Evolution of the Dominant Groups of Micro-organisms during the Composting Process of the Household Refuses from the Dschang Municipality – Cameroon

Aims: This study was aimed at identifying and characterizing the different microbial groups that are involved in the composting process of household waste from the city of Dschang.

Study Design: Three compost heaps of household wastes were studied, and a composite sample was collected once every two weeks during the four months period for microbiological analysis.

Place and Duration of Study: The Household Waste Composting Pilote Project of the Dschang municipality, during the four months study period.

Methodology: The total bacterial and fungal microflora have been identified according to the suspensions-dilutions technique on a specific solid medium, incubated and then counted. The confirmation test for fungi was the methylene blue.

Results: Three major groups of microorganisms were present in the compost from household waste from the Dschang municipality that we studied: Bacteria, Actinomycetes and Fungi. The density of bacteria decreases with the phases of the composting while actinomycetes and fungi are increasing. Among the microbial strains identified, some are present in all the composting phases (Pseudomonas, Penicillium, Rhizopus and Nocardia), others disappear in the cooling phase (Mucorspp) and others finally appear only at the phase of maturation (Saccharomycetes).

Conclusion: The evolution of fungal and bacterial diversity during the composting process is parallel to that of their density because the maintenance, the disappearance or appearance of certain strains can be explained by the variation in the temperature, moisture, pH, biodegradable organic matter and competitions between the microbial strains.