钢渣细砂混合去除生物二级处理出水中磷研究

Research on Phosphorous Removal of Biological Secondary Treatment Effluent by the Mixing of Steel Slag and Microsand

针对传统城市污水碳氮比低、生物二级处理脱氮同时TP去除效果差、二级出水TP含量较高且不稳定的问题,将钢渣细砂混合应用于深度除磷阶段,以提高TP的处理效率并降低混凝剂聚合硫酸铁(PFS)投加量。结果表明,进水TP的质量浓度为1.5~2.0 mg/L,钢渣和细砂质量比4:1混合投加、PFS的投加量为6 mg/L时,出水TP的质量浓度仍达到0.434 mg/L(低于GB 18918-2002一级A标准),TP去除量为1.8 mg/L,去除率达80.6%,PFS投加量节省20%~40%,TP去除率提高17.57个百分点。通过真空电子扫描电镜观察发现,钢渣和细砂混合投加与PFS联用可改变絮体结构,使絮体小而密实;当沉降6 min时,絮体沉降体积提高65%左右,可有效缩短絮体沉降时间,提高沉淀效率。

Considering the low C/N ratio of traditional mtmicipal wastewater, the poor removal effect of TP during denitrification in the secondary biological treatxnent, and the high and unstable TP content in the secondary effluent, steel slag and microsand were mixed and applied in the stage of deep dephosphori- zation to improve the treatment efficiency and reduce the dosage of coagulants. The results showed that the effluent mass concentration of TP could still reach 0.434 mg/L ,which was lower than the first A standard of GB 18918-2002, the removal amount was 1.8 mg/L and the removal rate reached 80.6% when the influent mass concentration of TP was 1.5-2.0 mg/L, the dosage of steel slag and microsand mass ratio was 4：1 and the dosage of PFS was 6 mg/L. The dosage of the PFS could reduce 20%-40% and the treatment efficiency could be increased by 17.57 percentage points. The combination of steel slag and microsand mixed with PFS could change the flocs structure, which became small and dense through the vacuum scanning electron microscopy observation. The volume offloc settlement increases by 65% when the settlement time was 6 min, which could effectively shorten the settling time of flocs and improve the sedimentation efficiency.