Application Of Bio-electrochemical Techniques In Solving Aquaculture Water Pollution Problem

With the prosperous development of global fisheries,the aquaculture industry is facing problems such as the death of fish caused by the deterioration of water quality,the shortage of water due to the waste of large amounts of water resources,and the destruction of the surrounding environment caused by the discharge of aquaculture effluent.There is an urgent need for efficient and green solution,to ensure the healthy and sustainable development of the aquaculture industry.Microbial electrochemical method is a technical method for effectively removing water pollutants,which has the advantages of energy recovery.This study proposes microbial electrochemically intensifying treatment methods to solve the problem of water pollution in aquaculture:The system integrating constructed wetland（CW）and microbial fuel cell（MFC）for aquaculture tail water treatment verified the effectiveness of MFC in the treatment of aquaculture effluent.It further solves the problems of water resources and rapid deterioration of water quality in fisheries:A microbial fuel cell enhanced recirculating aquaculture systems（RAS）was built to ensure water quality and remediate the environment in a simulate high-density aquaculture environment.To improve the removal efficiency of pollutants,composite catalysts including Fe-Co,Fe-Sn-TiO₂,Mn-Sn-Ce/GAC were used for anode modification,respectively,which helped to meet the national aquaculture emission standards.This technology can increase the capacity of water treatment and environmental remediation performance,and simultaneously generating electrical energy.The specific research process and results obtained are as follows:（1）In this study,a constructed wetland system,simple in structure,was coupled with microbial fuel cells.The combined plant with microbial fuel cell is used to efficiently treat aquaculture effluent.The removal efficiency of COD,ammonia nitrogen and total phosphorus of MFC/plant system reached 73%,81%and 71%,respectively.A simulate high-density recirculating aquaculture system strengthened by microorganisms was built.The removal efficiency of COD,ammonia nitrogen and total phosphorus in the MFC/RAS system reached53%,69%and 49%,respectively.The water treatment efficiency of this system is favorable.It has been verified that the microbial fuel cell has a significant effect on treatment of aquaculture wastewater.（2）The anode modification of MFC was further optimized for treatment of RAS effluent then recycled back and reused.The composite modified anodic materials with Fe-Co,Fe-Sn-TiO₂ and Mn-Sn-Ce oxides were prepared with activated carbon granules as base electrodes using impregnation-roasting method,and the prepared catalysts were used as three-dimensional electrode,they were characterized and analyzed.Analysis shows that the catalyst has good redox performance.Anodic Fe-Sn-TiO₂ composite material system has the better sewage purification effect,and the removal efficiency of COD,ammonia nitrogen and total phosphorus reaches 86%,92%and 61%,respectively.（3）The MFC system can generate electrical energy and is proportional to the removal efficiency of pollutants,which is helpful for the treatment of aquaculture wastewater.Compared with the wetland system,the wetland system coupled with the microbial fuel cell can generate a voltage of 95-210 mV and a maximum power density of 557.2 mW/m².For the circulating aquaculture system,the Mn-Sn-Ce anodic system can generate a maximum voltage of 474 mV and a maximum power output of 859.8 mW/m²,and can effectively realize the utilization of sewage resources and power generation.（4）Experiments have confirmed that excellent electricity generation can increase the output value of plants and animals,the fish weight of the MFC-CW system increases by 9.8%,and the plant length of Foxtail grass increases by 14%.The system using Mn-Sn-Ce anodic composite catalytic material for simulate high-density circulating aquaculture has the largest increase in output value,the fish weight gain increases by 15%,and the foxtail plant length increases by 21%.The performance of anode modification system is better,and it can simultaneously solve the problems of water quality,fishery output value and environmental restoration.