OPTIMIZATION OF MATURATION PERIOD FOR PRIMARY STABILIZED COMPOST

Abstract

In-vessel composting process is divided into two distinct phases: high-rate phase and curing phase. The first phase is performed in bioreactors and the second one often in exterior composting piles. In the bioreactor, primary stabilization takes place under short detention times of 5-10 days, while subsequent maturation takes place outside the bioreactor. Thus, maturation of primary stabilized compost requires larger space and longer time as compared to high rate phase transformation in reactor processes. Information on maturation process of compost using in-vessel techniques, especially rotary drum for the mixed organic wastes is rather limited. Thus, eight different maturation techniques namely Windrow (LIW = 6), Windrow (L/W = 2.5), Vermicomposting (Eisenia Foetida), Packing in Jute bags, Pile with longitudinal pipe for aeration (L/W = 6), Pile with longitudinal pipe for aeration (L/W = 2.5), Pile with lateral pipe for aeration (L/W = 6) and Forced aeration in bed have been tried to ptimize the maturation period. In addition, seasonal variation (Ambient temperature and Relative Humidity) effects on maturation were also taken into account. The quality of matured compost was assessed by analyzing various physico-chemical & biological parameters such as moisture content (MC), pH, EC, VS, TN, C N ratio, NH+4-N, NO3--N, NH+4-N/NO3--N ratio, TP, CO2 evolution rate, OUR, DOC, COD, BOD, BOD/COD ratio, heavy metals, nutrients and -athogenic indicators along with spectroscopic and thermal methods such as FT-IR and G/DTG. By examining these parameters, it is suggested that techniques T3 Jermicomposting), T8 (Forced aeration in compost bed), T7 (Pile with lateral pipe for gyration, L/W = 6) and Ti (Windrow, L/W = 6) were found suitable in delivering better uality matured compost within 2-4 weeks period. A new relationship has been worked at between easily measurable parameters such as moisture content, pH, VS and the Jrincipal maturation parameter i.e., CO2 evolution rate and found to be satisfactorily applicable to check compost stability and maturity.