Experimental Study On Bentonite And Fly Ash To Remove Phosphorus In The Effluent Of Secondary Sewage

The main cause of eutrophication is excessive phosphorus, how to effectively control the phosphours content in the water is the problem to be solved urgently.In this paper, natural bentonite and fly ash remove phosphorus by static test, and gets the good adsorption materials for phosphorus and new technology.The paper studys the properties、mechanism、influencing factors and kinetics of the bentonite and fly ash adsorption phosphorus by static test. In order to solve the slurry separation of bentonite and fly ash, static test of removal phosphorus with preparing chitosan coated adsorbents and the combination of adsorption and coagulation is investigated. The results show that:1)The adsorption effect of phosphorus by natural bentonite、fly ash and chitosan coated bentonite is good.The main factors of removal phosphorus with the three adsorbents are dosage、adsorption time、oscillation intensity、pH、ammonia nitrogen. We have got the primary and secondary factors and the best reaction conditions for phosphorus removal by many factors orthogonality tests.The phosphorus adsorption on three adsorbents conformes to Langmuir isotherm equation. The adsorption kinetics for three adsorbents fit pseudo second-order equation.It is easily spate separation after chitosan coated bentonite.2)The combination of adsorption and coagulation shows that the effect of phosphorus is good. For initial phosphorus of2mg·L-1,the rato of phosphorus is75.85%with response time30minute、20g·L-1fly ash、30mg·L-1PFS、oscillation intensity100r·min-1、pH7、no ammonia nitrogen existing. The presence of ammonia nitrogen has certain stimulative effect for phosphorus; For initial phosphorus of4mg·L-1,the results of orthogonal experiments show that the order of affecting phosphorus removal is PFS dosage>fly ash dosage>ammonia nitrogen concentration.3)Through the technical and economic analysis comparison, the combination of fly ash and PFS can effectively remove phosphorus and solve problem spate separation,which has the lowest reagent cost and is worth being popularized.