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Chu W.,Tongji University | Chu W.,Research and Service Center for Environmental Industry | Yao D.,Tongji University | Gao N.,Tongji University | And 2 more authors.

Pilot-scale tests were performed to reduce the formation of a range of carbonaceous and nitrogenous disinfection by-products (C-, N-DBPs), by removing or transforming their precursors, with an integrated permanganate oxidation and powdered activated carbon adsorption (PM-PAC) treatment process before conventional water treatment processes (coagulation-sedimentation-filtration, abbreviated as CPs). Compared with the CPs, PM-PAC significantly enhanced the removal of DOC, DON, NH3 +-N, and algae from 52.9%, 31.6%, 71.3%, and 83.6% to 69.5%, 61.3%, 92.5%, and 97.5%, respectively. PM pre-oxidation alone and PAC pre-adsorption alone did not substantially reduce the formation of dichloroacetonitrile, trichloroacetonitrile, N-nitrosodimethylamine and dichloroacetamide. However, the PM-PAC integrated process significantly reduced the formation of both C-DBPs and N-DBPs by 60-90% for six C-DBPs and 64-93% for six N-DBPs, because PM oxidation chemically altered the molecular structures of nitrogenous organic compounds and increased the adsorption capacity of the DBP precursors, thus highlighting a synergistic effect of PM and PAC. PM-PAC integrated process is a promising drinking water technology for the reduction of a broad spectrum of C-DBPs and N-DBPs. © 2015 Elsevier Ltd. Source

Luo J.,Tongji University | Feng L.,Tongji University | Feng L.,Research and Service Center for Environmental Industry | Chen Y.,Tongji University | And 4 more authors.
Journal of Biotechnology

An efficient and green strategy, i.e. adding nano zero-valent iron into anaerobic fermentation systems to remarkably stimulate the accumulation of short-chain fatty acids from waste activated sludge via accelerating the solubilization and hydrolysis processes has been developed. In the presence of nano zero-valent iron, not only the short-chain fatty acids production was significantly improved, but also the fermentation time for maximal short-chain fatty acids was shortened compared with those in the absence of nano zero-valent iron. Mechanism investigations showed that the solubilization of sludge, hydrolysis of solubilized substances and acidification of hydrolyzed products were all enhanced by addition of nano zero-valent iron. Also, the general microbial activity of anaerobes and relative activities of key enzymes with hydrolysis and acidification of organic matters were improved than those in the control. 454 high-throughput pyrosequencing analysis suggested that the abundance of bacteria responsible for waste activated sludge hydrolysis and short-chain fatty acids production was greatly enhanced due to nano zero-valent iron addition. © 2014 Elsevier B.V. Source

Wenhai C.,Tongji University | Tengfei C.,Tongji University | Tengfei C.,Changzhou University | Tengfei C.,Research and Service Center for Environmental Industry | And 4 more authors.
Ecotoxicology and Environmental Safety

Ultraviolet/persulfate (UV/PS) has been widely used to generate sulfate radicals for degradation of water organic pollutants in previous studies. However, its impacts on disinfection byproduct formation during post-chlorination of degraded compounds is unclear. The objective of this study was to evaluate the impacts of UV irradiation, PS oxidation, and the combined UV/PS advanced oxidation process (AOP) pre-treatments on halomethane formation during the following chlorination of chloramphenicol (CAP), a model antibiotic commonly found in wastewater-impacted water. Results showed that CAP could be transformed to more trichloromethane (TCM) than monochloromethane (MCM) and dichloromethane (DCM) in the presence of excess chlorine. UV photolysis, PS oxidation and UV/PS AOP all directly decomposed CAP to produce halomethanes (HMs) before post-chlorination. Moreover, UV and UV/PS pre-treatments both enhanced the formation of all the HMs in the subsequent chlorination. PS pre-oxidation decreased the TCM formation during post-chlorination, but increased the yields of MCM, DCM and total HMs. UV pre-irradiation significantly increased the bromide utilization of HMs, whereas UV/PS pre-oxidation decreased the bromine incorporation and utilization of HMs from the chlorination of CAP in a low-bromide water. UV irradiation, PS oxidation, and UV/PS AOP can inactivate pathogens and degrade organic pollutants, but this benefit should be weighed against a potential risk of the increased halomethane formation from degraded organic pollutants with and without post-chlorination. © 2015 Elsevier Inc. Source

Luo J.,Tongji University | Feng L.,Tongji University | Feng L.,Research and Service Center for Environmental Industry | Chen Y.,Tongji University | And 4 more authors.
Water Research

Adding alkyl polyglucose (APG) into an anaerobic treatment system of waste activated sludge (WAS) was reported to remarkably improve the production of short-chain fatty acids (SCFAs), especially propionic acid via simultaneously accelerating solubilization and hydrolysis, enhancing acidification, inhibiting methanogenesis and balancing carbon to nitrogen (C/N) ratio of substrate. Not only the production of SCFAs, especially propionic acid, was significantly improved by APG, but also the feasible operation time was shortened. The SCFAs yield at 0.3g APG per gram of total suspended solids (TSS) within 4d was 2988±60mg chemical oxygen demand (COD) per liter, much higher than that those from sole WAS or sole WAS plus sole APG. The corresponding yield of propionic acid was 1312±25mg COD/L, 7.9-fold of sole WAS. Mechanism investigation showed that during anaerobic treatment of WAS in the presence of APG both the solubilization and hydrolysis were accelerated and the acidification was enhanced, while the methanogenesis was inhibited. Moreover, the activities of key enzymes involved in WAS hydrolysis and acidification were improved through the adjustment of C/N ratio of substrates with APG. The abundance of microorganisms responsible for organic compounds hydrolysis and SCFAs production was also observed to be greatly enhanced with APG via 454 high-throughput pyrosequencing analysis. © 2015 Elsevier Ltd. Source

Chen Y.,Tongji University | Luo J.,Tongji University | Yan Y.,Tongji University | Yan Y.,Research and Service Center for Environmental Industry | And 2 more authors.
Applied Energy

In a previous publication the conversion of waste activated sludge (WAS) to short-chain fatty acid (SCFA) was reported to be significantly enhanced by carbohydrate addition. Herein, the effect of carbon to nitrogen (C/N) ratio, pH (especially alkaline pH), temperature and hydraulic retention time (HRT) (or solid retention time (SRT)) on SCFA production and the related mechanisms were investigated when kitchen waste was added to WAS fermentation system. By response surface methodology, the conditions for maximal SCFA production were optimized, i.e. pH 8, C/N ratio 22, temperature 37 °C and time 6. d. Mechanism exploration revealed that under the optimum conditions the general activity of anaerobic microorganisms, the activities of key acid-forming enzymes, and the ratio of Bacteria to Archaea were improved remarkably, whereas the increase of methane production was negligible. With the fermentation liquid from WAS and kitchen waste as the fuel in microbial fuel cells (MFCs), the performance of electricity generation was enhanced significantly compared with those in MFCs fed with ultrasonic-pretreated WAS or ultrasonic-pretreated WAS plus smashed kitchen waste, due to the increase of SCFA content and the decrease of viscosity of the fuel. © 2012 Elsevier Ltd. Source

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