General

Composting – A Solution to the Burning Problem of Solid Waste Management

There exists a humongous problem of solid waste management being faced by the entire world. Garbage generated and gathered in our houses, offices, businesses and industrial establishments is essentially what is called as solid waste. And with growing population, urbanisation and industrialisation, more trash is being produced which is a constant threat to environment and health safety. Every day waste is a mix of organic and inorganic stuff and if not managed and disposed properly, pose monetary and social ramifications. Industrial waste consists of toxic chemicals which cause negative impacts on health and the environment (Zerbock, 2003).

Flooding is caused when the trash and toxic garbage clogs drains. Burning the waste is also not the right option as it can lead to air pollution and cause acute respiratory illness among the masses. When these toxic wastes enter water bodies, they pollute rivers and even seep into the ground water thereby rendering it unfit for drinking. The United States, China, Brazil, Japan and Germany are the leading trash generators. The United States alone produced about 228 million tons of waste in 2006 and the number increased to 254 tons by 2013 (Liu et al, 2015).

More than half of what we incautiously discard as garbage is organic matter, which is now being composted in order to produce rich manure for our plants. Composting does solve the problem of waste disposal to some extent and the key to a clean, trash free city lies in citizens performing their civic duty of waste segregation and composting. Wet waste in particular contains all nutrients for producing natural manure (Barr, 2004).

Composting

Composting is a natural process of converting organic matter into a rich fertiliser, fondly named as ‘black gold’. By composting wet aka organic waste, we return the nutrients back to the soil making it fertile and to ensure the continuity of cycle of life. Finished and final compost appears dark brown, crumbly and odour is like a forest floor (Reddy, 2011).

Composting requires 4 conditions:
1. Carbon contained in dried leaves, grass, sawdust, paper
2. Nitrogen from fruit and vegetable waste, coffee grounds
3. Oxygen
4. Water in the right quantity

Composting types

Onsite or backyard Composting

This is a method of carrying out the process of composting within your own premises or for people who generate small quantities of waste. For e.g. small quantities of food scraps, yard trimmings and paper can compost onsite. Many entities, organizations and educational institutions have found on-site food waste composting to be an efficient and effective way of alleviating the quantity of stuff they are paying to have hauled off as garbage while, at the same time, generating a valuable natural resource to increase soil fertility and nourish landscape grass and other flora (Tanskanen, 2006).

Vermicomposting – composting with worms

Vermicomposting is a process of converting organic matter or a heterogenous mixture of decomposed food scraps, vegetable waste, coffee grounds, tea bags, bedding material etc into black, earthy-smelling, nutrient-rich humus by the use of worms. The worms used in vermicomposting are called redworms (Eisenia foetida), also termed as red wigglers, manure worms, red hybrid or tiger worms.

The worms break down the organic waste into high quality compost called castings. Worm bins are easy to find and one pound of worms (approximately 800 to1,000 worms) can devour up to half a pound of organic matter per day. The bins can be customized to match the volume of organic waste that will be converted into castings. It normally takes three to four months to generate ready to use castings. The other by-product of vermicomposting process known as “worm tea” is used as a liquid fertilizer for houseplants or gardens (Garg & Satya, 2006).

Aerated (Turned) Windrow Composting

Windrow composting is a type of composting which is suited to generate large quantities of compost. Wastes produced by big communities, high volume food processing industries, restaurants, hotels, eateries and cafeterias are turned into a valuable compost by windrow composting. Also, this process needs assistance by experts in order to market the end product. In many countries, the local governments make the compost available to the residents at a low or no price.

Composting involves forming biodegradable waste like animal wastes and crop residues into rows of huge piles called “windrows” and aerating them periodically either manually or mechanically turning the piles. The ideal pile length is between 4 and 8 feet with a width of 14 to 16 feet. The temperature of the windrows must be monitored and logged repeatedly to ascertain the optimum time to turn them for faster compost generation. Large piles of pulverized wastes such as yard trims, grease, liquids, and animal by-products can be composted through this type of composting (Hassen et al, 2001).

Aerated Static Pile Composting

Aerated static pile method of composting generates compost relatively faster (3 to 6 months). It is appropriate for a homogenous mixture of biodegradable waste and works well for large volume producers of yard trimmings and biodegradable municipal solid waste (e.g., food wastes, paper stuff) such as food industry, local governments, farms, eateries and landscapers. This method, however, does not work well with animal by-products or grease from food processing industries. In aerated static pile composting, organic waste is mixed in a large pile and to aerate biodegradable organic material, no physical manipulation during primary composting is done. The amalgamated admixture is usually placed on pierced embellishment, providing air circulation for controlled aeration. It may be in windows, open or covered, or in closed containers. Air blowers might be activated by a timer or sensors.

As far as cost and feasibility is concerned, this composting method is most commonly used by larger and professionally managed composting facilities. The technique is also used for capital intensive and industrial installations (Rasapoor et al, 2009).

In-Vessel Composting

In-vessel composting can process large quantities of biodegradable garbage without requiring as much space as the windrow method and it can give bed to virtually any type of degradable waste (e.g., meat, food wastes, biosolids, animal wastes). In this technique, organic waste is turned into a compost within a building, a container, a vessel, within a drum, silo, concrete-lined trench, or similar equipment. These equipment’s allow air flow, moisture and temperature control. The material is mechanically turned or mixed to make sure the material is aerated. The size of the vessel can vary in size and capacity.

This technique generates compost in just a few weeks. It takes few more weeks or may be a month until the compost is ready to use because the microbial degradation needs to balance and the pile needs to cool down (Kim et al, 2008).

Composting as a Waste Management Technique

By segregating, recycling and composting, a family of four can alleviate their waste from 1000 Kg to less than 100 kg annually. Composting is a means of accomplishing all three of the R’s i.e. Reduce, Recovery and Reuse. Through composting the amount of garbage sent to the landfill is brought down, the biodegradable matter is reused instead of being dumped and it is recycled into a useful soil fertiliser (Taiwo, 2011).

References

Barr, S. (2004). What we buy, what we throw away and how we use our voice. Sustainable household waste management in the UK. Sustainable Development, 12(1), 32-44.

Garg, P., Gupta, A., & Satya, S. (2006). Vermicomposting of different types of waste using Eisenia foetida: A comparative study. Bioresource technology, 97(3), 391-395.

Hassen, A., Belguith, K., Jedidi, N., Cherif, A., Cherif, M., & Boudabous, A. (2001). Microbial characterization during composting of municipal solid waste. Bioresource technology, 80(3), 217-225.

Kim, J. D., Park, J. S., In, B. H., Kim, D., & Namkoong, W. (2008). Evaluation of pilot-scale in-vessel composting for food waste treatment. Journal of hazardous materials, 154(1), 272-277.

Liu, A., Ren, F., Lin, W. Y., & Wang, J. Y. (2015). A review of municipal solid waste environmental standards with a focus on incinerator residues. International Journal of Sustainable Built Environment, 4(2), 165-188.

Reddy, P. J. (2011). Municipal solid waste management. The Netherlands: CRC Press/Balkema.

Rasapoor, M., Nasrabadi, T., Kamali, M., & Hoveidi, H. (2009). The effects of aeration rate on generated compost quality, using aerated static pile method. Waste Management, 29(2), 570-573.

Tanskanen, J. H. (2000). Strategic planning of municipal solid waste management. Resources, conservation and recycling, 30(2), 111-133.

Taiwo, A. M. (2011). Composting as a sustainable waste management technique in developing countries. Journal of Environmental Science and Technology, 4(2), 93-102.

Zerbock, O. (2003). Urban solid waste management: Waste reduction in developing nations. Written for the Requirements of CE, 5993.

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