Inorganic nitrogen transformations in the treatment of landfill leachate with a high ammonium load: A case study

• Published in: Environmental monitoring and assessment 2007-01, Vol.124 (1-3), p.51-61
• Main Authors: Parkes, Stephen D, Jolley, Dianne F, Wilson, Stephen R
• Format: Article
• Language: English
• Subjects: Aeration; Alkalies - chemistry; Applied sciences; Biological and medical sciences; Biological treatment of waters; Biotechnology; Carbonates - chemistry; Carbonates - metabolism; Chemodenitrification; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Industrial applications and implications. Economical aspects; Landfill leachate; Magnesium; Metals, Heavy - chemistry; nitrification; Nitrite accumulation; Nitrites; Nitrites - chemistry; Nitrites - metabolism; Nitrogen - chemistry; Nitrogen - isolation & purification; Nitrogen budget; Nitrous Acid - chemistry; Other wastewaters; Oxidation-Reduction; Pollution; Ponds; Quaternary Ammonium Compounds - chemistry; Quaternary Ammonium Compounds - metabolism; Reduction; Temperature; Transformations; Wastewaters; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - isolation & purification; Water Purification - methods; Water treatment and pollution; Wetlands
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-006-9208-7

The inorganic nitrogen transformations occurring at a municipal waste leachate treatment facility were investigated. The treatment facility consisted of a collection well and an artificial wetland between two aeration ponds. The first aeration pond showed a decrease in ammonium (from 3480 (± 120) to 630(± 90) mg [dot operator] L-¹), a reduction in inorganic nitrogen load (3480 to 1680 mg N [dot operator] L-¹), and an accumulation of nitrite (< 1.3 mg-N [dot operator] L-¹ in the collection well, to 1030 mg-N [dot operator] L-¹). Incomplete ammonium oxidation was presumably the result of the low concentration of carbonate alkalinity (~2 mg [dot operator] L-¹), which may cause a limitation in the ammonium oxidation rate of nitrifiers. Low carbonate alkalinity levels may have been the result of stripping of CO₂ from the first aeration pond at the high aeration rates and low pH. Various chemodenitrification mechanisms are discussed as the reason for the reduction in the inorganic nitrogen load, including; the reduction of nitrite by iron (II) (producing various forms of gaseous nitrogen); and reactions involving nitrous acid. It is suggested that the accumulation of nitrite may be the result of inhibition of nitrite oxidizers by nitrous acid and low temperatures. Relative to the first aeration pond, the speciation and concentration of inorganic nitrogen was stable in the wetlands and 2nd aeration pond. The limited denitrification in the wetlands most probably occurred due to low concentrations of organic carbon, and short retention times.