Start-up of short-term nitrification/ANAMMOX process for treatment of landfill leachate

Due to the difficulty of nitrogen removal in the mature landfill leachate, a combined process consisting of short-term nitrification sequencing batch reactor (SNSBR) and anaerobic ammonium oxidation sequencing batch reactor (ASBR) was developed to treat the advanced stage landfill leachate. After the domestication and cultivation of 50 d, the concentration of NO2--N in the SNSBR effluent is maintained at about 500 mg/L, and the short-term nitrification rate can be maintained at above 98%. In order to eliminate the inhibition of the high concentration of NO2--N put on the anammox bacteria, the operation of ASBR was changed from the traditional type to the one of continuous influent during the reaction period and interval settle and effluent with the HRT being about 20 h. The experiment consisted of two stages, namely, the start-up and the domestication. During the start-up, as the concentration of NO2--N was increased from 60 mg/L to 395 mg/L, the ammonium and nitrite removal efficiency both reached over 98%, and total nitrogen volume removal rate was increased from 0.10 kg/(m3·d) to 0.75 kg/(m3·d). After domestication, mix the leachate into the influent by increasing the rate of 20% every phase. On the day of 156, all of the NO2--N in the influent came from the effluent of the SNSBR. The results show that nonbiodegradable COD of the leachate cannot inhibit the anammox bacteria, however, a little denitrification increases the total nitrogen removal efficiency of the system. The total nitrogen volume removal rate is 0.76 kg/(m3·d), and the concentration of COD, nitrite and ammonium in the influent and effluent is 295, 390, 295 and 246, 1.3, 0.6 mg/L, respectively. The nitrogen removal efficiency of the system can reach above 90% without any carbon source addition, which shows good performance of nitrogen removal efficiency.