The recovery of energy from municipal solid waste (MSW) has gained popularity in many industrialized countries, but its adoption in economically developing countries, especially in Africa, has been slow. While capital investments and technical requirements for waste-to-energy (WtE) systems are among the most important causes for this slow adoption, the unavailability of data on the thermochemical quality of MSW as a potential feedstock for energy recovery is also a limiting factor. In this paper, Harare, a typical African city, was selected as a case study. The evaluation was based on the analysis of the MSW’s composition, moisture as-discarded, thermochemical properties and energy content. The results show that the quality of the MSW is comparable to that in regions outside Africa where WtE has been a success. The combustible fraction exceeded 75 wt% making it ideal for thermal treatment without requiring supplementary fuel. With an MSW throughput of 421,757 tonnes year ⁻¹ (11.1% of which is recycled), and a lower heating value of 10.1 MJ kg ⁻¹ , the energetic potential was estimated at 3.8 × 10 ⁶ GJ. MSW thermal treatment via conventional technologies can reduce the waste throughput to landfills by up to 40%, provide up to 112 GWh year ⁻¹ of electrical energy, and increase the annual share of electrical energy produced from bio-fuels and wastes from 1.3% to at least 2.2%. These benefits make thermal MSW treatment a suitable option for waste disposal in African cities.

Determination of particle-bound Polycyclic Aromatic Hydrocarbons (PAHs) emitted from co-pelletization combustion of lignite and rubber wood sawdust in a horizontal tube furnace is investigated using High Performance Liquid Chromatography with coupled Diode Array and Fluorescence Detection (HPLC-DAD/FLD). The particle-bound PAHs based on the mass concentration and the toxicity degree are discussed in the different size ranges of the particulate matters from 0.07-11 μm. In the present study, the particle-bound PAHs are likely abundant in the fine particles. More than 70% of toxicity degree of PAHs falls into PM_1.1 while more than 80% of mass concentration of PAHs falls into PM_2.5. The addition of lignite amount in the co-pelletization results in the increasing concentration of either 4-6 aromatic ring PAHs or high molecular weight PAHs. The high contribution of 4-6 aromatic ring PAHs or high molecular weight PAHs in the fine particles should be paid much more attention because of high probability of human carcinogenic. Furthermore, the rubber wood sawdust pellets emit high mass concentration of PAHs whereas the lignite pellets emit high toxicity degree of PAHs. By co-pelletized rubber wood sawdust with lignite (50% lignite pellets) has significant effect to reduce the toxicity degree of PAHs by 70%.

This paper studies the utilization potential of Refuse Derived Fuel (RDF) approach to recover the discarded plastics from Hatyai solid waste disposal site in Songkhla province, Thailand. The excavated plastic bag wastes from the closure landfill of Hatyai, unused plastic bag wastes and waste residues are the raw materials for RDF productions. The raw materials are characterized for proximate analysis and ultimate analysis. The RDF5 (Densified RDF) with different raw materials are produced and characterized in this study. All raw materials have low moisture content, high volatile solids, low ash content and low fixed carbon. Thus, these raw materials are suitable for RDF productions. Due to low sulfur content, the combustion of these RDFs has no risk for the global warming and acid rain cause. The various RDFs in this study include a plastic bag wastes-palm fronds-RDF (PP-RDF), an unused plastic bag wastes-palm fronds-RDF (UPP-RDF), a plastic bag wastes-palm fronds-cassava peels-RDF (PPCRDF) and a plastic bag wastes-palm leaves-rubber wastes-RDF (PPRRDF). The various RDFs are provided the good physical and chemical properties. The higher heating value (HHV) of PP-RDF, UPP-RDF, PPCRDF and PPR-RDF is 5,725, 5,674, 5,548 and 5,872 kcal/kg, respectively. The HHV of various RDFs is higher than the HHV criterion for RDF in the briquette form. Therefore, the plastic-wastes RDF has the potential for energy as solid fuels for kiln. According to this study, the plastic-bagwastes RDF in the briquette form is suitable for renewable energy.

Risk assessment of emitted particle polycyclic aromatic hydrocarbons (PAHs) from lignite-biomass pelletization burning focusing on size distribution and human health effects are investigated. The particles and PAHs are experimented by a tube furnace and high performance liquid chromatography coupled diode array and fluorescence detectors (HPLC-DAD/FLD), respectively. The carcinogenic, mutagenic, and toxic potencies of PAHs are also discussed in relative to the size distribution of emitted particle PAHs. The results indicate that the carcinogenic, mutagenic, and toxic potencies of PAHs are like to accumulate in the ultrafine particles finer than 0.65 µm. The ultrafine particles contribute the largest PAHs existences of carcinogenic, mutagenic and toxic substances; even though they register in the small mass fraction of PAHs. Moreover, the co-pellets burning can reduce the values of carcinogenic PAHs, carcinogenic equivalency quotients (BaP-TEQ), mutagenic equivalency quotients (BaP-MEQ), and toxic equivalency quotients (TCDD-TEQ) by more than 60%.

Airborne microplastics (AMPs) are increasingly recognized as an emerging air pollutant. However, observational data remains scarce in Southeast Asia. This study provides the first observations of AMPs in Phnom Penh, Cambodia, using µFTIR-ATR imaging. Number concentration, morphology, polymer composition, aerodynamic size distribution, Feret diameter, and surface aging characteristics were investigated together with meteorological parameters, gaseous pollutants, water-soluble ionic tracers, and HYSPLIT backward trajectories for source attribution. AMPs were dominated by polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), with 52% classified as fragments and 82% having Feret diameters smaller than 30 µm. AMP concentrations ranged from 0.55 to 1.27 MP m^-3 in TSP (mean: 0.97 ± 0.30 MP m^-3, n = 134) and from 0.23 to 0.49 MP m^-3 in PM2.5 (mean: 0.33 ± 0.10 MP m^-3, n = 46). Carbonyl and hydroxyl indexes indicate that PE and PP were relatively fresh and in low-to-moderate photo-oxidative aging states. Correlation analysis further indicates that PE and PP were mainly associated with local waste fragmentation, whereas PET was linked to precipitation scavenging and resuspension processes. In addition, HYSPLIT backward trajectories suggest regional transport of AMPs by the Southwest Monsoon from marine source regions, including the Indian Ocean, Arabian Sea, and Andaman Sea. These findings provide the first baseline dataset for AMP pollution in Phnom Penh, Cambodia and highlight the combined importance of local emissions and regional atmospheric transport in Southeast Asia.

Airborne microplastics (AMPs) are increasingly recognized as an emerging air pollutant. However, observational data remain scarce in Southeast Asia. This study provides the first observations of AMPs in Phnom Penh, Cambodia, using µFTIR-ATR imaging. Number concentration, morphology, polymer composition, aerodynamic size distribution, Feret diameter, and surface aging characteristics were investigated together with meteorological parameters, gaseous pollutants, water-soluble ionic tracers, and HYSPLIT backward trajectories to examine possible source attribution. AMPs were dominated by polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), with 52% classified as fragments and 82% having Feret diameter smaller than 30 µm. Across four independent 72-h sampling periods (n = 4), AMP concentrations ranged from 0.55 to 1.27 MP m⁻³ in TSP, with a mean ± standard deviation of 0.97 ± 0.30 MP m⁻³, and from 0.23 to 0.49 MP m⁻³ in the PM_2.5 fraction, with a mean ± standard deviation of 0.33 ± 0.10 MP m⁻³. In total, 134 particles were identified in TSP, of which 46 were detected in the PM_2.5 fraction. Carbonyl and hydroxyl indices indicated that PE and PP were relatively fresh and in low-to-moderate surface aging states. Pearson correlations suggested that the abundances of individual polymers were varied differently in relation to local environmental and precipitation-related variables; however, the limited number of sampling periods precludes source or process attribution. In addition, HYSPLIT backward trajectories showed that some air masses arriving in Phnom Penh had passed over marine regions under southwest monsoon flow. These findings provide the first baseline dataset for AMP pollution in Phnom Penh, Cambodia, and highlight the combined importance of local emissions and regional atmospheric transport in Southeast Asia.