Experimental Study On Treatment Of Mariculture Wastewater By Electrochemical Method

With the rapid development of mariculture industry,a large amount of mariculture wastewater containing pollutants is discharged into the offshore sea,resulting in water pollution and it will endanger human health and destroy the ecological environment.Electrochemical treatment technology has attracted much attention due to its high treatment efficiency,low management requirements,and rapid start-up.Due to its high salinity,mariculture wastewater is suitable for electrochemical treatment.In this experiment,the electrochemical method was used to treat mariculture wastewater,and the effluent after electrochemical system treatment was followed-up treated to provide a new treatment scheme for mariculture wastewater discharging up to standard.In this experiment,marine aquaculture wastewater was treated separately by electrocatalytic and electro-Fenton synergistic electrocatalytic system.The optimal reaction conditions of the system were determined through single factor and response surface experiments,then the treatment performance exploring the removal of pollutants in marine aquaculture wastewater at flow rate,flow direction,and oxidant reuse,determine the dynamic operating conditions of the system;The reaction mechanism of removing pollutants in the system is studied through the combination of quenching experiment,theoretical analysis and modern instruments;The residual chlorine that from the effluent treated by electrochemical system was treated by activated carbon adsorption method,adding sodium sulfite,calcium sulfite ball and sodium thiosulfate.The results show that:The electrocatalytic oxidation system constructed with DSA anode and stainless steel plate cathode could reach 100%removal of COD by the optimal reaction conditions which were initial pH of 7.97,plate spacing of 0.84 cm,external voltage of3.3 V,and treatment time of 100 min.The optimal reaction conditions of the electro-Fenton synergistic electrocatalytic system was constructed with DSA as anode,iron-loaded activated carbon+stainless steel plate as double cathode to treat mariculture wastewater could reach 100%removal of COD,that were applied voltage of 3.39 V,plate spacing of 1.07 cm,aeration volume of 134.84 L/h,and treatment time of 80min.The removal of COD in marine aquaculture wastewater by the electro-Fenton synergistic electrocatalytic system conforms to the zero-order kinetic model.The best conditions for dynamic operation of the system were that the water flow direction was perpendicular to the electrode plate direction,and the water flow rate was 10 mL/min.The oxidant reuse experiment determined that the optimal reaction conditions were that the raw water and the effluent after the reaction were mixed in a volume ratio of1:1,the reaction time was 60 min.The NH4~+-N,and COD in the effluent could meet the Water Drainage Standard for Sea Water Mariculture.It was concluded that active chlorine and hydroxyl radicals played an important role in the removal of pollutants by the quenching experiments.The electro-Fenton synergistic electrocatalytic system has a good effect on the removal of COD and nitrogen in marine aquaculture wastewater.The GC-MS,UV-Vis,and FIIR showed that the electro-Fenton synergistic electrocatalytic system has a good degradation effect on macromolecular organic pollutants in marine aquaculture wastewater.Activated carbon,sodium sulfite,calcium sulfite ball,sodium thiosulfate can effectively remove residual chlorine,and the sodium thiosulfate has the lowest treatment cost.The electro-Fenton collaborative electrocatalytic system was constructed in this experiment could effectively remove COD and nitrogen in mariculture wastewater,and it could be further promoted in the field of mariculture wastewater treatment.The results can provide reference for the industrial application of electrochemical treatment of mariculture wastewater.