Treatment Options for Municipal Solid Waste by Composting and Its Challenges.

Recovery and recycling of municipal solid waste biodegradable fraction (50-55%) are essential for attaining sustainability and a circular economy. Among organic waste treatment methods, composting is used to recycle organic fractions of waste. However, only 10-12% of municipal solid waste is utilized for composting treatment due to a lack of segregation practices and process challenges, including long process periods, odorous and greenhouse gas emissions, nitrogen loss, and low compost quality, which hinders large-scale practice. The current review paper discusses the challenges of composting treatment and its possible solutions. Various strategies were explored to address these challenges, such as utilizing microbial inoculum, additives, and optimization of physicochemical parameters. It also emphasizes the application of metagenomics for exploring key species. The knowledge about the microbial community and biochemical pathways (genome mining) can be exploited for the improvement of treatment efficiency. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01087-4.

Challenges and Control Strategies of Odor Emission from Composting Operation.

Composting is a biological decomposition process that occurs from microbial progression, which brings about the degradation and stabilization of various organic waste into compost. During composting, the emission of undesirable odor adversely affects compost quality and causes environmental deterioration. Also, odor emission from composting adversely affects human health and well-being. Ammonia (NH3), volatile organic compounds (VOCs), and hydrogen sulfide (H2S) are major components of odorous gases responsible for unpleasant odor. Physiological parameters such as pH, temperature, and aeration affect the pattern of odor emission during the composting process. The lack of techniques for the accurate identification and estimation of odor and control are some major challenges associated with composting. Therefore, the present review article concentrates on challenges and solutions to odor control. Biotrickling filter, optimization of process parameters, usage of additives, microbial inoculation, and pre-treatment techniques are practiced to lower odor emission during the process. The application of metagenomics may provide insight into the various biogeochemical pathways that can be explored in the future for odor control.