A negative-pressure aeration system for composting food wastes

Area of Science:

• Environmental Science
• Waste Management
• Soil Science

Background:

• Food waste composting is crucial for sustainable waste management.
• Traditional methods can lead to odor and ammonia (NH3) emissions.
• Developing efficient and environmentally friendly composting systems is essential.

Purpose of the Study:

• To evaluate a pilot-scale active aeration reactor for composting food waste.
• To assess the effectiveness of a biological filter in removing ammonia from emissions.
• To determine the quality and stability of the final compost product.

Main Methods:

• Utilized a pilot-scale reactor with negative pressure aeration (vacuum).
• Employed a biological filter bed to treat ammonia emissions.
• Monitored system parameters, compost stability, and fertilizer content over 60 days.

Main Results:

• Compost temperature exceeded 65°C within the first day, maintaining thermophilic conditions for 30 days.
• pH shifted from 5.2 to 4.3 then to 7.4 by day 60.
• Carbon-to-nitrogen (C/N) ratio decreased from 32 to below 20.
• Final compost analysis showed 1.6% nitrogen, 0.6% phosphate, 1.4% potassium, and <3 MPN/100mL total coliforms.
• Ammonia emissions were reduced to <1 ppm using the biological filter.

Conclusions:

• The active aeration system is effective for composting food waste.
• The biological filter successfully minimized ammonia emissions, ensuring environmental friendliness.
• The resulting compost is stable and rich in essential plant nutrients.