Home composting bins
Practical Action
Heavy metals of Arsenic, Lead, Cadmium and mercury are extremely harmful to both
humans and domestic animals.
Pathogens of diseases of Enteritis, Tuberculosis etc. Pathogens could be found in city
wastes since their thermal death points are specific, care should be taken to allow the
heating up of heaps.
Table: 4 Important Quality standards for compost
(Sri Lanka Standards SLS 1246:2003)
PROPERTIES
REQUIREMENTS
Physical parameters:
Colour
Keeping properties
Moisture content
Odour
Particle size
Sand content
Brown / grey to dark black
Not less than 12 months under room temperature
Not more than 25% by dry weight
Not unpleasant odours
Residue should be <2% through 4 mm sieve
<10%
Nutrient requirement :
Nitrogen
Phosphorous
Potassium
C:N ratio
Heavy metals
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
zinc
Biological parameters:
Faecal coli forms
Salmonella
Viable weed seeds
Minimum requirement
1.0%
0.5%
1.0%
10-25
max ppm (maximum parts per million)
10
1000
400
250
02
100
1000
Requirement
Should be free
Should be free
< 16 per square metre
Use of made compost
Compost is more important as a soil conditioner rather than a nutrient supplier. It improves the
soil chemical, physical and biological parameters so that it provides a better environment for
plant growth. This compost can be used as;
Mulch: spread a layer of compost 1-3 inches thick around the plants and over bare soil to
prevent soil erosion, conserve water and control weed growth.
Soil conditioner: mix about 4-5 inches of compost into soil when start a nursery,
vegetable garden or plant new trees.
Potting mixture: screen the compost through a ΒΌ inch mesh. Mix 2 parts of compost
with 1 part of sand and 1 part of top soil and use as a potting mixture for plants.
Recommendation for design improvement
A) Material of the bin
Metal composting bins are not suitable due to high corroding problems. The economic
benefit of the concrete composting bin is higher than the metal bin due to longer life
span. Plastic bins are convenient to use but cost is high compared to other designs and it
does not give a good protection especially against the rodents.
7