Nitrogen retention and emissions during membrane-covered aerobic composting for kitchen waste disposal

AbstractThe composting performance and nitrogen transformation during membrane-covered aerobic composting of kitchen waste were investigated. The aerobic composting products of the kitchen waste had a high seed germination index of ∼180%. The application of the membrane increased the mean temperature in the early cooling stage of composting by 4.5℃, resulted in a lower moisture content, and reduced the emissions of NH3 and N2O by 48.5% and 44.1%, respectively, thereby retaining 7.9% more nitrogen in the compost. The adsorption of the condensed water layer under inner-membrane was the reason for reducing NH3 emissions, and finite element modeling revealed that the condensed water layer was present throughout the composting process with a maximum thickness of ∼2 mm in the thermophilic stage. The reduction of N2O emissions was related to the micro-positive pressure in the reactor, which promoted the distribution of oxygen, thus weakening denitrification. In addition, the membrane cover decreased the diversity of the bacterial community and increased the diversity of ammonia-oxidizing strains. This study confirmed that membrane-covered composting was suitable for kitchen waste management and could be used as a strategy to mitigate NH3 and N2O emissions.KEYWORDS: Kitchen waste; aerobic composting; membrane cover; nitrogenous emissions; bacterial community Disclosure statementNo potential conflict of interest was reported by the author(s).Data availability statementThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.Additional informationFundingThis work was supported by the National Key Research and Development Program of China [grant number 2019YFC1906603], The Jiangsu Synergetic Innovation Center for Advanced Bio-Manufacture [grant number XTD2217], National Natural Science Foundation of China [grant number 42177348] and the Jiangsu Province Science and Technology Program [grant number BZ2022052].