Disinfection of Medical Solid Waste through the Application Ozone Technology: Feasibility and Effectiveness Study.

Background: We aimed to determine the feasibility of ozone for disinfection of infectious solid waste in hospital. Methods: Spores of Bacillus atrophaeus were used to monitor the process of inactivating microbial agents using ozone in medical solid waste in the hospitals of Tabriz City, Iran. For this purpose, culture medium containing the mentioned bacteria was placed in the bags containing medical wastes. The ozone generator was equipped with a constant dose of 5 grams per liter, with a discharge of 1 and 3 liters per minute and contact time of 10 to 120 min. Then the ozone exposure indicators were incubated for 24-48h at 36 ± 1 °C and, finally, the absence of colony growth in the culture medium was considered as the success of ozone in disinfection of infectious solid waste. This process was performed with 4-time replications. Results: The complete removal of B. atrophaeus was obtained for non-compacted and compacted infectious solid waste, at contact time of 15 and 50 min, respectively. The efficiency of removal of B. atrophaeus by the process of wet ozone injection through a glass column was 100% in 30 minutes and by separate injection of water vapor into the contact tank was 100% in 50 minutes. The results of this study showed that the use of ozone technology was effective in the inactivation and destruction of microbial agents in medical solid waste. Conclusion: Employing different advanced technology of oxidization especially ozone in order to decrease the environmental pollution is considered as one of management approaches.

Rapid humification of cotton stalk catalyzed by coal fly ash and its excellent cadmium passivation performance.

Due to industrialization, soil heavy metal pollution is a growing concern, with humic substances (HS) playing a pivotal role in soil passivation. To address the long duration of the compost humification problem, coal fly ash (CFA) in situ catalyzes the rapid pyrolysis of the cotton stalk (CS) to produce HS to address Cd passivation. Results indicate that the highest yield of humic acid (HA) (8.42%) and fulvic acid (FA) (1.36%) is obtained when the CS to CFA mass ratio is 1:0.5, at 275 ℃ for 120 min. Further study reveals that CFA catalysis CS humification, through the creation of alkaline pyrolysis conditions, Fe2O3 can stimulate the protein and the decomposition of hemicellulose in CS, and then, through the Maillard and Sugar-amine condensation reaction synthesis HA and FA. Applying HS-CS&CFA in Cd-contaminated soil demonstrates a 26.69% reduction in exchangeable Cd within 30 days by chemical complexation. Excellent maize growth effects and environmental benefits of HS products are the prerequisites for subsequent engineering applications. Similar industrial solid wastes, such as steel slag and red mud, rich in Fe2O3, can be explored to identify their catalytic humification effect. It could provide a novel and effective way for industrial solid wastes to be recycled for biomass humification and widely applied in remediating Cd-contaminated agricultural soil.

Utilization of industrial wastes in non-sintered bricks: microstructure and environmental impacts.

Recycling industrial solid wastes as building materials in the construction field exhibits great environmental benefits. This study designed an eco-friendly non-sintered brick by combining multiple industrial solid wastes, including sewage sludge, fly ash, and phosphorus gypsum. The mechanical properties, microstructure, and environmental impacts of waste-based non-sintered bricks (WNBs) were investigated comprehensively. The results revealed that WNB exhibited excellent mechanical properties. In addition, steam curing could further promote the strength development of WNB. The compressive strength of WNB with 10 wt% of sewage sludge reached 13.5 MPa. Phase assemblage results indicated that the incorporation of sewage sludge promoted the generation of ettringite. Mercury intrusion porosimetry results demonstrated that the pore structure of WNB varies with the dosage of sewage sludge. Life-cycle assessment results revealed that the energy consumption and CO2 emission of WNB were 45% and 17% lower than those of traditional clay bricks. Overall, the development of WNB in this study provided insights into the co-disposal of industrial solid wastes.

Sustainable waste management: a comprehensive life cycle assessment of bioethanol production from agricultural and municipal waste.

Biofuels have emerged as a promising and eco-friendly alternative to conventional fossil fuels. Biofuel sourced from rice straw (RS) and municipal solid waste (MSW), which are abundant residues from agricultural and municipal activities, present a sustainable solution to address waste management challenges. Utilizing life cycle assessment, this study quantifies the environmental advantages by assessing the reduction in greenhouse gas emissions, energy consumption, and other environmental impacts linked with employing these waste materials for biofuel production. Employing a cradle-to-gate approach as the system boundary for bioethanol production, with the functional unit set as per liter of bioethanol produced, the analysis reveals that the global warming potential (GWP) for ethanol from MSW is 4.4 kg CO2 eq., whereas for RS, it is 2.1 kg CO2 eq. per functional unit. The total environmental impacts were primarily due to enzymatic hydrolysis and electricity consumption for ethanol production from MSW and RS. Despite advancements, fossil fuel consumption remains a potential energy source for biofuel production. The cumulative energy demand stands at 18.6 MJ for RS and 71.5 MJ for MSW per functional unit, underscoring the potential to significantly reduce overall impacts by transitioning to a more environmentally sustainable energy source. The uncertainty analysis acknowledges the inherent uncertainties associated with data, assumptions, and methodologies, highlighting the crucial need for ongoing research and updates to enhance the accuracy of future assessments. This analysis forms the foundation for well-informed decision-making, providing valuable insights for policymakers, industry stakeholders, and consumers.

Solidification and utilization of municipal solid waste incineration ashes: Advancements in alkali-activated materials and stabilization techniques, a review.

Researchers are actively investigating methodologies for the detoxification and utilization of Municipal Solid Waste Incineration Bottom Ash (MSWIBA) and Fly Ash (MSWIFA), given their potential as alkali-activated materials (AAMs) with low energy consumption. Recent studies highlight that AAMs from MSWIFA and MSWIBA demonstrate significant durability in both acidic and alkaline environments. This article provides a comprehensive overview of the processes for producing MSWIFA and MSWIBA, evaluating innovative engineering stabilization techniques such as graphene nano-platelets and lightweight artificial cold-bonded aggregates, along with their respective advantages and limitations. Additionally, this review meticulously incorporates relevant reactions. Recommendations are also presented to guide future research endeavors aimed at refining these methodologies.

Enhanced solidification/stabilization (S/S) of fluoride in smelting solid waste-based phosphogypsum cemented paste backfill utilizing biochar: Mechanisms and performance assessment.

Phosphogypsum (PG) cemented paste backfill (CPB) is a primary non-hazardous method for treating PG. However, using traditional binders like cement increases global carbon emissions and mining operational costs while complicating the reduction of fluoride leaching risks. This study introduces a novel PG-based CPB treatment method using steel slag (SS) and ground granulated blast furnace slag (GGBFS) as binders, calcium oxide as an exciter, with biochar serving as a fluoride-fixing agent. We investigated the effect of biochar addition on the hydration and solidification/stabilization (S/S) of fluoride in SS and GGBFS-PG-based materials (SSPC). The results indicated that the optimal strength and performance for fluoride S/S were achieved with a biochar addition of 0.2 wt%. Compared to the control group without biochar, the strength increased by 54.3%, and F leaching decreased by 39.4% after 28 days of curing for SSPC. The addition of 0.2 wt% biochar facilitated heterogeneous nucleation and acted as a microfiller, enhancing SSPC's properties. However, excessive biochar reduced the compactness of SSPC. Additionally, the distribution of fluoride was strongly correlated with P, Ca, Fe, and Al, suggesting that fluoride S/S is linked to the formation of stable hydration products like fluorapatite, fluorite, and complexes such as [AlF6]3- and [FeF6]3-. These findings offer a promising approach for the safe treatment of PG and the beneficial reuse of solid waste from SS and GGBFS.

A comparison on the critical success factors of MSW and RDF power plant development in Thailand: Using an interpretive structural modelling and cross-impact matrix multiplication applied to classification analysis.

Waste-to-energy (WtE) power plants, supplied mainly with municipal solid waste (MSW) and refuse-derived fuel (RDF), which convert waste into electricity, have emerged as a solution to Thailand's waste management problems. This study focused on identifying and studying the critical success factors (CSFs) that influence the success of MSW and RDF power plants in Thailand. This study employed interpretive structural Modelling and cross-impact matrix multiplication applied to a classification analysis to evaluate the impact of these CSFs on the development of WtE projects. The results showed that, for MSW, most CSFs were related to energy and waste management policies, followed by waste quality for electricity generation. In addition, strong financial resources and appropriate power plant locations are important for MSW management success. Conversely, for RDF, most CSFs were sufficient waste quality for electricity generation and performed well according to licensing conditions. In this study, high-level CSFs indicated that these factors were crucial for MSW and RDF development. CSFs differ based on specific technologies and regulations. However, sufficient waste quality (heating value and moisture content) is a common CSF in the MSW and RDF technologies. This study provides valuable insights into the CSFs that affect the development of WtE. Understanding and addressing these CSFs is essential for the development and operation of WtE power plants in Thailand and other countries with similar conditions. Thus, policy-makers and other stakeholders can make informed decisions to ensure the success of WtE projects.

Unveiling the abundance and potential impacts of microplastic contamination in commercial organic fertilizers/compost produced from different solid waste.

This study comprehensively investigated the abundance, morphologies, and polymer types of plastics, larger (1-5 mm) and smaller (< 1 mm) microplastics (MPs), in organic fertilizers using spectroscopic and microscopic methods. MPs abundance varied depending on the type of waste employed. MPs were detected in 80% of the investigated compost samples, while macro/meso plastics were found in only four samples. Compost from mixed municipal solid waste exhibited the highest MPs contamination (23100 ± 3615 items/kg dry weight), whereas compost produced from canteen waste had the lowest contamination (100 ± 65 items/kg dry weight). Smaller MPs were dominant in all samples. The estimated loads of MPs introduced into agricultural soil exceeded the previous studies. Common morphologies observed were sheet, film, fragment, and fiber, while dominant polymer types were polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and polystyrene (PS). Heavy metals, including Cr, Cu, Ni, and Pb, were identified in association with MPs. Results indicate that the utilization of appropriate waste for composting and upgrading fertilizer regulations is crucial to protect the environment and human health from smaller MPs.

Factors influencing willingness to pay for improved solid waste collection services among households in urban cities in Uganda: empirical evidence from Lira City.

Waste management in Lira City, Uganda faces significant challenges, particularly in the area of waste collection. Pollution and health risks from uncollected waste are rampant, posing serious threats to human health and the environment. This persistent problem demands urgent attention and effective solutions to improve waste collection and safeguard the well-being of the community and the natural surroundings. This study aimed to assess households' willingness to pay for improved waste collection services, examine their waste management practices, and identify influencing factors. We employed a multistage sampling technique to randomly select 585 household heads and conducted key informant interviews with city officials and private waste collectors. Data analysis was conducted with STATA 17 and results showed that 48.12% of households were willing to pay an average of UGX 3012 ($0.84) per month for better services. Factors including education level, occupation, distance to waste collection sites, and environmental awareness significantly influenced this willingness. The study highlights a significant gap in public awareness and understanding of efficient solid waste management practices and concludes that enhancing public awareness is crucial for improving environmental health and safety in Lira City.

Optimization of municipal solid waste incineration for low-NOx emissions through numerical simulation.

With urbanization, municipal solid waste (MSW) generation is increasing. Traditional landfill methods face land shortages and environmental pollution. Waste incineration, which reduces waste and recovers resources, has become a key management method. However, nitrogen oxides (NOx) produced during incineration severely impact the environment, requiring improved control technologies. This study optimized three denitrification technologies-air staging, flue gas recirculation (FGR), and selective non-catalytic reduction (SNCR)-using numerical simulations. The research provides support for improving waste incinerator efficiency and stability while reducing NOx emissions, aiding the sustainable development of waste incineration technology. By optimizing the primary and secondary air distribution ratios, the initial NOx generation was reduced by 8.39%. When 20% of the recirculated flue gas was introduced as secondary air, NOx generation was reduced by 23.54%, and boiler efficiency increased to 83.78%. The study examined the impact of different sludge mixing ratios on the temperature and NOx emissions within the context of municipal solid waste (MSW) incineration. Initially, the study aimed to address the environmental concerns of NOx emissions during the incineration process by exploring how the introduction of sludge at various mixing ratios would affect combustion parameters. The results showed that a sludge mixing ratio between 3 and 13% optimized the combustion process with 7% being the most effective in balancing temperature control and NOx emissions. Specifically, the best value of the sludge mixing ratio refers to achieving an optimal reduction in NOx emissions while maintaining stable incinerator operation. The chemical compositions of the sludge included key elements such as carbon (C), hydrogen (H), nitrogen (N), sulfur (S), and oxygen (O), with approximate proportions of C: 31.2%, H: 4.7%, N: 2.5%, S: 0.6%, and O: 31.8%.

Solid waste dumpsite leachate and contiguous surface water contain multidrug-resistant ESBL-producing Escherichia coli carrying Extended Spectrum ß-Lactamase (ESBL) genes.

Dumpsites generate leachates containing bacteria that may carry antibiotic resistance genes, such as extended spectrum ß-lactamase (ESBL). However, the contribution of dumpsite leachates in the environmental spread of ESBL genes has not been investigated in greater detail. This study aimed to quantify the impact of Ajakanga dumpsite leachate on the spread of ESBL genes through surface water. The susceptibility of Escherichia coli isolated from dumpsite leachate and the accompanying surface water to selected antibiotics was assessed by the standardized disc diffusion method. The isolates were evaluated for phenotypic ESBL production using the double disc synergy test (DDST). The detection of ESBL genes in the isolates was carried out using a primer-specific polymerase chain reaction (PCR). Escherichia coli isolates from leachate (n = 26/32) and surface water (n = 9/12) expressed ESBL phenotype. The ESBL-producing isolates showed the highest level of resistance to the 3rd generation cephalosporin antibiotics: cefotaxime (100%), cefpodoxime (97%), ceftazidime (97%), with low resistance observed to imipenem (6%) and azithromycin (3%). All the isolates were multidrug-resistant, showing resistance to three or more classes of antibiotics. All the ESBL-producing E. coli obtained carried blaCTX-M, 21/35 (60%) carried blaTEM while none of the isolates bore blaSHV. This study found that ESBL-producing Escherichia coli from dumpsite leachate and nearby surface water had identical resistance signatures indicating the relatedness of the isolates, and that dumpsite leachate could contribute to the transfer of ESBL-producing bacteria and their genes to receiving surface water. This study has necessitated the need for a review of the guidelines and operational procedures of dumpsites to forestall a potential public health challenge.

Simulation of red mud/phosphogypsum-based artificial soil engineering applications in vegetation restoration and ecological reconstruction.

Red mud and phosphogypsum are two of the most typical bulk industrial solid wastes. How they can be efficiently recycled as resources on a large scale and at low costs has always been a global issue that urgently needs to be solved. By constructing a small-scale test site and preparing two types of artificial soils using red mud and phosphogypsum, this study simulated their engineering applications in vegetation restoration and ecological reconstruction. According to the results of this study, the artificial soils contained a series of major elements (e.g. O, Si, Al, Fe, Ca, Na, K, and Mg) similar to those in common natural soil, and preliminarily possessed basic physicochemical properties (pH, moisture, organic matter, and cation exchange capacity), main nutrient conditions (nitrogen, phosphorus and potassium), and biochemical characteristics that could meet the demands of plant growth. A total of 18 different types of adaptable plants (e.g. wood, herbs, flowers, succulents, etc) grew in the test sites, indicating that the artificial soils could be used for vegetation greening and landscaping. The preliminary formation of microbial (fungal and bacterial) community diversity and the gradually enriched arthropod community diversity reflected the constantly improving quality of the artificial soils, suggesting that they could be used for the gradual construction of artificial soil micro-ecosystems. Overall, the artificial soils provided a feasible solution for the large-scale, low-cost, and highly efficient synergistic disposal of red mud and phosphogypsum, with enormous potential for future engineering applications. They are expected to be used for vegetation greening, landscaping, and ecological environment improvement in tailings, collapse, and soil-deficient areas, as well as along municipal roads.

Integrated assessment of environmental and economic impact of municipal solid waste incineration for power generation: A case study in China.

Municipal solid waste incineration for power generation is significant for reducing and reusing solid waste. The study conducted an integrated assessment of environment and economy on municipal solid waste incineration in China, from a "cradle to grave" perspective using 1 tonne of municipal solid waste incineration as the functional unit. The environmental impacts of each month are also calculated to analyze the dynamic change throughout one year. The results indicate that the environmental impacts are mainly concentrated in marine ecotoxicity, freshwater ecotoxicity, human carcinogenic toxicity, and human non-carcinogenic toxicity. Flue gas purification, waste incineration and transportation are the key processes, which account for 65.61 %, 18.50 %, and 11.93 % of the overall environmental impact, respectively. Urea, activated carbon, chelating agent (EDTA) and diesel fuel for transportation are key factors. The life cycle cost (LCC) is 132.26 RMB/t of waste, of which the initial capital causes the largest economic cost. When considering power generated from municipal solid waste incineration to replace electricity supply from the power grid, it achieves significant environmental benefits and the normalized environmental impact value changes from 0.85 to -12.19. The findings provide references for municipal solid waste treatment to mitigate the environmental impact and reduce the economic burden across the entire life cycle.

Applying cultural perspective in Indonesia municipal solid waste management process towards a grounded climate concept and action: A mini-review of opportunities and challenges.

This mini-review emphasises the role of municipal solid waste (MSW) as the biggest contributor to climate change, as well as the need for more grounded climate action. The UN Framework Convention on Climate Change (UNFCCC) 2023 Synthesis Report by the co-facilitators on the technical dialogue Key Finding 3 of applying the 'whole-of-society' approach in this article is interpreted as a cultural approach in MSW management planning and implementation process. Using anthropological critiques of development, the cultural approach is frequently considered an obstacle or a justification for a project's failure rather than an important aspect of the people being developed. Therefore, the goal of this mini-review is to showcase the findings and explore the practical application of UNFCCC Key Finding 3, emphasising its importance in every phase of the solid waste management process for climate action. This mini-review argues that applying a cultural perspective presents both opportunities and challenges. More importantly, without careful acknowledgement and consideration, opportunities can become challenges, if not vice versa. The discussion section explores the ways in which religious and economic conditions might offer a contextual understanding and effective techniques for managing MSW at the local level. To apply Key Finding 3 in practice, academia needs to move away from generality and embrace multiple 'modernities', while practitioners also need to include cultural perspectives to complement scientific knowledge.

Unlocking the significant worldwide potential of better waste and resource management for climate mitigation: with particular focus on the Global South.

Numbers do matter; the Intergovernmental Panel on Climate Change (IPCC)'s 2010 data that the waste sector is responsible for just 3% of global greenhouse gas (GHG) emissions has led to the misperception that solid waste management (SWM) has little to contribute to climate mitigation. Global efforts to control methane emissions and divert organic waste from landfills had already reduced direct emissions. But end-of-pipe SWM has also been evolving into more circular waste and resource management, with indirect GHG savings from the 3Rs (reduce, reuse, recycle) which IPCC accounts for elsewhere in the economy. The evidence compiled here on both direct emissions and indirect savings demonstrates with high confidence that better waste and resource management can make a significant contribution to climate mitigation, and must form a core part of every country's nationally determined contribution. Even the most advanced countries can still achieve much from the 3Rs. In the Global South, the challenge of extending waste collection to all and stopping open dumping and burning (sustainable development goal 11.6.1), essential to improve public health, can be turned into a huge opportunity. Moving early to divert waste from landfill by separation at source and collecting clean organic and dry recycling fractions, will mitigate global GHG emissions, slash ocean plastics and create decent livelihoods. But this can only happen with targeted climate, plastics and extended producer responsibility finance; and help to local communities to help themselves.

Influence of mandatory waste classification on environmental and economic impacts of residual waste treatment in Xiamen, China.

Mandatory waste classification has been widely considered as an effective solution for reducing the production and treatment amount of municipal solid waste. However, there is limited evidence regarding whether and how waste classification can affect the composition of residual waste (RW) and its environmental economic impacts. Here, an accounting method recommended by the Intergovernmental Panel on Climate Change, field surveys and cost-benefit analysis was utilized to investigate the changes in RW composition, environmental impacts and economic benefits under the waste classification policies implementation in Xiamen, China. This study found that: (1) The implementation of waste classification policies led to a significant increase in recyclable content from 17% to 51% and a decrease in organic content from 56% to 32%. (2) Waste classification effectively reduces greenhouse gas emissions from landfilling and incineration by an additional 0.34 tCO2-eq t-1 RW. (3) The introduction of mechanical recycling achieves a saving of 0.47 tCO2-eq t-1 RW at 40% recycling efficiency, a 4.5-fold increase compared to business as usual (BAU). (4) The operational benefits (900 yuan t-1 RW) from the recyclables sorting system offset the total expenses of investment, operation and waste disposal. The study successfully demonstrated that RW source-classified management can optimize the structure of waste composition, reduce environmental emissions and offer detailed guidance for the development of solid waste management systems in other cities in China.

Effectiveness of NGOs in mountainous solid waste management: A case study from Healing Himalayas in Rakchham, Himachal Pradesh, India.

Non-governmental organizations (NGOs) play a critical role in addressing solid waste management (SWM) challenges in remote mountain communities, including the ecologically fragile Himalayan region. This study evaluates the impact of Healing Himalayas, an NGO, in Rakchham village, Himachal Pradesh, India. The objectives were to evaluate the effectiveness of Healing Himalayas' decentralized SWM model in promoting stakeholder engagement and resource recovery, assess the role of collaborations between local authorities and the NGO in financing waste management practices, investigate the influence of tourism and seasonal variations on solid waste generation patterns and waste management practices in Rakchham, and material recovery facilities, followed by glass (36.7%), paper/cardboard (18.4%) and metal (4.1%). A fee-based system involving the local village council funded waste operations. Waste generation exhibited significant seasonal fluctuations, with tourism influxes driving increased volumes. Healing Himalayas' initiatives promoted community participation, with over 15 awareness workshops conducted. Key challenges included limited financial resources, inadequate infrastructure, lack of advanced treatment facilities and need for context-specific solutions like efficient wet waste management in cold climates. The study highlights Healing Himalayas' decentralized model's success in fostering stakeholder engagement, behavioural change and resource recovery. The findings inform effective strategies for NGO-led waste management initiatives tailored to remote Himalayan communities.

Circular economy life cycle cost for kerbside waste material looping process.

Rapid expansion in urban areas has engendered a superfluity of municipal solid waste (MSW) stemming from contemporary civilization, encompassing commercial sectors and human undertakings. Kerbside waste, a type of MSW, has the potential for recycling and reuse at the end of its first life cycle, but is often limited to a linear cycle. This study aimed to assess the life cycle costs of different separation and recycling methods for handling kerbside waste. A new life cycle cost model, drawing from the circular economy's value retention process (VRP) model, has been created and applied to assess the continuous recycling of kerbside glass. The study investigates two key separation techniques, kerbside recycling mixed bin recycling (KRMB) kerbside glass recycling separate bin (KGRSB) and analyses their impact on the life cycle cost of the recycling process. Additionally, the research explores two approaches of recycling and downcycling: closed-loop recycling, which pertains to the recycling of glass containers, and open-looped recycling, which involves the use of recycled glass in asphalt. The results showed when use annually collected waste as the functional unit, the KRMB model incurred lower costs compared to the KGRSB model due to its lower production output. However, when evaluated over a 1-ton production of glass container and asphalt, the KGRSB method demonstrated superior cost performance with a 40-50% reduction compared to the KRMB method. The open-loop recycling method (asphalt) incurred a higher cost compared to the closed-loop recycling method due to its larger production volume over a 21-year period.

Climate impacts of landfill gas emissions: Analysis for 20-year and 100-year time horizons.

Climate impacts of landfill gas emissions were investigated for 20- and 100-year time horizons to identify the effects of atmospheric lifetimes of short- and long-lived drivers. Direct and indirect climate impacts were determined for methane and 79 trace species. The impacts were quantified using global warming potential, GWP (direct and indirect); atmospheric degradation (direct); tropospheric ozone forming potential (indirect); secondary aerosol forming potential (indirect) and stratospheric ozone depleting potential (indirect). Effects of cover characteristics, landfill operational conditions, and season on emissions were assessed. Analysis was conducted at five operating municipal solid waste landfills in California, which collectively contained 13% of the waste in place in the state. Climate impacts were determined to be primarily due to direct emissions (99.5 to 115%) with indirect emissions contributing -15 to 0.5%. Methane emissions were 35 to 99% of the total emissions and the remainder mainly greenhouse gases (hydro)chlorofluorocarbons (up to 42% of total emissions) and nitrous oxide. Cover types affected emissions, where the highest emissions were generally from intermediate covers with the largest relative landfill surface areas. Landfill-specific direct emissions varied between 683 and 103,411 and between 381 and 37,925 Mg CO2-eq./yr for 20- and 100-yr time horizons, respectively. Total emissions (direct + indirect) were 680 to 103,600 (20-yr) and were 374 to 38,108 (100-yr) Mg CO2-eq./yr. Analysis time horizon significantly affected emissions. The 20-yr direct and total emissions were consistently higher than the 100-yr emissions by up to 2.5 times. Detailed analysis of time-dependent climate effects can inform strategies to mitigate climate change impacts of landfill gas emissions.

Application of optical images and analytical hierarchy process model for solid waste dumping site analysis in Kombolcha town, Northeastern, Ethiopia.

Improper open dumping of solid wastes caused different serious problems in fast-growing towns in Ethiopia like Kombolcha town. This unsuitable solid waste dumping management brings health challenges by spreading diseases, contaminating water, polluting air, and spreading of different disease-causing insects such as mosquitoes. Therefore, selecting suitable solid waste dumping site analysis (SWDSA) is very essential to minimize these negative effects related to improper solid waste dumping in such towns. The primary goal of this study is to use optical images and the AHP model to find appropriate solid waste dumping sites in Kombolcha Town. The nine governing factors such as soil texture, geology, faults, groundwater well points (GWWPs, rivers, roads, built-up, Land use land cover (LULC) and slopes, were considered to achieve the aim of this study. These factors were extracted and delineated from the various optical data such as Landsat 8 images, digital elevation model, Google Earth images, geological map, soil map, and also field survey. The factor classes and factors were ranked and weighted utilizing a comparison matrix according to importance and finally by applying the AHP spatial analysis extension tool in Arc GIS software the SWDSA map of the study area was generated. Therefore, as a result of this study about 19.4 km2 (22.8 %), 22.8 km2 (26.8 %), 20.5 km2 (24.1 %), 16.1 km2 (18.9 %), and 6.2 km2 (7.3 %) of the study area falls in not suitable, less suitable, moderately suitable, suitable and highly suitable ranges respectively. Based on the result of this further analysis, D is the 1st suitable site with a score is 83.6 %, site B is the 2nd suitable site is a score is 83.2 %, site C is the 3rd suitable site with a score of 65.1 % and site A is the last suitable site and scored 60.4 %. Therefore, this study strongly recommends that the waste management municipal office of Kombolcha town and other concerned government and non-government bodies apply and consider these identified the best suitable solid waste dumping sites.