Experiment And Optimization Of Polymer-contained Wastewater By Electrocoagulation

With the progress of tertiary recovery in China,Polymer-contained wastewater has become a major problem in sewage treatment.High polymer content,small oil particle size,high salinity,large amount of bacteria make a higher demand for wastewater treatment technology.Electrocoagulation has advantages such as wide application range,no chemicals and so on.Although electrocoagulation has made some progress in the field of polymer-contained wastewater,the systematic experimental research is not comprehensive yet.There are no dynamic tests and researches near the oilfield nor the determination of the best experimental conditions.In this paper,the study of polymer containing wastewater is taken as the research object.The combination of experimental and optimization research are used to explore the regularity of the treatment of wastewater by electrocoagulation technology,and to determine the best experimental conditions which are suitable for oilfield.In this paper,the following work is done on the basis of domestic and foreign research:1.Build a static electrocoagulation experiment system,the single factor analysis method is used to carry out the indoor and outdoor polymer-contained wastewater.Investigated the effects of different current density,initial pH,plate spacing,polymer concentration and other factors on the treatment.It is found that the effect of simulated polymer containing wastewater rises first and then becomes stable with the increase of current density,and the effect of oilfield sewage treatment increases first and then decreases.The treatment effect of acidic condition is better than alkaline condition,and the neutral condition is the best.The effect of plate spacing on the treatment effect is slightly lower than that of current density and pH value.Considering the energy consumption,the best plate spacing is 1cm.The polymer concentration has a great influence on the final treatment effect,and the treatment effect decreases with the increase of the polymer concentration.The best working conditions are as follows:the electrode spacing is 1 cm,and the current density is 4 mA/cm~2.The oil removal rate of simulated sewage and on-site wastewater are 98.99%and 99.6%,and turbidity removal rate 99.74%and 99.8%,respectively.The cost are 1.77 yuan/m~3 and 1.6 yuan/m~3.2.Based on the self-designed electrocoagulation dynamic device,we set up an experimental system close to the oil field and carried out exploratory experiments with different current density,flow rate and tilt angle.It is found that the experimental process is divided into rapid stage and stable stage.The higher current density and the flow rate were,the the shorter time to reach the stable stage were.With the increase of the angle of the plate,the removal rate gradually decreases and the optimum angle is 80 degrees,and the energy consumption is 2.32 kWh/m~3.When the electrode spacing keeps 1.8 cm,processing to 140min,the plate inclination angle is 80 degrees,the flow rate is 5 L/h,the current density is 14mA/cm~2,the indoor and outdoor final oil removal rate are 96.32%and 97.2%,and turbidity removal rate are 97.3%and 98.2%.3.The response surface method is used to optimize the dynamic experimental of the simulated wastewater treatment.The three aspects are the current density,the treatment flow rate and the plate inclination angle.According to the experiment of software design,establishing regression fitting equation,variance analysis and response surface analysis,it is concluded that goodness of fit which the quadratic model is better.We get the influence of any two factors and their interactions on the final processing effect,so as to verify the model.The conclusion is that the best condition is when the current density is 18.9 mA/cm~2,the flow rate is 5.5 L/h,and the plate inclination is 80 degrees.At this time,the oil removal rate is 97%,and the energy consumption is 3.5 kWh/m~3.