BIOCONVERSION OF MUNICIPAL SOLID WASTE INTO FORTIFIED COMPOST USING MICROBIAL MEDIATORS
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Date
2021
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AAU, Jorhat
Abstract
Rapid composting of municipal solid waste (MSW) collected from two different sites(main landfill of Jorhat municipal corporation and dumping site of Rowriah, Jorhat,Assam), was done using three different decomposers microbial consortiagroup (DMC @1%) for 60 days, and thereafter biofortification of the MSW compost was done by addition of plant growth promoting rhizobacteria (PGPR) for 20 days.The DMCgroup were previously isolated from polluted sites of Assam, and denominated as paper group, oil group and cement group. For comparison with MSW, agro-waste was also used in the study, which did not receive DMC, but received PGPR application after 60 days.At 80 DAI (days after inoculation),pHwas stabilized in the range between 7.40-7.76 in MSW I and 7.00-7.55 in MSW II, electrical conductivity (EC) was recorded to be in the range3.08-5.21 dS m-1(MSW I) and 1.55-3.85 dS m-1(MSW II).The temperatures during composting period were maintained between 27.33-28.66°C in MSW I and 28.66-32.33°C in MSW II, while the moisture content decreased in both sites at 80 DAI. Following PGPR application, total carbon content declined to a minimum of 17.24-24.82% in MSW I and 17.52-27.7% in MSW II, while total nitrogen content increased to 1.01-1.7% in MSW I and 0.85-1.53% in MSW II. Total phosphorus and total potassium content also exhibited increasing trend till the end of composting.At 80 DAI, C:N ratio declined over uninoculated treatment in both sites and ranged between10.37-15.90 (T1-T3) in MSW I and 12.26-13.13(T1-T3) in MSW II,.NO3-N elevated till the end of composting, contrarily, NH4+-Ndeclined to a minimum of 0.09-0.27% in MSW I and 0.08-0.27% in MSW II.CEC increased to 22.35-29.99 c mol (p+) kg-1 in MSW I and 22.43-28.17% c mol (p+) kg-1 in MSW II. Heavy metals, viz- Pb and Cdcontent decreased to 98.20-250 ppm(T1-T3) and 0.74-0.81ppm(T1-T3) during PGPR fortification.Total bacterial count of the fortified compost was displayed at 6.17 to 7.01Log cfu g-1in MSW I and 6.16 to 6.93 Logcfu g-1in MSW II, while fungi population recorded at 4.81 to 6.03 Log cfu g-1 in MSW I and 4.91 to 6.06Log cfu g-1 in MSW II. Actinomycetes population recorded at 6.70 to 6.99 Log cfu g-1in MSW I and 6.68 to 7.00 Log cfu g-1in MSW II at 80 DAI.Estimation of biologically important enzymes (phosphomonoesterase,dehydrogenase, arylsulphatase, and fluorescein diacetate hydrolysis) provided information on the rate of organic matter degradation following inoculation with DMC and PGPR biofortification. Upon addition of
PGPR, microbial biomass carbon (MBC) attained a range of higher values in between 210.66-1167.21 μg g-1 in MSW I and 201.46-1005.6 μg g-1in MSW II. Overall gradual drop of basal respiration rate and increment in microbial quotient was observed after addition of PGPR to MSW compost. A pot culture experiment was designed to check the efficacy of test plant Soyabean which exhibited that the MSW compost produced was non-toxic and displayed significant difference between the DMC treated plants over the uninoculated control. Study revealed that microbial mediators (DMC and PGPR) used during composting are efficient and can result in better bioconversion of MSW to usable compost.