Study On Sludge Water Of Wastewater Treatment Plant Is Used To Remaining Sludge Dehydration And Dephosphorization

At present,in our country,the effluent from most of the wastewater treatment plant is difficult to reach the national first class A discharge standard.It is necessary to use chemical dephosphorization to achieve it reluctantly,so it is urgent to upgrade the standard.In addition,there has been no sustainable disposal of municipal sewage sludge,and arbitrary disposal will have a serious impact on the environment.In this paper,the sludge water of water plant is ultilizated in a new way,which is used as a conditioning agent for dehydration and dephosphorization of remaining sludge in wastewater treatment plant.The main research results are as follows:(1)The dehydration and dephosphorization experiments were carried out with three influencing factors of sludge dosage,centrifugal time and speed of centrifuge.The feasibility of dehydration and dephosphorization by sludge from water plant was demonstrated.The results showed that the sludge dosage significantly affected the effect of dehydration and dephosphorization,and the removal rate of the total phosphorus of supernatant(TP)and the effect of dehyration was sharply increased,and centrifuge time and speed of centrifuge only affected the dehydration effect,in which centrifuge time played a key role in dehydration.(2)Orthogonal experiments were carried out on sewage sludge containing PAM and exclusive PAM respectively.The results showed that there was no effect on dehydration and dephosphorization of remaining sludge from wastewater treatment plant with or without regulating PAM.The optimum conditions of dehydration and dephosphorization from sewage sludge containing PAM are as follows:Waterworks sludge PAM after adjusting the dosage of 300 g/L,10 min centrifugal time,3233.4 r/min centrifuge speed.The phosphorus of supernatant TP maximum removal rate was 92.07% and the dehydrated sludge water content decreased to 69.6%,compared with before dehydration was reduced by 17.9%,the error of model predicted value were 1.9% and 0.89%.(3)The mechanism of remaining sludge dehydration and dephosphorization in water supply plant was studied.The results showed that the VSS/TSS,viscosity and CST of excess sludge decreased significantly after adding sludge from water plant.It is verified that sludge from water supply plant can improve the dehydration effect of surplus sludge.After adding sludge to water plant,the excess sludge pH is 6.67,the sludge specific resistance is the least,and the dehydration performance is the best.In addition,the heavy metal content of filtrate after dewatering of sewage sludge was detected and the heavy metal content in the reflux supernatant was far lower than the national A emission standard limit.The experimental results of phosphorus removal mechanism showed that the Coulomb attraction of iron and aluminum ions was dominant,and the adsorption of inorganic particles and activated carbon particles was the main mechanism of phosphorus removal from sewage sludge mixed with sewage sludge.(4)The pilot run test of single factor continuous operation showed that the TP removal rate and moisture content of supernatant could reach 98.5% and 62.8% when the optimal dosage of sludge was 100g/L.After running continuously for a month at a dosage of 100g/L,the removal rate of TP in the supernatant can reach 99.3%,and the TP content in the supernatant will be reduced from 319 mg/L to 2.24 mg/L,and the moisture content of sludge can reach 62.8% after dewatering.(5)Through benefit accounting,the combined treatment scheme of sewage sludge used for dewatering and phosphorus removal of excess sludge in wastewater treatment plant can effectively reduce the operating cost of sewage treatment plant by 658.69 yuan per day per ton,and reduce the total phosphorus content in the effluent of sewage treatment plant by 0.021 mg/L.