The Mechanism Research Of Phosphorus Removal Process Of Yangtze River To Donghu Lake Project

Donghu Lake is growing eutrophication, and one of the key elements to produce theeutrophication is P. As the drinking water of some provinces, the Yangtze River hasbetter water quality conditions. Through the Yangtze River to Donghu Lake Project,Yangtze River is linked with to Donghu Lake for improving the water quality ofDonghu Lake. However, According to Environmental quality standards for surfacewater (GB3838-2002), the lake’s phosphorus requirements are more stringent than theriver. so it is necessary for phosphorus removal before the Yangtze River flow into theDonghu Lake. This study uses jar tests as the Wuhan section of the Yangtze Riverwater to be the inlet water, the mixing conditions are: rapid mixing1min,400r/min;moderate mixing4min,120r/min; slow mixing8min,60r/min. Use5coagulants:Al2(SO4)3, FeCl3, PAC,PFS and PAFC, Test results are as follows:(1)Considering the treatment effect and market price, single dosing or polymer andsmall molecule coagulant compound dosing, PAC is the optimum inorganic coagulantby removing TP below0.05mg/L.(2)TP removal occurs mainly in the early stages of the settlement and the removal ofPO4-P mainly occurs in coagulation stage. When less coagulant dosage, TP removal isthe result of chemical reactions coagulation and sedimentation reactions. When thedosage continues to increase, the coagulation effect gradually weakened, TP removalis mainly the result of chemical reactions. For five kinds of coagulants, Al2(SO4)3and FeCl3have a good effect on the removal in PO4-P. The effect of PAFC forremoval PO4-P is close to a small molecule coagulant. The polymer coagulants PAC,PFS for non-soluble phosphorus removal is better. After adding coagulant, theproportion of different forms of PO4-P will change. The proportion of H2PO4-will beincrease, where HPO42-decreasing. For five kinds of coagulants, with the increasingdosage of PAC and PFS, The proportion of H2PO4-in PO4-P is about90%,where80%of PAFC and FeCl3and75%of Al2(SO4)3.(3)For raw water, adding the PAC coagulant and three different types PAM: positivePAM, negative and non-polar PAM simultaneously. It can be concluded that three kinds of coagulant aids can significantly reduce the settling time after coagulation. Comparing the treatment effect and economic factors in three coagulant aids, the optimal coagulant aid is non-polar PAM of dosage of0.05mg/L.(4)Dosing PAC and NPAM synchronously, it can remove the CODcr and TN in phosphorus removal process synchronously. The removal proportion of CODCr and TN is about30%and25%.(5) From the test, as PAC is the coagulant, coagulant dosage formula with variables TPis: By monitoring, the influent TP and PO4-P has some relevance, coagulant dosage formula with variables PO4-P is:(6) From the test, as PAC is the coagulant, the sludge volume formula after coagulation and sedimentation is:For the water, a is0.005. Chemical sludge generated mainly caused by non-dissolved substances while a small amount by chemical reaction.