COMPOST FROM MARKET GARBAGE AND THE FEASIBILITY OF REDUCING THE TIME REQUIRED USING AERATION AND LOCALLY ACCLI MATIZEC' MICROORGANISMS

Abstract

Solid waste collection and disposal is a major problem faced by all local authorities in SriLanka.The bulk of the waste, about 83%, is organic materials from vegetable markets andhouseholds. The predominant organic matter in waste makes itself ideal for biological treatmentprocess of waste management. The process of composting can be used to convert the waste to astable "humus like" product commonly known as compost, which could be used as a soilconditioner. This study was conducted using market garbage as the major ingredient, whichcontain 70% -90% moisture content and it was mainly directed to use low cost technology Themain objective was to reduce the production time and improve the quality of compost producedwith the use of inoculums and aeration

Six different types of treatments were carried out during the experimental period. The windrowmethod was used to prepare compost under indoor environmental conditions. Vegetable garbage,air-dried grass clippings, saw dust, cow dung and coir dust were used as the raw organicmaterials. The initial total weight of waste was 250Kg (by wet weight). The experimental unitwas 1.5m x 1.5m x 1m (length x width x height). Two percentages of stabilized compost (2.5%,5%) were used as the inoculums. Hollow triangular wooden frame was used to facilitate aerationand mixing was carried out once a week.

During the composting process physical changes (temperature, bulk density, changes indistribution of particle sizes), chemical changes (pH, organic matter, conductivity, C/N ratio) andbiological changes (C02 evolution, number of total coliform, invertebrates, weed seed viability,germination test) were determined to evaluate the em ctiveness of composting process.

The results showed that composting of market garbage using stabilized compost as seeding andaeration helped to produce good compost at the end of two months. The high temperature stagecaused the destruction of the pathogenic organisms (number of coliforms), viability of weedseeds and fly larvae. Weed seed (Ameranthes seeds) lost their viability when exposed to highertemperature (>60 DC) for about three days. The drop i_7lC/N ratio is rapid at the initial stages andslows down during maturation stage, whereas the temperature increased and then decreasedfaster. The decline in temperature and -e/N ratio are somewhat similar. In all cases, thecomposting occurred under alkaline conditions and finally it reached neutral values.

The final weights were approximately half of their original weights and the volume shrieked to1/3 of their initial volume. The bioassay indicated the level of completeness of compostingprocess and T2, T3 and T4 showed 100% germination at the end of 2 months.

When composting, high moisture, organic materials under tropical environmental conditions, itis necessary to add bulking material with frequent turning. When composting process is properlyoperated and managed final product can be obtained in 8 weeks.