Study On Conditioning And Deep Dehydration Process Optimization Of Municipal Sludge

At present,much attention has been paied on problem of sludge treatmentin China.In the past,water content only could be reduced to 80% by conventional mechanical dehydration.Deep sludge dehydration has become mainstream technology of sludge reduction and stabilization.However,at present,the deep sludge dehydration technology is mostly focused on the field of chemical conditioning and all relevant investigations study on excess activated sludge ignoring the sludge of biofilm process.Moreover,there is no in-depth study on the optimized operation of deep dehydration process.This paper used a sewage treatment plant in Shenzhen as an example,where two different sewage treatment process are located ——UCT(An improved A2 O process)and BAF(Biological Aerated Filters)as the first project a period and the two phase of the project,and took two kinds of sludge for research objects.The properties of two kinds of sludge were analyzed,and the organic matter content,filtration rate and floc characteristics were found to be different.Then it came to a conclusion that pertinence conditioning processes should be made on two kinds of sludge.In order to solve the problem of deep sludge dehydration,the traditional sludge specific resistance was placed by asimplified method whichwas easy for operation,low cost and accurate.The feasibility and effectiveness of different conditioning agents such as PAC,PAFC,FeCl3,PAM,limeand diatomite were studied through this method.It was found that the UCT sludge and the BAF sludge had completely different properties,so they should be conditioned by different agents respectively.Only lime could significantly reduce the specific resistance of BAF sludge,while other conditioning agents had no significant effect.A series of orthogonal experiments were conducted to analyze the effects of mixing ratios of two kinds of sludge and the dosage of conditioning agent on sludge conditioning.Finally,it was found that the two kinds of sludge should be conditioned respectively.The UCT sludge conditioning solution was the addition of 1 kg/tDS PAM+50 kg/tDS permeabilization reagent,and the BAF sludge conditioning solution was 50 kg/t DS permeabilization reagent +150 kg/tDS lime.Based on the existing deep sludge dehydration process,the characteristics and conditioning conditions of both kinds of sludge were analyzed,and the technological transformation of sludge pretreatment,pipeline distribution,stirring intensity,working procedures of filling pump and squeeze pump,filter cloth pickling and replacement was completed.Finally,50% of the sludge treatment capacity was increased,40% of the power consumption was saved,and the sludge water content was stabilized below 50%.In this paper,the chemical conditioning of two kinds of sludge produced in activated sludge and biofilm process was developed and employed in 600 t/day sludge reduction project successfully.The technological transformation experience in deep sludge dehydration was summed up.Final conclusion of this paper provides strong theoretical basis and practical support for upgrading of sludge dehydration system of sewage treatment plant.