Analysis And Improvement Of High-performance Compact Reactor In Municipal Sewage Treatment Plant

The municipal sewage treatment in our country have developed successfully, and different scale sewage treatment plants are building in succession.The project Xiaoshan municipal sewage treatment plant, completed in October 2000, with the processing capability of 1.2×10⁵ m³/d, uses high-performance compact reactor （HCR） as an aerobic biological process.Owning to the socioeconomic development, the complex compositions in waste water, the existing HCR process can not meet the new GB 18918-2002 （IB） criterion. In order to meet increasing demands in effluent water quality, development of effective processes for wastewater treatment is essential. By comparing and proving several processes, the results showed that A²/O process is a appropriate technological process which has many advantages including the high denitrogenation and dephosphorization performance, technically credibility, compact design, environmentally safe operation and economically feasible. Expansion and reconstruction of existing plant is convenient.The increasing demands in wastewater treatment have led to the analysis and improvement of existing wastewater treatment process based on the know-how and experience in Xiaoshan municipal sewage treatment plant. The influence of the hydraulic residence time, inner reflux ratio, the age of sludges and rate of sludges recycling on the quality of the effluent and the characteristics of sludges was discussed, and its importance as the control parameter of the process was examined. Combined above, an appropriate technological process was proposed, and proving the effectiveness with pilot-scale experiment.The results of pilot-scale experiment showed that under the conditions of sludge age 20-25 d^-1, backwash ratio 0.4-0.5, water quality of the effluent can meet GB 18918-2002 （IB） criterion. A₂/O process was employed as an effective way to improve HCR process in existing Xiaoshan municipal sewage treatment plant.