硝酸钙投加频次对污泥生物调理效果的影响

在接种了反硝化菌的剩余污泥中投加硝酸钙药剂,利用反硝化菌消耗NO₃^-进行反硝化作用去除污泥中易生物降解的有机物,利用Ca²⁺的中和、架桥作用,改善污泥的脱水性能.固定NO₃^-总投加浓度为100 mg·g^-1 TS,在6 d的时间内,按1次、2次、3次、6次的投加频次向污泥中投加硝酸钙.结果表明,1次投加对污泥脱水性能的提升最显著,较对照组而言,污泥CST降低了65.0%,SRF降低了73.2%,污泥脱水性能明显改善;投加硝酸钙后,污泥胞外聚合物中蛋白质含量大幅降低,S层、L层蛋白质分别从13.47 mg·L^-1、11.66 mg·L^-1降低至0.52 mg·L^-1、1.43 mg·L^-1;投加硝酸钙的污泥Zeta电位更趋于电中性.研究还发现,一次性投加硝酸钙产生了更多NO₂^-,有利于污泥结合水,即微生物细胞质的释放.释放出的有机碳被反硝化菌用作碳源,又增强了反硝化效果,从而促进了污泥EPS的破坏与降解,从而改善了污泥的脱水性能.

Effect of calcium nitrate dosing frequency on biological conditioning of sludge

Degradable organics in the excess sludge can be decomposed and sped up by denitrifying bacteria with Ca(NO₃)₂ added, which can enhance the dewaterability of sludge. With the total NO₃^- dosage of 100 mg·g^-1 TS, and the dosing frequencies of Ca(NO₃)₂ divided into 1, 2, 3 and 6 times during six days respectively, the dewaterability of sludge was observed. It was shown that the sludge CST could be reduced by 65.0%, the SRF was reduced by 73.2%, the protein in extracellular polymeric substance of sludge was reduced, and the protein in S-EPS and LB-EPS was reduced from 13.47 mg·L^-1, 11.66 mg·L^-1 to 0.52 mg·L^-1, 1.43 mg·L^-1respectiveLy, the Zeta potential tend to become electroneutral after Ca(NO₃)₂ added, which was helpful for improve sludge dewaterability. The results also indicated that sludge dewaterability could be improved greatly with Ca(NO₃)₂ added at one-time, since more nitrite could be produced, which could help release the microbial cytoplasm, the released organics in the microbial cytoplasm, could be used by denitrifying bacteria as carbon source.