THE EFFECT OF AMMONIA LOADING AND OPERATING TEMPERATURE ON NITRIFICATION AND DENITRIFICATION OF A HIGH AMMONIA LANDFILL LEACHATE

The effect of ammonia loading and operating temperature on the treatment of high ammonia, methanogenic, landfill leachate was investigated. Two single-sludge, nitrification-predenitrification systems were operated in parallel: one with a 10-day aerobic solids retention time, and the other with a 20-day aerobic solids retention time. The study consisted of two phases: an ammonia loading phase and a cold temperature phase. From the first phase, it was found that, at an influent leachate ammonia level of up to 1500 mg N/L, both systems produced an effluent of <1 mg NH4-N/L and approximately 170 mg NOx-N/L. Aerobic nitrite and anoxic ''free'' ammonia were both observed to increase as the ammonia loading was increased. When the inffuent ammonia was raised from 1500 to 2000 mg N/L, nitrification in both systems failed. During the second phase, the temperature was decreased from 20 to 10 degrees C while maintaining the leachate ammonia level at 1500 mg N/L. Aerobic nitrite accumulation and rising aerobic BOD5 were observed to begin at 14 degrees C. When the temperature was dropped from 12 to 10 degrees C, nitrification failed in both systems. In both cases, nitrification was re-established at 10 degrees C, by ceasing to waste solids and by stopping methanol addition.