Composting of Solid Waste, Objectives & Its Steps

By: Haseeb Jamal / On: Jul 06, 2017 / Solid Waste

Composting of Solid Waste:

Composting of Solid Waste is defined as the "biological decomposition of biodegradable organic constituents of waste under controlled conditions to a state sufficiently stable for nuisance-free storage & handling and for safe use in land applications".
About 70% of municipal solid waste is decomposable or compostable.
The main organisms involved in composting are:
- actinomycetes (filamentous bacteria), fungi, and protozoa.

To transform biodegradable Organic matter into biologically stable material thereby reducing the original volume of the waste,
To destroy pathogens, insect eggs, and other unwanted organisms and weed seeds that may be present in municipal solid waste.
To retain maximum nutrient content; and
To produce a product that can be used to support plant growth and as a soil amendment as fertilizer and soil conditioner.

The nature of waste.
The moisture content of solid waste.
Available nutrients in the solid wastes.
Other environmental factors.
Under controlled conditions, can be made more effective and efficient.
Organic matter + O2 + nutrients + microbes ------- New cells + resistant OM + CO₂ + H₂O + NH₃ + SO4 + heat.
Reduces weight/volume of the organic fraction of MSW.
Produces compost ( a humus-like material that can be used as a soil conditioner).
To produce methane - Bio Gas.

Also See: Hospital Waste | Types of Hospital Waste

Sorting/separation: removal of recyclable material, metals, debris, glass etc. -affects the quality of

to provide greater surface area for microbes to attack, to improve insulation, to facilitate homogenizing of initially heterogeneous material, and to reduce depth for oxygen diffusion.
If the size is too small, it impedes the diffusion of oxygen and CO₂ from the sites being attacked especially during the thermophilic stage when Oxygen demand is the highest.
Typical range for feed material = ½ - 2 inches.
Adjustment for waste properties (e.g C/N ratio)
Decomposition and curing/maturation

Types are: Static piles and in-Vessel composting

Preparation and marketing of the final compost product: Grinding, screening, air classification, blending with various additives, granulation, bagging, storage, and transportation