1. David T. Brown Dept. of Tourism and Environment Brock University
COMPOSTING
David T. Brown
Dept. of Tourism and Environment
Brock University

2. Composting:

3. The controlled biological decomposition of organic materials
Composting:
The controlled biological decomposition of organic materials

4. Composting
natural biological process, but for rapid composting and consistent quality, environmental conditions must be controlled
end product (compost) bears little resemblance to original wastes from which the compost was made
typically dark brown to black in colour, with crumbly texture and earthy odour

6. Finished compost humus-like, resembling rich topsoil
resistant to further microbial decomposition

7. Composting
typical volume reductions in excess of 50% of the original volume of the waste; effective & useful waste diversion strategy
good compost is devoid of organisms that may be harmful to human health

8. Uses of compost
high organic matter content => valuable soil amendment
may be used as low-grade fertilizer to supplement plant nutritional needs
may be used to condition heavy clay or mineral soils
promotes proper balance between air and water in soils
aids water infiltration, absorption, and ion exchange in soils

9. What can be composted?
any waste material with a high organic matter content is a potential candidate
used for centuries to stabilize human and animal wastes
used more recently for:
sewage sludges
industrial wastes (e.g. food, pulp & paper)
yard and garden wastes
municipal solid wastes (up to 70% organic matter by weight)

10. Controlling composting
To achieve maximum composting for any organic material, certain environmental conditions must be maintained in the compost pile => may be classified into interdependent
biological conditions
physical conditions
chemical conditions

11. THE BIOLOGICAL ENVIRONMENT
Key organisms:
bacteria
fungi
Actinomycetes
- play active role in decomposing organic matter

12. THE BIOLOGICAL ENVIRONMENT
Secondary organisms:
earthworms
insects
other soil invertebrates
play a less significant role in decomposition process compared to microorganisms
more important in mechanical breakdown of wastes (chewing, burrowing, movement, aeration)