Removal And Concentration Of Nitrogen/Phosphate/Carbonate Salts For Reuseby Electrodeionization Based Technology

With the rapid development of industrialization progresses, circulating nitrogen and phosphorus essentials have evoluted from necessary mateials for keeping ecosyatem to pollutants,and have caused eutrophication and other environmental issues;also due the existence of large carbon emissions in the wastewater treatment process(carbon emissions is a generic term on greenhouse gas emissions, the main greenhouse gas is carbon dioxide),causing the greenhouse effect and speeding up the global warming process.Hence,the nidrogen/phospahte/carbonate salt has become main treatment goal in wastewater.From another perspective,with the shortage of resource(especially phosphate) and the popular research of carbon dioxide synthesis,recover them for reuse has become more urgent. The traditional treatment process transformed contaminants into non-polutting sustances,it can not reach the target of recovery and cause lager resource waste,Looking for an method both has the ability of removal and recovey is important.Electro-deionization(EDI) is regarded as a high-tech,green,and environmental technology,has been widely studied in metal ions recovery and removal,but use it for anion ions purification is not too much.Based on electro-deionization technology that can purify the water and also concentrate ions, in this paper the untilization of EDI systems for nitrogen, phosphorus and carbonate removal and recovery is investigated.A five compartments EDI device is proposed (the targeted ions are NH4, PO43-),and the removal effect of this system is studied.By comparing the ED and EDI system,it revealed that by adding the resin in the dilute chamber, the energey consumption and removal efficiency will largely improved.After treatment, the N and P concentration in effluent can achieve 0.89mg/L and 0.15mg/L,also the current and solution cycling rate is investigated.The results showed that the current has great effect upon ion removal,but cycling rate has little impact on ion removal.In conclusion, among electromigration, convection, diffusion effects,the effect of electric field is dominant.Further research is discuss the concentration ability of self-designed appartus,it showed that operating in the continous mode,the N and P concentration in the effluent is constant,the ions get concentrated in the chamber, the concentration factor of N and P is 13 and 11 respectively.To deal with the problem of precipitation, a novel devive is proposed,it called selective-EDI.The results showed that the recovery efficiency can increased to above 90%.What's more,the energy consumption result is ideal,the cost for N and P recovery is 19.104g/kwh and 4.848g/kwh in the 0.18A current.The carboante salt in wastewater is considered as targeted ions.A novel four chamber EDI appartus is put forward.It simultaneously recover carbon dioxide and regenerate alkline solution.The operation parameters like current,flow rate,influent concentration,competeting ions is investigeted.The results indicated that in the optimial mode,the energy for recover CO2 is 1.41MJ/kg,the corresponding current efficiency is about 80%.Thus, with EDI technology-based process can be realized nutrients/carbonate ions removal and recovery, this method is expected to become a new treatment process contaminants.