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Composting
27-1-2007
What is composting?
Composting is the process of producing
compost through aerobic decomposition of
biodegradable organic matter.
Compost produced at the end of the process
can be used in farming and gardening to
improve soil quality.
Principles of Composting
Composting is the controlled decomposition of
organic matter.
Rather than allowing nature to take its slow course,
a composter provides an optimal environment in
which decomposers can thrive. To encourage the
most active microbes, a compost pile needs the
correct mix of the following ingredients:
Carbon, Nitrogen (from composting materials)
Oxygen (from the air)
Water
Type of composting
Active (hot) composting
~55oC
Higher temperature kill most pathogens
Regularly stirring ensure aeration
Faster (take weeks)
Passive (cold) composting
~30oC
Much slower (may take months)
May develop anaerobic condition, releasing odor and
greenhouse gas (e.g. methane)
Carbon : Nitrogen ratio
High-carbon sources provide the cellulose needed
by the composting bacteria for conversion to
sugars and heat. (e.g. starch and cellulose)
High-nitrogen sources provide the most
concentrated protein, which allow the compost
bacteria to survive and multiply. (e.g. animal
manures, fruit and vegetable trimmings, leaves)
The most rapid composting occurs with the ideal
carbon:nitrogen ratio of 25~30: 1 by dry chemical
weight.
Garden Composting
Links
(section 1.2.1)
Composting in Hong Kong
Composting in Hong Kong is restricted to
livestock waste at this moment.
Only 23 tonnes out of 200 tonnes of
livestock waste collected daily is used in
composting by contractor (EPD, 2003)
Take 6-8 weeks for compost to become
mature
Location of Sha Ling Livestock
Waste Composting Plant (SLCP)
Click to
Link
Further reference
Wikipedia
Green Hong Kong Campaign—Green
School Handbook