污泥胞外聚合物的提取方法及其对污泥脱水性能的影响

采用7种不同方法提取污泥胞外聚合物(EPS),并研究污泥不同层EPS剥离前后对污泥脱水性能的影响.结果表明,甲醛+NaOH和2%EDTA提取法对污泥中紧密结合的胞外聚合物(tightly bound extracellular polymeric substances,TB-EPS)提取效率最高,总固体(SS)中的EPS提取量分别为128.9 mg.g-1和42.38 mg.g-1,但提取后细胞破裂严重,不能代表污泥EPS的真实含量,不宜采用.加热法较为温和,提取效率较高,总SS中EPS产量为21.97 mg.g-1.污泥剥离黏液层(Slime层)、松散结合的胞外聚合物(loosely bound extracellular polymeric substances,LB-EPS)和TB-EPS层后污泥的脱水性能大幅度改善,其中Slime层EPS含量越高污泥的脱水性能越差,当污泥EPS大量地释放到溶液中即Slime层时污泥的CST值大幅度升高,污泥的脱水性能变差.石湖墟和昂船舟污泥初始的毛细吸水时间(CST)为132.9 s和229.9 s,当剥离Slime层时这2种污泥的CST值分别为80.8 s和79.4 s,脱水性能得到明显改善.

Optimization of Extracellular Polymeric Substance Extraction Method and Its Role in the Dewaterability of Sludge

Seven commonly adopted extraction schemes were selected to extract extracellular polymeric substance (EPS) from the sludge, and the dewaterability of sludge was also investigated before and after extracting EPS. Results showed that Formaldehyde+NaOH and 2% EDTA methods were proved to be effective in extracting EPS from the sludge, and the total EPS production of the total suspend solid was 128.86 mg·g^-1 and 42.38 mg·g^-1, respectively. However, the cell destructed seriously after extracted by Formaldehyde+NaOH and 2% EDTA methods. Heating method was a gentle and efficient method, and the total EPS production was 21.97 mg·g^-1. Sludge dewaterability was largely improved after extracted slime, loosely bound EPS and tightly bound EPS from the sludge flocs. It was also found that the higher content of EPS in slime, the worse dewaterability of sludge, and sludge dewaterability would be deteriorated when EPS was released from other layers to slime. Capillary suction time (CST) values of sludge from the ShekWuHui and Stonecutters Island Treatment works were 132.9 s and 229.9 s compared to 80.8 s and 79.4 s, separately after extracted Slime from sludge flocs, and the dewaterability of sludge was greatly improved.