Study On The Precipitation Mechanism Of Chemical Phosphorus Removal

China's environmental protection awareness is increasingly strong.With the improvement of China's wastewater discharge standards,wastewater treatment plants in various regions have been upgraded,and many wastewater treatment plants have failed to meet the total phosphorus content discharge standards.Therefore,in-depth treatment of total phosphorus has become a focus of research and exploration at this stage.Based on the theoretical research of chemical phosphorus removal,the optimum phosphorus removal agent and the effect of crystal nucleus on the treatment effect of chemical phosphorus removal were studied.This paper explores the theoretical basis of chemical phosphorus removal,explores several phosphorus removal agents such as Fe2+,Fe3+ and Al3+,and finds that the state of derivatives of each substance is affected by the p H degree.The concentration of each substance in the solution can be solved through the concentration of phosphate and p H in the reaction solution.Based on the calculation of total phosphorus concentration and equilibrium constant,it is found by comparative analysis that Fe3+ is the best chemical phosphorus removal process for several metal ions,and there is a certain linear relationship between total phosphorus and total iron concentration under the ideal control condition.However,in the actual solution reaction process,the precipitation of iron phosphate is greatly affected by p H,which leads to the dissolution of the precipitation of iron phosphate under the condition of peracid,and the peralkali leads to the transformation of the precipitation of iron phosphate to the precipitation of iron hydroxide.During the formation of iron phosphate precipitation,there is a nucleation phenomenon in the early stage,namely the transition process from metastable solution to steady-state solution.There is no flocs precipitation before the formation of this process,and the flocs precipitation phenomenon begins when the particle size is larger than the critical radius of precipitation.The results showed that the phosphorus removal efficiency of the group with and without crystal nucleus was higher than that of the group without crystal nucleus.In addition,the experiment state was changed and the oscillator was used for continuous shaking reaction.Compared with the test tube experiment,the chemical phosphorus removal effect was improved by 93.64%.Three different crystal types of steel slag,activated carbon and activated sludge were added in the reaction state of the oscillator,and the treatment effect of steel slag > activated carbon > activated sludge was found.