Organic matter and concentrated nitrogen removal by shortcut nitrification and denitrification from mature municipal landfill leachate.
An UASB+Anoxic/Oxic (A/O) system was introduced to treat a mature landfill leachate with low carbon-to-nitrogen ratio and high ammonia concentration. To make the best use of the biodegradable COD in the leachate, the denitrification of NOx- -N in the recirculation effluent from the clarifier was carried out in the UASB. The results showed that most biodegradable organic matters were removed by the denitrification in the UASB. The NH4+ -N loading rate (ALR) of A/O reactor and operational temperature was 0.28-0.60 kg NH4+ -N/(m3 x d) and 17-29 degrees C during experimental period, respectively. The short-cut nitrification with nitrite accumulation efficiency of 90%-99% was stabilized during the whole experiment. The NH4+ -N removal efficiency varied between 90% and 100%. When ALR was less than 0.45 kg NH4+ -N/(m3 x d), the NH4+ -N removal efficiency was more than 98%. With the influent NH4+ -N of 1200-1800 mg/L, the effluent NH4+ -N was less than 15 mg/L. The shortcut nitrification and denitrification can save 40% carbon source, with a highly efficient denitrification taking place in the UASB. When the ratio of the feed COD to feed NH4+ -N was only 2-3, the total inorganic nitrogen (TIN) removal efficiency attained 67%-80%. Besides, the sludge samples from A/O reactor were analyzed using FISH. The FISH analysis revealed that ammonia oxidation bacteria (AOB) accounted for 4% of the total eubacterial population, whereas nitrite oxidation bacteria (NOB) accounted only for 0.2% of the total eubacterial population.
Zhang
Shu-jun
SJ
College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022, China. zsj@emails.bjut.edu.cn
Peng
Yong-zhen
YZ
Wang
Shu-ying
SY
Zheng
Shu-wen
SW
Guo
Jin
J
D001419:Bacteria / Q000235:genetics / Q000378:metabolism; D019149:Bioreactors; D017404:In Situ Hybridization, Fluorescence; D009584:Nitrogen / Q000378:metabolism*; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012037:Refuse Disposal; D014874:Water Pollutants, Chemical / Q000378:metabolism*
D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D009584:Nitrogen