Evaluating the Maturity and Quality of Solid Waste Compost through Phospholipid Fatty Acid Biomarkers

Maturity and quality of compost when used as soil amendment are very important and need to be taken into consideration. Phospholipid fatty acids (PLFAS) composition has high correlation with chemical and biological parameters for compost maturity. This study was undertaken for making compost from sewage sludge and municipal refuse with some additives to enhance decomposition. The municipal solid waste(MSW) was mixed with equal weight of de-watered sewage sludge(DSS), and then treated with these additives in separate bioreactors as: control (no amendment), zeolite, clayey soil, fly ash, lime, and effective microorganisms (EM) inoculum. Composts were analyzed for C:N ratio and microbial diversity during decomposition. Thirty nine types of PLFAs were identified, which belonged to nine major categories. Results from all the treatments depicted that straight, monounsaturated fatty acids (SMUFA) and straight, saturated fatty acids (SSATFA); SSATFA both representing for fungi were in the highest amount. These were followed by branched, saturated fatty acids (BRANCHED FAMES) that signify the presence of G +ve bacteria and actinomycetes. The straight, hydroxyl fatty acids (SOH-FAMES) specifying the anaerobic microbes were the lowest among all. A small number of aerobic G -ve bacteria was also noticed by the presence of branched, saturated, and hydroxyl fatty acids (BSHFA) and cyclopropyl fatty acids. The C:N ratio was at the lowest with EM that enhanced decomposition more than with other amendments. The EM as well as lime increased the concentration of all the PLFAs as compared with control. Therefore, both EM and lime can be the best choice amendments for rapid composting leading to early maturity and better quality of the compost product.