Characterization and enhancement of household solid waste composting using effective microorganisms

Résumé fourni par la source

Household organic solid waste is a growing environmental burden in Zanzibar. This study evaluated effective microorganism (EM) inoculation as a means of accelerating household organic waste composting and improving final compost quality. Composting was conducted over 60 days in triplicate bins of three working volumes (6, 9, and 21 L) filled to approximately 60% of capacity, comparing two treatments: EM-inoculated and an uninoculated control. Activated EM was applied as a liquid inoculum at a fixed rate scaled to feedstock load (10 mL of activated EM working solution per kg wet feedstock) and mixed homogeneously with the feedstock. Temperature, moisture, pH, and electrical conductivity (EC) were monitored throughout; chemical indices (organic matter, C/N ratio, N–P–K, humic substances, heavy metals) and biological indicators (germination index, microbial counts, Shannon diversity, qPCR/sequencing of dominant taxa) were measured in mature compost. EM-inoculated bins reached 65 °C within 3 days vs. 55 °C in controls and sustained thermophilic conditions (≥55 °C) for 10 vs. 6days ( F = 8.23, p = 0.01). Moisture remained within 50%−60% in EM treatments ( p = 0.03). EM compost showed faster organic matter loss (28% vs. 35% at day 60; p = 0.02), higher nitrogen retention (2.1% vs. 1.7%; p = 0.01), improved phosphorus and potassium content (+15% and +18%; p < 0.05), a lower final C/N ratio (18 vs. 22; p = 0.02), earlier EC stabilization (3.5 vs. 4.0 dS/m; p = 0.04), greater humification (+35% vs. +20%; p = 0.03), higher microbial diversity (Shannon 3.8 vs. 3.1; p = 0.02), and superior maturity (germination index 85% vs. 70%; p = 0.01). Heavy metals remained below permissible limits in all treatments ( p > 0.1). These findings indicate that EM inoculation accelerates composting, yields a nutrient-dense and phytotoxicity-safe product, and can support decentralized waste management in resource-constrained communities.

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