Composting is a natural process that stems through microbial succession, marking the degradation and stabilization of organic matter present in waste. The use of microbial additives during composting is considered highly efficient, likely to enhance the production of different enzymes resulting in better rate of waste degradation. In lesser developed countries, composting has emerged as a vital technology to recycle the biodegradable waste while generating a useful product. Depending on the composition of the waste material, it can either directly undergo composting or homogenized prior to secondary waste treatment methods such as landfilling. However, a relatively expensive downstream handling all along is a main hurdle towards economics of the process. Although basic methodology and recent approaches are known in crucial aspects of the process through various reviews, exploring the behavior of effective microbial additives will be resourceful. In this review, to fill in the gap, studies related to microbial composting of municipal solid and food waste were acknowledged. Here in, factors that could slow down the composting process and affect the compost quality were addressed. Lastly, the review pictured a positive simulation and stated how excellent results, can be achieved by microbial additives during composting.

Purpose The work aimed to investigate the effect of cow dung and cellulolytic bacteria on humic characteristics during municipal solid waste composting. Four Bacillus isolates (B. subtilis, B. tequilensis, B. venezuelans and B. amyloliquefaciens) sourced from dumpsite soil were formulated as consortium for the study. Methods Four treatments were considered with addition of bulking agents (ratio 1:7:6) to 15 kg MSW. Treatment Cs 1 (control): only MSW, Cs 2 : MSW + cellulolytic bacterial inoculum @ 5 ml (2 × 10 9 CFU ml −1); Cs 3-MSW + cow dung slurry @ 1 kg (1:100 based on wet weight) and Cs 4-MSW + cellulolytic bacterial inoculum @ 5 ml (2 × 10 9 CFU ml −1) + cow dung slurry @ 1 kg (diluted 1:100 based on wet weight). The analyses of humic acids were done by elemental analyzer, UV and Fourier transform infrared spectroscopy during 90 days of composting. Results MSW amended with consortia of effective microorganisms and cow dung slurry projected highest humification degree at 82.4% (P < 0.01). Highest temperature (63 °C) was recorded in the treatment Cs 4 during composting. The data corresponded to an increase in H/C ratio (0.9%) with a decrease in C/N (14.8%) and O/C ratio (0.5%). In addition, most stabilized values for E 4 /E 6 ratio (4.1) and E 2 /E 3 ratio (2.1) were observed in Cs 4. The humification indices manifest positive regression values (F (4, 1) = 0.007; P < 0.01) and 99% significant model. Conclusion In the study, bio-augmentation (bacterial consortia and cow dung slurry) to MSW composting facilitates early maturity compared to other inoculated/uninoculated treatments. The result substantiates the effect of temperature on the humification rate of composting.

An investigation was carried out in laboratory to find out the effect of ambient temperature and different treatments on passive bin composting of municipal solid waste (MSW). A potent cellulase degrading inoculum (Bacillus subtilis, B. amyloliquefaciens, B. nakamurai and B. velezensis) sourced from dumpsite soil and cow dung slurry was used as addon to MSW composters. Treatments were tested during summer (26-45 °C) and winter (5-22 °C) season to profile the physiochemical, enzymatic and microbial changes during 90-day study. In addition, a kinetics model for MSW composting was derived for the rate of organic load degradation deducing the first order kinetics rate (K r), limiting velocity (K m) and dissociation constant (K d). The results of the present investigation revealed that ambient temperature hastened the degradation of organic substrates in case of MSW amended with microbes and cow dung (60 days) as indicated by the achieved maximum kinetics reaction rate, 0.0131 day −1 (R 2 = 0.993) and reduced C/N ratio (11.6%). Also, enzymatic profiles; dehydrogenase (170.1 µg TPF g −1 day −1), cellulase (96.1 µg glucose g dwt −1 h −1) and urease (539.1 μg NH 4 +-Ng dwt −1 h −1) with a high temperature profile (47-63 °C) in the finished summer compost, Cs 4 supported the results. Whereas, winter composting could not attain the desired results and produced immature compost even after 90 days. Statistical analysis (proximal cluster analysis, hierarchical cluster analysis and ANOVA) and kinetics study showed that ambient temperature in collaboration with addons significantly influenced the compost maturity.

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This chapter describes how “Solid waste” (SW) is a term usually applied to an assorted collection of wastes produced in urban areas, the nature, characteristics and quantity of which varies from region to region. Waste generation is influenced not only by lifestyle of the region's inhabitants, but also by copiousness and type of the region's natural resources. Composting of municipal solid waste is, therefore, a simple and cost-effective technology for treating the organic fraction of municipal solid waste. As the composting proceeds there occurs drastic change in microbial communities, and resemblance to the initial community is lost with process. Generally, three categories of microorganisms play a vital role in composting process: bacteria, actinomycetes and fungi. It is primarily the mesophilic (> 45 °C) and specifically the thermophilic bacteria (< 60 °C), that plays a major role by rising the temperature of the piles. This chapter mainly focused on composting process for Municipal waste stabilization and role of microbes in the process.