NSWAI

Composting

Composting is a biological process used for the conversion of organic waste materials into stable humus-like material known as compost. Application of this process includes yard waste, separated and commingled MSW. Most aerobic composting processes (windrow, static pole and in-vessel) involve three steps of preprocessing of waste, aerobic decomposition, and product preparation or marketing. The process offer simple operation however it is a net energy user due to the need of oxygen supply (forced aeration). This process also requires large land area. Other problem associated in this process includes odor, and the quality of compost for marketing. To enhance the economics of compost, it should be of consistent size, free from contaminants such as glass, plastic, and metals, and free of objectionable odor. Composting is an excellent method of recycling biodegradable waste from an ecological point of view. However, many large and small composting schemes have failed because composting is regarded as a disposal process, and not a production process. It is essential to consider the marketing and quality of the product.

The composting process occurs in two major phases. In the first stage, microorganisms decompose the composting feedstock into simpler compounds, producing heat as a result of their metabolic activities. The size of the composting pile is reduced during this stage. In the second
stage, the compost product is “cured” or finished. Microorganisms deplete the supply of readily available nutrients in the compost, which, in turn, slows their activity. As a result, heat generation gradually diminishes and the compost becomes dry and crumbly in texture. When the curing stage is complete, the compost is considered “stabilized” or “mature.” Any further microbial decomposition will occur very slowly.

The Composting can be classified into two broad Categories
Windrow Composting
In-vessel
Vermi Composting

Vermi composting
It is the end-product of the breakdown of organic matter by some species of earthworm. Vermi compost is a nutrient-rich, naturalfertilizer and soil conditioner. The process of producing vermi compost is called vermi composting. The earthworm species most often used are Eudrillus eugineae, Eisenia foetida or Lumbricus rubellus. Small scale vermi composting is done in bins of varying size and style and three different types of practices, such as non-continuous, continuous vertical flow and continuous horizontal flow, are adopted. The methods for large scale vermi composting are windrow and raised bed or flow through systems. Flow-through systems are well suited to indoor facilities, making them the preferred choice for operations in colder climates. Kitchen waste, except oily and spicy items are suitable for worms. But too much kitchen waste leads to putrification before the worms can process it and becomes harmful to the worms. Similarly, material sprayed with pesticides, high-water-content materials like watermelon, woody part of garden waste etc are hindrance to the process. The worms digest proteins and fats in meat scraps, but these materials attract scavengers. Regular removal of composted material, adding holes to the bin, or using a continuous-flow bin etc improve oxygen supply to worms. Insufficient oxygen leads to anaerobic reactions, producing strong odor and creating toxic environment for the worms.

Research Paper on Municipal Solid Waste Composting

www.insipub.com/jasr/292-297.pdf
http://www.idosi.org/gjer/gjer4(1)10/8.pdf
http://www.gnest.org/journal/Articles_in_press/497_Karagiannidis_revised_31-12-09_%20proof.pdf
www.p2pays.org/ref/12/11566.pdf
http://ejournal.icrisat.org/agroecosystem/v2i1/v2i1vermi.pdf
http://www.indiaenvironmentportal.org.in/files/Vermicomposting.pdf
http://www.environmental-expert.com/Files/0/articles/9047/Vermicomposting_article_for_the_biofertilizer_people.pdf
http://inderscience.metapress.com/app/home/contribution.asp?referrer=parent&backto=issue,4,12;journal,6,13;linkingpublicationresults,1:120365,1
http://www.e-journals.in/PDF/V5N4/810-813.pdf

Links for Composting

http://www.soils.ns.ca/composting.html
http://compost.css.cornell.edu/MSWFactSheets/msw.fs1.html
http://www.compostinfo.info/content/SET%20Critical%20Review%20MSW%20Composting%20Exec%20Summ.pdf
http://www.encyclopedia.com/doc/1P3-603533341.html
http://www.faqs.org/abstracts/Environmental-services-industry/Compressed-windrow-composting-in-California-Anaerobic-composting-for-MSW.html
http://compost.css.cornell.edu/MSWFactSheets/msw.fs.toc.html
http://compost.css.cornell.edu/MSWFactSheets/msw.fs5.html
http://www.water.siemens.com/en/products/sludge_biosolids_processing/composting/Pages/ips_composting_system.aspx
http://www.unescap.org/esd/energy/information/biomass_seminar/MunicipalSolidWaste.pdf
http://journals.mui.ac.ir/jrms/article/viewArticle/3505
http://www-tnswep.ra.utk.edu/activities/pdfs/ms-W.pdf
http://www.jgpress.com/BCArticles/1999/11992.html
http://www.ramiran.net/doc04/Proceedings%2004/Chica.pdf
http://www.sciencepub.org/nature/0101/18-wei.doc
http://www.almitrapatel.com/docs/025.doc
http://www.compostinfo.info/content/SET%20Critical%20Review%20MSW%20Composting%20Exec%20Summ.pdf
http://www.waste-technology.co.uk/Composting/composting.html