化学辅助生物除磷过程中EPS与Fe-P的交互作用

The Interaction between EPS and Fe-P in the Process of Chemically Assisted Biological Phosphorus Removal

为探究污水厂最佳投药比以及胞外聚合物(EPS)对化学除磷的影响,首先选出最优的化学除磷药剂,然后配制EPS-Fe-P沉淀模拟污水厂回流污泥,探究EPS的含量、化学除磷剂的投加量、pH的改变以及离心分离对污泥再吸附磷的能力影响。结果表明,在TP为1.5~5 mg/L时单独使用聚合硫酸铁(PFS),投量为1.51∶1即可达到城镇污水处理厂污染物排放标准(GB 18918-2002)一级A标准。EPS与PFS的络合更容易产生更大的聚凝体,有利于游离和胶体态的磷固定。使用MINEQL+软件进行模拟分析不同pH和铁磷比条件下溶液中的离子分布情况,结合试验综合分析得出中性条件下PFS的除磷效果最为稳定,铁投量达到3∶1后沉淀的吸附能力不再有明显提升。磷的再吸附主要依靠沉淀而非溶液中的胶体及离子。

To explore the best dosage ratio of chemical phosphorus removal agents in a sewage plant,the influence of extracellular polymer(EPS)on chemical phosphorus removal was investigated.Firstly,the optimal agent of chemical phosphorus removal was selected.Then the EPS-Fe-P sediment was prepared to simulate the return sludge of the secondary sedimentation tank,and the influences of EPS content,the dosage of chemical phosphorus removal agent,pH,and centrifugal separation on the ability of sludge to adsorb phosphorus again were explored.The results showed that when TP is 1.5-5 mg/L,the removal can reach the Class I A standard of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918-2002)under the polyferric sulfate(PFS)dosage of 1.51:1.The complexation of EPS-PFS was easier to produce the larger aggregates,which was conducive to the fixation of free and colloidal phosphorus.By comprehensive comparison,the phosphorus removal effect of PFS is the most stable under neutral conditions.After the iron dosage reaches 3:1,the adsorption capacity of precipitation will not be significantly improved.The phosphorus resorption mainly relies on precipitation rather than colloids and ions in the solution.