Application Study On Electroosmosis Dehydration Of Sludge In Chongqing Municipal Waste Water Treatment Plant

Since the current sludge moisture content of the municipal waste water treatment plants(WWTPs)in Chongqing is around 80%,the volume of sludge is large,which increases transportation costs and disposal costs,and also limits the choice of sludge disposal methods.Therefore,reducing the moisture content of sludge from municipal WWTPs is the key to solving sludge treatment and disposal.The main technologies for deep dewatering of produced sludge are plate-frame high-pressure dehydration,hotdrying dehydration,electro-osmotic dehydration,etc.Among them,the sludge electroosmosis dewatering technology stands out in the sludge deep dewatering technology because it can directly connect with the existing sludge dewatering process and without the need to add chemical agents.This study provides theoretical support for the application of on-site electroosmotic dehydrator through laboratory pre-experiment.The phenomenon that is difficult to directly explain in the application test is supplemented by laboratory optimization experiments.Through preliminary experiments on the electro-osmotic dewatering operation conditions of the sludge of Lijiatuo WWTP,the voltage gradient should be controlled preferentially,and then the mud volume and dewatering time should be controlled according to the treatment effect and efficiency of the demand;The effective current of dehydration has the largest proportion in the total current,such as preventing the following conditions: excessive increase in resistance of the anode region leads to poor dewatering effect at the later stage,excessive thickness of the sludge causes an increase in ineffective current,and the mechanical pressure is too small and the water remains in the reactor;and uneven thickness of sludge laying.Through the application test,the electroosmotic dehydration of the sludge from the four WWTPs of Xiaojiahe,Chengbei,Jiguanshi and Beijiao,combined with the treatment efficiency,energy consumption and effect,the better operating conditions are: voltage gradient 24~36V,cycle time 10~20min,the thickness of the incoming mud is 8~12mm,and the mechanical pressure is 0.3~0.4MPa.The water consumption of sludge from 50% to 50% or 60% is 0.190~0.250 kW.h/kg;among them,the energy consumption of raw sludge reduced to 60% is 0.080~0.120kW·h/ Kg,the original sludge energy consumption reduced to 50% is 0.120~0.130kW·h/kg;the energy consumption is closely related to the nature of the mud and the operating conditions.When the amount of mud and mechanical pressure is properly controlled,the same treatment effect can be achieved.From the perspective of reducing energy consumption,it is recommended to adopt a low voltage + long time processing mode;from the perspective of improving processing efficiency,it is recommended to use high voltage + short Time processing mode.Through the optimization experiment,the electroosmotic dehydration of the sludge after conditioning in Lijiatuo WWTP is combined with the sludge treatment route of sludge mechanical dewatering + electroosmotic dehydration.It is recommended to use fresh activated sludge for mechanical dewatering and sludge mechanical dewatering process.It is recommended to add a suitable PAM ratio of 2~3‰.It is not recommended to add PAC and other coagulants during the mechanical dewatering process of sludge.The moisture content of mechanical dewatered sludge is controlled to be 80.0%~81.5%.The sludge after mechanical dewatering should be as soon as possible.Select appropriate electroosmotic operating conditions for sludge electroosmotic dehydration.