酸处理对活性污泥脱水性能的影响及其作用机理

Acid treatment of waste activated sludge for better dewaterability

用硫酸对活性污泥进行脱水前预处理,可使污泥中水分分布发生有利于机械脱水的变化,即结合水含量减少、可脱水程度增大,从而改善活性污泥脱水效果。试验数据表明,只加阳离子PAM调理,污泥经过板框压滤脱水后(压榨时间30min)泥饼含水率为76.14%;经过酸化预处理后再加阳离子PAM可以使泥饼含水率降至70.24%。不管是过滤脱水还是离心脱水过程,酸处理对污泥脱水速率没有太大影响,却可以提高污泥可脱水程度。进一步研究发现,酸处理的机理是:酸处理使污泥中胞外聚合物ECP水解、微生物细胞瓦解,从而絮体内部间隙水、细胞内部间隙水被释放变成自由水,污泥水分分布发生变化,污泥可脱水程度提高,最终导致污泥脱水效果好。

Dilute sulfuric acid was employed to pre-treat waste activated sludge to improve the performance of mechanical dewatering. Acid treatment dissolved cellular polymers and freed up a major portion of bound water, making the conditioned sludge more dewaterable. The acid pretreatment improved the performance of a frame type filterpress the water content of the filter cake was lowered to 70.2 % （from 76.1 %）. Similar improvement was noted in the centrifugation dewatering runs. The dewatering rate was not significantly changed by the acid pretreatment.