Highly effective biological nitrogen removal from high ammonia landfill leachate

A two-stage UASB (UASB1 + UASB2)-A/O system was investigated to improve nitrogen removal efficiency from the landfill leachate with high-concentration ammonia. Two different operational patterns: Denitrification occurring firstly in the UASB1 (technique 1) and denitrification only in A/O anoxic zone (technique 2) were contrastively studied. Under the condition of recirculation ratio 300%, ammonia nitrification efficiency of 2 kinds technique was about 99%, but TN removal efficiency of technique 1 was 21% higher than technique 2. The difference of variation rule of inorganic carbon (IC) and pH value of 2 kinds of technology was great. Technique 1 owing to utilizing completely raw water carbon source, the highly effective denitrification was obtained, ample IC and higher pH value in system was maintained, and nitritation of 75%-95% nitrite accumulation efficiency was realized. Able or not effectively utilizing organic carbon source was the basic reason of producing variation of nitrogen removal.