Partial stream digestion of residual municipal solid waste

Area of Science:

• Environmental Engineering
• Waste Management
• Biotechnology

Background:

• Residual municipal solid waste (MSW) digestion capacity in Europe shifted significantly, with residual waste digestion capacity growing from 13% in 1998 to over 52% by 2006.
• Partial digestion of MSW organics has emerged as a key strategy to minimize dewatering requirements and subsequent wastewater treatment.

Purpose of the Study:

• To evaluate a mechanical-biological treatment (MBT) plant employing partial anaerobic digestion for residual MSW.
• To assess the efficiency of biogas production and the quality of the end product.

Main Methods:

• A MBT plant processed 25,000 tons/year of residual MSW, with 2/3 undergoing anaerobic digestion and the remaining 1/3 mixed with the digestate.
• The mixture was aerated in tunnels for 4-6 weeks.
• Dry fermentation produced digestate with 35% solids, eliminating the need for dewatering.

Main Results:

• Biogas production averaged 125.7 Nm³/ton, with a methane content of 56.2%.
• The process yielded a stabilized end product suitable for landfilling, meeting stringent German inert landfill standards.
• No wastewater was generated due to the dry fermentation process and high solids content of the digestate.

Conclusions:

• Partial anaerobic digestion of residual MSW in an MBT plant is an effective strategy for waste stabilization and biogas production.
• This approach significantly reduces operational challenges associated with dewatering and wastewater management.
• The process generates a compliant end product for landfilling, contributing to sustainable waste management.