降雨过程对污水处理厂无机颗粒物特性及活性污泥的影响

取消初沉池的污水处理厂，粒径小于200 μm细微无机颗粒物将直接进入生化池，或悬浮或沉积，进而影响生化池的运行。以山地城市某污水处理厂为例，跟踪监测了夏季2个月的6次降雨过程中旋流沉砂池进出水无机颗粒物的粒径和浓度，并同期测定了生化池活性污泥浓度以及污泥MLVSS/MLSS比值。研究发现：旱季旋流沉砂池进出、水中的无机颗粒物平均粒径分别为65.25 μm及54.14 μm，浓度均值分别为146 mg·L-1及128 mg·L-1，无机颗粒去除率12.33%；降雨旋流沉砂池进出、水中的无机颗粒物峰值平均粒径分别为140.48 μm及94.54 μm，峰值平均浓度分别为2 167 mg·L-1及1 591 mg·L-1，无机颗粒去除率26.58%；旋流沉砂池对粒径≥200 μm颗粒的去除较稳定，对细微无机颗粒物的去除效率约10%。研究进一步发现，降雨中颗粒物浓度分别与雨前晴天数及平均雨强呈线性正相关关系。通过核算生化池无机颗粒物的物料平衡关系，得知研究期间生化池累积无机颗粒物总量410.25 t，其中399.45 t沉积在底部，其余悬浮于活性污泥混合液中。活性污泥MLVSS/MLSS由0.52降至0.40，MLVSS由1 410 mg·L-1降至930 mg·L-1，污泥活性下降，系统运行效能受到影响。

Influence of rainfall process on inorganic particle characteristics and activated sludge in wastewater treatment plant

Fine inorganic particles with sizes of -1 and 128 mg·L-1, respectively.During rainfall events,the removal rate of the swirl grit chamber was 26.58%,during which the peak volume average diameters of inorganic particles in the influent and effluent were 140.48 μm and 94.54 μm,respectively;meanwhile,the mean peak concentrations of these particles in the influent and effluent were 2 167 mg·L-1 and 1 591 mg·L-1,respectively.The removal rate of the swirl grit chamber for inorganic particles with sizes of ≥200 μm was stable,but for particles with sizes of -1 to 930 mg·L-1).Decreases in the activity of sludge can be harmful to the effective operation of WWTPs.