Research On The Efficiency Of Electrocatalysis-Electroflocculation Processing Ship Domestic Sewage

With the development of the shipping industry,the discharge amount of ship sewage gradually increases,and the water pollution is worsening.The international maritime organization?IMO?has issued the latest specification,the nitrogen and phosphorus emission standard has been further improved,and the ship domestic sewage treatment technology is facing new challenges.In this study,the method of combining electrocatalytic oxidation with electroflocculation/electrocatalytic?EO-EC/ER?reduction in two-stage electrolysis was proposed to achieve decarbonization and nitrification by electrocatalytic oxidation process,and denitrification and dephosphorization by further electroflocculation/electrocatalytic reduction,so as to achieve synchronous and efficient removal of carbon,nitrogen and phosphorus in sewage.The influence of different factors on the treatment effect of coupling device was studied through static test,so as to determine the optimal operating condition,analyze its reaction mechanism,and provide theoretical basis for practical application.The primary electrolysis is electrocatalytic oxidation,the influence of current density,chloride ion concentration,pH value,plate spacing and other operating parameters on the removal of COD and ammonia nitrogen by DSA electrode?Ti/Sb-SnO2/?-PbO2/?-PbO2?was studied by static test.Under the optimal condition,the removal rate of COD and ammonia nitrogen is up to 95.6%and 98.78%,and the by-product chloramine production is also the lowest.With the increase of chloride ion concentration,increased degradation effect of ammonia nitrogen,COD degradation effect is reduced,and found that the ammonia nitrogen in preference to COD degradation,through the mechanism analysis,the ClO^-in preference to·OH,and ClO^-oxidation effect of COD is poorer,when reduced to a certain concentration of chloride ions,OH began to a large number of generated,COD degradation was quickly at this time.The secondary electrolysis is electroflocculation/electrocatalytic reduction coupling.In order to explore the coupling mechanism and optimize the coupling effect,when the electrical catalytic reduction run separately,different cathode materials and ratio and different influencing factors on denitrification effect and the influence of nitrogen gas selectivity was first studied,eventually the double TiO2-Pd/Sn?2:1?for electric catalytic reduction cathode was chosen,through the analysis of the mechanism of Sn and Cu is the activity metal of NO₃^-?NO₂^-,Pd is active metal of NO₂^-?N₂,found that although high current density can improve the effect of denitrification,but will reduce nitrogen gas selectivity,and negative ion HCO3-the biggest influence on denitrification.The effect of current density,pH value,plate spacing and other operating parameters on the simultaneous removal of nitrate and phosphate was studied.The removal rates of nitrate and phosphate were 99.5%and 98.8%respectively under the optimal operating conditions.Compared with the effect before and after coupling,it was found that the removal rate of nitrate after coupling was 1.77 times higher than that of electrocatalytic reduction alone,and the effect of air floatation was significantly weaker than that of electroflocculation alone,which shortened the settling time of flocculation.Finally,the effect of continuous operation of two-stage electrolysis experimental device on the treatment of different loads of carbon,nitrogen and phosphorus pollutants in simulated domestic sewage of ships was investigated.COD,ammonia nitrogen and TP of effluent all met the international emission standards,indicating that the treatment device had stable effect and certain load resistance.