The Study On Removal Of Nitrogen And Phosphorus In Aquaculture Effluent Using Seawater Battery

As a new type of high energy power source,seawater battery has the advantages of low cost,abundant resources,high specific capacity,low potential,small density,renewable,safe,and reliable,et al.In recent years,effluentsproduced by mariculture had exceeded the total land-based effluents with the rapid development of China's mariculture,whichresulted inammonianitrogen,phosphate and other nutrients increased dramatically,caused severe deterioration of the coastal environment.And then,the sustainable development of aquaculture industry was limited,and coastal waters ecosystem was unbalanced.In the presentstudy,NH4+ and PO43-ions were removed from simulant marine aquaculture effluentsby using seawater battery system.Mg2+ ions produced from magnesium cathode could react with NH4+ and PO43-ions to generate MgNH4PO4· 6H2O,which is an agricultural slow release fertilizer.Through above reaction,the NH4+ and PO43-ions contained in effluents were transformed into fertilizer,and the electric energy generated also could be used by farmers.On this account,the purpose of waste resource utilization was achieved.The effects of parameters,such as concentration of sodium chloride,pH value,temperature,and electrodessurface area,on the characteristic of seawater battery were investigated.The results shown that the current increased with the salinity,pH,temperature and the surface area of the electrodes increasing,nevertheless,it decreased with the increasing of pH.The voltage and salinity was positivelycorrelated,however,the voltage was inversely proportional to temperature and pH.The effects of pH,initial ammonia concentration,ratio of nitrogen and phosphorus on the removals of ammonia nitrogenand phosphorus were studied by using magnesium and titanium as cathode and anode,respectively.Experiment results indicated that the removal efficiencies of ammonia nitrogenand phosphate were respectively 85.34%and 98.4.6%,when pH was 9.5,and ratio of nitrogen to phosphorus was 1:1.1.Glucose and potassium biphthalate were added into simulated seawater for investigating the effects of organic pollutant and antibiotic on the removal of ammonianitrogenand phosphate.The results shown that the removal efficiencies of ammonianitrogenand phosphatehad an obvious decrease,and COD value had a slight decreasecompared with that of glucose and potassium biphthalate were absent.The output current and voltage of the battery were decreased when 50 mg different antibiotics were added to seawater,and the removal efficiencies of ammonianitrogenand phosphate also decreased.After a period of time,the removal efficiencies of ammonianitrogencontinued decreased,however theremoval of phosphate increased,and finally phosphate removal had the similar results with that of arntibiotics were absent.The effluents from a fishery(Dongshan,Fujian,China)were treated by seawater battery,the removal efficiencies of ammonianitrogen andin fish and shrimp ponds were 51.9%and 52.5%,respectively,and the phosphate were 99.5%and 98.5%,respectively.These findings indicated that high removal efficiencies of NH4+ and PO43-could be obtained when the seawater battery technology was used to treat aquaculture effluent.