Study On Concentration Of And Recovery Of Nitrogen And Phosphorus Nutrient In Urine By New Electro-dynamic Inspissation Technology

Nitrogen and phosphorus are the major limiting factors in eutrophication of surface waters,as well as important energy and resources.With the popularity of ammonia fuel cell,nitrogen-containing compounds are becoming an alternative energy source.Especially the shortage ofphosphorus resources has become a worldwide crisis.In recent years,more attention has been paid to the recovery and utilization of nitrogen and phosphorus in wastewater and achieved some results.However,the traditional nitrogen and phosphorus removal processes which mainly depends on chemical and biochemical methods,often exist different defects like the application of the precipitation agent or coagulant aids bringing high cost and secondary pollution.Therefore,searching for a green process with nitrogen and phosphorus removal and material recovery will be the key research direction in the future.The high concentration of nitrogen and phosphorus in the urine is the main source of nitrogen and phosphorus in urban sewage,which accounts for 80%and 50%of the load respectively.Therefore,the separation of urine and the treatment and recovery of nitrogen and phosphorus alone can reduce the investment,scale and operation cost of the municipal wastewater treatment plant with the acquisition of nitrogen and phosphoru,s resources.Based on the analysis of the current status of urine treatment,the electric deionization technology has been chosen to remove and recover nitrogen and phosphorus in urine.The“electro-dynamic inspissation(EDI)”technology applied in this experiment is a combining process based on the technology of ion exchange and electrodialysis.It overcomes the concentration polarization and chemical regeneration existed in original single process and can treat low concentration solution efficiently.a new electrochemical deionization apparatus of six compartments was designed to achieve the continuous regeneration of resin on line without addition of chemicals.By using its purification and separation function,not only the nitrogen and phosphorus nutrients in the urine are treated as pure pollutants,but also been taken as an important target so as to explore the effects of electromigration,convection and diffusion on the migration of single nitrogen and phosphorus ions,and the concentration of nitrogen and phosphorus nutrients in the urine of EDI system is simulated in order to systematically study the purification and recycling effect of EDI on nitrogen and phosphorus nutrient in urine.The results showed that the electric deionization device can effectively recycle and separate nitrogen and phosphorus from urine.Through the exploration of the influencing factors of single nitrogen and phosphorus enrichment and recovery,it was found that the influence of current on ion-migration is dominant with the organic urea been affected by the influent speed.Taking artificial urine as the research object,the optimal operation conditions for recovery of nitrogen and phosphorus were found to be:0.19 A current and 4 L/h influent flowrate.Under this operation condition and device condition,the nitrogen and phosphorus elements in the actual urine can also be well enriched,separated and removed.And the concentrationratio ofphosphate was 4.4,the removal rate was about 90%.The concentration and recovery of urea was positively related to the flowrate ofwater,and the energy consumptionofrecoveryunitphosphate and urea was 23.66 Kw·h/g and 0.352 Kw·h/g,respectively.Basedon its environmental friendliness,it provides a new idea for the recovery of nitrogen and phosphorus nutrients in the urine.