Proceedings of the International Conference on Sustainable Solid Waste Management, 5-7 September 2007, Chennai, India. pp.126-133 Efficiency Improvement of Solid Waste Management Systems with Load Reduction: A Case Study in Kandy City, Sri Lanka Amila Abeynayaka 1 and D.R.I.B. Werellagama 2 1 Sustainable Development Programme, United Nations University Office, 2 Department of Civil Engineering University of Peradeniya, Sri Lanka. Email: 1 aabeynayaka@yahoo.com, 2 indukaw@pdn.ac.lk ABSTRACT Kandy city the capital of central province of Sri Lanka is facing severe problems with managing solid waste. Higher amount of short term biodegradable waste make the solid waste management difficult. Unnecessary weight and odour from rotting waste make temporary storage, collection and transport difficult. Hence load reduction plays an important role in solid waste management. In this study composition of solid waste of households was determined at both the point of generating and at the point of disposal. Then a comparison of compositions was done. A questionnaire survey was done to identify the residents behavior about home composting and source separation. The findings show that the short term biodegradable waste percentage is very high at the point of generation. Though less number of residents practice home composting and source separation there is a considerable number of residents that can motivate to practice it by proper planning of solid waste management system. Finally load reduction methods were proposed to improve the efficiency of solid waste management system. Keywords: Solid waste, Kandy city, 3R, Home composting, Source separation, Load reduction 1.0 INTRODUCTION The issue of solid waste (SW) is becoming a major problem in the Asian developing countries though the countries still generate much less than developed countries when per capita figures are compared. Landfill is the most common method used to dispose SW in Asian developing countries. Yet with development and population growth the land availability will be a major problem to the landfills. On the other hand with restricted facilities for waste hauling and landfill management such as transporting vehicles and compacting vehicles, face difficulties to accommodate the immerging amounts of SW. Hence the load reduction on solid waste management (SWM) system at the point of generation and at the centralized disposal facility is essential. Composition analysis at both point of generation and disposal site is necessary to design and implement an effective waste management system. In this study SW was analyzed at both point of generation (households) and at the point of disposal (landfill site) to identify the composition of SW. Kandy city is the capital of central province of Sri Lanka. The city falls within the up country wet 126
Sustainable Solid Waste Management zone of Sri Lanka, where annual average rainfall is 3175 mm. Kandy has an average temperature level range of 21 to 26 o C. Yet in dry periods the temperature of the city area rises up to 29-30 o C. The city land use mainly consists of home gardens, commercial activity areas, public institutions, forests, markets etc. The study mainly focused to identify the properties of residential SW generated in the Kandy city area. Hence a relatively high residential land use area was chosen for the study. Kandy lake catchment area which tentatively consists of around 2000 residential units was chosen for the analysis. SW generated within the Kandy city is collected and transported to the landfill site located in Gohagoda about 6 km away from the city. SWM in the city region is doing by two institutions including Kandy Municipal Council (KMC), the Local authority in the area and Care Kleen, a privet sector SWM company. SWM of the study area is operated by KMC. 2.0 METHODOLOGY The study consisted of following methods to collate data an the SWM system. 1. Solid waste composition analysis at households (point of generation) 2. Solid waste composition analysis at Gohagoda landfill (point of disposal) 3. Questionnaire survey among the households to identify the SWM behavior of the residents 4. Middleman shop and middleman behavior survey 5. Engineers, public health inspectors (PHIs), supervisors and collection workers interviews For the household waste composition analysis and the questionnaire survey a sample of household units was chosen. Tentatively the study area consists of 2000 households. 20 % of total units was randomly chosen for the study. First the study area was identified using available maps. Then the area was marked in a Kandy city map. The city map was used to identify the existing roads and streets. Yet the available maps in the study area produced by the survey department were modified in 1993. According to Adikari (2004) in the study area from 1956 to 1999 home garden land use has increased from 90 ha to 109 ha, natural forest land has decreased from 86 ha to 74 ha and grassland has decreased from 19 ha to 4 ha. Hence with field visits new land developments and streets were identified. The streets identified through maps and field visits were listed. Then the total number of houses in each street was counted. From each street 20 % of the houses was chosen for the questionnaire survey. 2.1 Solid Waste Composition Analysis at Households Each household was asked to dispose their SW into a bag given on the previous day. Residents were instructed to dispose only the waste that they generally dispose to the KMC SW collection system. The collected waste form the houses was separated into seven components including short term biodegradable, long term biodegradable, polythene and other plastics, metal, glass, paper, and other minor components. Then the weights of each component were measured. 2.2 Solid Waste Composition Analysis at Gohagoda Landfill SW samples were taken from the collection trucks of KMC in the study area once it arrived to the disposal site at Gohagoda landfill. Then the collected sample size was reduced to a reasonable size to sort by quartering technique. After that the reduced sample was separated into the seven components 127
Efficiency Improvement of Solid Waste Management Systems with Load Reduction: A Case Study in Kandy City described in the household waste composition analysis. Finally the weights of each component were measured. 2.3 Questionnaire Survey Among the Households to Identify the SWM Behavior of the Residents Questionnaire survey was conducted among 20 % of households to collect the information about SWM. Under the survey the information related to composting and source separation of the residents were collected. (The questionnaire survey was conduct among 20 % of household chosen by randomly as described above). 2.4 Middleman Shop and Middleman Behavior Survey Trough field surveys the available middleman shops, SW separation and recycling facilities in the study area and nearby environs were identified. Collection methods and difficulties facing with SW collection and operation were also discussed with the middleman shop owners and workers. 2.5 Engineers, PHIs, Supervisors and Collection Workers Interviews Engineers, PHIs, supervisors and collection workers were interviewed to collate date related to the SWM system in the area. Mainly focused data included available resources, collection procedure, health aspects, frequency of collection, collection rout planning, difficulties, possible improvements and the workers behavior. 3.0 RESULTS AND DISCUSSION 3.1 Composition of Solid Waste in Kandy City Study Region Figure 1 shows the summarized results of composition analysis obtained by quartering the SW collected directly from the households. 68 % of waste is short-term biodegradable waste and about 15 % is high value recyclables. Biodigradable (Long term) 11% Polythene & other plastics 3% Metal 2% Biodigradable (Short term) 68% Others 1% Paper 5% Glass 10% Figure 1 Composition of SW at House Holds (Weight Basis) The largest portion of solid waste represents short term biodegradable waste which includes kitchen waste, tree leaves, grass etc. This contains higher moisture content. Food waste a major constituent of short term biodegradable component of municipal SW has higher amount of moisture content 128
Sustainable Solid Waste Management compared with its weight. Table 1 shows specific weights and moisture contents of common waste found in municipal residential regions. Food waste has higher specific weight range compared with other common components. Glass, wood and metal also has higher specific weight values. Table 1. Specific Weights and Moisture Content Data for some Selected Solid Wastes (Extracted from Tchobanologlous et al., 1993) Type of waste Specific weight range (kg/m 3 ) Moisture content range (% By wet weight) Residential (uncompacted) Food wastes 130-480 50-80 Paper 40-130 4-10 Cardboard 40-80 4-8 Plastics 40-130 1-4 Yard waste 60-225 30-80 Wood 130-320 15-40 Glass 160-480 1-4 Aluminum 65-240 2-4 Other metals 130-1150 2-4 Municipal solid wastes In compactor truck 180-450 15-40 Normally compacted land fill 360-500 15-40 Well compacted land fill 590-740 15-40 According to JICA (Japanese International Corporation Agency) study team SWM survey 2003 in Kandy district the bulk density of municipal SW is 0.3 kg/l while that of Japan is only 0.15 kg/l. Compactors the common SW transporting vehicle used in the study area were imported from Japan. They were designed for properties of SW in Japan (i.e. low density and high compression). In the study area compacters are ineffective due to low compressibility. On the other hand vehicles with heavy loads are not suitable to the existing road conditions. With heavy load first the road destroyed, then the vehicle get struck in mud. This was happened few occasions on the Gohagoda landfill. Figure 2 shows the summarized results of composition analysis obtained by quartering the SW of collection vehicles at Gohagoda landfill site. 61 % of waste is short-term biodegradable waste and about 15 % is high value recyclables. The largest portion of solid waste represents short term biodegradable waste which includes kitchen waste, Tree leaves, grass etc. The landfill at Gohagoda is now almost filled to its full capacity. Hence KMC similar to many local authorities in Sri Lanka is facing severe crisis of land for SW disposal. Sort term biodegradable waste contains higher moisture content. Specific weight of the short term biodegradable waste is relatively higher than the normal solid waste. Compression ratio of the waste is also low due to kitchen waste content (Table 2). Even for well compaction the compression ration is relatively low. Hence transportation and placing in a landfill is inefficient. 129
Efficiency Improvement of Solid Waste Management Systems with Load Reduction: A Case Study in Kandy City Biodigradable (Long term) 16% Polythene & other plastics 2% Metal 5% Glas s 7% Paper 7% Others 2% Biodigradable (Short term) 61% Figure 2 Composition of SW at Disposal Location (Weight Basis) Table 2. Ratio of Compacted Weight to Uncompacted Weight (Extracted from Oweis and Khera, 1998) Waste component Normal compaction Well compaction Food waste 2.9 3.0 Paper 4.5 6.2 Plastics 6.7 10.0 Textiles 5.6 6.7 Rubber and leather 4.0 5.0 Yard waste 3.3 3.3 Glass 4.3 5.3 Metals 1.2 1.3 3.2 Temporary SW Dumping Locations Existing collection system consists of temporary SW dumping locations, collection vehicles and crew. 50 80 households use common temporary dumping locations. Residents throw waste into those places. Collection vehicles collect waste from those dumping locations. Scattering of waste around temporary dumping locations were observed. This mainly happen due to cows, monkeys, dogs, cats and crows who search for food from those dumping locations. The food waste (short term biodegradable component) attracts the scavengers. Hence the reduction of food waste at the pint of generation would give a solution for this also. During rain periods the run off water takes solid waste from those dumping locations, which adds pollutants to natural water bodies including the Kandy Lake and River Mahaweli. The rotting waste produces leachate which pollutes the ground water and surface water bodies. In some places where the scattering occurred, all the waste was not collected by the collectors. Odour is another problem at those dumping locations which diminishes the quality of fresh air in the surrounding area. The odour causes residents to through SW from far distance to the SW collection bin, which possibly cause scattering SW around the bin. Scattered waste beside streets causes environmental and aesthetic 130
Sustainable Solid Waste Management hazards in the surrounding areas. With warm humid-tropical climate the average temperature about 25 o C in the Kandy region increases the bacterial activities. Hence the degradation of waste is high, so the waste can not keep at temporary dumping locations for long time. Breeding of house fly is another problem in temporary dumping locations. Hence the full clean of waste bin at least once per life cycle days of fly is essential. Even waste is collected daily basis, if there are remaining parts in the bin, the breeding can take place. Hence reduction of short term bio-degradable waste is important at the point of generating. For that home composting can be promoted. 3.3 Difference between the Compositions of SW at Point of Generation and Point of Disposal There is a difference between the compositions of SW at the point of generation and disposal site. A reduction of short term biodegradable waste can be observed (Table 3). At point of generation and temporary dumping locations in the study area percentage of short term biodegradable waste is higher than the measured values at the dumping location Gohagoda. It happens due to animal eating as observed and loss of moisture at the temporary dumping locations. According to the table long term biodegradable waste percentage has increased by 45.5. This may due to reduction of short term biodegradable waste and practical errors. People cut tree branches in weekends, if the waste collected only in one day the composition fingers may inaccurate in such a case. Polythene bags may escape with the wing at the temporary dumping locations. Glass bottle were colleted by the collection workers during the journey, this may cause a reduction in glass content in SW at point of disposal. Table 3. SW Component Percentage Variations from Point of Generation to Point of Disposal Waste component Component percentage Variation as a percentage variation out of total of same component /(%) Short term biodegradable -7-10.3 Long term biodegradable 5 + 45.5 Polythene and other plastics -1-33.3 Metal 3 + 150.0 Glass -3-30.0 Paper 2 + 40.0 Others 1 + 100.0 3.4 Questionnaire Survey Data Via the questionnaire survey the properties related to residents SWM was collected. Table 4 illustrates the data related to home composting and source separation. Table 4. Summarized Questionnaire Survey Data (Residents Choices) Property Doing Willing to do Not willing to do No idea Home composting /(%) 9.8 31.4 52.9 5.9 Source Separation /(%) 14.4 46.4 40.2 2.0 3.5 Home Composting 9.8 % of households are doing home composting at the moment. Yet it dose not indicate that all the short term biodegradable waste generated from those houses tune into compost and no such waste is 131
Efficiency Improvement of Solid Waste Management Systems with Load Reduction: A Case Study in Kandy City contributed to KMC collection system from those units. Inspection experiences of SW collected from those houses indicates there are some short term biodegradable components exist. In the present study no deep composition analysis was done to identify the SW composition variation due to home composting. If so a better idea can be taken about the effect of home composting to the composition of SW collecting by KMC. 31.4 % of households is willing to do home composting. It gives a 41.2 % of total value. More than half (52.9 %) the residents are not willing to do home composting. In Kandy city region the inadequate space was a major limitation to keep a home composting units. 3.6 Source Separation 14.4 % of households are doing source separation at the moment. Mainly they separate glass, metal and paper from the food waste. Yet in most cases only the clean part of the collected matter goes into the middlemen shops. Source separation is also practiced by the very few among the residents. Considerable amount of people are willing to do it if a proper collection system exists to collect sorted waste (Table 4). Yet the number who dose not knows or dose not willing to do the source separation is high. Hence actions must take to get the contribution of all the people to the proper SWM system. The working staff for waste collection is less than the standard values. The issue becomes more critical with the poor health conditions and higher absentees rates of the labours. There are middleman shops in the reachable distance (within 2 km) from the households. Table 5 indicates the market prices in the Kandy city region in year 2005. For clean recovered materials there is a good value. Yet the majority of residents do not like to go and sell the separated stuff to the middleman shop. They prefer the home visiting buyers. Though there are such buyers in near by areas, the collection visits are not done in continues and regular manner. With limited space in the urban households temporary storage is a major limitation for such buyer collection system. Therefore the residents tend to throw the recyclable items as SW. Table 5. Market Values of Recovered Materials (Extracted from Abeynayaka et al, 2005) Component Value /(LKR/kg) Paper 4-20 Glass 10-30 Metal 10-90 Polythene 3-30 Collection workers try to recover valuables from the SW disposed at the temporary dumping locations before they put it into the collection vehicle. Though it seems to be a positive fact, it causes delay in SW collection, reduction of efficiency of workers, scattering of waste, and poor health effects to the workers. Yet with promoted source separation at the houses and separate bins for each component at the street level the effect would be minimized. Also the quality and quantity of separated recyclables will be improved. If the KMC workers can collect the valuable recyclables from the households in daily or any other scheduled basis the system will function well. 132
Sustainable Solid Waste Management 4.0 CONCLUSION Huge amount of short term biodegradable waste create an unnecessary load on SWM system in Kandy city. Present there is a 10 % reduction of short term biodegradable waste from point of generation to point of disposal. Reduction of short term biodegradable waste will improve the efficiency of SWM system. Present 9.8 % of people are doing home composting in the Kandy city study area. 31.4 % of residents are willing to do it. Home composting should be promoted by providing technical and infrastructure facilities. Future studies must be done to identify how much short term biodegradable waste is converted into compost and what percentage is contributed to the collection system by escaping the home composting system and what are the reasons for that. Present source separation practice in the study area is not sufficient. Yet considerable amount of people are willing to do it if there is a proper collection system for separated waste. Source separation should be promoted and it should be coupled with the existing SWM system, workers and middleman shops. ACKNOWLEDGEMENT The authors wish to express their sincere gratitude to the University of Peradeniya for the support provided to execute and conduct the study; Mr. Thissa Athukorala, Department of Sociology, University of Peradeniya for his valuable advice for the questionnaire survey, and the participants of the questionnaire survey. REFERENCES Abeynayaka A., Sumanasooriya A.M.S., and Deshapriya A.V.N., Identification of toilet waste and solid waste pollution sources in Kandy lake catchment area. Final year research project report, Department of Civil Engineering, University of Peradeniya, pp.48, (2005). Adikari A. M. S. B., Land Use Changes in Kandy Lake Catchment and Water Pollution in Kandy Lake, Western Region Megapolis Planning Project, World Trade Centre West Tower, Level 19, Echelon Square, Colombo (2004). JICA Study Team, Present solid waste management in Kandy, Japanese International Corporation Agency Solid waste management survey Kandy, Sri Lanka. (2003) Oweis I.S. and Khera R.P., Geotechnology of waste management, PWS publishing company, 1998. Boston, USA, pp. 23 (1998). Tchobanologlous G., Theisen H. and Vigil S., 1993. Integrated solid waste management. McGraw- Hill, Inc.1993 International edition, pp.28 (1993). 133