COMPOSTING OF SOLID WASTE, OBJECTIVES & ITS STEPS - Composting of Solid Waste is defined as "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. Objectives of composting of solid waste. 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. Composting time depends on: The nature of waste. 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 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. Composting period 2-6 weeks

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Composting of Solid Waste, Objectives & Its Steps

By: Haseeb Jamal 

Composting of Solid Waste:

·      Composting of Solid Waste is defined as "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.

·       Main organisms involved in composting are:

o     actino-mycetes (filamentous bacteria), fungi and protozoa.

Objectives of Composting of solid waste

·      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.

Composting time depends on:

1.    The nature of waste.

2.    Moisture content of solid waste.

3.    Available nutrients in the solid wastes.

4.    Other environmental factors.

5.    Under controlled conditions, can be made more effective and efficient.

6.    Organic matter + O2 + nutrients + microbes ------- New cells + resistant OM + CO₂ + H₂O + NH₃ + SO4 + heat.

7.    Reduces weight/volume of the organic fraction of MSW.

8.    Produces compost ( a humus like material that can be used as a soil conditioner).

9.    To produce methane - Bio Gas.

Steps in Composting of solid waste:

PRE-PROCESSING

Receiving

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

Size Reduction/Screening:

·      to provide greater surface area for microbes to attack, to improve insulation, to facilitate homogenizing of initially heterogeneous material, to reduce depth for oxygen diffusion.

·      If size is too small, it impedes the diffusion of oxygen and CO₂ from the sites being attacked especially during thermophylic 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

Windrow Composting

·      Triangular piles 7 feet high and 14-16 feet wide at the base

·      Turning by front end loader or mechanical turner twice per week

·      Composting period 2-6 weeks

Haseeb Jamal. I am a Civil Engineer, graduated from University of Engineering and Technology, Peshawar, Pakistan in 2010. I also have a PG-Diploma in Disaster Management and MS in Urban Infrastructure Engineering (In Progress). My expertise include civil related softwares like AutoCAD, SAP2000, MS Project, Primavera, MS Office and GIS. My technical skills include project management, monitoring and evaluation, structural assessment, disaster risk management, Quantity survey, land survey, material testing, site management and technical writing. I am trained in writing project progress reports as well as proposals and concept papers. I have also received advanced training on surveying, proposal writing, Monitoring and Evaluation of projects as well as organizations.I have worked as Project Engineer at National Research and Development Foundation, Peshawar and CENCON Associates. I also worked with Spectra Engineering Solutions as Senior Civil Engineer in monitoring of World Bank and UNDP funded projects all over Khyber Pakhtunkhwa and FATA. Currently, I am working as Deputy Manager Development at NayaTel, Peshawar.

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