Experimental Study on the Partial Nitrification of High Concentration Ammonia-nitrogen Wastewater Based on PNH Technology

This experiment takes the activated sludge from MBR membrane aerobic tank as inoculated sludge,adopts the combined process of aerobic tank and efficient sedimentation tank,and studies the partial nitrification of high concentration ammonia-nitrogen wastewater in the conditions of dissolved oxygen in aerobic tank being above 2mg/L,temperature 30±1°C,the pH in the start-up period between 7.5and 7.6,and the pH in the improving period and steady-running period between 7.0and 7.1.The results show that,after 36days,the influent concentration of ammonia is 4 645mg/L,the maximum ammonia loading reaches 8.9kg-N/(m3·d-1),the maximum accumulation rate of nitrite is up to 99.9%and the conversion rate of ammonia varies from 53.5%to 97.2%.It can be concluded that it is possible to effectively suppress the activity of the nitrite-oxidizing bacteria,screen the ammonia-oxidizing bacteria and quickly start the reaction of partial nitrification through the way of increasing the concentration of free ammonia under the optimal conditions of pH,DO and temperature.Meanwhile,it is acceptable to decrease the accumulation rate of effluent nitrite and the conversion rate of ammonia by increasing the amount of influent,which makes the ratio of nitrite nitrogen and ammonia nitrogen in effluent reach 1.32to meet the requirements of the following anammox process.