| The treatment and reuse of oily wastewater is still a hot spot at present.With the industrial development and a series of indispensable links such as post-processing assistance,organic solvents,surfactants and other substances are discharged together with the oily wastewater,which makes the oily wastewater more complicated.Based on the characteristics of electronic control membrane separation technology,such as simple operation,no need to add agents,small floor space,stable effluent,etc.,it has a great advantage in the treatment of various types of wastewater adhesion,and the key to electrochemical treatment of oily wastewater is to effectively remove organic compounds by means of flocculation,oxidation and air flotation.In this study,the mechanism and effect of electrochemistry on the removal of oily wastewater were investigated,and the optimum parameters of electrochemistry were determined by condition optimization.The removal effect of electrochemistry on single oily wastewater,mixed oily wastewater and actual oily wastewater was studied,and the mechanism of electric field demulsification and aggregation was explored.The main research contents are as follows:(1)The n-hexadecane and surfactant(SDS)were used as the main representative of simulative oily wastewater,configured to COD concentration of 2000 mg/L of oily wastewater,explores the monopolar and bipolar electrochemical technology the effect of the treatment of oily wastewater,The experimental results indicated that the bipolar of COD removal was 77.89%,higher than monopolar(66.88%)11.01%,the results exhibited that high electric field strength is beneficial to electric demulsification.The results show that when the current density is 0.17,0.34 and 0.67m A/cm2,the COD removal rates are 50.28%,65.60%and 77.85%,respectively.When the p H value is 5,7 and 9,the COD removal rates are 79.13%,77.89%and 71.43%,respectively.When the electrolyte concentration is 17,34 and 68mmol/L,the COD removal rates are 65.34%,72.63%and18.99%,respectively.The parameters of current density,electrolyte concentration and initial p H were also optimized respectively.The results explain that higher current density,appropriate electrolyte concentration and weak acid initial p H are beneficial to improve the electrochemical removal efficiency.(2)The surface charge of the oily wastewater was studied by the influence of electric field in the electrochemical process.Select anion(SDS),nonionic(TWEEN 80)and the positive ions(CTAB)surfactant mixed with oily wastewater,which were configured as a representative of the three kinds of oily wastewater.The initial p H was 7.00,the current density was 1 m A/cm~2 and sodium chloride was 10 mmol/L.The TOC removal of three kinds of oily wastewater after electrochemical was 93.96%,82.88%and 10.05%,respectively.The TOC content in scum,solution and precipitation after electrochemistry was studied.The results showed that pollutants in scum of SDS wastewater was 87.20%,while was only 2.13%in the scum of CTAB wastewater.The removal of three oily wastewater was SDS>Tween80>CTAB,and the pollutants are mainly removed in the form of scum.(3)The simulated and actual oily wastewater was treated by electrochemical and ultrafiltration membrane process.The results showed that the effluent quality of ultrafiltration membrane was stable.The membrane flux was analyzed,and the results showed that the membrane flux by the neutral condition was higher than the acid and alkaline flux.The influence of hydraulic residence time on oily wastewater was investigated.The results showed that with the increase of hydraulic residence time,the COD removal of electrochemical increased from 70.40%to 74.32%and78.30%,and the turbidity removal rate was 74.03%,93.75%and 95.68%,respectively.After membranes treatment,COD removal rate increased by 3.93%,4.11%and 4.67%,and turbidity removal was 98.87%,99.44%and 99.97%,respectively.It can be seen that the COD removal of membrane is about 70-80%,and turbidity removal rate is above 99%. |
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