Impact of Urbanization on Municipal Solid Waste Management: A System Dynamics Approach

Transcription

1 International Journal of Renewable Energy and Environmental Engineering ISSN , Vol. 2, No. 1, January 214 Impact of Urbanization on Municipal Solid Waste Management: A System Dynamics Approach RAJESH R. PAI, LEWLYN L. R. RODRIGUES, ASISH OOMMEN MATHEW, SUNITH HEBBAR Department of Humanities and Management, Manipal University, Manipal, Karnataka, India pairajesh.m@gmail.com, rodrigusr@gmail.com, asishmathew@gmail.com, sunithhebbar@rediffmail.com Abstract: Today, increasing population and rapid development are posing challenges on the environmental sustainability. One of the major concerns is on effective management of Municipal Solid Waste (MSW). This includes nonhazardous garbage, rubbish, and trash from homes, institutions, and industrial facilities. Garbage contains moist wastes like food, meat and vegetables; rubbish encompasses mostly dry constituents such as glass, textiles, paper, and plastic objects; and trash includes bulky waste materials and objects that are not collected routinely for disposal such as discarded mattresses, appliances, and pieces of furniture. Therefore waste should be traced and has to be recovered as much as possible. Even though, there are different policies to counter this problem, the compliance is a cause of concern. Having identified this need, an attempt has been made to study the impact of increasing population on the amount of waste generation through System Dynamics (SD) Modeling on the basis of which effective strategies could be developed for managing the same. Keywords: Municipal Solid Waste, Urbanization, System Dynamics Introduction: Municipal waste is a term coined to the solid waste produced by the people and the society in their day to day operations. In other terms, these are also called as domestic waste. In order to study the analysis of waste management, it is very important to define what it is: Waste analysis is the detection of waste creeks, their origins, their composition and their destinations which is often accomplished through waste audit or assessment procedure (Franchetti, M., 29). This is achieved by observing the facility, as well as tracking and quantification with an intension of minimizing the waste which is termed as waste minimization. Waste minimization is defined as the process of reducing waste streams through source reduction, reuse and recycling of materials, there by achieving a healthy environment (Franchetti, M., 29). The specific challenges in reducing the waste lies with the composition and type of generation of waste. For example industrial waste varies in their composition and it is in more concentrated form which contains hazardous materials than compared to that of municipal solid waste and therefore it requires technologies and specific handling procedures (Vesilind, P. A., Worrell, W. A., Reinhart, D. R., & Vesilind, A., 22) for decomposition and recycling. Whereas municipal solid waste contains mixed household waste, recyclables such as newspapers, aluminum cans, milk cartons, plastic soft drink bottles, steel cans, household hazardous waste, commercial waste, litter and waste from community trash cans, bulky items (refrigerators, rugs, etc.), including construction and demolition waste (Cheremisinoff, N. P., 23). In both categories, there exists major opportunities for prevention and resource recovery. There are variety of methods for disposing solid waste which vary globally which includes methods like dumping in open space, sanitary landfilling, incineration, and composting. Sanitary landfilling is prevalent in many developed countries, while in underdeveloped or less developed countries it is rare. In developing countries, low cost methods like dumping in open spaces, appears more acceptable than the other disposal methods. Despite the huge environmental problems, it is considered the main disposal method of urban solid waste in many of the cities (Zanjani, A. J., Saeedi, M., & Vosoogh, A., 212). Literature review: Identifying the gap, this paper tries to draw the relationship between population explosion and municipal waste generation. Population has a great effect on waste generation which impacts the environment and sustainability which includes: space availability, landfill leachate, global warming, loss of habitat and consumption of natural resources (Franchetti, M., 29). The composition of municipal solid waste depends upon a large number of factors such as the lifestyle of the people, their relative standards of living, general consumer patterns, and the level of technological advancement of a particular country (Mavropoulos, A., 211). There could be several sources for the generation of Municipal Solid Waste (MSW), some of them are listed in table 1. After the Second World War, landfills was the principal waste disposal method in the cities which later transformed to dumping in open space (196 onwards) this resulted in a larger municipal waste stream with a higher plastics content (Wolsink, 21). Similarly, one can observe that the main contributor for the generation of solid waste is the residential sources which contributes 48% in the total than compared to that of construction and others forms of IJREEE 216 Copyright 213 BASHA RESEARCH CENTRE. All rights reserved.

2 RAJESH R. PAI, LEWLYN L. R. RODRIGUES, ASISH OOMMEN MATHEW, SUNITH HEBBAR waste (Figure 1). This indicates that the residential waste has to be controlled for the sustainability of healthy habitat. According to Antonis Mavropoulos (211), the amount of waste generation are largely determined by two factors: first, the population in any given area, and second, its consumption patterns which are controlled by the evolution of Gross Domestic Product per Capita (GDP/c). As the number of household increases, the average waste generated per household also increases, which is shown in the Figure 2. It is clear how population, waste generated and per capita waste are related, but it still implies that individuals in a population are the originators of waste. Source Residential Industrial Commercial Institutional Construction and demolition Municipal services Process (manufacturing, etc.) Agriculture Table 1: Source and types of solid waste (Source: Hoornweg, Daniel and Laura Thomas 1999) Types of solid wastes Food wastes, paper, cardboard, plastics, textiles, leather, yard wastes, wood, glass, metals, ashes, special wastes (e.g., bulky items, consumer electronics, white goods, batteries, oil, tires), and household hazardous wastes. Housekeeping wastes, packaging, food wastes, construction and demolition materials, hazardous wastes, ashes, special wastes. Paper, cardboard, plastics, wood, food wastes, glass, metals, special wastes, hazardous wastes. Paper, cardboard, plastics, wood, food wastes, glass, metals, special wastes, hazardous wastes, biomedical waste. Wood, steel, concrete, dirt, etc. Street sweepings; landscape and tree trimmings; general wastes from parks, beaches, and other recreational areas; sludge. Industrial process wastes, scrap materials, off-specification products, slay tailings. Spoiled food wastes, agricultural wastes, hazardous wastes (e.g., pesticides). Figure 1: MSW by weight (Source: Environment Canada, 2) India is the second most populated nation in the world. According to the Census of 211, it is estimated that India has a population of 1.21 billion which contributes to 17.66% of the world population. Because of increasing population growth and rapid urbanization, bigger and denser will be the cities resulting in the MSW generation (Greedy, D. & Thrane, J., 28). In these cities lies 7% of India s urban population and generate 13, tonnes per day (TPD) or 47.2 million tonnes per year (TPY) with a per capita waste generation rate of 5 grams/day (Annepu, R. K., 212). Figure 2: Generation, Population & Per capita generation (Source: U.S, EPA December 21) Figure 3: Total Population & Urban Population Growth in India (Source: Sustainable solid waste management in India, 212)

3 Impact of urbanization on municipal solid waste management: a system dynamics approach It is seen from Figure 3 that nearly 25% of the total populations in India are in the urban regions than compared to that of rural region. This indicates that majority of the wastes are generated from the peoples living in urban regions at a rate of 188,5 TPD. From the global perspective, USA is considered to be major nations for the generation of solid waste which releases 229 million tonnes per year and is expected to increase by 12% in the year 225 (Figure 4). Figure 4: Highest solid waste generators in India, USA and China from 212 to 225 (Source: World Bank, 212) Considering the Figure 1, 2 and 4, it is very important for the individuals in current scenario to improve the disposal of municipal solid waste and also, it is seen from literary evidences that the increase in population results in the generation of waste. Hence, there exists a proper way of disposal to ensure that the land can be occupied for living. Based on the impact of the population on the generation of the municipal solid waste in terms of domestic waste and hospital waste, a system dynamics model is drawn using the simulation software called Vensim PLE which is developed by Ventana Systems (Vensim, P. L. E., 21). System dynamics (SD) is a methodology and mathematical modeling technique for framing, understanding, and discussing complex issues and problems. It was developed in the 195s by Professor Jay Forrester of the Massachusetts Institute of Technology in order to help corporate managers improve their understanding of industrial processes (Michael J. Radzicki & Robert A. Taylor, 28). Kumar Venkat (25), applied this concept in drawing the model for municipal waste recycling and considered the impact of population and per capita waste generation and observed that there is an exponential increase in the generation of waste without considering the percentage of waste recycled. S.O. Ojoawo, O.A. Agbede & A.Y Sangodoyin (212), applied the concept of system dynamics in the case of waste generation by drawing a stock and flow diagram and observed that population in the urban region increases sharply in time than compared to the steady increase in the rural areas. Research Methodology System Dynamics methodology is used in this paper which is basically a computer aided approach to policy analysis and design. This method is applied to problems arising in complex social, managerial, economic, or ecological systems literally any dynamic systems characterized by interdependence, mutual interaction, information feedback, and circular causality (System Dynamics Society, 211). This methodology includes: Problem identification, System Conceptualization, Model formulation, Simulation & validation, and Policy analysis & improvement (Sushil, K, 1993). Based on the previous works of various authors and through other source of information in this field a stock and flow diagram is drawn emphasizing the physical structure of the system and various factors influencing it (Sterman, J., 2). Model development This paper highlights the impact of population on the generation of municipal solid waste by considering the waste generated from the households and the other sources. Therefore municipal solid waste is the sum of waste generated through households and the hospital wastes. The factors such as total population, population growth, population decline, discharge volume of domestic waste, collection volume of domestic waste, and collection volume of hospital waste are considered to be the main parameters in this study. These factors together contribute to the change in the generation of municipal solid waste. The dependency diagram for all these variables are shown in the figure below. Total population: The total population is the difference between the population growth and the population decline. Growth of the population depends upon the population births and the population immigration (where are people are entering to the nation or country to stay permanently or temporarily) which increase the population in that nation and the Population decline is dependent upon the population emigration (where people are leaving the country or nation to other countries) which decreases the population and population deaths. This has a direct influence on the total population (Figure 6). Figure 6: Dependency diagram for total population

4 RAJESH R. PAI, LEWLYN L. R. RODRIGUES, ASISH OOMMEN MATHEW, SUNITH HEBBAR Population growth: The growth of the population is one of the major parameter which increases the total population directly results in the waste generation. The growth of the population is dependent upon population births which in turn is dependent upon population (population of state) and fractional birth rate i.e. people per person per year and also the impact factor of pollution on population birth (Figure 7). Discharge volume of domestic waste: Discharge volume is defined as the rate at which the volume of waste is released at unit time and is dependent upon the total volume of residents, discharge coefficient (Figure 11). Figure 11: Dependency diagram for domestic waste Figure 7: Dependency diagram for population growth Population decline: The decrease in the number of population of that state is dependent upon the average life time of people and impact factor of pollution and also the current population (Figure 8). Collection volume of domestic waste: Collection of domestic waste is influenced by the domestic waste stock which is the combined parameter of discharge volume of domestic waste, discharge volume of institution disposal volume of domestic waste and domestic waste collection rate. Therefore more the collection rate there will be reduction in the domestic waste stock (Figure 12). Figure 8: Dependency diagram for population decline Emigration rate: It depends upon Net population migrants and the population emigration coefficient. Net population migrants is the difference between the emigration rate and the immigration rate whereas population emigration coefficient is the rate at which the emigration is taking place (Figure 9). Figure 12: Dependency diagram for immigration rate Collection volume of hospital waste: The waste generation from hospital primarily impacts the surroundings as hazardous affluent used in the treatments and surgeries is the major pollutant. Number of births is also considered to be the key factor in the generation of hospital waste. Some of common wastes in hospitals are human blood and blood products, used sharps (e.g., syringes, needles, and surgical blades), cultures and stocks of infectious agents and associated biologicals etc. (Stericycle, 213). So these infectious waste has to be collected and disposed on weekly, monthly, quarterly basis or as often as needed (Figure 13). Figure 9: Dependency diagram for emigration rate Immigration rate: Immigration rate depends upon the net population migrants and the immigration coefficient. Immigration coefficient is the rate at which the people or individual leave one country and go to other countries for food, shelter, job security, economic conditions etc. (Figure 1). Figure 13: Dependency diagram for collection of hospital waste Municipal Solid Waste (MSW): Figure 14: Dependency diagram for MSW Figure 1: Dependency diagram for immigration rate Municipal Solid Waste generation is the sum of the domestic waste (from households and institutions), hospital waste (syringes, tablets etc.) and also by categorizing the people into high, medium and low income people, which contribute in the generation of waste (Figure 14).

5 tonnes tonnes numbers numbers Impact of urbanization on municipal solid waste management: a system dynamics approach Results and discussions: Considering the total current population as 2.8 lakhs, the simulation is done and the results for its impact on the generation of waste can be summarized into two components: a) Impact of fractional birthrate on total population and municipal waste generation. b) Impact of immigration and emigration (net migrants) on the total population and the generation of waste. 4 M 3 M 2 M Total population In accordance to the increase in the total population the generation of waste increases. In the trial run for 2% birthrate the total number of municipal waste generation is close to 5 billion (5B) tonnes, similarly we can observe that when birthrate is 2% the waste generation climbs up to around 5.6 billion tonnes in 3 years time period (Figure 16). It can be concluded that as the population increases the generation of waste also increases until strict necessary action is taken by the individuals or by the government either to recycle or to decompose the waste. 1 M 7.5 M Total population 1 M Total population : Fractional birth rate 4% Total population : Fractional birth rate 3% Total population : Fractional birth rate 2% Figure 15: Effect of fractional birth rate on total population Form the graph (Figure 15) it can be observe that with the increase in birthrate from 2% to 4%, there will be a drastic increase in the total population which in turn increases the generation of waste. This was confirmed from the graphs of total population and from the municipal waste generation. As shown in the Figure for the 2% increase in the fractional birthrate the total population increase to around 2 million (2M) in 48 months (3 years). Similarly if the birthrate is increased to 2%, we can see from the graph that the total population will reach about 6 million in 3 years also when we increase the birthrate to 3 % the population increases drastically resulting in increase in population around 26 million in 3 years. 8 B Muncipal Solid Waste 5 M 2.5 M Total population : Immigration 2% Total population : Immigration 15% Total population : Immigration 1% Figure 17: Effect of immigration on total population The population not only dependent upon the fractional birthrate but also from the people or individuals coming from other countries or nations as immigrants. When we study the behaviour of the total population by increasing the immigration coefficient from 1% to 2% with an increment of 5% we can see that there is a significant increase in the total population in that country or the nation. 6 B 4.5 B 3 B 1.5 B Muncipal Solid Waste 6 B 4 B 2 B Muncipal Solid Waste : Immigration 2% Muncipal Solid Waste : Immigration 15% Muncipal Solid Waste : Immigration 1% Figure 18: Effect of immigration on MSW Muncipal Solid Waste : Fractional birth rate 4% Muncipal Solid Waste : Fractional birth rate 2% Muncipal Solid Waste : Fractional birth rate 3% Figure 16: Effect of immigration rate on MSW With the increase in the immigration coefficient from 1% to 2% as in the Figure 14 you can see from the graph (Figure 18) that there is a minimal increase in the generation of waste which indicates that even though the percentage variation is small it has some influence on the generation on waste and it also concludes that the immigration is also a parameter which acts as a contributor for the waste generation.

6 tonnes RAJESH R. PAI, LEWLYN L. R. RODRIGUES, ASISH OOMMEN MATHEW, SUNITH HEBBAR Implications: It can be observed that when the collection rate is increased from 2% to 4% (Figure 19) there will be a reduction in the municipal solid waste i.e. when the collection rate is 2% the municipal solid waste is about 7.5B (billion) tonnes and when the collection rate is 3% the waste generation is also reduced to 6.9B tonnes and this can still be reduced when the collection rate is maintained at 4% i.e. (6 billion tonnes). 8 B 6 B 4 B 2 B Muncipal Solid Waste Muncipal Solid Waste : Collection rate 4% Muncipal Solid Waste : Collection rate 3% Muncipal Solid Waste : Collection rate 2% Figure 19: Effect of collection rate on MSW Figure 2: Stock and Flow diagram for Municipal Solid Waste Conclusion From the above results it can be concluded that, with the increase in population one can observe that there is an exponential increase in the MSW generation. Hence, necessary action should be taken so as to reduce the waste either by disposing it or recycling periodically. The other way is to conduct awareness programs for the people in the cities regarding the waste generation and its effects on human health and sustainability. Proper planning should be followed by industries. By practicing this we can reduce the generation of some waste so that it creates a healthy environment both for the humans and the animals to live. Scope for future work The above mentioned research work is restricted to only a portion of total waste generation i.e. by considering domestic waste and the hospital waste (Figure 2). It can be extended by considering other forms of waste generation such as industrial waste, commercial waste, construction and demolition waste, agricultural waste and also biodegradable waste References [1] Matthew Franchetti, (29), Solid waste analysis and minimization: A systems approach, McGraw Hill, Professional. [2] Vesilind, P. A., Worrell, W. A., Reinhart, D. R., & Vesilind, A. (22). Solid waste engineering. Pacific Grove: Brooks/Cole. [3] Cheremisinoff, N. P. (23). Handbook of solid waste management and waste minimization technologies. Butterworth- Heinemann. [4] Zanjani, A. J., Saeedi, M., & Vosoogh, A. (212). The effect of the waste separation policy in municipal solid waste management using the system dynamic approach.

7 Impact of urbanization on municipal solid waste management: a system dynamics approach International Journal of Environmental Health Engineering, 1(1), 5. [5] Mavropoulos, A. (211). Waste management 23+. Retrieved January 4, 211, from world.com/articles/print/volume-11/issue- 2/features/waste-management-23.html. [6] Wolsink, M. (21). Contested environmental policy infrastructure: Socio-political acceptance of renewable energy, water, and waste facilities. Environmental Impact Assessment Review, 3(5), [7] Annepu, R. K. (212). Sustainable Solid Waste Management in India. Columbia University, New York. [8] Greedy, D. and Thrane, J. (28). Closed for business - A look at the closure of open dumps. Retrieved January 11, 28, from world.com/articles/print/volume-9/issue- 6/features/closed-for-business-a-look-at-theclosure-of-open-dumps.html [9] Vensim, P. L. E. (21). Ventana Systems, Inc. Available at: vensim. com. [1] Michael J. Radzicki and Robert A. Taylor (28). "Origin of System Dynamics: Jay W. Forrester and the History of System Dynamics". In: U.S. Department of Energy's Introduction to System Dynamics. Retrieved 23 October 28. [11] Venkat, K. (25). Municipal Recycling: A System Dynamics Model..