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Article

Compositional Analysis of Municipal Solid Waste from Tshwane Metropolitan Landfill Sites in South Africa for Potential Sustainable Management Strategies

by
Khanyisile Lepota
1,
Kasturie Premlall
1 and
Major Mabuza
2,*
1
Department of Chemical, Metallurgical and Materials Engineering, Faculty of Engineering and the Built Environment, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa
2
Department of Chemical Engineering Technology, Faculty of Engineering and the Built Environment, University of Johannesburg, P.O. Box 17011, Doornfontein, Johannesburg 2088, South Africa
*
Author to whom correspondence should be addressed.
Waste 2025, 3(3), 22; https://doi.org/10.3390/waste3030022
Submission received: 6 June 2025 / Revised: 5 July 2025 / Accepted: 10 July 2025 / Published: 15 July 2025
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Abstract

The modern world has brought extensive socioeconomic and ecological changes. Urbanization in developing nations has significantly increased municipal solid waste, necessitating in-depth understanding of waste composition particularly in developing nations for sustainable management practices. This study aimed to classify and characterize waste while evaluating potential waste management methods. Mixed methods were used to examine landfilled waste from Soshanguve and Hatherley sites in Tshwane Metropolitan, South Africa, using techniques such as Fourier transform infrared spectroscopy, X-ray fluorescence, proximate, and ultimate analysis. Seasonal variations in waste components were analysed over two seasons. The study identified that both sites are predominantly composed of organic waste, accounting for over 42 wt.%, with moisture content of ~50 wt.%, and minimal recyclables (<5 wt.%). Seasonal variations in MSW were significant for glass (<4% increase), organic waste (<5% increase), while plastic decreased by ~7% during spring. The biodegradable waste showed high carbon (>50%) and oxygen (>40%) levels, low ash content (<18%), and calorific values of 15–19 MJ/kg. Biodegradables mainly contained oxides of calcium, silicon, iron (III), and potassium with chemical composition indicating functional groups that emphasize composting and energy recovery benefits. The research provides insights into sustainable waste management, revealing waste composition at Tshwane landfills, aiding informed decision-making for resource usage and environmental conservation.

1. Introduction

The modern society has brought significant changes in people and communities, both socioeconomically and ecologically. Waste generation is the one of the predominant environmental issues that is rapidly expanding worldwide [1]. Waste production is anticipated to rise as the world’s population grows over the next few decades [2] due to urbanization, industrialization, and economic growth. In the year 2016, global waste generation was 2.01 billion tonnes, with projections of 3.4 billion tonnes by 2050 [3]. Approximately, 122 million tonnes of waste are generated in South Africa annually with the Gauteng Province accounting for almost 42% of the total waste generated [4]. Municipalities generate significant amount of municipal solid waste (MSW), with over 90% disposed of in open and unregulated areas [5], posing risks to public health, ecosystems degradation, causing greenhouse gas emissions (GHG) and contaminating groundwater supplies [6] thereby prompting efficient waste management techniques [7].
Municipal solid waste management is a major challenge in urban areas in both developed and developing countries [8]. Various approaches including landfilling, composting and thermal treatment, are used, with landfilling dominating globally [9]. Despite its cost-effectiveness, mostly adopted in many African nations [7,10], landfilling produces greenhouse gases, leachate, odor, dust, and fire hazards [11,12,13]. However, when properly managed, the landfilled waste can be utilized as a sustainable renewable energy source. Optimal waste management requires classification and characterization to evaluate material recovery, identify sources, design equipment, and determine waste characteristics for selecting treatments and meeting environmental protocols [14]. Waste classification systems have been implemented in several nations globally to manage MSW sustainably [15,16]. This approach involves the collection and sorting of waste into specific categories, utilizing methods such as materials flow analysis and site-specific sampling techniques [17,18]. However, the findings vary by region, making data comparison difficult.
Waste composition encompasses all criteria essential for informed decision-making in solid waste management. The characterization of municipal solid waste (MSW) aims to ascertain its physical and chemical properties [19], thereby facilitating the identification of urban-specific and regionally pertinent opportunities for waste reduction and recycling. This process provides detailed insights into waste streams and enables the development of tailored waste management strategies for urban areas. Consequently, numerous studies on MSW characterization, its economic use, and the revenue generated from waste management have been conducted globally across various geographical, climatic, political, and environmental contexts [10,20,21,22,23,24]. Reliable data on waste components and properties is also crucial in waste management, which can vary seasonally and by location [25]. Seasonal changes in waste generation rate, quantity and composition impact collection and treatment approaches [26]. Earlier studies show that seasonal variation changes waste physical and physico-chemical characteristics [25,26,27], particularly the organic waste fraction and moisture content (Mc), which are primarily affected by seasonal dynamics [28]. Abylkhani, et al. [25] examined MSW seasonal fluctuations in Astana, Kazakhstan, and discovered that high proportions of organic material were observed in summer season, accounting for 47.2 wt.%. Another study [29] showed that cold seasons see less fresh food consumption while warm seasons lead to higher biodegradable waste from tourism and outdoor activities while Denafas, et al. [30] discovered that the quality of recyclable and residual MSW in four European cities was affected by seasonal variations. Therefore, seasonal analyses in MSW research are important because they allow for more proactive and efficient waste management strategies. Physical factors such as pH, moisture content, calorific value (heating value), and components of the waste also affect treatment methodologies. The calorific value and moisture content play an important role in establishing the optimal waste disposal and management options [31].
Few waste characterization studies have been conducted in South African municipalities [32,33,34]. Ayeleru, Okonta and Ntuli [14] classified waste from compacted MSW in the City of Johannesburg (CoJ) using site-specific sampling. However, studies on compacted waste hinder accurate assessment of waste stream origin and composition, complicating evaluation of management strategies. Nell, et al. [35] characterized MSW in Stellenbosch municipality over a year based on household solid waste destined for landfill. Another study investigated MSW generated in Soweto township within Johannesburg municipality and provided waste management recommendations [36]. Understanding waste data is crucial, yet comprehensive data on landfilled waste and seasonal variations remain lacking in South African municipalities including City of Tshwane (CoT). Thus, this study focuses on classifying and characterizing uncompacted waste through seasonal site-specific sampling. Characterizing the waste will provide knowledge of its physical and chemical composition, which is essential for sustainable interventions, particularly given rising waste generation and lack of landfills in the CoT.
The study aims to comprehensively determine the composition of MSW generated at the CoT municipality. The research was conducted in the municipality through classification of the generated waste with the objective of establishing trends in its physical and chemical composition. Seasonal variations were examined to ascertain the impact of seasonal changes on the physical composition of the waste for sustainable management. Additionally, the chemical composition of the generated waste was analysed through waste characterization to propose a sustainable solid waste management system. The findings of this study can serve as a foundation for enhancing local and national MSW management guidelines.

2. Materials and Methods

2.1. Study Approaches

In the study, a mixed methods approach was employed. Primary and secondary data were collected from Tshwane municipality waste management offices and landfills, incorporating quantitative and qualitative techniques. Qualitative data (analyzed daily records and monthly reports) offered insights into MSW management system dynamics, while quantitative investigations identified waste composition from landfills as prescribed by the American Society for testing and materials (ASTM) D5231-92 [37] for determination of the composition of unprocessed municipal solid waste. Furthermore, activities were implemented prior to waste sampling. A preliminary study evaluated the feasibility of the sampling strategy, waste collection, and categorization systems. Interviews were conducted with Tshwane landfill municipal authorities, including landfill site management (sites manager), two overseers (one from each site), twenty waste collectors (ten from each site), and reclaimers (four employees of reclaimers from each site). High MSW scavenging activities were observed at both landfill sites during the physical field study. Random truck sampling was used to gather samples instead of other methods (such as cluster sampling, stratified sampling, cone and quarter method). Interval sampling is used in the random truck sampling technique, which minimizes bias and is straightforward to implement. Primary data were obtained through waste classification of approximately 100 kg of MSW per sampling event. Further laboratory analyses were conducted on biodegradable materials employing the cone and quarter sampling method. Secondary data came from literature reviews, government records, and earlier research [20,38,39].

2.2. Study Area

The study area is located in the northern region of Gauteng Province in South Africa; the CoT stands as one of the province’s primary metropolitan areas. As the largest metropolitan municipality in the country, it spans 6268 km2 and houses approximately 3.5 million residents [40]. The city experiences a moderately arid subtropical climate, characterized by extended, hot, rainy summers and brief, cool, dry winters [41]. The city has four active landfills receiving general waste from the city’s seven regions. This paper assesses the Soshanguve (SSL) and Hatherley (HL) landfill sites (Figure 1), established in 1995 and 1998, respectively. The SSL site is located near the Soshanguve township, one of the largest in South Africa. Established in 1974, the township spans 126.77 km2 and is home to about 403,162 people. In contrast, the HL site is close to Mamelodi Township, which is a 45.19 km2 area with a population of roughly 334,577 and is part of the CoT municipality [41]. According to the reclaimers’ committee, new developments near HL attract a large number of reclaimers, posing safety issues.

2.3. Sampling and Classification

In contrast to the International Organization for Standardization (ISO) 14,001 waste management procedures, which place an emphasis on effective practices such as waste reduction, reuse, and recycling, this study focuses on using the ASTM for waste management, which offer guidelines and test methods for handling municipal solid waste. Municipal solid waste sampling occurred from July to October 2022, following ASTM D5231-92 [37]. Bi-weekly sampling and classification events were held for three days each week, collecting 90–100 kg of MSW per session using a random truck sampling plan. This approach considered the available space at landfill sites and personnel safety. Waste was sorted into ten (10) categories (including paper & cardboard, organic, plastic, glass, metal, textile, sanitary, wood, and miscellaneous waste) per ASTM guidelines. Plastics were further categorized into polyethylene (PET), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polyvinyl chloride (PVC), polystyrene (PS), and others.
Samples of MSW were collected and classified into individual components in two steps through manual sorting, illustrated in Figure 2. Samples were placed on a plastic sheet for manual sorting, and components were placed in pre-weighed labeled bins with recorded masses. The first step involved separating larger waste pieces (no smaller than a can) into categories: paper (cardboard, magazines, packaging, others), wood, glass, metal (ferrous and non-ferrous), plastic, textile, and sanitary waste. The final step classified smaller remaining waste such as rubber, metal, wood, organic (food and yard), glass, and paper waste. The remaining fraction, a mix of organic, paper, and wood waste, was termed miscellaneous. After recording the mass, a laboratory sample was taken using the cone and quartering method for analysis.

2.4. Seasonal Variations

Seasonal variations were studied during the winter season including July and August months while the spring season included September and October months. The data collected during the months of Winter and Spring seasons were reported as the average of the two months per season for a combined period of four months. Samples were collected bi-weekly as prescribed in the sampling and classification section.

2.5. Characterization

2.5.1. Moisture Content

The moisture content (Mc) was determined according to the standard test method for moisture, ASTM D2974–07, through oven-heating using a constant temperature of 105 °C for 2 h [42]. A 1 kg sample of MSW was placed in a pre-weighed dish and placed in an oven. The Mc of the MSW was then calculated as a percentage as shown in Equation (1):
M c   ( wt . % ) = W 1   −     W 2 W 1
where
  • W1 = initial mass in kg
  • W2 = final mass in kg of waste
  • Mc = moisture content in wt.%.

2.5.2. Proximate and Ultimate Analysis

The thermogravimetric analysis (TGA) was conducted using a STA 449F5 instrument (NETZSCH, Selb, Germany). The dried OFMSW samples were ground using a laboratory sample mill (SM-450L, Laboratory-Instruments, MRC Labs—Cambridge, UK) and sieved to a particle size 100% passing 75 µm sieve. The analyses were performed on a dry basis using aluminium crucibles in an inert nitrogen atmosphere. The heating rate was 5 °C/min from 30 °C to 900 °C, with an isothermal stage of 5 min at 800 °C. Elemental analyses were carried out using an Elemental organic analyser Flash 2000 by Thermofisher Scientific. This analysis was conducted to determine the carbon, hydrogen, nitrogen and sulphur (CHNS) content in the MSW samples. The analysis presents the weight percent of H, C, N, and S while oxygen (O) is calculated as the difference.
In the light of technological advances and motivational drive to utilize biodegradable waste as a raw material to both reduce the environmental burden of its disposal and address the concerns about future resources for energy, both TGA and CHNS-O were utilized to estimate the energy content of the OFMSW obtained from both landfill sites. The determination of energy content in the OFMSW was obtained by employing established correlation in terms of higher heating value (HHV). The HHV of each sample from both landfill sites is calculated by using Equation (2) adopted from Sheng and Azevedo [43].
HHV = − 1.3675 + 0.3137   C + 0.7009   H + 0.0318   O
where
  • HHV = higher heating value on a dry basis in MJ/kg
  • C = carbon composition in%
  • H = hydrogen composition in%
  • O = oxygen composition in%.
The low heating value (LHV) of each waste sample was also calculated by employing Equation (3) adopted from Themelis and Kim [44].
LHV = HHV − 0.212   ×   H − 0.0245   ×   ( M c + 9 H )
where
  • LHV = Low heating value in MJ/kg
  • HHV = High heating value in MJ/kg
  • H = hydrogen composition of the waste in % (dry basis)
  • Mc = Moisture content of waste on as-received basis (%).

2.5.3. X-Ray Fluorescence

The OFMSW was analysed for the concentrations of elements present in the samples by an X-ray fluorescence (XRF) spectrometer (XRF ZSX Primus II, Rigaku–Japan, Tokyo). Fresh OFMSW samples from both landfill sites, were air-dried for four days [45] at room temperature before being homogenized in a laboratory sample mill (SM-450L, Laboratory-Instruments) and sieved to a particle size passing a 75 µm sieve in preparation for the analysis. The XRF analyses results are presented as oxides.

2.5.4. Fourier Transformed Infrared Spectroscopy

The attenuated total reflectance-Fourier transformed infrared (ATR-FTIR) spectroscopy (Spectrum TWO Lita, PerkinElmer, Springfield, IL, USA) was employed to determine the chemical composition of the waste, a critical step in the optimization of waste management strategies and the assessment of environmental impact. The analytical technique used powdered, dry materials, therefore, fresh OFMSW samples were prepared using the method mentioned in Section 2.3. A sample of 0.000012 kg was used to measure the FTIR spectra under ambient conditions in the mid-infrared area at wave number range of 500–4000 cm−1 using the transmission mode. The resolution was set to 4 cm−1, 16 scans were recorded, averaged, and corrected against ambient air as background.

2.6. Statistical Analysis

The results were expressed as mean ± standard deviation and compared using OriginPro 2018 v9.5.0 ® software to ensure precision and reliability. This method calculated the average of a data set and used the standard deviation to indicate the variability or uncertainty in the data. Analysis of variance (ANOVA) and Tukey test were applied with a significance threshold set at p < 0.05 to denote statistical significance.

3. Results and Discussion

3.1. Waste Classification

During the assessment of MSW classification, the organic fraction (kitchen & yard waste) was found to have the highest percent in all the sampling and classification events contributing more than 40 wt.% of the total average MSW analysed, illustrated by Figure 3. The high fraction of organic waste indicates that landfill gas emissions are active, and potent methane is being release to the atmosphere as the landfills are not engineered for gas collection. Recyclable material such as metal had the least average mass composition of the total MSW mass analysed, contributing up to an average of 5 kg at SSL and 1.40 kg at HL landfill sites, respectively. This can be a result of reclaimers who collect recyclables from door-to-door at residential and commercial areas.
Waste such as paper (including cardboard), plastic, and glass formed the main fractions of recyclable materials. The average paper fractions were 15.27 wt.% for SSL while HL had an average fraction of 13.44 wt.%. Refused cardboard fraction comprised of food packaging and carton boxes such as egg trays, and (milk, juice, cereal, and flour) packaging. The fraction of paper was high at both sites where a few stationaries such as notebooks, files, and magazines were observed during the sampling events when compared to plastic and glass refuse. Plastic components were classified into PET, LDPE, HDPE, PVC, and PS; where PET waste comprises vegetable oil, soft drinks, sports drinks, and water bottles, LDPE includes disposable polyethylene bags, HDPE contains grocery bags, juice, household cleaner, and hair care bottles, PVC includes children’s toys and clear food packaging, and PS includes disposable plates, cutlery, trays, and Styrofoam products. The PET components contributed 4 wt.% for HL and 7 wt.% for SSL, while LDPE and PS components contributed 37.00 wt.% and 9 wt.% respectively. These waste fractions contributed over 10.00 wt.% towards the total average MSW. Glass components which were mostly beverage bottles were also observed with an average of 5.01 wt.% for SSL and 4.25 wt.% for HL, respectively.
Another observed fraction was for the sanitary component, with an average composition of 12.88 wt.% at SSL whereas HL had 14.45 wt.%. Sanitary waste includes used diapers and menstrual hygiene products, which can pollute the environment if discarded improperly in landfills where non-decomposable materials can remain for generations, causing plastic pollution. When inaccurately dumped, the chemicals employed in their manufacture may leak into water resources and soil, polluting ecosystems and endangering human health. Sanitary waste disposal with MSW may lead to exposure to pathogens and viruses responsible for various enteric diseases [46]. The MSW was also comprised of small fractions of less than 3 wt.% textile and 1 wt.% rubber. This small fraction can be an indication that these components are being recycled by waste pickers. The fraction of wood had an average composition of 2.76 wt.% for SSL while HL had an average of 3.55 wt.%. Reclaimers at both sites recycle wood which is mostly used beneficially as primary fuel in households.
Miscellaneous waste in this study refers to the small components of mixed organic, wet paper, and wood. This category of waste contributed an average of 4 wt.% for SSL while an average of 5 wt.% for HL was obtained towards the total average of MSW weight percent analysed. The high percentage of organics and recyclables in the MSW suggests that waste treatment techniques of organics and recovery of recyclables seem to be the efficient and eco-friendly options. The findings highlight the importance of proper waste management and reduction of recyclable materials.
The MSW physical composition fractions in weight percent (wt.%) from Tshwane were compared with studies from the City of Johannesburg in South Africa and other global major cities as listed in Table 1. In comparison, the results show that the fraction of plastic, organics, paper, and cardboard waste was higher, indicating the differences in food consumption, living practices, and economic conditions. The waste fraction of paper and cardboard of the present study was relatively higher to the other cities as presented in Table 1, but it was well comparable to the study conducted in Johannesburg. This indicate that the level of recycling these components in the studied areas in South Africa is low when compared to the other global cities which shows that there is still potential for recovery and recycling of these components at SSL and HL landfills.
The organics percentage was higher compared to the Johannesburg study but lower than the other cities except for Harare which had a comparable percentage of organics to the present study. The study conducted in Johannesburg used noncompacted and compacted waste which might have contributed to the low organic fraction due to reduced weight and moisture content of the waste [14]. The high organic fraction of the global cities indicates that food consumption and organic disposal is high, and the organics have high level of moisture content as well, especially Kampala city in Uganda. Statistics reveal that in most developing countries, MSW is dominated by organic content [9]. The results showed a clear correlation between the present study and global MSW components composition.

3.2. Effect of Seasonal Variations

Seasonal fluctuations in the waste components were examined; the findings are shown in Figure 4. Spring saw high paper proportion at SSL, with stationaries like notebooks, files, and magazines being observed. Metal fractions decreased slightly at both landfill sites during spring months, while metals and glass fractions mostly come from non-alcoholic and alcoholic bottles. Increased beverage consumption in spring led to a rise in glass bottles, by increments of approximately 3.82 wt.% for SSL and 3.24 wt.% for HL, primarily from alcoholic drinks. The results agree with other studies [25,51] where higher glass disposal occurred in the warm season.
There was a slight seasonal variation from both landfills of organics shown in Figure 4, with an average increment of 2.36 wt.% at SSL while a 4.67 wt.% average increase was observed at HL during the spring season. The seasonal variation can be attributed to several factors including load-shedding, change in lifestyle of residents and consumption habits, and finally, the level of moisture content in waste of the two seasons. Food spoils had increased both residentially and commercially due to load-shedding which increases the amount of food wastage disposed especially in spring season where the temperature and moisture varies [52]. Waste containing high moisture content and low lignin percentage is generated in spring and humid time which contributes to the seasonal variation in organic fractions [53]. The increase in the organic fraction in spring increases the generation and release of landfill gas emissions. It is important to note that the study had limitations; just two seasons’ worth of data on seasonal fluctuations were gathered, ignoring the summer, which is the wettest time of year. Overall, the components exhibited significant differences between the two seasons at both sites, though data from the same season or month showed no significant difference between components (p > 0.05).
Figure 5 provides a comprehensive analysis of the composition of plastic where LDPE and PS both exhibit high quantities at both sites. These components showed high levels in spring than in winter months. The PS waste was dominated by disposable plates and other Styrofoam products. Components such as PET and PVC showed elevated levels in spring months for both sites with HL having the most variation compared to SSL. The PET waste composed mainly of water, soft and sports drink bottles. A decrease in HDPE components was observed from both sites during the spring months and the components were mostly grocery bags, juice and hair care bottles. The overall reduction in plastic usage was approximately 6.77% for SSL, whereas HL experienced a decrease of less than 4.5%.

3.3. Waste Characterization

3.3.1. Moisture Content Analysis

The Mc analysis was conducted to determine the amount of moisture available in the MSW. Table 2 presents the findings of the analysis conducted on paper, organic fraction (kitchen and yard), and miscellaneous waste. The three components were analysed for moisture content since they all have organic content and are recyclable using different techniques. The organic waste had a high average moisture content of 53.78 wt.% at SSL while an average of 50.96 wt.% was reported for HL. The moisture content contributes to the fraction of organic waste, and it also facilitates degradation of the waste [54]; an increase above 60.00 wt.% of waste moisture allows the creation of anaerobic regions which support anaerobic metabolism [54].
The paper fraction had the least average moisture content at both sites (3.80 wt.% at SSL and 3.67 wt.% at HL) while both organics and miscellaneous waste had Mc > 60 wt.% falling within the optimal moisture required for composting. Kumar, et al. [55] revealed that when feed waste is between 60 and 80% humid, the highest rates of methane production are achieved. In contrast, a high moisture content in feed MSW requires the use of supplementary fuel to facilitate combustion in thermal processes [56]. This is because moisture influences the calorific value and combustibility of MSW. An increase in moisture content decreases the calorific value of the waste due to the heat of vaporization of water [57]. Given the significant impact of moisture on the efficiency of energy recovery during the thermal treatment of waste, the moisture study findings (±50 wt.%) support the adoption of biological treatment processes such as composting and landfill gas recovery approaches.

3.3.2. Proximate and Ultimate

Table 3 is a summary of the chemical content in MSW samples. Both samples consisted of high volatile matter which could be attributed to the presence of fats and cellulose [19]. The ash content on both MSW samples were 15.11% for HL and 17.25% for SSL, respectively. The low content of ash is an advantage to the environment and waste management as it offers the possibility of having small quantity of heavy metals, salts, chlorine and inorganic pollutants to the bottom ash if the MSW could be considered for combustion [8,58].
Ultimate analysis for the MSW samples is presented in Table 3. The elemental content of C, H, N, S, and O differ slightly between the two MSW samples, with both samples exhibiting no presence of sulphur, implying the benefits of using MSW as a renewable energy source [8,58]. The highest elemental percentage distribution recorded is carbon with 53.06% for HL and 50.04% for SSL. The high carbon content of both samples indicates their considerable potential as an energy source [59]. To ascertain energy recovery potential of the organic fraction, the calorific values of MSW samples from both sites were computed. The HHV values were determined to be 18.96 MJ/kg at HL and 17.86 MJ/kg at SSL, respectively. The LHV value was also determined as it represents energy utilized in MSW thermal treatment, in contrast to the HHV [57]. The LHV was slightly lower than the HHV with HL waste having 16.26 MJ/kg while SSL had 15.25 MJ/kg. The calorific values of the waste from both sites exceed the threshold set by the World Bank for an average annual LHV to be at least 7 MJ/kg and not to fall below 6 MJ/kg [60] The elevated calorific values found in the waste, despite its high moisture and organic contents, are likely attributed to the inclusion of food oils, animal fats, and grease in the MSW. These constituents are abundant in lipids, which have a high energy density and release a significant amount of energy when ignited [61].
Similar studies evaluating the energy potential of MSW were carried out in other regions globally. In Iskandar, Malaysia, Tan, et al. [62] found that the average calorific values recorded for organic waste were ranging from 15 to 25 MJ/kg. In Visakhapatnam, India, the calorific values of MSW ranged between 5.68–7.11 MJ/kg with the MSW requiring pre-treatment strategies to remove excessive moisture content for thermal treatment to be implemented successfully [63].
The Tanner diagram as shown in Figure 6 was also used for assessing the viability of Tshwane waste for combustion. Waste is theoretically viable for combustion when it falls within the proposed grey shaded area indicating a combustible fuel. According to the diagram, MSW mixtures on wet weight basis (wb) with ash content ≤60%, moisture content ≤50% and combustible (organics) content ≥25% can maintain self-sustained combustion without auxiliary fuel. Mixtures outside the shaded area can still burn but with the support of auxiliary fuel [64]. The present study indicates that the ash content (15–17%) and organic matter (50–53%) fall within the combustible region of the Tanner diagram, while the moisture content exceeds the proposed threshold of ≤50% by approximately 1–4%. Komilis, Kissas and Symeonidis [57] state that substrates with moisture content up to 60% wb can still achieve self-sustained combustion, provided their organic matter content exceeds 40%, as is the case in the present study. This discovery may elucidate the elevated LHV seen for both waste mixtures from the Tshwane municipality. According to the results, the organic fraction of the MSW can be utilized for energy generation as an option to reduce it in landfills and for mitigation of GHG emissions.

3.3.3. X-Ray Fluorescence (XRF)

A comprehensive oxide composition was obtained in the samples to gain a better understanding of the chemical structure and properties of OFMSW samples, as shown in Figure 7. It shows that both OFMSW contain mainly CaO, SiO2, Fe2O3, K2O and 12 other combining oxides. Similar analysis results were obtained by Tursunov and Abduganiev [65]. The variable chemical composition of MSW ash stems from diverse products in the waste stream. The behaviour and characteristics of ash components vary depending on the ash-forming materials in the solid fuel and thermal process conditions [66]. Thermal treatment of the MSW can cause fouling on heat exchanger surfaces due to the presence of SiO2, K2O and Na2O, while slag deposits on steam generator surfaces at average temperatures could be increased by SO3 and Cl oxides [36]. Organics high in CaO can increase hydrogen while reducing gasification tar and enhance boiler tube protection due to their high content of Fe2O3 [67]. The elemental composition of the waste indicate that the waste can be of good quality in waste to energy projects.

3.3.4. Fourier Transform Infrared (FTIR)

The FTIR analytical technique was applied to identify the chemical functional groups available in the biodegradable materials from both sites. The obtained spectra were interpreted with reference to spectra assignments of Smidt, et al. [68], Grube, et al. [69] and Biyada, et al. [70]. The assignment of the infrared adsorption bands is reported in Table 4 while the FTIR spectra of both samples are reported in Figure 8 respectively. The spectra from both landfill sites exhibited almost similar infrared spectra. The spectra present in Table 4 confirmed the presence of crystalline cellulose, as well as hemicellulose and lignin, through the bands recorded in the range of 3400–3200 cm−1.
The broad band observed at around 3290 cm−1 to the stretching vibration of the hydroxyl (O-H) functional group could be attributed to the adsorbed water in the organic materials. An asymmetric (CH2) 2930 cm−1 and symmetric (CH3) 2860 cm−1 stretching of the aliphatic functional group were also observed on both samples. The aromatic carbon (C=C) vibration and carboxyl (C=O) stretching were found at 1680 cm−1. In both samples, C-H bending of the carbonyl functional group peak was detected at 1440 cm−1, while greater intensity of the C-H binding was observed in HL sample. The representative transmittance of aromatic CO- or phenolic-OH stretching vibration detected at around 1280–1315 cm−1 was also observed. A strong band that appears at 1030 cm−1 is attributed to aromatic ethers, polysaccharides and carbohydrates was also observed. The spectra are in collaboration with the ultimate, proximate and XRF analysis results, which emphases that the organic fraction can be used for energy generation.

4. Conclusions

The study analysed the physical composition of MSW from CoT landfills to determine sustainable waste management and treatment approaches. Results showed high biodegradable waste (42–45 wt.%), suggesting organics can be used for energy generation. In thermal conversion processes, the high moisture content in organics hinders effective energy recovery; however, in the fermentative process, it actually enhances energy recovery. Paper and plastic were the second highest waste components, suggesting recycling. Seasonal differences in recyclables and biodegradable waste were found, with high organics during spring indicating increased greenhouse gas emissions.
The physical and chemical properties of biodegradable waste revealed high moisture content (>50%), signifying potential for composting and energy recovery. The samples had high volatile matter and carbon content, with volatile matter at 48.85% for HL and 44.78% for SSL. The elevated carbon content of above 50% indicates potential of biodegradable waste as energy feedstock. The absence of sulphur suggests the benefits of using MSW as a renewable energy source. The elevated calorific values (15–18 MJ/kg) of the waste from both sites indicates that energy generation through thermal treatment is possible. The samples were mainly composed of CaO, SiO2, Fe2O3, and K2O oxides, with spectra indicating the presence of various functional groups, including hydroxyl and amide groups, fatty acids, carbohydrates and lignin compounds.
Further studies are suggested to analyse waste generation trends in households, industries, and commercial sectors as well to choose the most accurate sustainable management option at point source. Biodegradable waste can be utilized for composting and waste-to-energy projects, aiding in nutrient recovery and energy production. Biogas produced from biodegradable waste through the fermentation process is a renewable energy source that contributes to a sustainable ecosystem. The study also recommends studying waste seasonal fluctuations, focusing on the four seasons.

Author Contributions

Conceptualization, K.L. and K.P.; methodology, K.L.; validation, K.P.; formal analysis, K.L.; investigation, K.L.; resources, K.P., M.M. and K.L.; data curation, K.L.; writing—original draft preparation, K.L.; writing—review and editing, K.P. and M.M.; visualization, K.L.; supervision, K.P. and M.M.; project administration, K.L. and M.M.; funding acquisition, K.P. and M.M. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Research Foundation (NRF) OF South Africa, grant numbers TTK1207264411 and TTK2204224344. The APC was partially funded by the University of Johannesburg and Tshwane University of Technology.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The raw data supporting the conclusions of this article will be made available by the authors on request.

Acknowledgments

The authors acknowledge the Tshwane Metropolitan for consenting to the project in the municipal facilities, and landfill facilitators for participating and cooperating to ensure successful and safe waste classification events. Furthermore, they express gratitude to the Tshwane University of Technology (TUT) for its financial support and provision of research facilities, as well as the University of Johannesburg for undertaking some of the analyses.

Conflicts of Interest

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Abbreviations

The following abbreviations are used in this manuscript:
OFMSWOrganic fraction of municipal solid waste
HLHatherley landfill
SSLSoshanguve landfill
MSWMunicipal solid waste
wt.%Moisture content
McMoisture content
adbAir-dry basis
dafDry-ash free basis

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Waste 03 00022 g001
Figure 1. Location of the two landfill sites used in this study, (a) Soshanguve and (b) Hatherley.
Figure 1. Location of the two landfill sites used in this study, (a) Soshanguve and (b) Hatherley.
Waste 03 00022 g001
Waste 03 00022 g002
Figure 2. Procedure for sorting MSW [25].
Figure 2. Procedure for sorting MSW [25].
Waste 03 00022 g002
Waste 03 00022 g003
Figure 3. Physical composition of MSW from both sites, respectively.
Figure 3. Physical composition of MSW from both sites, respectively.
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Waste 03 00022 g004
Figure 4. Seasonal variation of MSW composition from HL and SSL sites.
Figure 4. Seasonal variation of MSW composition from HL and SSL sites.
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Waste 03 00022 g005
Figure 5. Average weight percent of plastic composition that was analyzed in (a) HL, and (b) SSL sites.
Figure 5. Average weight percent of plastic composition that was analyzed in (a) HL, and (b) SSL sites.
Waste 03 00022 g005
Waste 03 00022 g006
Figure 6. The Tanner triangle for the valuation of MSW combustibility.
Figure 6. The Tanner triangle for the valuation of MSW combustibility.
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Figure 7. XRF surface characteristics of biodegradables obtained from the sites.
Figure 7. XRF surface characteristics of biodegradables obtained from the sites.
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Waste 03 00022 g008
Figure 8. Spectra showing the composition of the biodegradables collected from both sites.
Figure 8. Spectra showing the composition of the biodegradables collected from both sites.
Waste 03 00022 g008
Table 1. The MSW composition (wt.%) of Tshwane City compared with other cities.
Table 1. The MSW composition (wt.%) of Tshwane City compared with other cities.
Country
/City		Paper &
Cardboard		Organics
& Wood		PlasticMetalTextile & Leather/RubberGlassMixed
/Other		References
Tshwane, SA 13–1644–4910–170–11–33–63–6This research
Johannesburg,
SA 		12–1913–2918–285–103–114–1515–20[14]
Kampala,
Uganda 		5.3083.207.700.900.401.101.40[47]
Harare,
Zimbabwe		7.0046.0013.002.004.004.0024.00[48]
Ghana 5.0061.0014.003.003.003.0011.00[49]
Gujranwala,
Pakistan 		7.9061.409.500.100.000.0021.10[50]
Globally 17461242514[3]
Table 2. Average moisture content (Mc) of biodegradables from each site.
Table 2. Average moisture content (Mc) of biodegradables from each site.
MSW CategorySSLHL
Mc (wt.%)RangeMc (wt.%)Range
Paper 3.80 ± 0.913.10–4.703.67 ± 0.523.30–4.20
Organic waste 53.78 ± 9.4542.50–58.3050.96 ± 6.3247.10–54.50
Miscellaneous waste 27.99 ± 4.0322.90–30.0029.91 ± 7.8824.60–35.10
Table 3. Summary of proximate & ultimate analyses and estimated calorific value of biodegradables.
Table 3. Summary of proximate & ultimate analyses and estimated calorific value of biodegradables.
ParametersHLSSL
Proximate analysis (%), adb
Moisture content14.3215.02
Volatile matter48.8544.78
Ash content15.1117.25
Fixed carbon21.7222.95
Ultimate analysis (%), daf
Carbon53.0650.04
Hydrogen3.362.98
Nitrogen1.981.78
Sulphur00
Oxygen41.6045.20
Higher heating value (MJ/kg)18.9617.86
Lower heating value (MJ/kg)16.2615.25
Table 4. Assignments of the main vibrations of the spectra.
Table 4. Assignments of the main vibrations of the spectra.
Wavenumber (cm−1)Band Assignments
3400–3200(OH) hydroxyl groups in lignin, cellulose and hemicelluloses intermolecular hydrogen-bonded.
2930–2860(C-H) aliphatic methylene, alkanes and fatty acids groups.
1700–1600(C=O, C=C) amides and aromatics groups.
1440–1300(C-H, N-O, C-N) in cellulose and hemicelluloses.
1250–900(C-O-C, C-O, C-O-P, C-N, C-H) stretching vibration of different groups of lignin, cellulose and hemicelluloses.
1030–1020(C-O-C) stretching vibration of lignin and polysaccharides.
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Lepota, K.; Premlall, K.; Mabuza, M. Compositional Analysis of Municipal Solid Waste from Tshwane Metropolitan Landfill Sites in South Africa for Potential Sustainable Management Strategies. Waste 2025, 3, 22. https://doi.org/10.3390/waste3030022

AMA Style

Lepota K, Premlall K, Mabuza M. Compositional Analysis of Municipal Solid Waste from Tshwane Metropolitan Landfill Sites in South Africa for Potential Sustainable Management Strategies. Waste. 2025; 3(3):22. https://doi.org/10.3390/waste3030022

Chicago/Turabian Style

Lepota, Khanyisile, Kasturie Premlall, and Major Mabuza. 2025. "Compositional Analysis of Municipal Solid Waste from Tshwane Metropolitan Landfill Sites in South Africa for Potential Sustainable Management Strategies" Waste 3, no. 3: 22. https://doi.org/10.3390/waste3030022

APA Style

Lepota, K., Premlall, K., & Mabuza, M. (2025). Compositional Analysis of Municipal Solid Waste from Tshwane Metropolitan Landfill Sites in South Africa for Potential Sustainable Management Strategies. Waste, 3(3), 22. https://doi.org/10.3390/waste3030022

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