Waste Treatment Methods Research Articles

Towards sustainable electricity generation: Evaluating carbon footprint in waste-to-energy plants for environmental mitigation in Iran

The environmental impacts of municipal solid waste have become a critical issue in Iran due to rising waste generation and limited waste treatment methods. From a global warming perspective, in 2018, Iran was the seventh-highest greenhouse gas emitter in the world. An implementation should demonstrate that it is possible to estimate the environmental impact of climate change. A simple carbon footprint estimation model for waste-to-energy power plants with a life cycle assessment using the 2006 Intergovernmental Panel on Climate Change (IPCC) guidelines is presented in this study. For this purpose, first the system boundary is determined. Then, the total emissions of each part within boundary are identified in terms of total greenhouse gas emission (and expressed in mass of carbon dioxide equivalent). In conclusion, the carbon footprint of generating one kWh of electricity is estimated. The final emission of the Tehran power plant is calculated at 24.46 ktCO2eq/year. Thus, the carbon footprint is estimated to be 1351.94 g CO2eq/kWh. Key parameters that affect carbon footprint are divided into two groups: emission parameters and electricity generation parameters. The sensitivity analysis of effective parameters showed the distance travelled and weight of waste transported during waste transportation, the fossil carbon content in waste composition has the highest effect on carbon footprint. The study shows a 1.2-fold difference between the carbon footprint of two current scenarios of waste treatment: landfill and waste-to-energy plant. The life cycle emissions of landfills exceed of waste-to-energy plants, indicating that these systems can contribute significantly to addressing the current environmental challenges. Additionally, they offer advantages in terms of electricity generation.

Use of municipal solid waste incineration (MSWI) bottom ash as a permeable subgrade material: An experimental and mechanism study

ABSTRACT As a traditional method of waste treatment, municipal solid waste incineration (MSWI) has become one of the main methods of urban waste treatment. However, as a byproduct of MSWI, a large amount of MSWI bottom ash is not reused in current practice. This study innovatively posits MSWI bottom ash as an eco-friendly adsorbent rather than a pollutant, exploring its potential application as a permeable subgrade material. The results reveal that MSWI bottom ash exhibits promising properties to serve as a permeable subgrade material to achieve the permeability and improve the sustainability for subgrade. Due to the arrangement of its particles, it shows excellent performance in shear strength and permeability, which are comparable to or surpass those of sandy soils. The average pore width of 14.200 nm allows heavy metal substances to be encapsulated within the matrix, significantly reducing their leachability, thereby aligning with environmental friendliness standards. Its adsorption capacity is about 6.60 mg/g, and the adsorption capacity per volume is 3.66 times and 2.04 times that of fly ash and clay, respectively. The mechanism analysis shows that the adsorption process is monolayer heterogeneous adsorption. This paper presents a novel perspective on reusing MSWI bottom ash and provides evidence supporting its effective utilization as a permeable subgrade material, offering substantial environmental benefits through enhanced adsorption ability. Implications: Municipal solid waste incineration (MSWI) is a common method for municipal solid waste treatment, while the MSWI bottom ash is often not reused. This paper explored the explores the feasibility of using MSWI bottom ash as a permeable road base material. The results show that the particle arrangement enables excellent shear strength and permeability, comparable to sandy soil. It meets safety requirements for the leaching of heavy metals and acts as an adsorbent for pollutants leaching from permeable pavements. Furthermore, the mechanisms underlying these behaviors of MSWI were confirmed by microstructural and mineralogical analyses. These indicate that MSWI bottom ash has great potential as a permeable road base material. This paper provides a clear understanding of the physical, mechanical and environmental properties of MSWI bottom ash, which can promote its reuse in practice.

Characterization of glass composite material by pressureless sintering of soil and its application to uranium contaminated soil as a waste form

Abstract When operating and dismantling a nuclear facility that handles uranium, the surrounding soil may be contaminated, emphasizing the need for appropriate treatment and disposal methods for soil waste. This study assessed high-temperature sintering technology for uranium contaminated soil waste to overcome limitations in existing decontamination methods and the volume increase associated with current solidification technology. The sintering process was found to effectively vitrify and re-mineralize complex chemical components in the soil. Sintered bodies were produced under varying conditions, adjusting molding pressure, heating temperature, and time. Optimized conditions resulted in sintered bodies with a volume reduction rate exceeding 30 % and a compressive strength surpassing 10 MPa, indicating a significant impact on the phase conversion and re-mineralization of silt and clay minerals. The soil sintering mechanism was identified through comprehensive microscopic observations and mineral phase change analysis. Leaching evaluations of sintered bodies, made from simulated uranium-contaminated soil, demonstrated their applicability to contaminated soil wastes. Additionally, it was confirmed that the sintering temperature of the soil could be lowered by incorporating a small amount of B2O3, suggesting a means to enhance the economic feasibility of the treatment process. The findings of this study highlight the applicability of pressureless sintering technology, based on glass composite materials, capable of simultaneously reducing and stabilizing uranium-contaminated soil waste.

A life cycle assessment of building demolition waste: a comparison study

Globally, building demolition waste constitutes a considerable environmental problem. The environmental implications are not only associated with volume but also with carbon embodied in the waste. These adverse environmental impacts associated with the generated waste can be minimised through appropriate waste management strategies. This study proposed a mathematical model from the end-of-life perspective to examine two waste treatment methods. The model was illustrated by a case study of three approved building construction systems by a current UK supermarket referred to as construction methods CM1, CM2 and CM3 to assess the construction system with the least carbon dioxide emission. Landfilling and recycling were assumed as waste treatment methods to examine the preferable waste treatment method. Results showed that recycling is the most preferred method of waste treatment method of the supermarket. This was revealed by the amount of demolition waste material recycled (more than 90%) from each of the CM compared with the volume of waste materials landfilled (<10%) and the associated carbon dioxide emissions. Steel has the highest carbon reduction potential contributing ∼80% in each case study compared with concrete ∼1%. Finally, CM1 has the lowest carbon dioxide emission, with both CM2 and CM3 emitting ∼3% more.

Virulence profile of Candida spp. isolated from an anaerobic biodigester supplied with dairy cattle waste

Anaerobic biodigesters play a crucial role in enhancing animal waste management. However, the presence of pathogens in the biodigestion process poses a significant concern. Candida spp., a widespread fungus known for its opportunistic nature and adaptability to diverse environmental conditions, including reciprocal transmission between humans and animals, is one such pathogen of concern. Therefore, it is imperative to assess the virulence profile of Candida spp. originating from anaerobic biodigestion processes. Here we demonstrate that strains isolated from the biodigestion process of dairy cattle waste exhibit noteworthy virulence mechanisms, surpassing the virulence of clinical control strains. After we identified strains from affluent, effluent, and biofertilizer, we observed that all analyzed isolates produced biofilm. Additionally, a substantial proportion of these isolates demonstrated phospholipase production, while only a few strains exhibited protease production. Furthermore, all strains exhibited resistance or dose-dependent responses to amphotericin B and itraconazole, with the majority displaying resistance to fluconazole. In the in vivo test, we observed a significant correlation (p < 0.05) between the LT50 and biofilm formation as well as hyphae/pseudohyphae production. Additionally, some isolates demonstrated a quicker nematode-killing capacity compared to clinical controls. Our findings underscore the considerable pathogenic potential of certain Candida species present in the dynamics of anaerobic biodigestion. Importantly, the anaerobic biodigester system did not eliminate Candida strains from dairy cattle waste, highlighting the need for caution in utilizing biodigester products. We advocate for further studies to explore the virulence of other microorganisms in various animal production contexts. Furthermore, our results emphasize the urgency of enhancing waste treatment methods to effectively eliminate pathogens and curb their potential dissemination.

Assessment of Water Quality Parameters in Lake Hayq, Northeastern Ethiopia.

Lake Hayq is one of the highland lakes of Ethiopia that furnishes very important ecosystem services, fishing, tourism, transportation, drinking water, livestock watering, and irrigation. However, the lake ecosystem is being degraded by pollution, siltation, and excessive growth of macrophytes, buffer zone degradation, overfishing, and climate variability. Therefore, this study was conducted to assess the physicochemical, heavy metals, and biological water quality parameters of Lake Hayq. Physiochemical (pH, water temperature, conductivity, TDS, total alkalinity, dissolved oxygen, Ca2+, Mg2+, Na+, K+, NH4+, NH3, NO2 -, NO3 -, CO3 -, HCO3 -, SO4 2-, PO4 3-, SiO2, and total phosphorus), heavy metals (Pb, Fe, Zn, Cr, Cu2+, Mn2+, and Ni), and biological (BOD5 and total coliforms) water quality parameters were analyzed both in situ and ex situ. The physicochemical parameters were measured using portable water quality measuring multimeters, the heavy metal analysis was done using the Atomic Absorption Spectrometer, the BOD5 was measured using a BOD5 meter, and the total coliform analysis was done using the spread plate technique. The collected data were analyzed using multivariate, two-way ANOVA to see the mean difference among sampling sites and seasons through the application of SPSS 16. Most of the water quality parameters of Lake Hayq have met the WHO standards for recreation, aquatic life, and drinking water quality. However, some parameters, such as Pb, BOD5, and total coliforms, were above WHO water quality permissible limits. Therefore, ecohydrological (nature-based) waste treatment methods such as macrophyte restoration in buffer zones and ecofriendly farming activities should be practiced to minimize the contamination of the lake.

The potential of Nordic microalgae in nutrient removal from anaerobic digestion effluents

AbstractAnaerobic digestion is a promising method for organic waste treatment. While the obtained digestate can function as fertilizer, the liquid fraction produced is rather problematic to discharge due to its high nitrogen and chemical oxygen demand contents. Microalgae have great potential in sustainable nutrient removal from wastewater. This study aimed at evaluating native Swedish microalgae cultivation (batch operation mode, 25°C and continuous light of 80 μmol m−2 s−1) on anaerobic digestion effluent of pulp and paper sludge (PPS) or chicken manure (CKM) to remove ammonium and volatile fatty acids (VFAs). While algal strains, Chlorella vulgaris, Chlorococcum sp., Coelastrella sp., Scotiellopsis reticulata and Desmodesmus sp., could assimilate VFAs as carbon source, acetic acid was the most preferred. Higher algal biomass and cell densities were achieved using PPS compared to CKM. In PPS, Coelastrella sp. and Chlorella vulgaris reached the highest cell densities after 15 days, about 79 × 106 and 43 × 106 cells mL−1, respectively. Although in PPS, ammonium was completely assimilated (195 mg L−1), this was only 46% (172 mg L−1) in CKM. Coelastrella sp. produced the highest biomass concentration independently of the medium (1.84 g L−1 in PPS and 1.99 g L−1 in CKM). This strain is a promising candidate for nutrient removal and biomass production in the aforementioned media, followed by Chlorella vulgaris and Chlorococcum sp. They have great potential to reduce the environmental impact of industrial anaerobic digestion effluents in Nordic countries.

An Intelligent App-based System for Waste Segregation and Collection

Municipal solid waste generation in India is increasing as a result of rapid urbanisation and a growing population. Due to gaps in the existing waste collection, treatment and recovery methods, large-scale unscientific disposal and lesser waste recovery have been observed. Insufficient source segregation, unorganised efforts, less awareness and indifference towards malpractice, and a lack of strict implementation were identified as the causes through literature review, surveys and interviews, Therefore, there is a need for a system of interventions, which organises efforts toward waste management and reduces the tolerance for source segregation errors. This paper aims to provide a solution that increases community participation and prevents the generation of mixed waste to ensure waste recovery. The proposed framework integrates municipal solid waste, human elements, and technology into an intelligent app-based system. This includes a smart bin that segregates waste at the source through image classification and an application for communication and data collection.

Review of the Existing Organic Waste Management Situation in Kerala

In India, the rapid economic development has resulted in a change in the lifestyle of urban dwellers, which has changed the composition of the waste generated. Due to the high volume of waste generated, the collection, transportation, and disposal stream requires a highly efficient system. It requires knowledge of what the wastes are comprised of, how they need to be collected and disposed of, and the participation of citizens, local governments, and private entrepreneurs. With the vision to transform Kerala into a garbagefree state and achieve full-scale environmental health, Kerala has notified the principle of 3Rs in the State Policy on Solid Waste Management. As per Suchitwa Mission annual report 2019-2020, in the year 2019-2020 Kerala has generated 10,044 TPD of Municipal Solid Waste. With a population growth rate of approximately 10.24%, Kerala could generate 16,565 TPD of waste in 2036. This increase in waste generation could put substantial pressure on the existing waste management system of Kerala. Thus, there is a greater need to investigate alternative waste management options and expand the capacity of the waste management system in Kerala. Landfills have also been widely unsuccessful in the state of Kerala. According to the Suchitwa mission' s latest data, Kerala has 51 notified dumpsites of which only 31 are in operation and 14 dumpsites have a volume≤ 800 m3. Additionally few dumpsites are very close to human settlements and located close to each other. In the current article a detailed review of the waste generation, composition, organic waste treatment and disposal methods are made, and gaps in the present waste management practice are outlined. The identified gaps are examined to fulfill the defined requirements in the solid waste management law of the respective state and the comprehensive rules laid down by the Government of India (Gol) in its Solid Waste Management Rules 2016.

Possibility of Ceylon Tea Waste Conversion to Biochar – a short review

A few countries fulfil global tea demand, and Sri Lanka, formerly known as Ceylon, is one of the top tea exporters. Tea is Sri Lanka's largest agricultural export, with an annual production of approximately 340 million kg. Consequently, the tea industry generates significant quantities of tea waste. Unfortunately, the Sri Lankan tea industry often ignores proper tea waste management, relying on open dumping and burning, which can harm the environment despite the biodegradable nature of the waste. Among a number of modern waste management methods, pyrolysis is gaining increasing attention as a sustainable waste treatment method as it transforms waste into carbonaceous materials, biofuel and syngas, leaving no waste behind at comparatively lower temperatures (400-600℃). Considering the nature of the Ceylon tea industry, which mainly uses conventional tea production processes, this short review article mainly focused on the effect of tea pyrolysis temperature, derived biochar activation methods, and their uses. Biochar derived from tea waste has demonstrated remarkable utility in various fields. By converting waste into stable carbonaceous materials, it not only mitigates local emissions but also serves as a reliable long-term carbon storage. Moreover, biochar and activated carbon derived from tea waste has proven efficient and cost-effective for removing water, soil, and air contaminants. Industry can obtain financial benefits by introducing derived activated carbon as an adsorbent. These facts highlight the suitability of adopting low-temperature pyrolysis of tea waste and biochar production to the Ceylon tea industry using simple techniques such as double-barrel systems that can be operated with the excess heat produced in boilers.

Effective fixation of Cu(II) and Cr(III) in solution by food waste biochar – Innovative and valuable treatment method for municipal solid waste

Enhancing biochar's adsorption and solidification performance in compound-polluted aqueous solutions remains a crucial task for achieving the cost-effective removal of heavy metals from water bodies. The study examined the removal performances and mechanisms of Cu(II) and Cr(III) using biochar prepared from food waste at temperatures of 350 °C, 450 °C, and 550 °C (FWB-350, FWB-450, and FWB-550). FWB-450 exhibited the highest overall effectiveness in adsorbing Cu(II) and Cr(III), demonstrating the adsorption capacity (Qe) of 40.283 and 21.456 mg/g in single-solution, respectively. Thermodynamic parameters indicate that the adsorption process involves physical and chemical reactions involving heat absorption. The impact of Cr(III) on the adsorption of Cu(II) is more apparent in the mixed competitive system. The pH, the oxygen-functional groups and carbonate ion quantity of FWB are crucial in improving Cu(II) and Cr(III) adsorption by affect the hydrolysis, complexation, and ion exchange processes. The presence of alkaline earth metal ions in FWB, like Ca(II), aids in the elimination of Cu(II) and Cr(III) through ionic precipitation and ion exchange, correspondingly. Furthermore, FWB adsorbed with Cu(II) and Cr(III) is relatively less hazardous than solid waste. The study validates the resource utilization of FW and its potential application of biochar in heavy metal adsorption.

ANAEROBIC CO-DIGESTION OF DIFFERENT TYPES OF COW DUNG WITH FOOD WASTE

The value of manure as a source of clean energy can be increased through the conversion of animal waste into energy, which can also reduce the negative effects that animal waste disposal has on the environment. Anaerobic digestion (AD) is a potential bioprocess for the utilisation of waste biomass and the conservation of energy. It is also an alternative method of energy recovery and waste treatment that produces biogas, which can be used to generate either electricity or heat and is a byproduct of the digestion process. In this study, different types of cow dung in terms of nutritional processes (grass: bran); 100 % grass, 95 % grass: 5 % bran, and 80 % grass: 20 % bran were taken for anaerobic co-digestion with food waste. The purpose of this study is to investigate the production of biogas as well as the properties of anaerobic co-digestion using different types of cow dung under mesophilic temperature (37°C). Biogas production was measured by the water displacement method. The pH value, Organic Matter (OM) content, C/N ratio, and Volatile Acid (VA) were recorded throughout the experiment. Samples of 100 % grass accumulated the highest biogas production (1250 ml) followed by samples of 80 % grass: 20 % bran (1080 ml) and samples of 95 % grass: 5% bran (780 ml) between the 20th and 23rd days. This shows the sample of 100 % grass-feeding has a better performance on biogas production among the samples.

Treatment Method of Radioactive Waste Liquid Containing U and Cs

Radioactive waste liquid will not only cause heavy metal and radiation pollution in the environment, but also enter the human body from a variety of ways, threatening human life and health. Among them, uranium and cesium, due to their high fission yield, long half-life and high solubility of salt compounds in water, need to be treated urgently. The treatment methods of radioactive u and C waste liquid, such as ion exchange method, solvent extraction method, adsorption method, membrane separation method, chemical precipitation method, biological treatment method, adsorption method and combined process, are combed. The principle, characteristics and application of the method are reviewed, and the research direction and development trend are prospected. It has a certain reference value for the selection of radioactive waste treatment methods in different situations.

Long-term continuous degradation of carbon nanotubes by a bacteria-driven Fenton reaction

Very few bacteria are known that can degrade carbon nanotubes (CNTs), and the only known degradation mechanism is a Fenton reaction driven by Labrys sp. WJW with siderophores, which only occurs under iron-deficient conditions. No useful information is available on the degradation rates or long-term stability and continuity of the degradation reaction although several months or more are needed for CNT degradation. In this study, we investigated long-term continuous degradation of oxidized (carboxylated) single-walled CNTs (O-SWCNTs) using bacteria of the genus Shewanella. These bacteria are widely present in the environment and can drive the Fenton reaction by alternating anaerobic-aerobic growth conditions under more general environmental conditions. We first examined the effect of O-SWCNTs on the growth of S. oneidensis MR-1, and it was revealed that O-SWCNTs promote growth up to 30 μg/mL but inhibit growth at 40 μg/mL and above. Then, S. oneidensis MR-1 was subjected to incubation cycles consisting of 21-h anaerobic and 3-h aerobic periods in the presence of 30 μg/mL O-SWCNTs and 10 mM Fe(III) citrate. We determined key factors that help prolong the bacteria-driven Fenton reaction and finally achieved long-term continuous degradation of O-SWCNTs over 90 d. By maintaining a near neutral pH and replenishing Fe(III) citrate at 60 d, a degraded fraction of 56.3% was reached. S. oneidensis MR-1 produces Fe(II) from Fe(III) citrate, a final electron acceptor for anaerobic respiration during the anaerobic period. Then, ·OH is generated through the Fenton reaction by Fe(II) and H2O2 produced by MR-1 during the aerobic period. ·OH was responsible for O-SWCNT degradation, which was inhibited by scavengers of H2O2 and ·OH. Raman spectroscopy and X-ray photoelectron spectroscopy showed that the graphitic structure in O-SWCNTs was oxidized, and electron microscopy showed that long CNT fibers initially aggregated and became short and isolated during degradation. Since Shewanella spp. and iron are ubiquitous in the environment, this study suggests that a Fenton reaction driven by this genus is applicable to the degradation of CNTs under a wide range of conditions and will help researchers develop novel methods for waste treatment and environmental bioremediation against CNTs.

Strategic approach towards sustainability by promoting circular economy-based municipal solid waste management system- A review

The evolution of population and swift urbanization has augmented the quantum of municipal solid waste (MSW) across the globe. The MSW has numerous problems, such as health issues, climate change, societal imbalance, etc. Decision-makers continuously investigate a practical and viable solution for eradicating the solid waste management issue. The circular economy offers a critical solution for managing solid waste with a more organized and constructive approach. The study proposes the key facets to design a solid waste management system driven by the circular economy. The circular economy framework emphasizes the 4 R’s- Reduce, Reuse, Recycle, and Recover. The review instils the importance of a waste collection and sorting station, waste treatment methods, and recovery of valuables from waste. The importance of policies and legislation in solid waste management systems with cases of developed countries are also discussed. The study further elaborates on the various aspects of the circular economy, including economic, social, and environmental paradigms. An insight into achieving sustainability through a circular economy-based MSW management system is presented. CE-based waste management offers eco-friendly business models, environmental justice, and upliftment of social well-being. The paper acknowledges the worldwide business groups that have adopted the circular economy and are trying to achieve sustainability. The opportunities cited by globally renowned organizations to limit waste generation and observe material recycling and reuse in their workspace and products have also been highlighted. The study offers an understanding of the system that brings prosperity and harmony to society.

An extensible complex spherical fuzzy decision making model based selection framework for the food waste treatment method

Food waste has been recognized as one of the most severe environmental problems globally. Food waste management is an effective procedure for achieving global food security, which requires rational and efficacious waste treatment and disposal techniques. Thus, selecting proper and suitable food waste treatment methods is one of the most significant food waste management issues. However, existing selection frameworks based on decision-making models for food waste treatment methods can seldom handle this issue with complicated uncertainty and periodic information. Accordingly, this paper aims to generate a complex spherical fuzzy information-based selection framework for evaluating the food waste treatment method with mutual support and periodicity decision information. First, the complex spherical fuzzy sets express subjective and uncertain selection information. Then, the power weighted average (PWA) operator for complex spherical fuzzy numbers is introduced to fuse the decision information of mutual support from experts that can reflect the impact of information with supportive relationships. Next, an extensible ARAS (Additive Ratio Assessment) approach-based selection framework is constructed to determine the most sustainable food waste treatment method in which the distance-measure-based weighting method is utilized to calculate the importance degrees of criteria. Finally, a case study of evaluating food waste treatment methods is expounded to display the application of the proposed framework. The result indicates that the alternativea2(Anaerobic digestion) is the most sustainable method for food waste treatment with the largest utility degree (0.920). After that, the comparison studies are also performed to illustrate further the reasonability and effectiveness of the proposed selection framework. The result shows that stakeholders can adopt the proposed methodology to improve the performance of the evaluation of food waste treatment.

Integrating insects into the agri-food system of northern Italy as a circular economy strategy

In response to the challenges posed by linear production processes and increasing waste generation, adopting sustainable circular economy strategies is paramount to mitigate environmental impacts. Among these strategies, the valorization of low-value biomass through insect-based bioconversion, particularly with black soldier fly larvae (BSFL) (Hermetia Illucens), has shown promise. This study aimed to evaluate the environmental benefits of a potential BSFL bioconversion system in the Emilia Romagna region, which is renowned for its substantial food residue generation, applying the life cycle assessment (LCA) methodology. A scenario analysis with secondary literature data for insect rearing, structure and processing was conducted. Results indicate that while BSFL bioconversion shows promising outcomes in some environmental impact categories, such as land use, it may not always outperform conventional waste treatment methods or animal feed and biodiesel alternatives in the market. To enhance the environmental performance of BSFL bioconversion at the regional level, attention should be given to structural components and energy efficiency. Additionally, using mixed substrates, including less valued meat residues, appeared to be a more promising approach for optimizing the sustainability of a BSFL bioconversion system as they can increase the productive efficiency of the structure. The legislative approval of utilizing meat residues in insect farming warrants, therefore, meticulous consideration, and further research is needed to guarantee its safe incorporation into insect diets.

Thermodynamic and environmental analysis of an auto-thermal supercritical water gasification system for ammonia and power production from chicken manure

Supercritical water gasification (SCWG) technology, a clean and efficient method for organic waste treatment, has considerable application prospects in the background of carbon emission reduction. In this study, an auto-thermal SCWG system of chicken manure for NH3 and power production was proposed for recycling waste resources. Thermodynamic analysis and environmental impact assessment were conducted under different operational conditions. The system exhibited optimal energy, exergy, and cold gas efficiencies of 62.34 %, 53.75 %, and 57.75 %, while simultaneously generating 3372.11 kg/h of NH3 and 1677.1 kW of net power, all within processing 10 t/h of dry chicken manure. The global warming potential of this system was only 3.31 kg CO2-eq/kg NH3 with carbon capture and storage. The sensitivity analysis indicated that the moderate increase in gasification temperature, higher feedstock concentration, appropriate preheated water flow, and suitable feedstock distribution ratio collectively enhanced system performance by mitigating exergy destruction in the partial oxidation and heat exchange process. By converting waste heat into electrical energy rather than industrial steam, the Organic Rankine Cycle system enhances the practical viability of waste heat recovery. This work expects to provide essential theoretical guidance for the scale-up and design of the biomass waste SCWG system.

A life cycle assessment of biological treatment scenario of municipal solid waste in developing country (case study: Makassar, Indonesia)

Municipal Solid Waste Management (MSWM) is a significant challenge in developing countries, including Indonesia, where landfilling is the predominant waste treatment method. This study examines the case of Makassar City, where landfilling is still in use while composting is utilized to a limited extent. The research aims to evaluate and compare the environmental impact with three alternative scenarios involving biological treatment and life cycle assessment (LCA) processing. The scenarios were examined: Business as Usual Scenario (BaU), Landfill and Composting, Landfill and Anaerobic Digestion, Landfill, Composting, and Anaerobic Digestion. The study considers waste transportation, landfilling, anaerobic digestion, and composting within its system boundary, using annual waste processing as the functional unit. Environmental impacts assessed include global warming, acidification, and eutrophication. The findings indicate that the BaU scenario has the highest environmental impact, particularly regarding global warming, with 8,436,685.61 kg CO2eq/year emissions. On the other hand, alternative scenario 3, which incorporates landfill management, composting, and anaerobic digestion, shows a relatively lower Global Warming Potential (GWP) emission. However, further measures are needed to effectively reduce emissions, such as implementing a cover for the compost pile and arranging the mixing.

Recycling and Utilization of Garden Waste

Garden waste mainly refers to the fallen leaves, branches, tree trimmings, shrub trimmings, lawn trimmings, and other plant residues generated during the natural or maintenance process of garden plants. If garden waste is treated as general solid waste landfill, cost, as well as environmental pressure will be increased. Hence, resource utilization of garden waste can reduce carbon emissions and significantly improve the quality of urban environmental construction. Based on this, this article focuses on the current status of garden waste treatment and utilization methods to analyze problems existing in the resource utilization of garden waste so as to look forward to the prospects of garden waste recycling and its contribution to the ecological civilization development of the garden greening industry.