Research On The Influencing Factors And Optimization Method Of Electroosmotic Dewatering For Sludge

With the increase of urban sewage discharge and treatment rate,sludge production increases.High water content is the main problem during sludge treatment and disposal.As a new dewatering technology,sludge electroosmotic dehydration technology has received extensive attention.There are many factors affecting the efficiency of sludge electroosmotic dehydration,but no unified conclusion has been reached.Therefore,it is important to explore the factors affecting electroosmotic dehydration and further improve the efficiency of electroosmotic dehydration.In this paper,the operating parameters of sludge electroosmotic dehydration experiment were optimized by self-made experimental device.The influence of a small range acid-base and inorganic salt conditioning on electro-osmotic dehydration were explored.Electrode conversion method was proposed.It has applied to the electroosmotic dehydration experiment,and the influence of electrode conversion time on the electroosmotic dehydration of sludge were explored.In this paper,the effects of operating conditions on electroosmotic dehydration in horizontal electric field electroosmotic dehydration without mechanical pressure were investigated,the operating parameters were optimized with the energy consumption analysis.The results showed that the effect of sludge electroosmotic dehydration was inversely proportional to the plate spacing and proportional to the voltage gradient and sludge height.However,the energy consumption increased with the increase of the voltage gradient,and decreased with the increase of the sludge height.When the plate spacing was 20 mm,the voltage gradient was 30V/cm,and the sludge height was 25 mm,the moisture content of the sludge after electroosmotic dewatering was the lowest one.Under the best conditions,the electro-osmotic dehydration process could be completed in 10 minutes.At the same time,electrochemical reactions and electromigration occurred during the electroosmotic dehydration process,which affected the properties of the sludge and filtrate after electroosmotic dehydration.The initial properties of the sludge were changed by the addition of acid and base and inorganic salts.The results showed that the initial change of sludge could promote electro-osmotic dehydration.The higher the conductivity,the better the electroosmotic dehydration effect,but the greater the increase in energy consumption.Acid-base regulation was beneficial to the sludge electro-osmotic dehydration,but there was no linear relationship between dehydration efficiency and pH.Among them,adding 1.2mol/L KCl to the sludge had the best dehydration effect,but the energy consumption was also the largest.When 0.5 mol/L NaOH was added to the sludge,the dehydration effect was the best and the increasing of energy consumption was the lowest.Finally,an electrode conversion method was proposed to improve the efficiency of sludge electroosmosis dehydration.The results showed that the electrode conversion method could promote the sludge electro-osmosis dehydration process while reducing energy consumption.The effect of electro-osmotic dewatering of sludge became better with the extension of the conversion time,but when the conversion time was extended to a certain extent,the promotion was no longer obvious.When the electrode plate spacing was 20 mm,the voltage gradient was 25V/cm,the sludge mud height was 25 mm,and the electrode conversion time was 20 s,after the electro-osmotic dehydration was finished,the moisture content of the sludge was 77.32%,and the energy consumption was 0.3312(kWh/kg).