Practical Issues
Composting is an entirely natural biological process. Simple compost piles are entirely effective at reducing waste volume, but they are slow, odorous, attract vermin, are uneven in their treatment and may fail to control pathogens.
Achieving consistent, pathogen-free compost, within a reasonable timeframe, on a large scale requires an appropriately engineered system.
HotRot 3518 at Bromley, New Zealand
The equipment should:
- Provide sufficient oxygen for aerobic degradation, while minimising cooling of the compost through excessive airflow
- Facilitate a sustained temperature in excess of 55ºC for three days to achieve sanitisation
- Ensure that all material is sufficiently treated, and that no short-circuiting or treated product contamination can occur
- Contain all odour and hazardous aerosols
HotRot 1509
In-vessel composting is relatively expensive compared to open systems. It is therefore typical to treat waste for a comparatively short time to achieve pathogen and odour reduction and limit vermin attraction. Further curing in static piles may then be necessary. The exact balance between composter residence time and curing will vary with the wastes treated and the goals and constraints of the operator.
