Research Of Reuse Of Coking Wastewater

Coking wastewater is an industrial wastewater produced in the process of coke converted from coal to gas.It contains many kinds high concentration of pollutants with toxic and harmful features.The treatment on wastewater generally was a combination process of pre-treatment,secondary treatment and tertiary treatment(depth of processing),but the application of membrane process as advanced treatment was rarely used in the industry.Biochemical treatment effluent was studied as raw water which was researched by the membrane process of ultrafiltration,nanofiltration and reverse osmosis.It shows that SS and turbidity can be effectively removed by ultrafiltration process with removal rate 70.88%and 65.58%,respectively.The optimal operating time of ultrafiltration is 40 minutes and ultrafiltration fouling can be removed by hydraulic and chemical cleaning.The optimal recovery rate of nanofiltration membrane should be set at 75%-80%,and the divalent ions like Ca2+ or other high-priced ions can be significantly retented by nanofiltration.The running efficiency of nanofiltration can be recovered by chemical cleaning.Reverse osmosis can effectively remove COD and conductivity with removal rate 93.39%and 95.85%,respectively.The combination of three series of membrane technology,including ultrafiltration,nanofiltration and reverse osmosis,can fully meet needs of circulating water.