Study On Electrode And Reactor For The Process Of Eletrochemical Treatment Of Polymer-containing Wastewater

In recent years,with the increasing demand for oil,oilfield production has entered the stage of tertiary oil recovery.The amount of wastewater containing polyacrylamide（HPAM）produced in the tertiary oil recovery process is gradually increasing.How to efficiently treat this wastewater has become a problem faced by major oil fields.HPAM is a polymer compound,which is difficult to be effectively degraded by conventional biochemical methods.As an advanced oxidation technology for wastewater treatment,electrochemical technology can effectively degrade pollutants in wastewater and improve the biodegradability of wastewater.It has been widely used in the treatment of various difficult-to-degrade industrial wastewater.In China,there are few studies on the treatment of HPAM-containing oilfield wastewater by electrochemical processes,and there are fewer studies on HPAM degradation efficiency and mechanism.Therefore,this topic explored the degradation performance and mechanism of different anode materials on polymer-containing wastewater.The degradation experiments of HPAM were carried out by the electro-coagulation process represented by iron electrode and the electrocatalytic oxidation process represented by Ti/SnO₂-Sb₂O₃/β-PbO₂.Single-factor experiments were conducted using iron plates as anodes and stainless steel plates as cathodes,including reaction time,voltage,current density,electrode spacing,initial pH and reaction temperature.Based on the single factor,three main factors were selected:reaction time,voltage and initial pH,and the response surface method was used to optimize the three factors.The best process parameters obtained by the response surface method simulation are:voltage 7.6 V,reaction time 10.5 min,initial pH=5.Three sets of parallel confirmatory experiments conducted under this condition,the average removal rate of the initial concentration of 200 mg·L^-1HPAM solution was 98.4%.It falls within the 95%confidence interval of the HPAM removal rate optimization results,indicating that the response surface method is reliable for iron electrode removal of HPAM optimization results.Ti/SnO₂-Sb₂O₃/β-PbO₂ electrodes with stable dimensions were prepared by thermal decomposition and electrodeposition.Using it as the anode and the stainless steel plate as the cathode,the single-factor experiment of current density,electrode spacing,initial pH and electrolyte concentration was studied and the degradation kinetics of HPAM was analyzed.The results showed that the removal rate of 200 mg·L^-1HPAM solution was 100%after treatment for 90 min under the conditions of current density of 20 m A·cm^-2,initial pH=5,electrolyte concentration of 6000 mg·L^-1 and electrode distance of 1 cm.The degradation process of HPAM conforms to the first-order kinetic model.Finally,the degradation mechanism of HPAM was analyzed by ion chromatography,three-dimensional fluorescence spectroscopy,infrared spectroscopy,gas chromatography and mass spectrometry.The results showed that HPAM was mainly degraded in the form of bond breaking oxidation.A set of electrochemical treatment process for wastewater containing polymer was designed,including electro-oxidation wastewater treatment system and degassing system.The size and shell of the electrochemical reactor were calculated in detail.Its size was 3500 mm×1000 mm×3000 mm,and the wall thickness was 14 mm.The dimensions of the degassing tank is designed,in which the diameter of the cylinder is1630 mm,the height of the cylinder is 3000 mm,and the wall thickness is 3 mm.In addition,the working electrode,power supply and auxiliary equipment are calculated and selected.