A membrane-covered, aerated compost pile uses buried air pipes, oxygen and temperature probes and a breathable fleece to turn sorted municipal waste into compost in about five to eight weeks. This article describes a pilot proposed for an agriculture ministry in South-East Asia, designed for 8 tonnes of compost a month.
The challenge: a small pilot with variable waste
The feedstock was municipal solid waste from local sources. Non-compostable items had to be removed by hand before composting, and the sorting trommel and turning machine were optional extras that would not be needed at pilot scale. The system had to be simple, weatherproof and controllable.
The design
- Output: 8 tonnes a month, in batches of 2 tonnes a week.
- Piles: four, each about 2 m long and 3.5 m wide under a cover of 4 by 6 m, starting 1.5 m high and settling to about 1 m.
- Product density: about 600 kg/m³.
Four piles allow batches to be staggered: one is filled each week while the others mature.
How it works
- Shred the sorted waste and lay it on a base over horizontal aeration tubes.
- Aerate. Medium-pressure aerators push air up through the pile. Stainless steel probes in the heap measure oxygen and temperature, and a central controller adjusts the aeration rate to keep oxygen and moisture right.
- Cover. The pile is covered by a non-woven UV-resistant polypropylene fleece, weighted down. It lets nitrogen, carbon dioxide and unused oxygen out but retains heat, moisture, odour and bacteria, and sheds rain.
- Mature. The process runs 5 to 8 weeks: 1 to 3 weeks biodegradation under cover, 2 to 3 weeks post-rotting under cover and 2 to 3 weeks exposed curing.
- Uncover and use the compost.
Why the cover matters
Rain-soaked piles go anaerobic, which causes odour, nutrient-laden leachate and wet compost that costs more to screen and transport. The fleece sheds water by capillary action and gravity along the slope. The cover is expected to last at least four uses, depending on care.
What is excluded
Inland transport, offloading, installation, civil works and foundations, electrical connections, site drainage, import duty and permits. The shredder and computer were listed as exclusions or options in different sections of the quotation, so confirm what is supplied.
What to consider for your own project
- Sort first. Contaminants such as plastics and glass reduce compost quality.
- Check regulations. In the UK, composting is regulated; see the Environment Agency composting permit guidance.
- Test the product. Heavy metals and stability matter for sale.
- Plan the market. Confirm who will use the compost before you build.
FAQ
How long does composting take?
Five to eight weeks in this system.
Why measure oxygen?
Aerobic bacteria need oxygen. Low oxygen produces odour.
Does it need turning?
No. Aeration pipes replace turning.
Starting a composting pilot?
Contact us about composting systems.