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Compost mixture influence of interactive physical parameters on microbial kinetics and substrate fractionation
Ardavan Mohajer1, Anne Tremier, Suzelle Barrington
1Department of Bioresource Engineering, Faculty of Agricultural and Environmental Sciences, Macdonald Campus of McGill University, 21 111 Lakeshore, Ste-Anne-de-Bellevue, Quebec, Canada H9X 3V9.
Waste Management (New York, N.Y.)
|April 17, 2010
Summary
Optimizing compost recipes for wastewater sludge involves adjusting moisture content and bulking agent particle size to enhance microbial activity and organic matter decomposition. This research identifies key physical properties for efficient biological treatment and soil amendment recycling.
Area of Science:
- Environmental Microbiology
- Waste Management & Recycling
- Biotechnology
Background:
- Wastewater sludge recycling as soil amendment is feasible via composting.
- Optimizing compost recipes enhances microbial activity for efficient treatment.
- Understanding physical property impacts is crucial for sludge composting.
Purpose of the Study:
- To measure microbial oxygen uptake rate (OUR) in sludge-wood mixtures.
- To estimate kinetic parameters: maximum growth rate (μm) and hydrolysis rate (Kh).
- To determine initial biodegradable organic matter fractions (MB(0), MH(0)).
Main Methods:
- 16 sludge and wood residue mixtures with varied moisture content (MC), waste to bulking agent (W/BA) ratio, and BA particle size were prepared.
- Microbial OUR was measured over 4 weeks using laboratory respirometry.
- A microbial model adapted from activated sludge processes was used to calculate kinetic parameters.
Main Results:
- Maximum growth rate (μm) showed a quadratic relationship with MC and negative association with BA particle size, maximized at ~50% MC and 8-12 mm BA size.
- Hydrolysis rate (Kh) linearly associated with MC and BA particle size.
- Biodegradable organic matter fractions (MB(0) + MH(0)) linked to MC, W/BA ratio, and their interaction, indicating oxygen availability is key.
Conclusions:
- Optimizing sludge composting requires a holistic approach to physical characteristics.
- Moisture content and bulking agent particle size significantly influence microbial kinetics.
- Oxygen availability, influenced by recipe parameters, is critical for biodegradable organic matter utilization.
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