Examensarbete i Hållbar Utveckling 45
A GIS-based Study of Sites for
Decentralized Composting and Waste
Sorting Stations in Kumasi, Ghana
A GIS-based study of sites for
decentralized composting and waste
sorting stations in Kumasi, Ghana.
Author: Hanna Öberg
Acknowledgement
In your hand you are holding a Master thesis written for the master degree in Sustainable Development at Uppsala University and the Swedish Agricultural University (SLU). The thesis is part of the project “Integrated Waste Management in Western Africa” (IWWA) funded by the EU with eighteen partners in different European and African countries. This thesis discusses organic waste management in developing countries and Geographic Information System (GIS). Funding for the thesis was obtained from SIDA through the scholarship Minor Field Study, administrated by SLU. I would like to dedicate my sincere gratitude to people who have helped me during my work with this thesis. I would like to thank my supervisor Dr. Cecilia Sundberg at SLU for all her help and valuable comments. She has been a great source of inspiration and her knowledge in the subject has been invaluable. Just as much I would like to thank my supervisor in Kumasi, Dr. Moses Mensah, at the Kwame Nkrumah University of Science and Technology (KNUST). From KNUST I would also like to thank Dr. John Ayer.
At the Kumasi Metropolitan Assembly (KMA) I would like to dedicate my gratitude to Mrs. Augustina Adjei Boateng for investing her time in this project by giving valuable information about waste management in Kumasi. I would also like to thank Mr. Marfo for his assistance during my fieldwork. Sven Smars at SLU and Karin Högdahl at Uppsala University have assisted by lending me equipment for my fieldwork.
Last but not least I would like to thank my dear friends in Ghana. Maxwell Appiah for his assistance during my fieldwork and his help with GIS. I am forever grateful to Amanda, Jennifer and Akyya for their hospitality and friendship during my stay. Ghana would not have been the same without you!
Abstract
Developing countries are facing a great challenge to collect, treat and dispose their waste in a more sustainable way. Today, most of the produced waste ends up on landfills, where they pose a great threat to the environment and human health. Kumasi, the second largest city in Ghana, faces the same issues as other cities in developing countries; waste management is run poorly and most waste ends up on the cities largest landfill, Dompoase, which will be full in a few years time. Issues such as low financial resources, bad urban planning and a growing population aggravate the implementation of a more sustainable development.
Since most solid waste in developing countries is organic, composting is a good option towards a more sustainable waste management. There are numerous amounts of articles stating that decentralized composting is the best option for developed countries. Decentralized compost facilities are less costly to install and maintain, they require less technology and decrease the cost of waste transportation. Transportation poses a large expense when it comes to waste management in developing countries. There is an advantage in integrating a more sustainable waste management in to the existing waste infrastructure since cities often are densely built up and there is a shortage of land. Therefore this thesis has investigated the possibilities of having waste sorting stations and decentralized compost facilities at public dumping sites in the Bantama area, one of ten sub-‐metros in Kumasi.
Based on literature and observations during field visits in the Bantama area, a classification scheme was developed. The classification scheme was designed to simplify identification and differentiation of the sites. It contains thirteen criteria to consider when planning for organic waste sorting stations and decentralized compost facilities. Suitable sites for sorting stations and decentralized compost facilities were selected by a SQL analyzes in a Geographic Information System (GIS). The analyzes was based on the classification scheme. The result shows that of twenty-‐one public dumping sites, seven were suitable as sorting stations and two sites were suitable for a decentralized compost facility. The expectation is that in due time and with infrastructure improvements, more than only seven communal sites can become sorting stations. When it comes to sites for composting the result reveals an issue in many cities – there is just not enough land to build as many decentralized facilities as would be necessary to recycle all organic waste. However, due to the advantages of having decentralized facilities, the recommendation is that Kumasi should start with a decentralized approach and as finance and technological skills exists the organic waste management can extend to also include larger facilities.
Further this thesis shows the advantage of having decentralized composting when it comes to transportation costs. A transport analyzes was done in a GIS, which showed the difference in transportation distances between having decentralized and centralized composting. The result showed that waste recycled close to its source, i.e. having decentralized waste management, is transported shorter distance compared to having centralized composting and thus saving on cost for transportation.
Keywords: Sustainable waste management, developing countries, organic waste, decentralized composting, sorting stations, waste transportation, GIS.
Sammanfattning
Utvecklingsländer står inför en stor utmaning att med hållbara metoder samla in, behandla och kasta sitt avfall. Idag hamnar större delen av allt insamlat avfall på deponier där de utgör fara för miljö och människors hälsa. Kumasi, som är den näst största staden i Ghana, är inget undantag utan står inför samma utmaningar som många andra städer i utvecklingsländer; avfallshanteringen är illa skött och största delen av stadens avfall hamnar på deponin Dompoase, vilken kommer vara full inom några år. Orsaker som låga finansiella resurser, brist på stadsplanering och en snabbt växande befolkning försvårar implementeringen av en effektivare och mer hållbar avfallshantering.
Eftersom största delen av hushålls-‐ och marknadsavfall i utvecklingsländer är organiskt, utgör kompostering en bra början till en mer hållbar avfallshantering. Många av de artiklar som berör ämnet anser att decentraliserad kompostering är det bästa alternativet för utvecklingsländer. De kostar mindre att implementera och underhålla, de är mindre teknologiska och kostnader för avfallstransporter minskar. Transportering av avfall utgör en stor del av avfallsbudgeten i utvecklingsländer och så även i Ghana. Det är en fördel att integrera en hållbar avfallshantering i den existerande avfallsinfrastrukturen, eftersom städerna oftast är tätbebyggda och det således är svårt att undvara nytt land för avfallshantering. Därför är fokus för denna uppsats att undersöka möjligheten att ha sorteringsstationer för organiskt avfall samt decentraliserade komposteringsanläggningar vid existerande allmänna sopstationer i stadsdelen Bantama, en av tio stadsdelar i Kumasi.
Baserat på litteratur och observationer under fältstudier i Bantama skapades först ett klassificerings-‐ schema. Klassificeringsschemat underlättar identifikation och differentiering av de allmänna sopstationerna. Det innehåller tretton olika kriterier att ta hänsyn till när man planerar för sorteringsstationer och kompostanläggningar. Passande områden valdes ut genom en SQL analys i geografiskt informationssystem (GIS). Analysen baserades på klassificeringsschemat. Resultaten visar att av tjugoen allmänna sopstationer var sju stycken lämpade för att ha sopsortering och två var lämpade för att ha en decentraliserad komposteringsanläggning.
Förhoppningen är att med tiden och med behövliga infrastrukturförbättringar kan fler än sju allmänna sopstationer utgöra sorteringsstationer. Vad gäller områden för komposterings-‐ anläggningar visar resultaten på en svårighet, som inte bara berör Kumasi utan många andra städer – det finns inte tillräckligt med landyta i städerna för att bygga så många decentraliserade anläggningar som skulle behövas för att återvinna all organiskt avfall. Trots detta så är rekommendationen att Kumasi borde börja med ett decentraliserat system på grund av dess fördelar. När finansiering samt tekniska kunskaper finns kan den organiska avfallshanteringen öka i omfång till att även inkludera större komposteringsanläggningar.
Vidare så visar denna uppsats på fördelarna med att ha decentraliserad kompostering utifrån ett transportperspektiv. En transportanalys gjordes i ett GIS och resultatet visade skillnaden i transportavstånd mellan att ha decentraliserad och centraliserad kompostering. Genom att återvinna avfall nära källan, med andra ord ha ett decentraliserat system, transporteras avfallet kortare avstånd jämfört med att ha ett centraliserat system. Således sparar man in på transportkostnader.
Nyckelord: hållbar avfallshantering, utvecklingsländer, organiskt avfall, decentraliserad kompostering, sorteringsstationer, avfallstransporter, GIS.
Abbreviations
SWM – Solid Waste Management KMA – Kumasi Metropolitan Assembly WMD – Waste Management Department GIS – Geographic Information System GHG – Green House GasesIWMI – International Waste Management Institute AWS – Abandoned Waste Site
KNUST -‐ Kwame Nkrumah University of Science and Technology MDG – Millennium Development Goals
Table of content
1. Introduction 1.
1.1 Aim 2.
2. Background 3.
2.1 Kumasi and sub-metro Bantama 3.
2.2 Solid waste management 4.
2.2.1 Municipal solid waste management in Kumasi 4.
2.2.2 Sanitation planning 7.
2.3 Transport and waste management 7.
2.4 Sorting of the material 8.
2.5 Organic waste management in Ghana 8.
2.5.1 Previous experiences in Ghana 9.
2.5.2 What are the conditions for composting in Kumasi? 9.
2.5.3 Decentralized composting 10.
2.6 Geographic information system 11.
3. Method and material 12.
3.1 Data collection 12.
3.1.1 Literature studies 12.
3.1.2 Field studies 12.
3.2 Creating the classification scheme 13.
3.3 Geographic information system analyzes 13.
3.3.1 SQL-analyzes 14.
3.3.2 Network analyzes 14.
4. Results 14.
4.1 Classification scheme 14.
4.2 Defining the study sites 16.
4.3 Geographic information system analyzes 17.
4.3.1 Selecting the criteria and SQL analyzes 17.
4.3.2 Network analyzes 23.
5. Discussion of results 24.
5.1 Classification scheme 24.
5.3 Sorting stations 25.
5.4 Decentralized compost 25.
5.5 Network analyzes 26.
5.6 Lessons learnt from previous projects 27.
5.7 Recommendations for implementation and identified questions for
further studies 27. 6. Conclusion 28. References 30. APPENDIX 1 33. APPENDIX 2 34. APPENDIX 3 37.
1. Introduction
Humans have always produced waste and as the human society has developed, the amount of waste has increased. Countries today are facing a great challenge to collect, treat and dispose their waste in a sustainable way. Waste management differs greatly between developed and developing countries as well as between urban and rural areas. Urban areas face a more urgent problem to manage the large amount of waste produced in a limited space. Compared to many developed countries with a developed collection service and recycling industry, developing countries have a less developed waste management and besides some informal recycling industries most waste ends up on landfills. Due to lack of resources and ability to implement a sustainable waste management, waste management is difficult to manage in developing countries.
An unsustainable solid waste management poses a large threat to the environment. Landfills contribute to global warming by releasing greenhouse gases (GHG) as well as polluting soil and water. Five percent of the total GHG emissions come from landfills (IPCC, 2006). Further, an unsustainable waste management also poses a threat to human health and is aesthetically unpleasant. However, waste does not have to be a problem, it can also be a potential resource. To face the current and future problems in waste management developing countries have to implement more recycling and make waste management transports more efficient. Waste transportation is often a major part of the waste management budget. Since a large fraction of household waste in developing countries is organic implementation of composting is a good start towards a more sustainable waste management. Organic waste can be composted and used as fertilizers on farmland and provide benefits such as; minimizing the amount of waste on landfills, return nutrients to the soil and reduce the use of chemical fertilizer. There are numerous amounts of articles stating that decentralized composting is the best option for developed countries (Zurbrugg, C, I, Maqsood, & Enayetullah, 2005), (Hoornweg, Thomas, & Otten, 1999), (Rothenberger & Enayetullah, 2006). Decentralized composting recycles the waste near the source leading to less waste transportation costs. Further, smaller decentralized composting requires less technology compared to large centralized facilities and therefore the starting and operational costs are less (Rothenberger & Enayetullah, 2006).
However, even with the benefits decentralized composting can provide, there are obstacles. Cities in developing countries are often crowded and expand quickly. Therefore finding suitable land has shown to be an issue (Zurbrugg, C, I, Maqsood, & Enayetullah, 2005). This could be resolved by, as far as possible, integrate composting and the necessary sorting of waste into the already existing waste management infrastructure.
Ghana is a typical example of a developing country with an unsustainable waste management and limited means to implement one. Ghana also aspires to become a middle-‐income country by 2020 (NESSAP, 2009) and with greater wealth comes more waste. Kumasi, Ghana’s second largest city, faces great challenges in future waste management since the city’s largest landfill, Dompoase, will be full in a few years time and there are difficulties in finding land for a new landfill. The country has set goals to implement a more sustainable waste management in their Environmental Sanitation Policy. The target is that by 2013 20% of the household community, public levels and commercial areas should be provided with services and facilities for primary separation of solid wastes. Today, due to
lack of resources the managing of waste in Kumasi is poorly implemented and sanitation is difficult to manage.
Based on the above, this thesis aims to determine the possibilities for decentralized composting in Kumasi. Questions asked are; is there land for composting and can composting be integrated in to the existing waste management infrastructure? Will decentralized composting minimize transportation costs? What are the limitations to implement decentralized composting? How can sorting be implemented in to the existing waste management and can this lead to recycling of not only organic material? Based on these questions the aim and objectives were formed.
This thesis will focus on household-‐ and market waste disposed at transfer stations. The analyzes was limited to Bantama sub-‐metro. The tool Geographic Information System (GIS) was used for the required analyzes. The expectation of this study is that it will be extended to other sub-‐metros in Kumasi and also to other cities in Ghana and other developing countries. The target groups are therefore other students who have the opportunity to extend this research and the thesis also aims to stakeholders in Ghana and other developing countries.
1.1 Aim
The aim of this study was to make an assessment of sites for waste sorting stations and decentralized compost facilities in Kumasi, Ghana. The study was conducted as a preliminary study to facilitate the implementation of a sustainable waste management by suggesting suitable public dumping sites and abandoned waste dumping sites for sorting and composting.
The objectives of the study were:
• Objective I, to create a classification scheme for sorting stations and decentralized composting sites applicable to cities in developing countries.
• Objective II, to identify abandoned waste dumping sites and public dumping sites in Bantama sub-‐metro and categorize them according to the classification scheme using GIS.
• Objective III, to produce digitalized maps showing suitable sites for sorting stations and decentralized compost facilities.
• Objective IIII, to perform a network analyzes comparing driving distances between having decentralized and centralized compost facilities.
2. Background
2. 1 Kumasi and sub-metro Bantama
Ghana is situated in the bay of Guinea of West Africa (figure 1) in the area once known as the Gold Coast. Kumasi is, following the capital Accra, the second largest city in Ghana with a population of 2 million (KMA, 2010). Kumasi is a fast growing city with a population growth rate of 5.3% (KMAa, 2011). It is the capital of the Ashanti region, once a great kingdom. Today, the King of Ashanti has no political power but is still influential and in control of the land in the region through dozens of sub-‐ chiefs (Korboe D 1995). Their cultural and historical heritage still plays an important role in everyday life of the citizens and in the urban development. Kumasi has a strategic location in the middle of the country combining the north and the south road networks. It is therefore an important trading centre with the central market being one of the largest markets in West Africa. At the household level informal trading is the main source of income. The climate is classified as sub-‐equatorial with two rainy seasons from March to July and from September to October. Annual rainfall is 1350 mm. The natural vegetation is rainforest. Temperatures vary between 21.5 and 30.7⁰C with only little variation during the year.
Bantama, one of ten sub-‐metros in Kumasi, is situated North East of Kumasi with a population of 306,248. Bantama has a total of 22,548 households and the largest part of the population is under the age of twenty-‐nine (KMA, 2010). Bantama can be described as a typical area in Kumasi (Mrs Adjei Boateng 2011 pers. comm) with dense residential areas and narrow dirt roads. The population in Bantama mainly get their income from trading.
Figure 1. Map of Ghana (Wikipedia, 2007) and Africa (usaid, 2011).
2.2 Solid waste management
The Basel convention defines the word waste as: “Wastes are substances or objects which are
disposed or are intended to be disposed or are required to be disposed of by the provisions of national laws.” (Baker et al 2004 p. 5). Shortly the definition of waste is any unwanted or useless material.
However, waste does not have to be useless, a sustainable waste management can recover resources from unwanted materials.
A solid waste management system contains of collection, transport, processing, recycling or disposal and monitoring of waste materials. A sustainable waste management reduces the effect on health, the environment and the aesthetics. Important factors to consider when planning waste management are economical, environmental, cultural and health factors. Compared to many developed countries with a well-‐developed collection service and a sustainable waste management focusing on the protection of environment and health, developing countries are behind. As wealth increases in developing countries more waste is produced and there is a need for a well functioning sustainable waste management.
Landfilling, last in the waste hierarchy, poses a large threat to the environment due to greenhouse gas (GHG) emissions. Five percent of the total global greenhouse gas emissions come from waste management, methane (CH4) being the largest source coming from anaerobic digestion of organic
material in landfills. CH4 has a 21 times higher global warming potential than carbon dioxide (CO2)
and also affects the degradation of the ozone layer (IPCC, 2006).
Landfilling is the most common used waste management worldwide and also in Ghana. Concerns about the health and environmental issues related to landfills have gotten stakeholders to find more sustainable ways to waste management. In modern waste planning resource recovery and “closing the loop” by reusing materials and returning nutrients are important factors.
2.2.1 Municipal Solid Waste Management in Kumasi
The Waste Management Department (WMD) of the Kumasi Metropolitan Assembly (KMA), is in charge of waste management in Kumasi and should as far as possible be self-‐financing. Most operational activities are privatized and the WMD is responsible for the overall management. Policy-‐ making is a governmental responsibility (Abdul-‐Nassir Saleh, 2002). There are a number of different companies dealing with waste management in Kumasi including Zoomlion (the largest one in Ghana)
MeskWorld, Sak-‐M, Wastegroup and ABC. In Bantama sub-‐metro the company MeskWorld handles the operational activities.
Waste management in Kumasi is insufficient, leading to an unclean and unhealthy environment. About 17% of the solid household waste generated in the city is dumped illegally, burned or buried by households, only 2% of the population has door-‐to-‐door collection. The largest fraction of the household waste, 81%, is taken to public dumping sites (KMA, 2011). These public dumping sites are referred to as communal sites and the terminology communal sites will therefore be used in this paper. The communal sites are transfer stations run by the KMA, WMD where locals dispose their waste for a minor fee. There are 155 communal sites in Kumasi. The pay-‐as-‐you-‐dump fee is 20 pesewas (0.09 Euro) per head load. The measurement “a head load” is usually one day’s waste from one household. A household collects their waste during a day and brings it, carrying on the head, to a communal site the next morning. Waste is collected and transported from the communal sites to a landfill every day or every other day (Mrs Adjei Boateng 2011 pers. comm).
Today, most of the waste from communal sites is transported to Dompoase landfill located in the outskirts, south of Kumasi. Dompoase landfill is an engineered landfill meaning that the landfill is constructed to prevent environmental impact from the waste. It was constructed in 2003 and has an expected lifetime of 15 years (Wikner, 2009). Kumasi is a fast growing city and there are difficulties in finding land for a new landfill site. Bantama area has a landfill, much smaller in size than Dompoase, called Amanfrom. Amanfrom is used when waste is collected in a close radius to the location of the landfill and also during the rainy season when the unloading platform at Dompoase is too muddy. To not put too much pressure on the platform more waste is then transported to Amanfrom (Mrs Adjei Boateng 2011 pers. comm).
The waste composition in Kumasi varies with the season. The average percentage of the household waste composition in Kumasi is shown in figure 7.
A large fraction of the household waste in Kumasi is organic which makes recycling of organic waste a good option towards a more sustainable waste management. Recycling of organic waste will decrease the amount of waste at Dompoase, decrease GHG emissions and return nutrients to the soil. Oragnic material 40% Plasqcs 20% Glass/bosles 1% Paper and cardboard 7% Metals 2% Texqles 7% Inert materials 21% Wood 2%
Figure 6. The Dompoase landfill in Kumasi (author’s photo)
2.2.2 Sanitation planning
In 2010 the Ministry of Local Government and Rural Development published a new sanitation policy; “The Environmental Sanitation Policy”. The main focus of the new policy is to meet the Millennium Development Goals (MDGs) target year of 2015 as well as to review the limitations of the old one from 1999. Since then it is slightly refocused in order to be forward looking and prepared for a changing lifestyle that comes with greater wealth.
The overall goal of the Environmental Sanitation Policy is to “develop a clear and nationally accepted vision of environmental sanitation as an essential social service and a major determinant for improving health and quality of life in Ghana.” (NESSAP, 2009 p. 13). The current state on Solid Waste Management (SWM) in Ghana is that there has been an increase in waste as well as a change in the type of waste, from biodegradable food-‐wrapping such as leaves to paper, to thin-‐film plastics and now also more dense styro-‐foam and plastics. Many of the current waste dumping sites, especially the ones in the larger cities, are causing bad smell as well as opposing a health hazard to people living around these areas (NESSAP, 2009). Further the sanitation policy declares that waste management in Ghana supports the waste hierarchy: reduction, re-‐use, recycling and recovery. The target is that by 2013 20% of the household community, public levels and commercial areas should be provided with services and facilities for primary separation of solid wastes. By 2015 this figure should be 25% and by 2035 90% (NESSAP, 2009). The potential for integrating recycling stations at communal waste dumping sites will be examined. It is expected that smaller recycling stations will in time meet the target of one major recycling station and also reduce the cost of transportation. When it comes to composting in particular the aim is to install windrow composting plants and the target is to compost 50% of biodegradable organic fraction of the municipal waste that will be source separated (15% by 2015). It is expected that within the planning period a minimum of four mechanized compost plants will be installed in metro areas (NESSAP, 2009).
Windrow composting is when organic waste is piled in long rows along triangular aerators. The rows need to be turned to improve porosity and oxygen content. It requires an area of 800 -‐ 1000 m2 and
has the capacity to serve a number of 2000 households and receive 4 tons of waste every day (Drechsel & Zurbrugg, 2006). Included in the area is not only the space required for the actual composting process but also space for office, parking area etc. The area can be scaled up or down depending on local conditions (Rothenberger & Enayetullah, 2006).
Today, most of the KMA’s budget goes to operation and maintenance of existing systems which limit the possibilities to work in the direction of a more sustainable waste management (Dahlman, 2009).
2.3 Transport and waste management
A large fraction of the waste management budget in developing countries goes to transportation. Therefore an important focus is to keep costs of transportation low when planning for a sustainable waste management. Having a decentralized approach to recycling of organic material would target this (UNESCAP), (Rothenberger & Enayetullah, 2006). It is one of the advantages with a decentralized system since waste is reused close to where it is generated (Zurbrugg, C, I, Maqsood, & Enayetullah, 2005). Cofie explains that in order to save as much as possible on waste transportation cost, composting should take place within the city-‐boundaries (Cofie, Dreschel, Agbottah, & van Veenhuizen, 2009). However, this might not be possible due to other issues such as availability of
land but should be kept in mind when planning for compost facilities. There is also the possibility of having non-‐motorized vehicles for shorter transportation distances (UN-‐HABITAT, 2010). Another aspect of transportation to consider is the distance in transportation for farmers interested in buying the finished compost product. There is a risk that less of the product will be sold if the transportation costs are too high for the farmer.
2.4 Sorting of organic waste
A transfer station is a site where waste is temporary disposed. Skitt explains the term as: “A place
where waste from collection vehicles is aggregated and organized before being transported to disposal sites or treatment facilities.” (Skitt, 1992). In literature, the term transfer station is used both
for sites where waste is sorted and for sites where waste is only aggregated, without being sorted. Since this paper will discuss sites for sorting of waste the term sorting stations will be used instead of transfer stations.
Sorting is a crucial part of the composting process. A well managed sorting secures a good supply of fresh organic waste to compost facilities and the product produced will be of high quality and free from heavy metals. Sorting can either be done by citizens at household level or done by workers at designated sorting stations. This thesis will look into whether the communal sites in Kumasi can function as sorting stations. The idea is to have two containers at the sorting stations, one for mixed household waste and one for pure organic waste. Further there should be room for a table where sorting will occur. Having sorting at the communal sites are favorable since a more sustainable waste management will be integrated in to the existing waste management infrastructure. It is favorable since the land is already designated to waste management and locals are accustomed to bring their waste to these sites. It will also provide employment opportunities where waste pickers can be involved in the process. Waste pickers are people from marginalized groups who get their income from separating useful material at landfills to sell or use (Wilson, Velis, & Cheeseman, 2006). There is an advantage with hiring waste pickers to work at sorting stations since they are already familiar with waste sorting and recycling. Further, a job would provide them with a more steady income and hopefully a healthier working environment.
2.5 Organic waste management in Ghana
Organic-‐ or biodegradable waste is waste from plant or animal sources. There are two ways to process organic waste: with the presence of oxygen by composting (aerobic) or without oxygen by biogasification (anaerobic). Composting is the most common biological treatment world-‐wide (McDougall et al 2001 p. 248). When dealing with organic waste in developing countries compost is seen as a preference compared to anaerobic digestion since it is a more simple process requiring less technological resources (Hoornweg, Thomas, & Otten, 1999). It has benefits such as minimizing the amount of waste on landfill, return nutrients to the soil, reduce the use of chemical fertilizer and can be started with little capital and operational cost. With composting, large amount of waste produces an odorless and stackable product as well as decreases the volume compared to the volume of the input material. A study from SLU shows that Kumasi can reduce their GHG emissions by 19.000 – 21.000 tons CO2 every year by composting its organic household waste (Boström, 2010).
2.5.1 Previous compost experiences in Ghana
Ghana has had compost facilities and the most well known facilities are Buobai in Kumasi and James town and Teshi-‐Nungua in Accra. All three facilities were windrow compost plants, James Town was designed to produce 200 tons per year and Teshi-‐Nungua to produce 38.000 tons per year while the one in Kumasi was designed to produce 37 tons per year (Drechsel et al, b, 2004). Facilities of this size are referred to as centralized compost facilities. The quality of the compost produced in Kumasi proved to be well with a high content of nutrients and free from toxics and heavy metals (Cofie, Dreschel, Agbottah, & van Veenhuizen, 2009). Unfortunately none of the compost facilities are currently in use. The experiences from the projects in Ghana as well as examples from other West African countries show that the reasons for failure where too low revenues as well as that cost of transportation and maintenance were too high. Further, there was a problem in selling the product; at James town and Buobai producers were not able to sell the product and at Teshi-‐Nungua the product was sold but did not manage to cover the high operation and maintenance cost (Drechsel et al, b, 2004). Mrs. Adjei Boateng says that some of the reasons Buobai failed was: when donor founding ran out there was a problem finding new funding and the project ended. The plant was also not popular with the local community who didn’t want a compost facility in their “backyard”. The facility still remains on the ground without any current usage (Mrs Adjei Boateng 2011 pers. comm).
2.5.2 What are the conditions for composting in Kumasi?
Fifty-‐five percent of the total household waste is organic (figure 7). In a year the total amount of organic waste produced in Kumasi is 64.000 tons from households and 60.000 tons from markets. When including other sources of waste available for composting such as: sawdust, industry and livestock manure, Kumasi has a total of 230.000 – 250.000 tons available for composting every year (table 2). Based on these figures it is clear that there is no shortage of fresh supply for composting in Kumasi (Dreschsel et al, a , 2004).
Table 1. Total amount of waste and organic waste
The benefits of using compost as fertilizer are many. It improves the soil structure, adds nutrient and trace materials, lightens heavy soils and gives better infiltration of air and water (UNESCAP). Three groups of buyers have been identified in Ghana; urban farming systems, peri-‐urban farming systems and real estate developers and landscape designers. Estimations done by the International Waste Management Institute (IWMI) shows that around 11.000 tons of compost could be absorbed every year by different farming systems (Drechsel et al, c, 2004). Backyard farming in urban areas is common in Kumasi. Nearly two thirds of households practice backyard farming. Urban and peri-‐ urban farming accounts for 60% of the total food consumption in the city (Dahlman, 2009).
Today, most farmers use poultry manure as fertilizer and a few combine it with chemical fertilizers (Drechsel et al, c, 2004). Kumasi has more than 300 registered poultry farms. They pose a large competition and limit the potential market to compost. Compost is not officially accepted as a fertilizer by many of the farmers in Ghana (Zurbrugg, et al. 2004). However, farms producing goods for export have more pressure to keep a higher standard and are more interested in soil input with a high quality such as compost fertilizer (Drechsel et al, b, 2004).
As explained above supply of fresh material is not an issue for Kumasi. The challenges are rather socio-‐economic issues such as the gap between farmer’s willingness to pay and estimated compost price. Therefore composting can so far only be sustainable with subsidies (Cofie, Dreschel, Agbottah, & van Veenhuizen, 2009).
2.5.3 Decentralized composting
There are numerous amounts of articles stating that decentralized composting is the best option for developed countries (Zurbrugg, C, I, Maqsood, & Enayetullah, 2005), (Hoornweg, Thomas, & Otten, 1999), (Rothenberger & Enayetullah, 2006) etc. Decentralized composting is the composting of waste in limited quantities located near urban residential areas. Sizes can vary from small backyard composting installations to plants processing 3 to 10 tons of organic waste daily. Decentralized facilities are less technology dependent and there is a less risk of failure compared to centralized facilities (Rothenberger & Enayetullah, 2006). They are also cheaper to construct and since they are less technology dependent they require less operational costs. Along with lower starting cost and operational costs there is a cost efficiency in transportation by reusing waste close to where it is generated (Rothenberger & Enayetullah, 2006), (Zurbrugg, Drechsel, Patel, & Sharatchandra, 2004). Decentralized composts are also more labor intensive and will create employment opportunities and a source of income for locals. Even if the recommendation is that a decentralized approach is the most sustainable for developing countries there are obstacles and decentralized compost facilities are also prone to some of the problems as centralized ones. Another issue with decentralized composting is finding suitable land (Zurbrugg, Drechsel, Patel, & Sharatchandra, 2004), (Drechsel et al, d, 2004). Most cities in developing countries are facing a population growth and expansion of the city boundaries, which makes it more difficult to find suitable land (Zurbrugg, C, I, Maqsood, & Enayetullah, 2005). This is also the situation in Kumasi. If possible, there is an advantage in using already designated waste management sites for composting (Drechsel et al, b, 2004).
At the time of writing Zoomlion is currently planning for a compost facility in Kumasi. The facility would be large, producing 200-‐400 tons a day (Rockson 2011pers. comm). However, the compost plant has not been constructed yet and this figure is very uncertain. However, it is clear that the
facility is planned to be a lot larger than the decentralized ones discussed in this paper. The plant will be located in the south of the city.
Ghana’s Environmental sanitation policy states that the goal is to install windrow composting as part of their organic waste management (NESSAP). The previous compost facility in Kumasi, Boubai, was windrow composting, thus the knowledge of such a facility exists.
While doing the literature study there has not been any sources claiming that centralized compost facilities are more suitable for developing countries. Large-‐scale composting plants previously operating in urban areas in developing countries have proved to be uneconomical (Dulac, 2001). These compost stations have failed due to various numbers of reasons such as: poverty, demographic growth, economic fluctuations and fiscal austerity (Drechsel et al, b, 2004). The differences between centralized and decentralized can be seen in the table below.
2.6 Geographic Information System
Geographic Information System (GIS) is a computerized system that can store, analyze and display geographically referenced information combined with database information. It has the ability to relate different information in a spatial context. GIS is used in a number of different fields, for example; archeology, urban planning, remote sensing, land surveying and natural resource planning. Geographically referenced information, i.e. identified according to a location on the globe, can be stored as raster-‐ or vector images. Raster images are stored as pixels in rows and columns with each cell storing a single value. Vector data is stored as points (ex. houses, wells), lines (ex. roads, rivers) or as polygons (ex. landuse, city boundary). Database information is stored as attribute tables connected to the map-‐layers (the raster-‐ or vector images). Differently combined data can reveal relationships, patterns and trends to the user that is difficult to associate in any other way. As an example map layers showing topography, rivers and houses can be combined and analyzed to see which houses in a residential area that might be exposed to flooding. GIS helps the user to display data in a way that is easily understood by people from different fields, education and language. There are a numerous amount of tools helping to analyze the data. Below follows a description of tools used for the analyzes in this thesis.
Large-‐scale centralized composting system Decentralized composting system
Depend on highly mechanized technology. Simple technology and labor intense.
Large investments for advanced machineries. Low capital cost and locally available materials. High operation and maintenance costs and a high degree
of specialized skills to operate and maintain. Comparatively less maintenance costs and low level skills required. Less interaction and involvement of the residents.
Having the residents separate their own waste reduces the volume of solid waste for disposal, increases the value of recyclables and enhances the environmental awareness of the community.
Transportation cost is high as all waste needs to be
transported to disposal facilities located far from the city. Reduces the cost of transportation. Quality of compost is poor due to large quantity of
unseparated waste with high risk of contamination. Quality of compost is good because waste is efficiently separated twice and risks for contamination are minimized. Table 2. Large-‐scale centralized vs. Decentralized composting (UNESCAP).
Structured query language (SQL) is a standardized language used to select, retrieve and modify data stored in a relation database (ESRI, 2011). It is the most used standard among databases. In GIS, SQL is used to retrieve information from an attribute table. SQL was used for selecting suitable sites for sorting stations and decentralized compost sites.
A network analyzes can be used to find the most optimal route between two or more points. A network can be defined as “a set of geographic locations interconnected in a system by a number of
routes” (Lo & Yeung, 2007, p. 389). It is a system of lines topologically structured meaning that all
lines are interlinked without any fractures on the lines. A network can be roads, underground, a river system or electrical wiring, to mention a few. Examples of analyzes on road networks can be finding the shortest route between two or more points, fleet routing, travel directions, closest facility, service area etc. In order to perform a network analyzes a basic requirement is to have information in the attribute table about the length of each line segment. Other information valuable for network analyzes can be speed limits, one-‐way streets, traffic congestions and prohibited turns (Eklundh, 2000), (Lo & Yeung, 2007). In GIS the user specifies the rules for the network (distance, speed-‐limit etc.) and the locations of two or more points. It is in between these points where the result will be calculated. In this thesis network analyzes is used to find the shortest route between suggested sorting stations and the suggested decentralized composting site as well as between suggested sorting stations and the suggested centralized compost facility.
3. Method and material
3.1 Data collection 3.1.1. Literature studies
In order to get some basic understanding of the topic as well as the geographical area to be studied, some basic information were obtained from literature. The literature, both international and Ghanaian, came from a variety of different sources such as published articles and reports, internet, the national environmental sanitation strategy and action plan and MSc and BSc thesis from KNUST library. Personal contact with KMA’s WMD and The Statistical Office were also sources of information.
3.1.2. Field studies
Necessary data was collected during field visits in Kumasi. Three months in Ghana also gave a general understanding of prevailing waste management condition in the country as well as an understanding of Ghanaian culture and customs.
The field work took place in Bantama sub-‐metro. Mrs. Adjei Boateng, research and development officer at the WMD, chose Bantama since it is the sub-‐metro with the most communal-‐ and abandoned sites. Data from the communal sites was collected in December, during the dry season. A first visit to the sites gave information about the location of the sites. The locations of the communal sites in Bantama area have not previously been marked in a map. Contact was initiated through personal contact with the WMD. All necessary data for the analyzes was collected during a second visit to the sites. The geographic location and area was collected with a GPS, in the coordinate system
