Study On Treatment Of Simulated Nitrogen And Phosphorus Wastewater Using Magnesium Ammonium Phosphate Method

On the one hand, massive emissions of nitrogen and phosphorus leads to the pollution of water, on the other hand results in the loss of phosphorus resources. As the one of the most effective ways for recycling nitrogen and phosphorus from wastewater, MAP has been extensively studied at present. Limiting factors of MAP used in wastewater treatment include the following two points. Firstly, the treatment costs will be increased because of adding Magnesium source. Secondly, magnesium ammonium phosphate is physical and chemical method,it have poorer treatment effect for low concentration of nitrogen and phosphorus wastewater. How to improve the treatment effect of low concentration of nitrogen and phosphorus on method of magnesium ammonium phosphate is one of the difficult and important to study.This article studied the feasibility of using magnesium ammonium phosphate method removed orthophosphate in high nitrogen and low phosphorus wastewater, which is on the basis of studying the optimum reaction conditions when Mg Cl2 · 6H2O solution, Mg SO4 solution, Mg O solid and(MgCO3) 4 · Mg(OH) 2 · 5 H2O solid as plus magnesium source, and the article also obtained the best source of magnesium while considering the treatment effect and economic factors. The research is mainly focused on the integration of the fluidized bed reactor, which used for nitrogen and phosphorus magnesium ammonium phosphate method.on the basis of studying optimal operation parameters of the fluidized bed reactor, It’s better treatment effect of low concentration of nitrogen and phosphorus wastewater be proveg through the experiment. The studies obtained the following main conclusions:Single factor experimental results showed that, Mg Cl2·6H2O solution and(MgCO3)4·Mg(OH)2· 5H2O solid as the best of soluble magnesium source and insoluble magnesium source, the optimal reaction conditions were p H = 10.5, stirred for 30 min, stirring intensity was 100 r / min, n(Mg) :n(N) = 1.1, n(P) :n(N) = 1.0; p H = 8, stirred 1.5h, stirring intensity was 120 r / min, n(Mg) :n(N) = 1.3, n(P) :n(N) = 1.0; the corresponding removal rates of ammonia nitrogen and orthophosphate were 82%, 92% and 80%,84%.The inflow concentration of ammonia nitrogen and orthophosphate were 100 mg / L and 70 mg / L, adding Mg Cl2 · 6H2O solution and(MgCO3) 4 · Mg(OH) 2 · 5H2O solid as a source of magnesium and made reaction under the best controlled conditions of two sources magnesium. The removal rates of ammonia nitrogen and orthophosphate were 30.5%, 80.6% and 25.0%, 73.3%. Although the removal efficiency of nitrogen and phosphorus adding Mg Cl2·6H2O solution was slightly better than adding magnesium carbonate solid, however, adding Mg Cl2·6H2O solution will cause secondary pollution, and require a higher p H value factors. SO, the testing chose basic carbonate magnesium as the best source of magnesium. The results also demonstrated removal of phosphorus in the form of MAP in High nitrogen and low phosphorus wastewater is feasible.With(MgCO3) 4 · Mg(OH) 2 · 5 H2O solid magnesium source, designed three factors and three levels orthogonal experiment which is p H, the concentration of ammonia nitrogen and the concentration of orthophosphate. The results showed that the primary and secondary order for effect factors of nitrogen and phosphorus removal rate was: p H> P concentration> N concentration. Considering the removal of ammonia nitrogen and orthophosphate, chose p H = 9, N = 200 mg / L, P = 50 mg / L as the optimal combination of orthogonal experiment.With(MgCO3) 4 · Mg(OH) 2 · 5 H2O solid magnesium source, using the integrative fluidized bed reactor disposed the simulated nitrogen and phosphorus wastewater. The experimental results showed that the smaller HRT, the greater removal efficiency of phosphorus. As the reaction time went on, the phosphorus removal rate corresponding to different HRT approach gradually. So, chose HRT = 10 min as the best HRT for fluidized bed reactor.Compared with a laboratory scale experiment, the advantage of removal rate of nitrogen and phosphorus by fluidized bed reactor is reflected in the 30 minutes after the start of the reaction,because of role of water in a fluidized bed reactor smashed larger magnesium ammonium phosphate grains which formed in the late. Experimental results show that the lower the sampling position on the fluidized bed reactor, the bigger the particle size, the better the performance of sedimentation, and are all greater than with the beaker contrast experiment under the condition of particle size。...