Saturday Dec 14, 2024
Saturday Dec 14, 2024
Monday, 24 April 2017 00:15 - - {{hitsCtrl.values.hits}}
In the aftermath of the recent unfortunate incident in Meethotamulla, the ‘Waste Free-Clean City project in Karadiyana, which has been awarded to Fairway Waste Management Ltd., is a timely measure towards ensuring that such a national calamity will never occur in future again. Following the launch of this project by the Government, Fairway Waste Management has begun the task of putting their plans into action.
Introduction
Fairway Waste Management has come up with a proposal to develop a solid waste processing facility at the Thumbowila-Karadiyana landfill site located in the Western Province of Sri Lanka. This will be an integrated waste processing facility to process 500 tons per day of fresh municipal solid waste received at the site. The proposed facility is designed to maximise energy production while having minimum environmental impact by optimising the recovery of energy and nutrients in the waste stream. The processing facility will reduce the amount of waste diverted to landfills by as much as 80% by mass and 90% by volume, whilst the fraction, which will be disposed in a suitably prepared landfill is mostly inert with no ill effects on the environment.
The design consists of a biological treatment plant that will process the fast degradable, high moisture content organic waste in a wet fermentation anaerobic digestion system. This system will treat a maximum of 115 tons of fast degradable organic waste per day. The remaining waste will be diverted to an incinerator facility having a capacity of 425 tons per day.
The project will supply a total of 79,000,000 kWh of electricity to the grid per year. This is sufficient to supply the demands of 35,000 households (based on the World Bank per capita energy use in Sri Lanka). In addition to electricity, the plant will generate liquid and solid fertiliser from the biological treatment of the organic fraction of the waste. It will produce 40,000 tons of liquid fertiliser per year, which will be processed to a high quality bio-fertiliser for the local market.
The environmental and social impacts of the current situation surrounding the management of waste disposal
Currently the mixed municipal waste as well as the source segregated household and commercial waste from eight local authorities is disposed at the Karadiyana waste-processing site. A small fraction of the source-segregated waste is processed as compost. All of the mixed waste is land filled. While the landfill is a managed landfill it does not meet the modern standards for a landfill by any measure. The site, which has been operational for several decades, contains more than 2,000,000 tons of waste that is polluting the surrounding waterways, ground water sources and the air. The environmental externalities due to open dumping caused by the site are palpable. Fairway Waste Management has estimated the monetary cost of the externalities, to the public, due to air pollution, GHG emissions etc. to be approximately Rs. 6,000/ton. The actual cost to the country is much higher due to the negative social impact, cost of health care (attributed to negative effects of the dump on surrounding communities), present value of future cost of remediation, cost for law and order arising from public protests, opportunity cost of the land etc.
The ‘Waste-Free Clean City’ Project
This is an initiative by the Ministry of Megapolis and Western Development to reduce waste as well as to find better and modern waste disposal solutions. The basic idea is to implement and enforce the 3Rs (Reduce, Reuse Recycle) principal and to effectively implement sustainable and environmentally sound end-of-the-pipe waste solutions, such as mass burn incineration and biological treatment facilities. Sri Lanka has a long way to go. A city will never be waste free, however, we can avoid piling the waste in landfills or rather minimise it. Incineration is the only way to do this and it is a must have solution.
Workings of the ‘Waste-to-Energy’ Concept
As far as Fairway Waste Management is concerned waste has an intrinsic value. It contains recoverable nutrients as well as energy that can be recovered through thermo physical or biological processes. All things when supplied with enough heat will burn releasing most often more energy than that was required to start the combustion process. One can think of a roadside garbage pile that is set on fire with a single match. If there is enough material with low moisture content it will burn releasing energy as heat in to the atmosphere.
A mass burn incinerator facility is simply a system that recovers the heat and converts it to electricity. It also cleanses the smoke and particulate matter that is released in the combustion process. It is possible to incinerate all of the waste but doing so is not the most environmentally sound solution, and it can be inefficient to burn the high moisture content waste consisting of fast degradable organic waste. It is for this reason that Fairway Waste Management has incorporated a biological process to treat the organic fraction so that not only energy but also nutrients are recovered from the waste stream.
The decomposition of organic matter can occur in the presence of oxygen, aerobic decomposition, and in the absence, an aerobically. Anaerobic decomposition is a naturally occurring process that produces biogas-containing methane as a by-product. In fact anaerobic decomposition is an ongoing process deep in the Karadiyana landfill, which produces biogas. Biogas consists of methane, CO2 and water vapour. Methane is also known as natural gas that escapes in to the atmosphere where it acts as a potent green house gas.
However, if the process is controlled and the bio gas is collected it can be combusted to produce electricity. Fairway Waste Management will install the largest and most advanced anaerobic digestion system in the region in Karadiyana to treat as much as 36,000 tons of organic waste per year. Additionally as a by-product the plant will produce 45,000 tons/year of liquid fertiliser and 7,500 tons/year of solid fertiliser.
Parties involved
Fairway Holdings and Sustainable Alternatives Ltd. formed a consortium to bid for the project when the Ministry of Megapolis and Western Development called for proposals in 2016.
Technology
The technology involved, mostly consists of a mass burn incineration with energy recovery boiler and an advanced flue gas cleaning system meeting European Union emission standards. The incinerator is a moving grate type with a four-stage heat recovery boiler. The flue gas cleaning system will assure that the emissions exceed the standards required in the country and will meet EU2010 emission standards. The plant design is based on The European Union guidelines for Waste Incineration. Fairway Waste Management will be utilising expert consultants from Denmark and the Netherlands to design and commission this project.
Environmental, social and economical benefits of the final outcome
There will be a significant reduction of the volume of landfill by more than 90%. The project will produce green electricity to power more than 35,000 households. Apart from saving the country’s fossil fuel (coal and heavy diesel) used to produce power, the project will be an immediate benefit to the communities that live around the Karadiyana garbage site. At the moment the site emits large volumes of methane from waste that is digesting anaerobically. It can be seen bubbling out of puddles of leachate.
Methane is a potent green house gas with an environmental impact that is 20 times more than that of CO2. While the project will not stop the current level of emissions immediately, the organic waste that will be kept out of the landfill will stop future emissions from occurring. It will eliminate the leachate that now washes into the ground and surrounding water bodies and it will also reduce the levels of SOx and NOx (harmful GHG emissions) in the landfill area. The lack of fresh waste in an open dump will eliminate the rodents and mosquitoes that can breed and spread diseases. The commissioning of the project will be the beginning of the reclamation process of the land that at present is an eye sore to the surrounding communities.
Public outreach
Fairway Waste Management will contribute to capacity building by working closely with local universities on the project. As of now there are several academics who are experts in solid waste management, biological waste processing and thermal processing who are working with the Government and with Fairway Waste Management on this project. These relationships will no doubt be further strengthened by actively involving research students and academic staff on areas of mutual interest.
This facility will be used to encourage and help the academic staff from universities to learn about the latest technologies in waste management. The plant operators will be trained by the best in the industry and the engineering staff will be hired locally to run the plant with specialised training provided to make the operation and maintenance of the plant a local effort. It can be confidently stated that Fairway Waste Management’s CSR efforts will contribute towards building a community of experts that will lead the waste-processing sector in the country in future.
Fairway Waste Management can be reached at: [email protected].
