In-vessel composting system
Enclosed vessels and tunnels for fast, controllable, low-odour fermentation.
Read more →
01
System comparison on the numbers that matter
| System | Residence | Footprint for 100 t/day fresh | Labour | Odour control | Capital |
|---|---|---|---|---|---|
| Open windrow, turned | 25–35 days | 3,500–6,000 m² | High — turner plus loader | Difficult — extraction impractical | Low |
| Covered windrow, turned | 25–35 days | 3,000–5,000 m² | High | Moderate — building extraction | Low to medium |
| Groove / trench with turner | 18–25 days | 2,000–3,500 m² | Medium | Moderate — can be enclosed | Medium |
| Aerated static pile | 14–21 days | 1,500–2,500 m² | Low — no turning | Good — pile can be covered and extracted | Medium |
| In-vessel (tank / tunnel) | 7–12 days | 600–1,200 m² | Low, but disciplined loading | Excellent — closed process with treated exhaust | High |
Footprint and labour figures are planning values for a temperate climate and typical manure-based feedstock. In monsoon or cold climates the covered and in-vessel options gain further advantage.
02
The four variables that decide whether composting works
- Moisture, 50–60%. Below 40% microbial activity slows sharply; above 65% the pore space fills with water and the pile turns anaerobic, which is where odour comes from.
- Free air space and porosity. Bulking agents — straw, wood chips, rice husk — hold the structure open. A pile that compacts into a wet mass cannot be aerated by turning alone.
- Carbon to nitrogen ratio, 25–30 : 1. Below 20 : 1 nitrogen is lost as ammonia and the plant smells of it; above 40 : 1 the process stalls for lack of nitrogen.
- Temperature, 55–65 °C for a sustained period. This is the sanitation window. It is not achieved by luck; it follows from the three variables above plus a consistent turning or aeration regime.
03
How the system is chosen
- 01
Start with the site
Available area, distance to neighbours, prevailing wind, climate and the permitted operating hours eliminate two of the four systems immediately in most projects.
- 02
Then the feedstock
Wet slurry needs dewatering or a dry amendment before any system performs. Fibrous dry manure works in any system; wet sludge and food waste usually need enforced aeration.
- 03
Then the product
A plant selling bulk compost can tolerate a longer, less controlled cycle. A plant selling bagged granules needs cured material with consistent moisture and maturity, which favours controlled systems.
- 04
Then the operating capability
Turning systems reward disciplined daily operation; aerated and in-vessel systems reward instrumentation and maintenance. Choose the system your team can actually run.
- 05
Only then the machinery
Turners, blowers, vessels, loaders and conveyors are selected to serve the system, not the reverse.
04
Curing is part of the system, not an afterthought
Thermophilic composting stabilises the material; curing matures it. Curing runs at lower temperature for two to six weeks with occasional turning, and it is where remaining phytotoxicity disappears and where moisture is brought to the value the processing line needs. Plants that skip curing produce material that continues to heat in the bag, generates condensation, and forms clumps in the granulator feed.
Design the curing area as a separate, covered, ventilated bay with enough volume for 2–4 weeks of production. It is one of the cheapest additions to a plant and one of the most reliable predictors of product quality.
05
System pages
Aerated static pile
No turning, engineered air distribution, lower labour and good odour containment.
Read more →Windrow composting
The classic turned-pile system and what it demands of the site.
Read more →Fermentation tank
Vertical and horizontal vessels: volume, aeration, discharge and installation.
Read more →Choose the right fermentation system
Send the feedstock, the daily tonnage and the site constraints; we return a system recommendation with footprint, residence time and odour control scope.
FAQ
Plant engineering questions
What retention time does organic fertilizer composting need?
Thermophilic fermentation of 7–12 days in a controlled vessel, 14–21 days in an aerated pile, or 18–35 days turned in bays or windrows, followed by 2–6 weeks of curing. The controlled systems are faster because aeration is enforced rather than periodic.
Why does my compost smell like ammonia?
Ammonia means the carbon to nitrogen ratio is too low — usually a manure-heavy mix — or the pile is anaerobic in patches. Add a carbon source such as straw or wood chips and check that moisture and free air space allow air to move through the pile.
How do I know when the compost is finished?
Three practical checks: temperature returns to ambient after turning, the material is dark and crumbly with an earthy smell and no recognisable feedstock, and a germination or maturity test on the finished material shows no inhibition. We specify the checks and the record sheet in the commissioning package.
Can composting be done in winter?
Yes, but with provision. Piles lose heat from the surface, so deeper piles, covered bays or in-vessel systems are used, and the fermentation area is sized for the slower rate. Cold-climate plants usually favour in-vessel or covered bay systems for this reason.
Send us your design basis
Tell us the feedstock, the daily tonnage and the product you want to sell. The engineering team replies with the plant configuration, the equipment scope and the information we still need before layout drawings start.
- Feedstock profile — type, moisture, contamination, seasonal peaks
- Capacity — t/day fresh material or t/h finished fertilizer
- Product — powder, granules, bagged retail, bulk compost
- Site — available area, power supply, water, access road
Prefer to talk first? WhatsApp +86 182 0399 3035 or email [email protected].