Preparation Of Coagulant Withsteel Pickling Waste Liquid And Application In Urban Sewage Dephosphorization

As the dangerous solid waste,steel pickling liquors will pollute the environment and be waste if they cannot be dispose properly.This topic takes steel pickling liquor A(ZnⅡ)and steel pickling liquor B(CaⅡ)as raw materials to perpetrate four types of ferric coagulants which are used for dephosphorization of municipal wastewater by two methods(added dihydric phosphate or not): A1 type(Zn),A2 type(P,Zn),B1type(Ca),B2 type(P,Ca),respectively.And researched the influence and influence factors of phosphorus removal effects,the amount of heavy metal in the effluents after coagulation with different coagulants prepared by different preparation methods and raw materials,researched the amount and the distribution of heavy metals in the form in sewage sludge samples,assessed the potential environmental risk of the sewage sludge samples.The results showed that:(1)Preparation methods and raw materials affect the dephosphorization effect of coagulants.In the same dosage,treatment effects for the removal of TP and COD of B2-style and A2-style coagulants are better than that of B1-style and A1-style coagulants,treatment effects for the removal of TP and COD of B-style coagulants are better than that of A-style coagulants.The removal rates of TP and COD can reach over 98% and 70% in optimal volumes.(2)The phosphorus content in the original water has certain influence on the removal of heavy metals in the process of coagulation,and The effects range from big to small is Pb,Zn,Ni,Cr.When the phosphorus content in the inflow is excessive,the heavy metals removal rates of A1-style and B1-style coagulants are better than that of the A2-type and B2-type coagulants which are added dihydric phosphate in the preparation process;when the phosphorus content in the inflow is low,the treatment effect of the type A2 and B2 coagulant in the preparation process is better than that of A1 and B1.dihydric phosphate In optimal volumes,the concentrations of heavy metals in the effluents after coagulation meet the requirement of national standards.(3)Phosphate and Ca(Ⅱ)have a fixed effect on heavy metals.The distributions of heavy metal forms showed that the stable state contents of heavy metals in sludge after coagulation by A2-type and B2-type coagulants,was higher than that of A1-stype coagulant and B1-stype coagulant.The contents of heavy metals in sludge after coagulation by B1-stype and B2-stype coagulants are higher than those of the A1-type and A2-type coagulants,respectively.(4)The sludges produced by coagulation have the potential environmental risks in land utilization,but they can be applied after reducing the heavy metals contents.The analysis of heavy metal morphology and potential environmental risks showed that the potential environmental risks of Cr and Ni in sludge was low,Pb was moderately polluted to the environment,and Zn had higher potential environmental risks.Although the amounts of heavy metals in sludge is in the national standard range,but they are far higher than that of soil environmental background values of heavy metals in eastern Shandong province.The amounts of heavy metals in sludges must be reduce to the safe values range before the sludge land use,especially the amount of zinc and Pb.