Characterization of high rate composting of vegetable market waste using Fourier transform-infrared (FT-IR) and thermal studies in three different seasons.

Fourier transform-infrared (FT-IR), Thermogravimetry (TG), Differential thermal analyses (DTA) and Differential Thermogravimetric (DTG) studies of a mixture of vegetable waste, saw dust, tree leaves and cow dung for microbial activity (feedstock) and their compost were reported in three different seasons i.e. winter, spring and summer. The correlation between spectral studies and compost composition provide information regarding their stability and maturity during composting. FT-IR spectra were conferred the functional groups and their intensity and TG, DTG and DTA for wt. loss, rate of wt. loss and enthalpy change in compost. Weight loss in feedstock and compost at two different temperatures 250-350 and 350-500°C was found 38.06, 28.15% for inlet and 14.08, 25.67% for outlet zones in summer and 50.59, 29.76% for inlet and 18.08, 25.67% in outlet zones in spring season, higher (5-10%) than winter. The corresponding temperatures in DTA in the samples from inlet to outlet zone were; endotherm (100-200°C), due to dehydration, exotherm (300-320°C), due to peptidic structure loss and exotherm (449-474°C) due to the loss of polynuclear aromatic structures, which were higher by 4°C and 10-20°C and rate of wt. loss was higher by 5-10% in spring and summer season, respectively than winter season composting, reported regardless of the maturation age of the compost. Relative intensity of exotherms (300-320/449-474°C) gave the thermally more stable fractions of organic compound. Our results indicated that the rotary drum composting of organic matters in spring and summer season gave higher molecular complexity and stability than the winter season.