A kind of magnesium ammonium phosphate decomposition and its product recycling method for precipitation ammonia

Abstract

The invention relates to a method of decomposing magnesium ammonium phosphate and circularly settling ammonia for products. The method mainly comprises the following steps: adding collected magnesium ammonium phosphate solids into a magnesium ammonium phosphate; then, adding a chorine-containing oxidizing agent at an effective chorine-nitrogen (Cl / N) ratio of (7.6-11):1; adjusting the pH of the solution in a range of 5-7 and reacting for 5-20 minutes; then, adjusting the pH of the reacted solution to below 4 for treating ammonia-nitrogen wastewater; in the reuse process, controlling the Mg:P:N molar ratio within a range of (1-1.1):(1-1.1):1, adjusting the pH of wastewater in a range of 8.5-9.5 and controlling the reaction time at 10-30 minutes. The method provided by the invention is quick in decomposing reaction of magnesium ammonium phosphate, free from secondary pollution of ammonia nitrogen, simple in process method and less in investment, and the ammonia nitrogen removal efficiency in reuse of magnesium ammonium phosphate decomposing products is high.

Description

Technical field [0001] The invention belongs to the field of wastewater treatment, and particularly relates to a method for decomposing magnesium ammonium phosphate and cyclic ammonia precipitation of its products. Background technique [0002] Ammonia nitrogen (NH 3 -N) is one of the substances that cause the eutrophication of water bodies, and it is also a pollutant that is mainly controlled in the water environment. The ammonia nitrogen in the water body mainly comes from the discharge of industrial production and urban domestic sewage. One of the most direct and effective ways to curb the increasing trend of ammonia nitrogen pollution is to ensure that enterprises meet the discharge standards. Magnesium ammonium phosphate (MAP) precipitation has the characteristics of high deamination efficiency, rapid reaction, good solid-liquid separation performance, and simple operation. The reaction equation is as follows: [0003] Mg 2+ +NH 4 + +HPO 4 3– +6H 2 O→MgNH 4 PO 4 ·6H 2 O↓+H +...

AI Technical Summary

Problems solved by technology

However, this method also has the same problem of by-products as high-temperature direct pyrolysis, but the content of by-products is less than that of high-temperature direct pyrolysis. 3 (PO 4 ) 2 , Mg 2 P 2 o 7 etc. gradually increase, so that the removal rate of ammonia nitrogen gradually decreases with the increase of the number of cycles, and finally leads to the failure of pyrolysis products

[0010] In summary, the main problem of the existing magnesium ammonium phosphate recycling decomposition method is: in the process of decomposing magnesium ammonium phosphate, it is easy to produce a large amount of Mg 3 (PO 4 ) 2 , Mg 2 P 2 o 7 and other ineffective components, and as the number of recycling increases, such by-products gradually accumulate, resulting in a decrease in the removal efficiency of ammonia nitrogen in decomposition products, which limits the recycling of magnesium ammonium phosphate