Development of an efficient biodegradation system for solid waste composting using indigenous microorganisms

Abstract

This thesis describes a study conducted to produce compost using vegetable market garbage, as the main ingredient .The main objective was to reduce the time of production and to produce good quality compost by inoculation and aeration. Low cost windrow method was used under indoor environmental conditions where six different types of treatment were studied, each lasting eight weeks. The experimental heap was 1.5m X 1.5m x 1m (length X width X height) and a hollow triangular wooden frame 1.5 m X 0.3m X 0.3m (length X width X height) was used to facilitate aeration. Initial weight of the feedstock was 250 kg and the heap was turned once a week. The first trial was carried out using 80% market garbage, 10% cow dung, 5% sawdust and 5% coir dust. For subsequent experiments' the composition used was 50% market garbage, 10% cowdung 10% saw dust 5% coir dust and 25 % air-dried grass clippings. Mature compost 2.5 % and 5 % were used as inoculum in the third and fourth runs respectively. The fifth run was conducted without turning the heap and the sixth one without the frame for aeration and also without turning the heap. Physical chemical and biological changes were determined during the composting process to evaluate the effectiveness of the process. Enzymatic activity of microorganisms, which were active during the compo sting process, was also studied. Seed germination in the final compost was tested by introducing Raphanus sp seeds. The results indicated that a weight reduction of 50% occurred and the high temperature recorded during the initial stages helped to reduce pathogen and weeds. Diverse and dense indigenous beneficial microorganisms were present and macro organisms played an important role in reducing the particle size. Turning the windrows for aeration and addition of matured compost was found to accelerate the rate of compo sting. Use of 5% mature compost gave a higher rate of composting than 2.5%. From determinations of temperature, C/N ratio CO2 production, pH bulk density and seed germination it was concluded that when the process is properly controlled good quality compost can be obtained in about eight weeks.