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Feng L.-J.,Zhejiang University | Zhu L.,Zhejiang University | Yang Q.,Zhejiang University | Yang G.-F.,Zhejiang University | And 3 more authors.
Bioresource Technology | Year: 2013

A novel drinking water biofilm pretreatment process with reed addition was established for enhancement of simultaneously organics and nitrogen removal. Results showed that nitrate removal efficiency was positively related with the influent C/N ratio, reaching to 87.8±2.8% at the C/N ratio of 4.7. However, the predicted trichloromethane (THM) levels based on total organic carbon (TOC) and UV254 were high with the increase of influent C/N ratio. Combined with the pollutants removal performance and microbial community variation, an appropriate C/N ratio via reed addition was determined at 2.2 for the continuous biofilm reactor. With adjustment of hydraulic retention time (HRT), the highest of nitrate removal efficiency (74.2±1.4%) and organics utilization efficiency (0.63mg NO3--Nmg-1TOC) were achieved at an optimum HRT of 18h, with both low effluent NO3--N (0.88±0.03mgl-1) and TOC (2.86±0.67mgl-1). © 2012 Elsevier Ltd. Source

Feng L.-J.,Zhejiang University | Xu J.,Zhejiang University | Xu X.-Y.,Zhejiang University | Xu X.-Y.,Joint Center in Integrated Water Management and Protection | And 4 more authors.
International Biodeterioration and Biodegradation | Year: 2012

In recent years, nitrogen pollution has been increasingly serious in natural waters including drinking source water. A simulated river biofilm reactor fed with contaminated drinking source water was established to evaluate the effects of dissolved oxygen (DO) partitioning and step feeding on the nitrogen removal performance and biofilm microbial community. Results showed that after the hydraulic retention time of anoxic zone extending and step feeding, the effluent concentration of ammonia was below 0.2 mg L -1, and the removal efficiency of total nitrogen increased from 12.02% ± 4.59% to 34.98% ± 2.65%, which indicated the occurrence of simultaneous nitrification and denitrification. The results of denaturing gradient gel electrophoresis showed that the microbial community of biofilm obviously shifted via DO controlling and step feeding. Low DO concentration favored the enrichment of denitrifying bacteria and coexistence of algae and bacteria, and the pattern of step feeding could increase the community abundance. The dominant heterotrophic bacteria species of biofilm in oligotrophic niche belonged to Hyphomicrobium sp., Pseudomonas sp., Chloroflexi sp., Enterobacter sp., Pantoea sp., and Synechococcus sp., which were mostly associated with denitrification and refractory organics utilization. It was worth noting that the ammonia-oxidizing bacteria (AOB) community of biofilm was stable throughout the whole experiment, and Nitrosomonas sp. was the predominant AOB in the oligotrophic niche. © 2012 Elsevier Ltd. Source

Zhu L.,Zhejiang University | Lin H.-Z.,Zhejiang University | Lin H.-Z.,Wenzhou Environmental Protection Design Scientific Institute | Qi J.-Q.,Zhejiang University | And 3 more authors.
Water Research | Year: 2012

Using a combined zero-valent iron (ZVI) and anaerobic sludge system as the platform, the hydrogen utilization and reductive mechanism of p-chloronitrobenzene (p-ClNB) were investigated in the study. Results showed that the corrosion of ZVI could be used as a source of electron donor for anaerobic microorganisms, and then enhanced reductive transformation of p-ClNB and production of methane. Thereinto, the transformation of p-ClNB was observed to have priority for the utilization of H 2. The enhancement factors (Q') for the reductive transformation of p-ClNB with exogenous H 2, reduced ZVI (RZVI), industrial ZVI (IZVI), and nanoscale ZVI (NZVI) as electron donors were 4.1-5.6, 14.8-35.1, 2.8-4.6, and 1.5-5.7, respectively. Results demonstrated that RZVI was the most effective type of electron donors, which was attributed to the production and utilization of H 2/[H] simultaneously via the ZVI corrosion and microbial metabolism. It is hopeful for the application of ZVI to enhance the reductive transformation of analogous persistent organic pollutants in the anaerobic sludge system. © 2012 Elsevier Ltd. Source

Zhu L.,Zhejiang University | Ding W.,Zhejiang University | Ding W.,Sinopec | Feng L.,Zhejiang University | And 3 more authors.
Environmental Science and Pollution Research | Year: 2012

Introduction: An aerobic denitrifier was isolated from the Hua-Jia-Chi pond in China and identified as Pseudomonas mendocina 3-7 (Genbank No. HQ285879). This isolated strain could express periplasmic nitrate reductase which is essential for aerobic denitrification occurred when the dissolved oxygen (DO) level maintains at 3-10 mg L-1. Methods: To determine whether the ability of isolated strain is exhibited in the bioremediation of polluted drinking source water, the heterotrophic nitrification and aerobic denitrification characteristics of P. mendocina 3-7 under different cultural conditions such as oxygen level, nitrate and organic concentrations were studied from the nitrogenous balance in the paper. Results and conclusions: By measuring the nitrogen balance in all experiments under different culture conditions, the removal of total organic carbon and ammonium was positively correlated with total nitrogen removal, especially under high substrate level. With substrate concentration decreasing, ammonium and nitrate removal occurred separately, and ammonium was completely utilized first under low substrate concentration. Compared to that under high substrate level, the specific growth rate of P. mendocina 3-7 was not low under the low substrate level and the pollutant removal efficiencies remained high, which implies the stronger nitrogen removal and acclimatization capacities of the strain in oligotrophic niches. © 2012 Springer-Verlag. Source

Feng L.-J.,Zhejiang Ocean University | Feng L.-J.,Zhejiang University | Yang G.-F.,Zhejiang University | Zhu L.,Zhejiang University | And 2 more authors.
Bioresource Technology | Year: 2014

The removal performances of nitrogen and trace levels of endocrine-disrupting pesticides (cypermethrin and chlorpyrifos) were studied in the enhanced biofilm pretreatment system at various substrates concentrations and dissolve oxygen (DO) niches. No significant change of EDPs removal occurred with the increased feed of ammonia nitrogen in aerobic batch tests or nitrate in anaerobic batch reactors, but significantly enhanced via reed addition both in aerobic and anaerobic conditions. Simultaneously enhanced denitrification and EDPs removal were achieved in the anoxic niche with reed addition. The results of denaturing gradient gel electrophoresis (DGGE) indicated that new bands appeared, and some bands became more intense with the reed addition. Sequences analysis showed that the dominant species belonged to Methylophilaceae, Hyphomicrobium, Bacillus and Thauera, which were related to the nitrogen or EDPs removals. In addition, the growth of functional heterotrophic microbes may be promoted via reed addition. © 2014 Elsevier Ltd. Source

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