The pathway of in-situ ammonium removal from aerated municipal solid waste bioreactor: nitrification/denitrification or air stripping?

Abstract

In-situ ammonium removal from municipal solid waste (MSW) landfill is an attractive method due to its economic advantages. In this study, two simulated MSW bioreactors with different degrees of initial bio-stabilization were utilized to investigate the effects of intermittent aeration mode and the addition of activated sludge on the removal of ammonium. The results showed that up to 90% of ammonium could be removed and the amount of NO(x)-N produced was less than 1% of NH4 (+)-N removed in both reactors. The pH values increased rapidly and finally arrived at a high level of 8.5-8.8. The efficiency of ammonium removal was improved by increasing the continuous aeration time, but it was not affected by the addition of activated sludge. A portion of liquid escaped from the reactors in the form of vapour, and as high as 195-258 mg L(-1) of NH(4) ( +)-N was detected in the vapour collector. According to calculation, nitrification was inhibited by the high level of free ammonia in the bioreactors. As a result, air stripping was enhanced and became the primary pathway of ammonium removal. Therefore, controlling free ammonia concentration was essential in ammonium removal from the aerated MSW bioreactor.

Determinants of Optimal Aerobic Bioreactor Landfilling for the Treatment of the Organic Fraction of Municipal Waste

“…-Several nitrogen transformation processes, such as nitrification, ammonia air stripping, favored under aerobic conditions (He and Shen, 2006;Hao et al, 2010). Hybrid -Combination of aerobic and anaerobic processes.…”

Application of landfill treatment approaches for stabilization of municipal solid waste

“…Ammonia-nitrogen in a closed landfill is the key parameter that will affect the ability to release a landfill from regulatory oversight . Studies showed that in-situ aeration promoted a dramatic decrease in ammonia-nitrogen concentrations even under low biodegradable C/N conditions Hao et al, 2009). Heterogeneity of the waste environment does not always allow for uniform distribution of oxygen promoting the formation of anoxic and aerobic pockets.…”

Nitrogen pools and flows during lab-scale degradation of old landfilled waste under different oxygen and water regimes

“…So far, investigations addressing the fate of nitrogen mainly focused on insitu aeration as a strategy to lower the concentration of NH 4 in landfill leachate, with numerous reports of significant NH 4 reduction in landfill leachate during and after in-situ aeration (e.g. Hao et al 2010;Hrad et al 2013;Prantl et al 2006;Ritzkowski et al 2006). The observed reduced nitrogen concentrations were explained by nitrification and denitrification processes within the waste body (Berge et al 2006;He et al 2006;Onay and Pohland 1998;Price et al 2003;Vigneron et al 2007).…”