Cao Xiuqin, Wang Fei, Yang Ji
School of Environment and Energy Engineering, Beijing University of Civil Engineering and Architecture, 1#Zhanlanguan Road, Xicheng District, Beijing 100044, China.
School of Environment and Energy Engineering, Beijing University of Civil Engineering and Architecture, 1#Zhanlanguan Road, Xicheng District, Beijing 100044, China.
Environ Res. 2023 Nov 15;237(Pt 2):116958. doi: 10.1016/j.envres.2023.116958. Epub 2023 Aug 22.
The dewatering capacity of sludge is a key factor in sludge disposal and reuse. In this study, the effects of conditioning with three conditioners (polyacrylamide (PAM), poly aluminum sulfate (PAS), and sludge biochar (SAC)) and their combined conditioning effect at different doses on the dewatering performance of digested sludge were systematically investigated. The mechanism of change in dewatering performance was analyzed based on rheological principles. A Box‒Behnken multifactor experiment based on the response surface method (RSM) was also used to establish a quadratic multiple prediction model for the solids content of filter cake to obtain the optimal ratio of coupled treatment. The results showed for individual conditioner use, PAM with a dose of 3‰ had the best effect on sludge dewatering, and the dewatering effect of the combined conditioner sludge treatment was better than that of the sludge treated with individual conditioners, with the solids content of the filter cake exceeding 35%. The Herschel-Bulkley model was used to fit the rheological data, and the results showed that the yield stress decreased with increasing PAM dose and gradually increased with increasing PAS and SAC doses. The thixotropy of sludge after SAC conditioning was evident compared to that after PAM and PAS conditioning. The yield stress of sludge decreased and flowability deteriorated after combined conditioning. There was a linear relationship between the dewatering performance of conditioned sludge and thixotropy and yield stress, which indicated the feasibility of using rheological indices to evaluate changes in sludge dewatering performance.
污泥的脱水能力是污泥处置与再利用的关键因素。本研究系统地考察了三种调理剂（聚丙烯酰胺（PAM）、聚硫酸铝（PAS）和污泥生物炭（SAC））及其不同投加量下的联合调理作用对消化污泥脱水性能的影响。基于流变学原理分析了脱水性能的变化机理。还采用基于响应面法（RSM）的Box-Behnken多因素试验建立了滤饼固体含量的二次多元预测模型，以获得联合处理的最佳配比。结果表明，单独使用调理剂时，投加量为3‰的PAM对污泥脱水效果最佳，联合调理剂处理污泥的脱水效果优于单独使用调理剂处理的污泥，滤饼固体含量超过35%。采用Herschel-Bulkley模型对流变数据进行拟合，结果表明，屈服应力随PAM投加量的增加而降低，随PAS和SAC投加量的增加而逐渐升高。与PAM和PAS调理后的污泥相比，SAC调理后污泥的触变性明显。联合调理后污泥的屈服应力降低，流动性变差。调理后污泥的脱水性能与触变性和屈服应力之间存在线性关系，这表明使用流变学指标评估污泥脱水性能变化的可行性。
