Exceptionally high-rate nitrification in sequencing batch reactors treating high ammonia landfill leachate

The nitrogen removal capacity of a suspended culture system treating mature landfill leachate was investigated. Leachate containing high ammonium leve ls of 300-900 mg N/L was nitrified in a bench scale sequencing batch reacto r. Leachate from four different landfills was treated over a two year perio d for the removal of nitrogen. In this time, a highly specific nitrifying c ulture was attained that delivered exceptionally high rates of ammonia remo val. No sludge was wasted from the system to increase the throughput and up to 13 g/L of MLSS was obtained. Settleability of the purely nitrifying bio mass was excellent with SVI less than 40 mL/g, even at the high sludge conc entrations. Nitrification rates up to 246 mg NI(L h) (5.91 g N/(L d)) and s pecific nitrification rates of 36 mg N/(gVSS h) (880 mg N/(gVSS d)) were ob tained. The loading to the system at this time allowed complete nitrificati on of the leachate with a hydraulic retention time of only 5 hours. Followi ng these successful treatability studies, a full-scale plant was designed a nd built at one of the landfills investigated.