Study On Adsorption And Recovery Of Nitrogen And Phosphorus In Urine By Electroflocculation And Modified Sawdust

The removal of nitrogen and phosphorus in water is the main factor to prevent eutrophication in water.Urine,a kind of wastewater rich in nitrogen and phosphorus,is also the main treatment body of water in the rural"toilet revolution".In this study,urine was taken as the main research and treatment object.Flocs were adsorbed with phosphorus by electric flocculation process,and then modified wood chips were filled with filter column as the adsorbent of nitrogen and phosphorus adsorption matrix and flocs.The experiment mainly investigated the influence of the optimum test parameters of the electrocoagulation process,such as electrode spacing,electrolysis time,current density and initial p H of water,on the electrolysis efficiency of electrocoagulation.The preparation and adsorption properties of modified wood chips were studied,and the best conditions for adsorption reaction were also studied.The results showed that the total phosphorus could be flocculated by electric flocculation.The electrolysis time was 80min,the current density was 60A/m2,the electrode spacing was40mm,and the initial p H value was 8.The total phosphorus recovery rate was 95.62%.Is obtained by orthogonal test,the initial p H and current density,plate spacing between these three factors effects on the electric flocculation reaction recovering phosphorus from big to small order is:electrode spacing>the initial p H>current density,plate spacing but electrical flocculation process not join Cl-,unable to realize to the ammonia nitrogen adsorption and recovery,the removal rate of ammonia nitrogen is always fluctuate within a certain scope,therefore consider joining of modified sawdust.The modified method can effectively improve the adsorption performance of wood chips.Nitrogen and phosphorus will be released after the wood chips are soaked for a long time,while the modified wood chips have stable physical and chemical properties,and the organic pigments are effectively treated.BET specific surface area method and SEM scanning electron microscope results confirm that the modified wood chips have increased the specific surface area and the number of holes.When the adsorption time is 150min,the adsorption reaction can reach the equilibrium state,the optimal reaction temperature is 25℃,the optimal dosage of modified poplar and modified Chinese fir is 40g/L,and the optimal p H value of nitrogen and phosphorus in the adsorption of modified wood chips is 8.To further explore the modified sawdust of ammonia nitrogen adsorption process,on the adsorption kinetics and adsorption isotherm experiments,according to the results of the fitting of visual observation and the comparison of correlation coefficient,it is concluded that the quasi level 2 dynamic model and the Langmuir isotherm adsorption model describes more fit,the adsorption process occurred in a relatively homogeneous chemical adsorption monolayer,adsorption properties for favorable adsorption.The best reaction conditions for the electroflocculation reaction were as follows:the reaction time was 60min,the current density was 40A/m2,the distance between plates was40mm,the initial p H was 8,the inlet water temperature was maintained at 25±1℃,the total phosphorus recovery rate was 79.38%,and the removal rate of ammonia nitrogen was 5.85%.After the electroflocculation reaction produced water and passed through the filter column,it can be seen from the test that the optimal filtration rate of modified wood chips was 1.2m/h,the adsorption rate of total phosphorus was 98.32%,the adsorption rate of ammonia nitrogen was 88.58%,and the removal rate of ammonia nitrogen in the water was 95.86%.The excellent adsorption treatment efficiency was 4h at the beginning of the reaction,and the previous adsorption efficiency was still in a good state.The flocculation produced by electric flocculation and Fe²⁺and Fe³⁺will affect the chromaticity of the effluent.Modified wood chips can remove the chromaticity and bring the chromaticity to grade A standard of sewage discharge.