Study On The Treatment Of Tertiary Oil Recovery Wastewater By Electrocoagulation

With the reduce of petroleum resources and development of polymer flooding oil production technology,most of the oil field in our country has entered a stage of tertiary oil recovery and produced a large number of polymer waste water each year.This kind of waste water has high viscosity and hard to be biodegraded.The treatment effect is difficult to reach to a new emission standard by existing water treatment facilities.This topic select tertiary oil recovery waste water come from Daqing oil field as the research object.The method of electrocoagulation has been used to deal with waste water and to investigate the effect of various factors on treatment effect and treatment cost during the process of electrocoagulation in order to get the best operating conditions of electrocoagulation.At the same time,the experiment also studied the treatment effect of chemical coagulation method on treating tertiary oil recovery waste water,which can provide a basis and reference for treating tertiary oil recovery waste water as well as other waste water containing PAM or other high-molecular polymer by electrocoagulation.In this study,the water quality of tertiary oil recovery wastewater has been analyzed,and the nature of tertiary oil recovery waste water has been studied through the preliminary exploration.The research compared the influence of different kinds of plates,pH,current density,stirring speed,reaction time,plate spacing on treatment effect during the process of electrocoagulation,then the influence of several main factors on treatment effect and the interaction between several main influencing factors has been investigated through the orthogonal experiment.In order to optimize the experimental conditions with best treatment effect and the lowest treatment cost,further study about the influence of the temperature,the additive amount of electrolyte,cathode plate type,the water quality conditions,ratio of the area and volume(A/N),the different way of plate combinations and the current mode on the electrocoagulation treatment effect and the treatment cost has carried on.Research shows that the electrocoagulation for treating tertiary oil recovery waste water has good treatment effect,when aluminum plate as electrode,pH=4,plate spacing=1 cm,stirring speed=600 r/min,reaction time=20 min,electricity quantity-1.848 A min,A/V=37.33 cm2/cm3,single stage type connection mode,using direct current power supply,the electrocoagulation has the best treatment effect and the lowest treatment costs.Through the analysis of the main characteristics of tertiary oil recovery waste water and the mechanism of electrocoagulation treatment of tertiary oil recovery waste water found that the removal of COD mainly determined by flocculation,and the electrochemical oxidation has no effect on COD removal,in addition,the removal of COD is mainly associated with the amount of dissolved aluminum and pH value.The amount of dissolved aluminum mainly related to the current density and reaction time,when other conditions is determined,the amount of dissolved aluminum is linearly related to the applied electric charges.In addition,the dissolution of aluminum will happen in both the anode and cathode when the aluminum plate as cathode and anode.In addition,other factors can also affect the amount of dissolved aluminum,which affect the treatment effect of the tertiary oil recovery waste water.Experiment contrasted the treatment effect of chemical coagulation and electrocoagulation for treating the tertiary oil recovery waste water,through the analysis of the results found that the treatment effect as well as treatment cost of chemical coagulation is similar to electrocoagulation's.However,the electrocoagulation with gas floating function has greater advantages than ordinary chemical coagulation when treating the waste water with large quantity of oil.If further optimize the structure of electrode and electrode type,the treatment effect of electrocoagulation will be further improved,and has more broad application prospects than ordinary chemical coagulation method.