Stocking Density Optimization for Enhanced Bioconversion of Fly Ash Enriched Vermicompost

Area of Science:

• Environmental Science
• Soil Science
• Waste Management

Background:

• Stocking density significantly influences vermicomposting efficiency.
• Optimal stocking densities for fly ash-based mixtures are not well-established.
• Vermicomposting offers a sustainable method for waste recycling and nutrient recovery.

Purpose of the Study:

• To determine the optimal earthworm stocking density for vermicomposting a fly ash-cow dung-waste paper (FCP) mixture.
• To evaluate the impact of different stocking densities on biodegradation rates, nutrient release, and compost maturity.
• To identify the most effective stocking density for producing humified and nutrient-rich FCP vermicompost.

Main Methods:

• Four stocking densities (0, 12.5, 25, and 37.5 g worms/kg) were tested for FCP mixture vermicomposting.
• Compost maturity was assessed through humification parameters and enzyme activities (β-glucosidase, FDA hydrolysis).
• Nutrient content, including Olsen-P and (NO₃ + NO₂)-N, was analyzed.

Main Results:

• Stocking densities of 25 and 37.5 g worms/kg led to faster compost maturity and higher humification.
• These higher densities also resulted in a significantly lower final C/N ratio (10.4-11.1).
• A stocking density of 25 g worms/kg yielded the highest Olsen-P (61.0% increase) and (NO₃ + NO₂)-N release.

Conclusions:

• While compost maturity is achievable at 12.5 g worms/kg, 25 g worms/kg is optimal for accelerated production.
• This density ensures faster humification and superior nutrient enrichment in FCP vermicompost.
• The study provides a recommended stocking density for efficient FCP vermicomposting.