Efficiency Of Advanced Treatment Of Refinery Wastewater By Ceramic Membrane Coupling Process

Substandard discharge of refinery wastewater will not only increases the concentrations of pollutants in water,but also poses a serious threat to water ecological security and even human health.Advanced treatment of wastewater for reuse is an effective way to alleviate water pollution and water scarcity.In recent years,in order to protect the environment and respond to public opinion,refining wastewater discharge standards have been constantly improved,and the upgrading and reconstruction of wastewater treatment and zero discharge are also the goal pursued by many industrial enterprises.However,the current advanced treatment process has many problems such as long process,wide area,low recycling efficiency,etc.It is difficult to cope with the current shortage of land and limited reserve land for advanced processing equipment.Therefore,it is very significant to research and develop of efficient coupling and integration new technologies and methods for the treatment of wastewater.Through the water investigation and analysis,it is found that there are many pollutants such as alkanes,olefins,aromatics,sulfides and aminations in refinery wastewater.Alkanes,ethers and alkynes can be biodegradable,however,alkenes,aromatic compounds,sulfuric acid esters and amines are difficult to biodegrade and become the focus of advanced treatment.Based on this,the efficiency of wastewater treatment by ceramic membrane separation,coagulation,advanced oxidation and adsorption technology was investigated:（1）the removal efficiency of turbidity was over 90%by ceramic membrane filtration,and the effluent turbidity was around 0.2 NTU;（2）the removal efficiency of COD was 56.4%by Fenton oxidation process in the presence of 1.2 mmol/L Fe²⁺and 1.8 mmol/L H₂O₂ under pH 4.1,the removal efficiency of COD was 75%by activated carbon adsorption in 4 g/L activated carbon under pH 7.Besides,the fluorescent pollutants could be efficiently degraded by these two methods,（3）the combination of Fenton oxidation and activated carbon adsorption not only decreased the optimal dosing of active carbon to 1 g/L,but also further improved the effluent quality.According to the aboved analysis for the efficiency of various water treatment technologies,the coupled Fenton oxidation-activated carbon adsorption-ceramic membrane filtration process was established,in which the total hydraulic retention time of this process was 2 h.In this coupled process,the powder activated carbon was directly added to the membrane tank,and the process maintained stable through optimization of the dosing of active carbon and operation parameters.Under the conditions of activated carbon concentration of 40 g/L,carbon replacement rate of 4%/d,and initial flux of ceramic membrane of 82 L/（m²·h）,the coupled process system operated stably with high treatment efficiency,and the effluent met the design requirements.Compared to the direct filtration,the ceramic membrane in the coupled process had higher flux and anti-fouling performance.the critical flux of ceramic membrane was 60L/（m²·h）in the case of direct membrane filtration,which was increased to 82 L/（m²·h）in the coupled process.In addition,coupled process showed a good ceramic membrane pollution resistance,and the total resistance ceramic membrane(1.2×10¹22 m^-1)was obviously lower than the direct filtration(5.1×10¹²m^-1).Moreover,membrane surface washing-water backwashing-NaClO solution backwashing cleaning method had good cleaning effect in both filtration modes.The membrane flux recovery rate was 90%and 97%for direct filtration and the coupled process,respectively.Research results of advanced treatment of refinery wastewater by ceramic membrane coupled process analyzed the characteristics of pollutants in refinery wastewater,revealed the removal rules of organic pollutants by different water treatment technologies in the coupled process,as well as the anti-pollution characteristics and membrane cleaning behavior of ceramic membranes.The research results are expected to provide theoretical and technical references for the advanced treatment of refinery wastewater,wastewater treatment plants upgrading or other water treatment fields.