Study On The Process Of Phosphorus Removal From Industrial Wastewater

Nitrogen and phosphorus are the key factors leading to eutrophication of water.Phosphorus is a valuable non-renewable resource.With the increasingly strict emission standards and the scarcity of phosphorus resources,the research and development of wastewater nitrogen and phosphorus removal technology and phosphorus resource recovery technology is undoubtedly of great significance.The struvite precipitation method?also known as magnesium-ammonium-phosphate precipitation method?is a new method for nitrogen and phosphorus removal of wastewater.This simple,efficient,and rapid method can simultaneously remove and recover ammonia nitrogen and phosphorus in the waste water,and the recovered struvite,also known as magnesium ammonium phosphate?Mg NH₄PO₄·6H₂O?,can be recycled and is an excellent slow release fertilizer.Therefore the struvite method has attracted more and more attention and has broad development and application prospects.The paper discusses the treatment of wastewater containing high concentrations of phosphate and ammonia nitrogen by struvite precipitation method,the total phosphorus content?TP?content of effluent water is as low as that of domestic wastewater,which is convenient for large-scale centralized biological treatment.The paper discussed in detail the effects of p H value,molar ratio of material,reaction time,reaction temperature,substance concentration and stirring speed on the phosphorus removal efficiency of simulated wastewater,high concerntration industrial phosphate wastewater and low concentration biogas slurry.Furthermore,the reaction kinetics related to struvite reaction was studied.The main conclusions are as follows:In the simulated wastewater phosphorus removal ecperiment,Na₂PO₄·12H₂O and NH₄Cl were used to prepared high concerntration?TP:5442 mg/L?and low concerntration?TP:340 mg/L?simulated phosphate wastewater.The results show that the optimal conditions for the reaction were determined as follows:p H 10,Mg:P:N molar ratio of1.5:1.06:1,the stirring speed was 200r/min.Reaction time and temperature was 30 min and25°C,respectively..Under these conditions,the phosphorus removal rates reached99.37%and 96.02%,respectively.Among them,the p H value had the greatest influence on the phosphorus removal effect,and the molar ratio of Mg:P:N was the second.The effect of temperature and reaction time on the phosphorus removal effect was not obvious.Based on the above results,industrial high concerntration phosphate wastewater with TP of 1768.2 mg/L was used as raw material,the influence factors of phosphorus removal were investigated,and the results show that the greatest influenceis p H,the second is the ratio of Mg:P:N,and the third is temperature.The results were consistent with that of the simulated wastewater experiments.The optimum p H of the reaction is 10.The best Mg:P:N is 1.5:1.06:1.Under these conditions,the phosphorus removal rate of industrial high concerntration phosphate wastewater reached 99.22%.Then a low concerntration phosphate wastewater from an animal farmwith with TP of138.3 mg/L was used as raw material also verified the criticality of the p H value.Increasing the ratio of Mg to N in the wastewater when the p H is fixed at 10 can effectively increase the removal rate of phosphorus.The optimum p H and Mg:P:N was 10and 1.5:1.06:1,respectively.At this time,the removal rate of the low phosphate concentration biogas slurry was 98.02%.Furthermore,kinetic studies of the reaction Mg²⁺+NH₄⁺+HPO₄^2-+6H₂O?Mg NH₄PO₄·6H₂O?+H⁺was investigated.The results show that the struvite precipitation reaction is a pseudo-first-order reaction.The activation energy of the reaction is16.80k J/mol,indicating that the reaction rate is fast and the temperature has little effect on the reaction rate.Therefore,the struvite precipitation reaction for phosphorus removal from wastewater can be operated at indoor temperature.In a word,the struvite precipitation method can effectively remove phosphorus from wastewater,and has good economic and environmental benefits.Exploring its optimal process conditions can process wastewater more efficiently;the resulting larger crystals are favorable for precipitation.Struvite precipitation method is a technically feasible,economical and environmentally friendly wastewater treatment method with good application prospects.