同时回收氮磷提高碱性发酵污泥脱水性能的机制研究

同时回收氮磷可以显著提高碱性发酵污泥的脱水性能,但是目前对其机制尚不清楚.通过批式试验,研究了ζ电位、二价离子、胞外聚合物、溶解性聚合物以及鸟粪石对碱性发酵污泥脱水性能的影响.结果表明,在最佳回收条件下(pH=10.0,n(P)/n(N)=1.3 mol.mol-1,n(Mg)/n(N)=1.9 mol.mol-1),镁离子不仅能使|ζ|电位减小到14 mV以下,而且使一价阳离子与二价阳离子比例降低到9 mol.mol-1以下;同时回收氮磷可以显著降低溶解性多聚物和胞外聚合物的含量,尤其是溶解性蛋白质和松散型胞外聚合物的含量;这些变化都促进了碱性发酵污泥的脱水.此外,鸟粪石的形成也有助于提高脱水效果.

Mechanisms of the Improvement in Dewaterability of Alkaline Fermented Sludge by Simultaneous Ammonium and Phosphate Recovery

Simultaneous ammonium and phosphate recovery could notably improve the dewaterability of alkaline fermented sludge, the mechanisms of which, however, remains unclear at present. The influence of zeta potential, divalent ions, extracellular polymeric substances (EPS), dissolved polymers and struvite were studied in batch experiments. Under the optimal ammonium and phosphate recovery condition i. e. pH=10.0, n(P)/n(N)=1.3 mol·mol^-1, n(Mg)/n(N)=1.9 mol·mol^-1], it was found that magnesium ion could not only decrease the absolute value of zeta potential to 14 mV, but also reduce the monovalent to divalent ions ratio to 9 mol·mol^-1, which promoted the dewaterability of alkaline fermented sludge; also, the dissolved polymers and EPS, especially the dissolved protein and the loosely bound EPS, reduced remarkably. Results showed that all the factors above promoted sludge dewatering. Furthermore, the struvite formed during ammonium and phosphate recovery improved the dewaterability.