder-activated carbon (PAC) was employed in the present study for removal of two commonly and widely occurring algal toxins, microcystin-LR (MC-LR), and microcystin-RR (MC-RR), which were obtained from cyanobacterial blooms. Results indicated that wood PAC has better adsorption capacity on MCs compared with shell and coal PAC. The Freundlich adsorption model can better describe the adsorption behavior of MCs onto PAC. And the pseudo-second-order kinetic model can better fit the adsorption process of MCs onto PAC. Moreover, the adsorption of MCs onto wood PAC was affected by temperature, pH, and anions. The adsorption rates increased with the decreasing temperature. And the adsorption capacity of wood PAC for MCs decreased with the increasing pH. Four kinds of anion hindered the adsorption and reduced the removal rate by 14–24%. Therefore, our study provides valuable information to address the water quality issues caused by microcystins, including selection of the most efficient PAC. © 2016 Balaban Desalination Publications. All rights reserved. Source

Zhu M.,Tongji University | Zhu M.,Jiangsu Post and Telecommunications Planning and Designing Institute Co. | Gao N.,Tongji University | Chu W.,Tongji University | And 4 more authors.
Ecotoxicology and Environmental Safety

The increasing use of algal-impacted source waters is increasing concerns over exposure to disinfection byproducts (DBPs) in drinking water disinfection, due to the higher concentrations of DBP precursors in these waters. The impact of pre-ozonation on the formation and speciation of DBPs during subsequent chlorination and chloramination of algal organic matter (AOM), including extracellular organic matter (EOM) and intracellular organic matter (IOM), was investigated. During subsequent chlorination, ozonation pretreatment reduced the formation of haloacetonitriles from EOM, but increased the yields of trihalomethanes, dihaloacetic acid and trichloronitromethane from both EOM and IOM. While in chloramination, pre-ozonation remarkably enhanced the yields of several carbonaceous DBPs from IOM, and significantly minimized the nitrogenous DBP precursors. Also, the yield of 1,1-dichloro-2-propanone from IOM was decreased by 24.0% after pre-ozonation during chloramination. Both increases and decreases in the bromine substitution factors (BSF) of AOM were observed with ozone pretreatment at the low bromide level (50. μg/L). However, pre-ozonation played little impact on the bromide substitution in DBPs at the high bromide level (500. μg/L). This information was used to guide the design and practical operation of pre-ozonation in drinking water treatment plants using algae-rich waters. © 2015 Elsevier Inc. Source

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