旁路微氧池污泥停留时间对污泥减量化的影响

Effect of retention time on sidestream bypass oxygen-limited sludge reduction process

研究了新型工艺——侧流式旁路微氧污泥减量工艺在不同微氧污泥停留时间下的污泥减量效果,监测了COD去除率、污泥产率和污泥性能的变化,并探索了微氧污泥回流后曝气池内兼性菌溶胞过程。结果表明,新工艺COD去除率高于传统工艺,但随停留时间延长而降低,微氧污泥停留3 d时高达93.59%,11 d时降至89.25%;新工艺表观污泥产率(MLSS/COD)低于传统工艺,其降幅随停留时间延长而增大,停留时间由3 d延长到11 d,降幅由50.14%升到58.59%;回流后第4小时,曝气池内COD骤然上升,MLSS和MLVSS都大幅度增加,推断此时为曝气池内兼性菌大量溶胞时间点;新工艺SVI值低于传统工艺,MLVSS/MLSS值高于传统工艺,改善了污泥沉降性能,提高了污泥活性。综合考虑COD去除率和污泥产率等方面后,确定新工艺微氧池的最佳污泥停留时间为3 d。

A new sludge reduction reactor sidestream bypass oxygen-limited sludge reduction process was proposed which was modified from the oxie-settling-anaerobic（OSA） process. The change of COD removal rate, sludge yield and sludge performance were monitored in the new process, and the process of faeultative bacteria cytolysis in aeration tank after oxygen-limited sludge＇ s baekflow was explored. The result shows that compared with conventional activated sludge（CAS） process, the removal rate of COD in the new process increased, while the rate declined with the improvement of retention time. When the retention time changed from 3 d to 11 d, it dropped from 93.59% to 89.25% , which shows no edg with the retention time extended without limit. Com- pared with CAS process, the sludge yield in the new process decreased, and the improvement of retention time can lead to the rise of its decreasing amplitude. When retention time was prolonged from 3 d to 11 d, sludge yield changed from 50.14% to 58.59%. In aeration tank, it was found that the COD, MLSS and MLVSS all grew instantly at the fourth hour after the completion of oxygen-limited sludge＇ s backflow, and the time was speculated as the moment of facuhative bacteria cytolysis. Compared with CAS process, the SVI of sludge in the new process decreased, while the MLVSS/MLSS increased. The settling performance and activity of sludge were both improved in the new process. The best oxygen-limited sludge retention time in the new process was 3 d when taking removal rate of COD and sludge yield into account comprehensively.