Method for improving activity of methanogens while reducing high-concentration ammonia nitrogen in anaerobic process

The invention discloses a method for improving the activity of methanogens while reducing high-concentration ammonia nitrogen in the anaerobic process, and belongs to the field of water treatment. The method comprises the following steps of: contacting high-concentration nitrogen-containing organic waste water with anaerobic microorganisms fully in an anaerobic reactor to perform reaction, and degrading to obtain a large amount of ammonia nitrogen; introducing the waste water into a crystallizing sedimentation tank partially, adding a dissoluble magnesium source and phosphates in a certain ratio, and regulating the pH value to 7.0 to 10.0, so that Mg , NH4 and PO4 in the waste water react to generate an ammoniomagnesium phosphate (MAP) crystal, and precipitating the MAP crystal; and stabilizing the pH value of treated supernatant to 6.5 to 8.0 by a pH regulating tank, and refluxing to the anaerobic reactor. By the method, ammonia nitrogen resources in the waste water can be recovered effectively, the phenomenon of the reduction of the activity of anaerobic sludge due to overhigh concentration of the ammonia nitrogen can be prevented, and the operation effect of the anaerobic reaction and the yield of methane can be improved.