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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.
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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)
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Further reference • Wikipedia • Green Hong Kong Campaign—Green School Handbook