草酸、壳聚糖与CaO联合调理对污泥脱水性能的影响

Effects of dewatering performance of sludge under the co-conditioning of oxalic acid, chitosan and CaO

为提高剩余污泥脱水性能,本文采用单因素实验确定草酸、壳聚糖和CaO各因素的影响水平范围,基于响应曲面优化法建立了污泥滤饼含水率预测模型,通过粒子群算法计算污泥滤饼含水率预测模型,优化草酸、壳聚糖与CaO联合调理污泥脱水的最佳配比,并分析了污泥调理过程中胞外聚合物(EPS)的变化特性,深入解析了污泥脱水的关键机制.结果表明,草酸、壳聚糖与CaO联合调理污泥能明显提高污泥脱水性能,调理后的污泥滤饼含水率为64.017%,最佳投加量分别为0.377,0.029,0.040g/g;模型拟合度良好(R^2=0.9651),方差分析表明草酸对于污泥滤饼含水率的影响为主要因素;草酸投加量与溶解型EPS(SL-EPS)呈显著正相关关系,而与紧密型EPS(TB-EPS)呈显著负相关关系.该研究成果可为剩余污泥脱水性能的提高提供技术与方法参考.

In this study, to improve the dewatering performance of waste sludge, single-factor experiments on the oxalic acid, chitosan and CaO were applied to determine the range and levels of their various factors. The prediction model of water content of dewatered sludge(WC) reduction efficiency was established using the response surface methodology(RSM). In addition, this prediction model was calculated and solved using the computing method of particle swarm optimization(PSO), which was used to optimize the optimal ratio of oxalic acid, chitosan and CaO for regulating the ratio of sludge dewatering. Finally, the characteristics of extracellular polymeric substance(EPS) were deeply analyzed to learn the key mechanism of sludge dewatering. The results showed that the combined treatment of sludge dewatering with oxalic acid, chitosan and CaO can significantly improve the sludge dewatering performance. The optimum values for oxalic acid, chitosan and CaO were 0.377, 0.029 and 0.040 g/g. Under this condition, the WC was 64.017%. And the prediction model fitted well(R^2=0.9651). The model variance analysis showed that oxalic acid was the main factor influencing the WC. Dosage of oxalic acid had a significant positive correlation with soluble EPS(SL-EPS) contents. However, the opposite trend was demonstrated with tightly bound EPS(TB-EPS). The research results can provide technical and method references for improving the dewatering performance of waste sludge.