Multi-step sequential batch two-phase anaerobic composting of food waste

Area of Science:

• Environmental Science
• Biotechnology
• Waste Management

Background:

• Food waste presents a significant management challenge globally.
• Anaerobic digestion is a key technology for waste stabilization and resource recovery.
• Optimizing anaerobic digestion processes is crucial for enhancing efficiency and methane production.

Purpose of the Study:

• To evaluate the performance of the novel MUlti-step Sequential batch Two-phase Anaerobic Composting (MUSTAC) process for food waste treatment.
• To assess the efficiency of the MUSTAC process in terms of volatile solids reduction and methane conversion.
• To determine the suitability of the MUSTAC process for resource recovery and waste stabilization.

Main Methods:

• The MUSTAC process integrates leaching beds for hydrolysis, acidification, and post-treatment with a UASB reactor for methane recovery.
• High-rate anaerobic composting techniques based on the rate-limiting step approach were employed.
• Rumen microorganisms were inoculated to enhance acidogenic fermentation efficiency.
• Two-phase anaerobic digestion and sequential batch operation were utilized to manage environmental constraints.

Main Results:

• The MUSTAC process achieved an 84.7% reduction in volatile solids (VS) and an 84.4% methane conversion efficiency.
• High organic loading rates (10.8 kg VS m(-3) d(-1)) and a short solids retention time (SRT) of 10 days were maintained.
• Methane yield reached 0.27 m3 kg(-1) VS, with a methane gas production rate of 2.27 m3 m(-3) d(-1).
• The post-treatment output was suitable for use as a soil amendment.

Conclusions:

• The MUSTAC process demonstrates simple operation and high efficiency for food waste treatment.
• It is a stable, reliable, and effective method for resource recovery and waste stabilization.
• The process offers significant advantages over conventional anaerobic digestion methods.