Quantification of Solid Waste Destined in Kigali City Nduba Dumpsite ()
1. Introduction
Rapid upward changes in urbanization, industrialization, population growth and lifestyles in Rwanda contribute to increasing the per capita municipal waste generation. The characterization and quantification of household solid waste in Kigali would bring together data on the generation rate and the composition of waste. This will help the authority to operate an efficient waste management system. Solid waste generation is an outcome of human activities. Poor solid waste management practices have a serious threat to health and environment because it may lead to air, soil and water pollution. Quantification and characterization of solid waste components consider an important step in solid waste management procedures [1]. The objectives of solid waste management in an area are to advance the environmental quality, safeguard its health, and strengthen its technical and economic efficiency [2].
Data on waste composition, production, and recycling are essential for designing routes of collection systems, determining placements for bins, and selecting appropriate solid waste disposal options, and it’s crucial if alternative waste management schemes should be developed. A reliable estimate of the quantity of solid waste generation in the city is very important for proper solid waste planning and management [3].
In Rwanda since 2005, improvements have been made in the management of solid waste, and municipal regulations have been implemented to prohibit the dumping of domestic waste outside of private property. Although solid waste collection has improved significantly, there is a health risk for garbage collectors (mainly women). Poor handling of solid waste poses serious safety and health risks, especially groundwater contamination [4].
The collected waste is transported directly to the vehicle’s landfill. In some areas, waste is transferred to the transfer area, where organic waste is sorted and recycled into compost and briquettes. In other areas, most of the organic waste is removed from the collection point and used to generate biogas, greatly reducing the amount of waste. Despite efforts to recycle, Rwanda’s waste recovery rate remains relatively low. In addition, the city of Kigali produces approximately 450 tons of solid waste, of which the proportion of organic waste comes from households, restaurants, hotels and markets [4].
2. Problem Statement: Collection of Solids Waste in Kigali City
Solid waste management is an important problem throughout the world. It is estimated that in 2006, the total amount of municipal solid waste generated globally reached 2.02 billion tonnes, representing a 7% annual increase since 2003 [5]. Between 2007 and 2011, the global generation of municipal solid waste was estimated to rise by 37.3%, an equivalent to roughly 8% increase per year.
The Republic of Rwanda has environmental challenges that have been faced by the population for decades. The waste management is a big challenge in Rwanda, especially within the urban areas. The solids waste generated from Kigali city are around 450 tons per day of which between 300 and 350 tons/day is contrary collected, only about 24% of those solids waste generated were disposed legally at Nyanza landfill but nowadays that landfill was full and replaced by the newest called Nduba dumpsite.
It is foreseen that in the incoming days it will be a challenge of waste disposal due to the rapid increase of waste which will be affected by the development and increase of population.
This paper consist of quantification of solid waste destined in Kigali city dumpsite by identifying the quantity and characteristics of municipal solids waste generated in Nyarugenge Sub-Urban part of Kigali and suggesting the means of their management.
The waste materials are not good as for cause a significant effect on the aesthetics, health, and environment. The collection of solids waste is still a problem in Rwanda as a developing country; various effects like less knowledge, ignorance, poverty, etc. cause this.
In Rwanda since 2005, improvements have been made in the management of solid waste, and municipal regulations have been implemented to prohibit the dumping of domestic waste outside of private property. Although solid waste collection has improved significantly, there is a health risk for garbage collectors (mainly women). Poor handling of solid waste poses serious safety and health risks, especially groundwater contamination [4].
The collected waste is transported directly to the vehicle’s landfill. In some areas, waste is transferred to the transfer area, where organic waste is sorted and recycled into compost and briquettes. In other areas, most of the organic waste is removed from the collection point and used to generate biogas, greatly reducing the amount of waste. Surroundings Despite efforts to recycle, Rwanda’s waste recovery rate remains relatively low. In addition, the city of Kigali produces approximately 450 tons of solid waste, of which the proportion of organic waste comes from households, restaurants, hotels and markets [4].
At the moment, there are some companies that are using to collect the waste for composition to another composite and disposing then to the dumps site. However, this is not on the required scale and cannot handle all solids waste generated in the city of Kigali as the waste found in some place in Kigali.
3. Materials and Method: Municipal Waste Generation Survey
3.1. Study Area
A solid waste generation survey was carried out in 6 selected villages of Nyarugenge sector, in Nyarugenge district of Kigali city municipality. These were Ganza, Muhabura, Biryogo, Umurimo, Umucyo, Umurava.
3.2. Survey Areas and Sample Sizes
The selected areas where the survey was carried out and the number of the areas under each class organization, the size of the samples that were considered are listed in Table 1.
3.3. The Geographical Location of Survey Areas
Rwanda is located in central Africa, to the east of the Democratic Republic of the Congo, at the co-ordinates 2˚00'S 30˚0'E. At 26,338 square kilometers (10,169 sq mi), Rwanda is the world’s 149th-largest country.
As shown in Figure 1, Nyarugenge is a district of Kigali City 1˚59'0''S, 30˚1'0''E, Rwanda at 134 km2. Its heart is the city center of Kigali (which is towards the west of the urban area and the province), and it holds most of the city’s businesses. Among 4 districts, is divided into 10 sectors (Imirenge): Gitega, Kanyinya, Kigali, Kimisagara, Mageragere, Muhima, Nyakabanda, Nyamirambo, Nyarugenge and Rwezamenyo.
3.4. Survey Methodology
The surveyed area is classified according to their classes, the reason of categorizing the residential area is that garbage quantity and composition is related to socioeconomic factors. The survey was carried out in Nyarugenge Sector of Nyarugenge District with three selected cells and in each cell, two villages were selected and in each village, 10 houses were surveyed.
In each of the survey villages, the sample size that was surveyed comprises 5% - 10% of the families within the designated villages. According to [6], when the sample size is as large as 5 - 10 times the size of the population, chi-square (X2) which is the measure of randomness holds true and hence reflecting the pattern consistent with the population being examined. However, low sample sizes (e.g less than 5 times the size of the population) cause deviations in the observation due to temporal and or spatial variations that can result in the exaggerated pattern being the output.
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Table 1. The selected areas where the survey was carried out.
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Figure 1. Case study (area of Nyarugenge district).
The survey was conducted every week for four weeks corresponding to a month, to estimate the quantity of municipal waste discharge over a day. Moreover, this survey was conducted between 24/June and 21/July. The sorting-and-weighing methodology was used for assessing the waste composition from each of the sample households for each week. In the survey, the amounts of solid waste generated and disposed of in each of the survey areas (villages) as was quantified. The methodology has the advantage of greater accuracy. (The staff helped in collection of the data). In addition, physical characterization of the solid waste streams to establish the various waste components that were generated in each of the sample household units in the survey areas was done. The types of solid waste components and their physical state were examined in detail.
3.5. Survey Duration and Manpower Requirements
Table 2 shows the duration and manpower requirements for this survey.
3.6. Material Requirement
The weighing balance was used for weighing the garbage generated from each model houses in Kigali city. Scale having the accuracy up to 100 g was used, so that the reliable weight of the lightest refuse could be measured. The total mass of garbage from each model house was weighted prior to sorting as and the two sacks were used for sorting the organic waste to inorganic waste as organic waste in the green sac and inorganic waste in a blue sac in further the other types of municipal waste were identified. The same procedure was adopted weekly over the study period.
Rubber gloves were used for hands protection as dust masks for respiratory protection. The results were recorded in a tabular format.
4. Results and Discussion: Waste Generation Survey
The sample of MSW from each weekly collection was taken to estimate the amount of municipal solid waste generated in Kigali City. The tables below show the different data collection from three cells in Nyarugenge: sector AGATARE (lower class), BIRYOGO (middle class), KIYOVU (high class).
Table 3 shows the various fractions of the MSW and their percentage generation rate collected during 4 weeks from ten (10) houses of AGATARE cell―UMUCYO Village. Organic waste formed the highest fraction, 81% of the entire waste stream from this cell, and Glasses were not found as part of waste in this village. Higher and lower generation rate of organics waste, glasses respectively could be attributed to the socio-economic activities in the area.
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Table 2. Estimate of the time period needed for carrying out all the phases of the solid waste generation survey.
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Table 3. Agatare cell―Umucyo village.
Table 4 shows the various fractions of the MSW and their percentage generation rate collected during 4 weeks from ten (10) houses of AGATARE CELL―UMURAVA VILLAGE. Organic waste formed the highest fraction, 73% of the entire waste stream from this cell. Higher generation rate of organics waste could be attributed to the socio-economic activities in the area.
Table 5 shows the various fractions of the MSW and their percentage generation rate collected during 4 weeks from ten (10) houses of BIRYOGO CELL―BIRYOGO VILLAGE. Organic waste formed the highest fraction, 78% of the entire waste stream from this cell, and Glasses and metals were not found as part of waste in this village. Higher and lower generation rate of organics waste, (glasses and metals) respectively could be attributed to the socio-economic activities in the area.
Table 6 shows the various fractions of the MSW and their percentage generation rate collected during 4 weeks from ten (10) houses of BIRYOGO CELL―UMURIMO VILLAGE. Organic waste formed the highest fraction, 78% of the entire waste stream from this cell and Glasses were not found as part of waste in this village. Higher and lower generation rate of organics waste, glasses respectively could be attributed to the socio-economic activities in the area.
Table 7 shows the various fractions of the MSW and their percentage generation rate collected during 4 weeks from ten (10) houses for KIYOVU CELL―GANZA VILLAGE. Organic waste formed the highest fraction, 59% of the entire waste stream from this cell and this fraction was less than other villages. The reason is that they manage the organic waste by using them for their gardens as fertilizer.
Table 8 shows the various fractions of the MSW and their percentage generation rate collected during 4 weeks from ten (10) houses of KIYOVU CELL―MUHABURA VILLAGE. Organic waste formed the highest fraction, 54% of the entire waste stream from this cell and this fraction was less than other villages. The reason is that they manage the organic waste by using them for their gardens as fertilizer.
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Table 4. Agatare cell―Umurava village.
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Table 5. Biryogo cell―Biryogo village.
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Table 6. Biryogo cell―Umurimo village.
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Table 7. Kiyovu cell―Ganza village.
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Table 8. Kiyovu cell―Muhabura village.
According to this survey, the average waste generated from the various types of households in Kigali city is summarized in Table 9.
Table 9 shows the summary of complete survey data of solid waste in Kigali city generated from different categories of model houses. The table shows different fractions of solid waste generated from surveyed Villages during the survey period of 4 weeks. From Table 5 and Table 6, it was seen that the waste generated from the households, the organic wastes are most generated at a rate of 78%. Kiyovu Villages (Ganza 59% and Muhabura 54%) generate a low quantity of organic waste than other villages. The reason is that they manage the organic waste by using them for their gardens as fertilizer.
As shown in Table 10, the solids waste generated daily is about 174.634 kg for 60 households. According to [7], the households in Kigali city have a much higher average consumption than those in other provinces. The number of households in Kigali city is about 309,947 households where the total households in urban areas (using Nduba dump site for waste disposal) is about 76% [7] corresponding to 235,560 households. However, the daily waste generated in Kigali city is about 685,613.8 kg.
Table 11 indicates the total quantity of biodegradable organic waste generated daily, monthly and annually.
Figure 2 shows that almost all waste generated in Umucyo village is organic waste and those from others (clothes, shoes, bones, hair, pampers) are the second largest proportion of material in Umucyo village. Comparing the composition of wastes generated, it is shown that the organic waste has higher rate than the other components. These differences reflect the biodegradable waste produced in the residential house at high rate.
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Table 10. Total quantity of solid waste generated in Kigali city.
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Table 11. Total quantity of biodegradable organic waste generated in Kigali city.
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Figure 2. Percentage of individual waste component in the entire waste stream Umucyo village―Agatare cell.
Figure 3 shows that almost all waste generated from Umurava village is organic waste. Waste from others (clothes, shoes, bones, hair, Pampers) is the second largest proportion of material in Umurava village. Comparing the composition of wastes generated, it is shown that organic waste has higher rate than the other components. These differences reflect the biodegradable waste produced in the residential house at high rate.
Figure 4 shows that almost all waste generated from Biryogo is organic waste and those from others (clothes, shoes, bones, hair, Pampers) make the second largest proportion of material in Biryogo village. Comparing the composition of wastes generated, it is shown that organic waste has higher rate than the other components. These differences reflect the biodegradable waste produced in the residential house at high rate
Figure 5 shows that almost all waste generated from Umurimo village is organic waste and those from others (clothes, shoes, bones, hair, Pampers) make the second largest proportion of material in Umurimo village. Comparing the composition of wastes generated show that organic waste has higher rate than the other components. These differences reflect the biodegradable waste produced in the residential house at high rate.
Figure 6 shows that almost of all Ganza village waste generated is organic waste and those others (clothes, shoes, bones, hair, Pampers) are the second largest proportion of material in Ganza village. Comparing the composition of wastes generated, it is shown that organic waste has higher rate than the other components. These differences reflect the biodegradable waste produced in the residential house at high rate.
Figure 7 shows that almost all waste generated from Muhabura village is organic waste and those from others (clothes, shoes, bones, hair, Pampers) make the second largest proportion. Comparing the composition of wastes generated show that organic waste has higher rate than the other components. These differences reflect the biodegradable waste produced in the residential house at high rate.
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Figure 3. Percentages of individual waste component in the entire waste stream in Agatare cell―Umurava village.
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Figure 4. Percentages of individual waste component in the entire waste stream in Biryogo cell―Biryogo village.
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Figure 5. Percentages of individual waste component in the entire waste stream in Biryogo cell―Umurimo village.
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Figure 6. Percentages of individual waste component in the entire waste stream in Kiyovu cell―Ganza village.
Figure 8 shows that almost all waste generated is organic waste and those from others (clothes, shoes, bones, hair, pampers) are the second largest proportion of material in surveyed area. Comparing the composition of wastes generated, it is shown that organic waste has higher rate than the other components. These differences reflect the biodegradable waste produced in the residential house at higher rate.
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Figure 7. Percentages of individual waste component in the entire waste stream in Kiyovu cell―Muhabura village.
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Figure 8. Percentages of individual waste component in the entire waste stream in Agatare, Biryogo, and Kiyovu cell.
5. Conclusion
The research was conducted in order to estimate quantification of municipal solids waste in Kigali city. A solid waste generation survey was carried out in 6 selected villages of Nyarugenge sector, in Nyarugenge district of Kigali city municipality. The survey was conducted every week for four weeks corresponding to a month, to estimate the quantity of municipal waste discharge over a day. The random sampling methodology was used for selecting the house to be surveyed and sorting-and-weighing methodology was used for assessing the waste composition and quantity from each of the sample households for each week. We successfully characterised and quantified the municipal organic solid waste and presented them to be higher than the other solid wastes. The results of this study demonstrated the challenge faced by Kigali city in terms of solid waste management and inspired the importance of focusing more efforts in managing municipal waste generated by recycling and using them for other intents such as electricity generation, briquettes production among others.
Acknowledgements
Authors would like to thank Dr. Eng. Muthumbi Waweru for his help with constructive idea. Special thanks go to COPED Company and City of Kigali for their contribution to data collection, and thank the University of Rwanda and Intra ICP ARISE scholarship for supporting us financially.