Qualitative assessment of compost engendered from municipal solid waste and green waste by indexing method

The present study aims at quantification of the quality of three varieties of composts made from municipal solid waste, green waste and combined waste by critically evaluating their physicochemical attributes, effect on soil fertility and metal pollution risk. Each waste type was treated with effective micro-organisms to compare the compost quality using Quality Control Indices. The effect of microbial consortia on the wastes was prominent resulting in decreased pH levels and increased electrical conductivity. C/N ratio ranged between 14-24 for waste composts without microbial treatment, and 8-11 for microbial treated wastes. The fertility parameter was observed to be more in microbial treated waste composts. Also, heavy metals concentration in waste compost without effective microbial treatment was higher than the types given EM. Based on the fertility and clean indices, the treated and untreated municipal solid waste and combined waste compost belonged to class RU-1 and class D, respectively. Moreover, compost prepared from treated and untreated green waste belonged to classes B and C respectively. In general, the prepared CW and GW composts have medium to high fertilizing potential and are fit for domestic as well as commercial use. However, MSW compost is not fit for agricultural purposes as it didn't improve soil fertility to a greater extent but can be used as a soil conditioner in limited quantity as it can cause metal toxicity. For this reason, proper segregation of inputs at the start of a composting process is necessary to improve its quality before being put to agricultural use as any unbalanced or unchecked content of mixed waste will affect the overall compost quality.Implications: Significance of the work: The research dealt with different combinations of segregated wastes to analyze the best fit solid waste compost. Experiments were conducted on the actual landfill site area to simulate the conditions for the process. The manuscript provides evidence and other facts advocating the use of composting for waste management and ultimately reducing pollution caused by landfilling. It ought to cause a multiplier effect if the same is to be followed in other parts of the world, and thus working our way toward getting the Smart city project to fruition. The results of the study exhibit the differences in physiochemical nature of various types of composts. A treatment of microbial consortium with restrictions enabled a conducive atmosphere in the colonies to thrive faster and initiate the process of decomposition. We observed that treated samples converted faster into compost as compared to non-treated samples. We also observed the effect of treatment on fertility parameters of prepared compost samples. In general, it was found that the organic carbon and C/N ratio declined while the total nitrogen and total potassium was observed to increase with very little to no change in phosphorous content, with the inoculation of beneficial micro-organisms throughout the composting course. A reduction in the heavy metal levels was observed in samples treated with active micro-organisms. The compost classification into A, B, C, and D classes represents the quality of compost and further use in agricultural land on commercial levels. The quality index values were determined highest for green waste compost (GWC). The municipal solid waste compost (MSWC) exhibited lowest index values. Therefore, based on the quality index values, the utilization of GWC will aid in reutilizing the green waste and in boosting soil fertility and reduce the waste quantity generation rates. It's also necessary to make compost making widespread among the farmers for a sustainable environment. The GWC has been considered as a sustainable option of waste management, being economically and ecologically viable.