Meethotamulla- Where to Next?
Eng. Thamara Dilhani Sri Lanka Sustainable Energy Authority
It was a preventable tragedy that Sri Lanka has been ever faced. However the things has gone to the past and what is needed to think of ‘where to Next?. This article is based on the findings of a research project carried out by the Sri Lanka Sustainable Energy Authority, and Department of Civil Engineering, The Open University of Sri Lanka in 2015 to find the solutions for selecting right technology for treating Sri Lankan garbage issue.
It is a clear fact that the Municipal Solid Waste (MSW) is consequently changing with composition and the characteristics with the life style of citizens. The statement has been proven once again by the study carried out by the said team at Meethotamulla dumping site in Colombo. The results revealed that from 2004 to 2015 Sri Lankan MSW composition has been differed.
With the ending up of three decays civil war Sri Lanka strives to transition to an upper middle income country sustained, averaging economic growth rate of +6.5%. Substantial improvements have been made in education, roads, reintegration of those affected by conflict, and generating income through new livelihoods which drives to change composition of MSW. Colombo district accommodate approximately 2.3 million persons apart from the large number of people daily travelling to the city because their work places are located in Colombo and suburbs or for other administrative purposes. These hosts and visitors generate significant amounts of solid waste which has now become huge burden to the local authorities. With the changing socio-economic status of a country it is expected that the municipal solid waste’s organic share gradually decreases while inorganic and combustible fractions progressively increases.
The previous MSW characterization had been conducted in 2004 by the Central Environmental Authority when the per capita Gross Domestic Production (GDP) was USD 1,035. Now the country’s per capita GDP has changed and in 2015 it was USD 2,135 indicating the requirement for a new MSW characterization within Colombo municipality.
Western province accounts for more than 60% of the country’s daily waste generation of which collected 3,700 tons/ day. There are two major garbage dump sites in western province; Meethotamulla and Karadiyana. Average daily MSW delivered to Meethotamulla dump site is approximately 800 tons/day while Karadiyana site receives 400-450 tons/day. It is estimated that around 250-300 tons/day of the solid waste is treated as composting or organic fertilizer in the Western province, and the rest is diverted to 16 non-engineered open-dump sites.
Sri Lanka Sustainable Energy Authority (SEA), which is guiding the development of various indigenous energy resource of the country, receives considerable number of wastes-to-energy project proposals based on main dump sites of Colombo municipalities. Majority of these project proposals are not technically sound due to lack of understanding of the local waste characteristics. Therefore a detailed characteristic study of MSW which include composition analysis, thermal characteristics and facilitate to select appropriate technology for project development was done in 2015.
The Colombo municipality includes six administrative districts namely D-01, D-02A, D-02B, D-03, D-04 and D-05. Waste generation within Colombo municipality is collected by the Colombo Municipal Council (CMC) through private contractors and are directed to Meethotamulla dump site which handles approximately 50% of waste collection of the Colombo district.
Other than the above six administrative areas, Kollonnawa municipality and waste generates from military camps located in the Colombo city are directed to Meethotamulla dump site which receives various types of solid waste that are classified as Debris (DE), Earth (EA), Garbage (GA), Red Earth (Red EA), Pruning Trees (TR) and other materials.
Generally, the composition of the waste stream vary during the calendar year due to cyclical patterns of local climate, social activities, demography and trade or commerce. The Meethotamulla generator based residential study was carried out to waste stream for the year and reflect cyclical patterns and seasonal variation distributed among different administrative districts and regions randomly during each day. Area District 1 District 2A District 2B District 3 District 4 District 5 Military Camps Kollonnawa MC Other Total 41.80 0.17 38.11 95.91 10.28 0.39 29.56 50.90 16.52 34.96 22.47 676.03
The biodegradable percentage has dropped from 65% to 54% between 2004 and 2015 while Polythene and plastics percentages have increased to 14% from 5.4% as well as paper and cardboard percentage has increased to 10% from 7% during the last decade.
It was discovered that biodegradable organic component has reduced whereas plastics including polythene, paper and cardboard percentages have increased over the decade indicates green light on ‘where to next’.
The combustible share (paper, cardboard, textile, rubber and leather, wood and timber, polythene and plastics) of MSW receiving in 2004 was only 17% while this share represents 31% in this latest analysis done on percentage composition of organic waste. In CMC, average moisture content of MSW is 63% whereas average calorific value is 13.35MJ/ Kg.
Noteworthy that the municipal solid wastes that were collected from areas comprise with high income residences, commercial and business entities (Bambalapitiya, Wellawatta, and Kirillapone) showed considerably higher calorific value than the other solid waste collection wards of CMC.
Energy content estimation of MSW is basically done by the proximate analysis that gives the amount of fixed carbon, volatile matter moisture content and ash content which shows the combustible capacity. The Meethotamulla dumpsite proximate analysis values were fixed into combustion triangle to see the possibility of waste to energy, which is one of the best option that to be picked up. Combustion triangle shows that the heating value is strongly influenced by the moisture content. According to the combustion parameters of Meethotamulla MSW, it lies slightly above the combustion possible without auxiliary fuel range of the combustion triangle and hence needed pre-treatment before doing the combustion. Since the actual moisture content of Sri Lankan waste lies 60 to 70%, the waste has to be pre-treated before it can be burned in a furnace.
Due to the heterogeneous nature of MSW, though it is difficult to make projections a comprehensive characterisation of municipal solid waste is crucial to the long-term efficient and economical planning for solid waste management. Often, the problem is more pronounced when the choice of the best treatment option, to dispose of the MSW, is at hand. Hence reliable information is needed in aligning waste management activities
The tragedy has taken place at the area where at the old dumping site that mixture of waste and soil. The CMC took care to spread a layer of soil over a garbage before compacting down to minimize environmental hazards. Hence it is required to do old garbage composition analysis before giving solution to the present problem at the site. The analysis has been carried out for the MSW provide a where to next. The segregation MSW of selected districts of CMC could be a way of supporting Waste- toEnergy projects which provides multiple benefits.
Colombo, Sri Lanka characterized with considerable high temperatures in the hottest months provided solution to the moisture of MSW through sun drying or press the waste to reduce the moisture content. It is clear that generation of electricity is possible with the addition of a supplementary fuel by introducing to this important source of energy while making the environment clean. Therefore, it is needed to think twice that moving the dumps to somewhere is worthy. However the authorities should implement by introducing correct technology and till that the dumps has to be separated from soil, sun dried and bailed till the infrastructure establishes. Solutions when the solution is the problem Where the problem, the solution is there. However what we need is to pick the appropriate solution, that would not be the most beneficial for all parties, but definitely it would be the most environmental and social friendly.
The writers acknowledge Eng. M.M.R.Pathmasiri, Eng. Harsha Wikramasinghe, Eng. Badrani Jayawardhana, Eng. Anjalee Dewaraja, Eng. K.A.A.S. Kulsooriya, Mr. Vimal Nadeera, Mr. N.G.R.P Aberathne, Ms A.D.C.Surathilini, Mr Gayan Subasinghe, Mr Uditha Jayampath, the CMC, Kollonnawa UC and the staff of Meethotamulla waste disposal site and Ms NPM Rajaguru, The Open University of Sri Lanka during the study.