Seeding effect on cocomposting wastewater biosolids with coal fly ash

Area of Science:

• Environmental Science
• Microbiology
• Waste Management

Background:

• Biosolids composting is crucial for waste management.
• Fly ash amendment presents unique challenges and opportunities in biosolids composting.
• Microbial inoculation is explored to enhance composting efficiency.

Purpose of the Study:

• To evaluate the seeding effect of various inocula on fly ash-amended biosolids composting.
• To compare the efficacy of isolated thermophilic bacteria, commercial decomposers, and recycled biosolids compost as seeding materials.
• To determine the most cost-effective and efficient method for improving organic matter decomposition.

Main Methods:

• Fly ash and biosolids mixtures were inoculated with thermophilic bacteria (Bacillus species), a commercial decomposer, or recycled biosolids compost.
• Composting efficiency was assessed by monitoring thermophilic bacteria populations, organic matter decomposition (CO2 evolution, weight loss).
• Different combinations of inocula, including milk powder, were tested.

Main Results:

• Microbial additives initially increased thermophilic bacteria but showed negligible improvement after 4 days.
• Combined inoculation of microbial additives and milk powder was more effective than individual inocula for organic matter decomposition.
• Isolated Bacillus species and recycled biosolids compost demonstrated comparable decomposition efficiency to commercial decomposers.
• 15% recycled biosolids compost (dry weight) achieved decomposition activity similar to bacterial cultures and commercial decomposers with milk powder.

Conclusions:

• Recycled biosolids compost is a viable and cost-effective seeding material for fly ash-amended biosolids composting.
• It offers comparable decomposition efficiency to more expensive alternatives.
• Further investigation into recycled biosolids compost as an additive is recommended to optimize composting processes.