| There is much superiority that the application of sequencing batch reactor (SBR) to treatment of sewage from small town with the characteristics of small quantity, low concentration, and water quality variation. In this paper, studies on treatment of such domestic sewage by SBR were performed in laboratory-scale and pilot-scale to expound the feasibility and economical analysis.By theoretical and experimental analysis, the characteristics of domestic sewage of small town were first presented in this paper, namely, small quantity, low concentration (the average value was about 80mg/L) and variation water quality (40-220mg/L).Because of these characterics, no surplus sludge was discharged from the facility to maintain the maximum sludge retention time, and then the steady efficiency and effluent quality can be achieved, the effluent COD was about 30mg/L in the practice of laboratory-scale and pilot-scale. Through 60 days' continuous monitoring of sludge properties, SVI can be maintained in the range of 80-110mL/g. All the results demonstrated that it was feasible for SBR to treat low concentration domestic sewage.Based on the experimental data, the biochemistry kinetics parameters of the low concentration domestic sewage of small town such as sludge yield coefficient a and sludge decay coefficient b were calculated and the value was 0.1605kgVSS/kgCODcr and 0.0217L/d respectively. By using these coefficients, the calculated value of MLVSS agreed well with the field observed value and the error was less than 10 percent.Then, the floating decanter of variable flow fitted for small sized SBR with daily capacity of 200m3 was developed, which was applied in the practice and approached a better effect.Finally, the technical-economic evaluation on the small sized sequencing batch reactor was made in this paper. The result showed that the process of SBR was the ideal technology to the treatment of low concentration sewage of small town. |
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