聚硅酸硫酸铝强化污水厂污泥脱水效能

以硅酸盐和铝盐为原料，通过共聚反应制备了2种Si/Al摩尔比的聚硅酸硫酸铝 (PASS) 絮凝剂。以某市政污水厂污泥为研究对象，比较了PAC和PASS调理后污泥比阻 (SRF) 、毛细吸水时间 (CST) 和泥饼含水率，并分析了胞外聚合物 (EPS) 的蛋白和多糖变化规律分析。结果表明，PASS能够有效的降低SRF、CST和泥饼含水率，且PASS的Si/Al摩尔比为1∶1时，脱水效果最好。经过PASS以及PAC调理后，溶解性EPS (SEPS) 和松散附着EPS (LBEPS) 的蛋白多糖的含量均有下降，而PAC调理后紧密附着层EPS (TBEPS) 下降，PASS调理后却存在上升阶段。通过污泥扫描电子显微镜 (SEM) 发现，污泥絮体表面由光滑、均匀分布变成了粗糙多孔，且Si/Al摩尔比为1∶1时孔隙率及孔径最大。SEPS和LBEPS蛋白多糖与CST和SRF具有正相关性。所制PASS的不计动力和设备损耗的工程成本比PAC要低。本研究结果可为PASS用于污泥脱水提供参考。

Effectiveness and feasibility of enhanced sludge dewatering in wastewater plants with PASS

Two Si/Al molar ratios PASS flocculants were prepared by copolymerization reaction with silicate and aluminium salts. The sludge specific resistance (SRF), capillary suction time (CST) and moisture content of sludge cake after flocculating with PAC and PASS were compared, and the changes of protein and polysaccharide of extracellular polymers (EPS) was analyzed. The results showed that PASS could effectively reduce SRF, CST and moisture content of sludge cake, and the best dewatering effect was achieved when the Si/Al molar ratio was 1:1. The contents of protein and polysaccharide in soluble EPS (SEPS) and loosely bound layer EPS (LBEPS) reduced after PASS and PAC flocculation. The contents in tightly bound EPS (TBEPS) also decreased after PAC conditioning, but after PASS conditioning, the contents exerted an increasing trend. The sludge scanning electron microscope (SEM) image revealed that the sludge floc changed from smooth and uniform distribution to rough and porous, and the porosity and pore size reached the maximum at Si/Al molar ratio of 1:1. Additionally, correlation analysis concluded that protein and polysaccharide in SEPS and LBEPS were positively correlated with CST and SRF. Finally, as to economic evaluation, it is found that the cost of PASS without power and equipment considerations was lower than that of PAC, which laid the engineering significance for the application of PASS for sludge dewatering.