Treatment of Landfill Leachate by Nitrous Nitrification/Denitrification in MBR

The removal of high-concentration ammonia nitrogen is always one of difficulties in treatment of landfill leachate.Therefore,a pilot-study on nitrous nitrification/denitrification for treatment of the leachate was carried out in membrane bioreactor(MBR).The results show that when the influent ammonia nitrogen concentration is less than 1 000 mg/L and the ammonia nitrogen loading is about 0.4 kgNH~+4-N/(m~3·d),the removal rate of ammonia nitrogen can reach 80% to 90%.When the free ammonia concentration in the reactor is above 5 mg/L,the nitrite accumulation rate reaches 80%,which indicates that the inhibition of free ammonia is the main cause leading nitrous nitrification/denitrification.The total nitrogen removal rate is about 70% when the influent C/N ratio is above 2 ∶1,suggesting that the carbon source demand is less than that in conventional nitrification/denitrification process.However,when the influent C/N ratio is decreased to 1 ∶1,the removal rate of total nitrogen is only 30%.