Study On The Treatment Of Oily Wastewater By Ultrasonic Electrocoagulation-membrane Filtration (Sono-ECMR

The reuse of oily wastewater is of great significance to solve the current shortage of water resources.In view of the shortcomings of the traditional oily wastewater reuse treatment process,such as long process flow,poor effluent quality and large floor area,a combined process assisted by ultrasound and combined with electrocoagulation and submerged membrane filtration was constructed to study the reuse treatment of oily wastewater.By changing the operating conditions of electrocoagulation,the removal effects of electrode combination,treatment time,current density,initial p H and electrode plate spacing on chemical oxygen demand(COD)and petroleum concentration of oily wastewater were investigated;On this basis,the treatment effect and mechanism of ultrasonic electrocoagulation-submerged membrane filtration combined process for synergistic removal of pollutants were studied.The mechanism of delaying membrane pollution under different operating conditions was explored by means of modern analysis means such as scanning electron microscope(SEM),energy spectrum analyzer(EDS),contact angle tester and Zeta potential analyzer.The results show that under the conditions of Al-Al-Al-Al plate combination,current density 12.5m A/cm~2,initial p H=7,plate spacing 1.0cm,40KHz ultrasound every 10min for 2min,the effluent quality is stable,the effluent COD concentration is always lower than 60mg/L,and the petroleum concentration is always lower than2mg/L.SEM images show that in a certain range,with the increase of current density,the filter cake layer formed on the membrane surface is relatively loose.The addition of intermittent ultrasound reduces the thickness of the filter cake layer on the membrane surface to a certain extent and delays the formation of membrane pollution;EDS energy spectrum analysis shows that the electrocoagulation reaction reaches saturation when the current density is greater than 12.5m A/cm~2,and the addition of intermittent ultrasound can effectively prevent the passivation of the electrode plate.The analysis of membrane contact angle shows that when intermittent ultrasound is added under the current density of 12.5m A/cm~2,the membrane surface roughness changes greatly and the contact angle decreases significantly,which is conducive to improving the removal effect of petroleum pollutants and preventing oil droplets from polluting the membrane.When the current density is 12.5m A/cm~2,the zeta potential on the membrane surface shows an increasing trend compared with the original membrane,whether ultrasound is added or not.Due to the increase of zeta potential on the membrane surface,the filter cake layer on the membrane surface can effectively prevent the adsorption and blockage of small and medium-sized oil droplets in wastewater to the membrane and delay the irreversible pollution of oil droplets to the membrane.This paper provides data and theoretical support for the optimization of process parameters,synergistic removal of pollutants and membrane pollution control mechanism of ultrasonic electrocoagulation submerged membrane filtration combined process for the treatment of oily wastewater.