Nitrogen removal through different pathways in an aged refuse bioreactor treating mature landfill leachate

Abstract

In this study, an aged refuse bioreactor was constructed to remove nitrogen in a mature landfill leachate. The nitrogen removal efficiency and the microbial community composition in the bioreactor were investigated. The results showed that the aged refuse bioreactor removed more than 90 % of total nitrogen in the leachate under the nitrogen loading rate (NLR) of 0.74 g/kg (vs) day, and the total nitrogen removal rate decreased to 62.2 % when NLR increased up to 2.03 g/kg (vs) day. Quantitative polymerase chain reaction results showed that the average cell number of ammoniaoxidizing bacteria in the bioreactor was 1.58×10 8 cells/g, which accounted for 0.41 % of total bacteria. The number of anammox bacteria in the reactor was 1.09×10 8 cells/g, which accounted for 0.27 % of total bacteria. Isotopic 15 N tracing experiments showed that nearly 10 % of nitrogen was removed by anammox. High-throughout 454 pyrosequencing revealed that the predominant bacteria in the bioreactor were Proteobacteria, Chloroflexi, Actinobacteria, Bacteroidetes, and Gemmatimonadetes, including various nitrifiers and denitrifiers with diverse heterotrophic and autotrophic metabolic pathways, supporting that nitrogen was removed through different pathways in this aged refuse bioreactor.

Responses of bacterial community structure and denitrifying bacteria in biofilm to submerged macrophytes and nitrate

“…A recent study34 showed that the abundance of nitrifying bacteria typically represents less than 1% of the total bacterial population in activated sludge, although those microbes are extremely important for nitrogen removal. Denitrifiers, including the genera Acidovorax , Azospira , Bacillus , Dechloromonas , Desulfovibrio , Flavobacterium , Hyphomicrobium , Meganema , Rhizobium , Rhodobacter , Rhodoplanes , and Thiobacillus , play an important role in treating mature landfill leachate35 and wastewater36. For example, Dechloromonas oxidizes benzene using nitrate as an electron acceptor37.…”

Microbial community shifts on an anammox reactor after a temperature shock using 454-pyrosequencing analysis

“…Therefore, this technique can provide wider and more complete information about microbial community structures than previous conventional molecular biology techniques. For these reasons, 454-pyrosequencing has gained interest in the study of complex microbial communities such as those of wastewater treatment environments (Hu et al, 2012;Xie et al, 2013). Despite the potential of 454-pyrosequencing, the use of this novel technique with anammox reactors is still scarce (Costa et al, 2014;Pereira et al, 2014).…”

Short tests to couple N 2 O emission mitigation and nitrogen removal strategies for landfill leachate recirculation

“…Similar to nitrite, nitrate can also be reduced by both autotrophic and heterotrophic denitrifying bacteria. The experiments in Part 3 showed that degradable carbon content played a pivotal role, indicating that the main microorganisms responsible for denitrification are typically heterotrophs (Lee et al, 2002;Xie et al, 2013). Carbon source is insufficient in our experiments, however, the autotrophic denitrifiers could still offset the loss, where the aged (45 years old) landfill bioreactor still possessed 3.8 mg N/kgsoil capacity of denitrification (Jokela et al, 2002).…”

“…Apart from that, emission surges fluctuate as a function of loading rates, soil properties (e.g. moisture content, pH value and texture) and leachate quality, particularly with respect to nitrogen speciation (Silva et al, 2008;Xie et al, 2013). In summary, the heterogeneity of waste composition and conflicting technical implications compound landfill management.…”