Managing organic municipal waste
Practical Action
Key considerations for planning composting
Raw materials and quality
The most significant determinant of the quality compost is the raw organic waste used. If
this is consistently uncontaminated, an appropriate composting process is likely to produce a
high-quality product. However, if your raw waste is contaminated, even careful composting
may not produce a safe and acceptable product. The following diagram summarises the
implications of using more materials from different sources.
Souurrccee
CommppoossttQQuuaaliltiytyanadnd
RRiisskk ooffCCoonntatamminiantaiotinon
PTyopteentoifalCCoonntatammiinnaation
Agricultural waste (manure,
straw, fruit/ vegetable residues
Vegetable market waste
QQuuaalliittyy
Pesticide remsidauinei,nsge,esdeseds
Pieces of packaging waste and street
sweepings
Segregated kitchen waste from
households
Depends on care taken in segregation
(packaging, glass)
Mixed Household Waste
RRiisskk
Difficult to control (Batteries, medicines,
human waste)
Organic matter from landfill
mining
NNo ococnotnrtorlool foifnipnuptumt mataetreiarila.lA. lAllal baobvoeve
plus healthcare and industrial waste.
High proportion of sand or stones.
Adapted from 'Marketing Compost’, Sandec 2008
There are a number of ways of ensuring high quality, including: carefully sourcing raw
materials; periodically conducting spot checks on raw materials; and carefully managing the
compost process. Community-engagement to ensure source-separation of waste can
significantly improve the quality of organic waste collected from households. Separated
waste lessens the risk of contamination from such items as batteries and means that the
organic waste is easier and safer to sort and handle. There are many such examples of
community recycling or resource recovery schemes in developing countries.
Quality is the most important factor for ensuring satisfied customers and continued sales. In
some countries farmers have been injured by glass and needles in low-quality compost they
apply to their land. Low-quality compost can also contain invisible contaminants such as
toxic compounds or heavy metals, which may affect the farmers and consumers in the long
run, and also pollute land and groundwater. Different markets will have different quality
requirements. However, all compost sold must have safe levels of pathogens, toxic chemical
and heavy metal contamination within national or international standards.
Human waste and organic waste management
Human waste (excreta or sewerage sludge) can be added to organic waste for composting.
This is called co-composting. Beware that in some societies there is a taboo on the use of
human waste and sewage as an agricultural input. This may limit the market for compost
produced in this way. Additionally there is a risk of spreading disease by using untreated
human excreta. In the UK there are examples of small-scale co-composting, but the product
is applied to trees, not food crops.
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