Aquatic environment

A novel integrated step-feed biofilm process for the treatment of decentralizeddomestic wastewater in rural areas of China


Hanwen Liang , Min Gao , Junxin Liu , Yuansong Wei , Xuesong Guo

DOI:

Received March 22, 2009,Revised December 09, 2009, Accepted , Available online

Volume 22,2010,Pages 321-327

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For wastewater treatment in rural areas, a novel three-stage step-feed wastewater treatment system, combined with a drop-aeration biofilm process, was tested in the laboratory to investigate its performance in removing suspended solids (SS), chemical oxygen demand (COD), NH4 +-N, total nitrogen (TN), and total phosphorus (TP). The removal rates of SS, COD and NH4 +-N were 90%, 80%, and 90% in e uent concentrations less than 10 mg/L, 50 mg/L and 8 mg/L, respectively. The TP removal rate was less satisfactory. The C/N ratio in the raw wastewater was often less than 3.5, and the removal e ciency of TN was therefore limited. A carbon-release batch experiment was carried out to measure the feasibility of enhancing denitrification at low influent C/N ratios. The result showed that the C/N could be over 9.0 in the supernatant. Polymerase chain reaction denaturing gradient gel electrophoresis technology was used to reveal the changes in the bacterial community during di erent stages of the integrated step-feed biofilm process. The results showed that banding patterns and the distribution of dominant bands for the same experimental period in di erent aerobic zones were similar. Phylogenetic analysis indicated that lanes 10, 11 and 12, which presented three aerobic zones at the same operation period, had the closest phylogenetic relationship among the lanes.

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