pH对高铁酸盐氧化剩余污泥的影响

Effects of pH on ferrate oxidation of excess sludge

针对高铁酸盐在酸、碱性环境下氧化性和稳定性的不同,采用pH调至1、3、5、7、9、11、13的剩余污泥,投加高铁酸盐溶液进行研究,考察污泥脱水性能(污泥比阻)以及减量化效果,包括破解液性质(氨氮NH_4^+-N、总氮TN、正磷酸盐PO43-、总磷TP、总有机碳TOC、溶解性有机物SCOD、胞外聚合物EPS)和污泥性状(混合液挥发性悬浮固体浓度MLVSS、污泥沉降比SV、污泥体积指数SVI、粒径)。结果表明:pH由低到高,破解液中各类污染物浓度总体呈现出两端高中间低的趋势,高铁酸盐在酸性和碱性条件下的氧化效果均优于中性条件。其中,pH达13时减量化效果最佳,氮素和有机物质溶出最多,然而此时的脱水性能最差;pH为1时破解液中磷素最多,达90.6 mg·L^(-1)。当pH为13,每g污泥(干重)的高铁酸盐投加量为15 mg Fe时,1 g MLVSS的污泥SCOD释放量达1.13 g,TN、SCOD、TOC释放量分别为179.3、3 507.9和1 134.3 mg·L^(-1),在达到污泥减量化效果的同时更有利于破解液的后期资源化回收和处理。

Due to the different oxidizability and stability of ferrate under acid and alkali environment, the ferrate solution was used to treat excess sludge under different pHs of 1、3、5、7、9、11、13. Sludge dewatering performances(sludge specific resistance) and reduction effects were investigated, as well as the solution characteristics(NH4+-N, TN, PO43-, TP, total organic carbon, dissolved organic COD, extracellular polymeric substances) and sludge properties(mixed liquor volatile suspended solids, sludge sedimentation ratio, sludge volume index, particle size). The results showed that the concentrations of pollutants in the disintegration solution were low at middle pHs, and high at acidic and alkaline pHs. The oxidation effects of ferrate under acid and alkaline pHs were better than that under neutral pH. At pH 13, both the best reduction effect and the most release of nitrogen and organic matter occurred, while the worst dewatering effect occurred. At pH 1, the most total phosphorus in the disintegration solution was observed, and up to 90.6 mg·L-1. At pH 13 and ferrate dosage of 15 mg Fe per gram dry sludge, SCOD release was 1.13 g SCOD per gram MLVSS, the release of TN, SCOD and TOC were 179.3, 3 507.9 and 1 134.3 mg·L-1, respectively, which was conducive to obtaining good sludge reduction effect, then resource recovery and disposal of the disintegration solution afterwards.