The effect of decreased ambient temperature on the biological nitrification and denitrification of a high ammonia landfill leachate

• Published in: Water research (Oxford) 2001-06, Vol.35 (8), p.2065-2072
• Main Authors: Ilies, P, Mavinic, D.S
• Format: Article
• Language: English
• Subjects: Aerobiosis; Ammonia; Ammonia - analysis; Ammonia - metabolism; Anaerobiosis; Applied sciences; Biological and medical sciences; biological treatment; Biological treatment of waters; Bioreactors; Biotechnology; Environment and pollution; Equipment Design; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; high ammonia leachate; Industrial applications and implications. Economical aspects; methanol; Nitrites - analysis; Nitrites - metabolism; operating temperature; Other wastewaters; Oxygen - analysis; Pollution; Temperature; Waste Management; Wastewaters; Water Purification - instrumentation; Water Purification - methods; Water treatment and pollution
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/S0043-1354(00)00477-2

This research investigated the nitrogen removal capabilities of a pre- and post-denitrification process, when treating sanitary landfill leachate containing an ammonia concentration of over 2200mg N/L, at operating temperatures down to 10°C. The treatment system employed is generally known as a 4-Stage Bardenpho process. Two parallel systems were operated throughout the study; each system had an aerobic solids retention time of 20 days and an external recycle ratio (return activated sludge) of about 3:1. During the entire experimental period, one system used an internal recycle ratio of about 4:1, while the other system used one of 3:1. Methanol was used as supplementary carbon source for denitrification. When operating temperature was decreased from 20 to 17°C, an approximate 15% decrease in denitrification was immediately experienced within both systems, with no noticeable affect on nitrification. This was an unexpected result. Subsequently, the temperature was further decreased to 14°C, and finally to 10°C. With the temperature at 14°C, aerobic wasting was also stopped and methanol loading was progressively decreased to match actual denitrification requirements. At 10°C, both systems suffered major nitrification and denitrification inhibition. Changes in operating parameters, such as a decrease in influent ammonia and methanol loading, as well as an increase in ambient temperatures, from 10 to 15°C, did not significantly improve overall system performance, within a reasonable time frame. Both denitrification and nitrification problems were mainly attributed to decreased ambient temperature, although other possible factors were noted; at project completion, about 50% of the incoming ammonia was being removed across the system.