Comparative life cycle assessment of system solution scenarios for residual municipal solid waste management in NSW, Australia

Life cycle assessment of plastic waste in Suzhou, China: Management strategies toward sustainable express delivery

The explosive growth of China's express delivery industry has greatly increased plastic waste, with low-value plastics not effectively utilized, such as PE packaging bags, which are often not recycled and end up in landfills or incinerators, causing significant resource waste and severe plastic pollution. A gate -to- grave life cycle assessment was adopted to assess the impacts of express delivery plastic waste (EDPW) management models (S1, landfill; S2, incineration; S3, mechanical pelletization), with Suzhou, China as a case. Results showed that mechanical pelletization, was the most environmentally advantageous, exhibiting a comprehensive environmental impact potential of -215.54 Pt, significantly lower than that of landfill (S1, 78.45 Pt) and incineration (S2, -121.77 Pt). The analysis identified that the end-of-life disposal and sorting stages were the principal contributors to environmental impacts in all three models, with transportation and transfer stages of residual waste having minimal effects. In terms of all environmental impact categories, human carcinogenic toxicity (HTc) emerged as the most significant contributor in all three scenarios. Specifically, S1 exhibited the most detrimental effect on human health, while S2 and S3 showed positive environmental impacts. Based on these findings, it is recommended that the application and innovation in mechanical recycling technologies be enhanced, the promotion of the eco-friendly transformation of packaging materials be pursued, and a sustainable express delivery packaging recycling management system be established. These strategies are essential for achieving more eco-friendly management of EDPW, reducing its environmental pollution, and moving towards more sustainable express delivery management practices.

Precision co-composting of multi-source organic solid wastes provide a sustainable waste management strategy with high eco-efficiency: a life cycle assessment

With the increase of organic solid wastes (OSWs), current waste management practices, such as landfill, incineration, and windrow composting, have shown weaknesses in both resource recycling and environmental protection. Co-composting has been used to achieve nutrient and carbon recycling but is accused of high ammonia emission and low degradation efficiency. Therefore, this study developed a precision co-composting strategy (S3, which adds functional bacteria generated from food processing waste to a co-composting system) and compared it with the current OSW treatment strategy (S1) and traditional co-composting strategy (S2) from a life cycle assessment (LCA) perspective. The results showed that compared with S1, the eco-efficiency increased by 31.3% due to the higher economic profit of S2 but did not directly reduce the environmental cost. The addition of bacterial agents reduced ammonia emissions and shortened composting time, so compared with S1 and S2, the environmental cost of S3 was reduced by 37.9 and 43.6%, while the economic profit increased by 79.8 and 24.4%, respectively. The changes in environmental costs and economic benefits resulted in a huge improvement of S3's eco-efficiency, which was 189.6 and 121.7% higher than S1 and S2. Meanwhile, the adoption of S3 at a national scale in China could reduce the emission of 1,4-dichlorobenzene by 99.9% compared with S1 and increase profits by 6.58 billion USD per year. This study proposes a novel approach that exhibits high eco-efficiency in the treatment of OSWs.

A Critical Review of Data Science Applications in Resource Recovery and Carbon Capture from Organic Waste

Municipal and agricultural organic waste can be treated to recover energy, nutrients, and carbon through resource recovery and carbon capture (RRCC) technologies such as anaerobic digestion, struvite precipitation, and pyrolysis. Data science could benefit such technologies by improving their efficiency through data-driven process modeling along with reducing environmental and economic burdens via life cycle assessment (LCA) and techno-economic analysis (TEA), respectively. We critically reviewed 616 peer-reviewed articles on the use of data science in RRCC published during 2002-2022. Although applications of machine learning (ML) methods have drastically increased over time for modeling RRCC technologies, the reviewed studies exhibited significant knowledge gaps at various model development stages. In terms of sustainability, an increasing number of studies included LCA with TEA to quantify both environmental and economic impacts of RRCC. Integration of ML methods with LCA and TEA has the potential to cost-effectively investigate the trade-off between efficiency and sustainability of RRCC, although the literature lacked such integration of techniques. Therefore, we propose an integrated data science framework to inform efficient and sustainable RRCC from organic waste based on the review. Overall, the findings from this review can inform practitioners about the effective utilization of various data science methods for real-world implementation of RRCC technologies.

Comprehensive assessment of food waste treatment emission reduction in China: a life cycle perspective

Food waste (FW) treatment has attracted increasing attention since waste classification occurred in China. Analyzing the environmental and economic impacts of different FW treatment technologies is required. In this study, four FW treatments, i.e., anaerobic digestion, black soldier fly (BSF) bioconversion, composting, and landfill, were evaluated using life cycle assessment (LCA) and life cycle cost (LCC). LCA results show that anaerobic digestion outperforms the other technologies, while LCC results indicate anaerobic digestion has the lowest economic benefits ($5.16) and landfill has the highest ($14.22). Bioconversion has the highest product revenue ($37.98). FW anaerobic digestion followed by treating digestate and waste crude oil was employed to investigate the environmental differences between waste classification and mixed incineration. Digestate gasification and conversion of waste crude oil to biodiesel are found to be environmentally friendly, and waste classification outperforms mixed incineration. Furthermore, we explored national-level environmental emission reduction with anaerobic digestion as the dominant technology via increasing resource utilization rate and applying household FW disposers. Results display that a 60% resource utilization rate decreases the overall environmental impact by 36.68% compared with current situation, and treating household FW separately at the source can further lead to emission reduction. This study provides a reference for selecting FW technologies for countries worldwide from environmental and economic perspectives, as well as a direction of resource utilization for how to reduce environmental emissions from treating the total FW produced by all humanity.

Exploring greenhouse gas emissions pathways and stakeholder perspectives: In search of circular economy policy innovation for waste paper management and carbon neutrality in Hong Kong

Waste paper disposed in landfills notably contributes to greenhouse gas (GHG) emissions and impedes more sustainable, circular alternatives, such as recycling. In Hong Kong, this unsustainable approach is currently dominant as 68% of waste paper products are treated in landfills in 2020. To contextualize the impact of local waste paper management and explore mitigation potentials of circular alternatives, this paper develops a quantitative assessment framework around GHG emissions development trajectories. Combining guidelines of the Intergovernmental Panel on Climate Change (IPCC), national GHG inventories, and local parameters from life cycle analysis, five GHG emissions projections were simulated along the Shared Socioeconomic Pathways (SSPs) until 2060. Most recent baselines indicate that Hong Kong's current waste paper treatment generated 638,360 tons CO₂-eq in 2020, comprising 1,821,040 tons CO₂-eq from landfill and 671,320 tons CO₂-eq from recycling, and -1,854,000 tons CO₂-eq from primary material replacement. Proceeding along a Business-as-Usual scenario under SSP5, GHG emissions will dramatically increase to a net 1,072,270 tons CO₂-eq by 2060, whereas a recycling-intensive scenario will lead to a net saving of -4,323,190 tons CO₂-eq. To complement the quantitative evidence on the benefits of waste paper recycling, field research was conducted to explore the feasibility of circular policy innovation from the perspective of recycling stakeholders. These empirical qualitative and quantitative findings from stakeholders' business routines and material transactions provide crucial indications for policy and institutional innovation: Essentially, for Hong Kong to improve waste paper recycling capacities and facilitate a circular economy (CE), local stakeholders require support via fiscal policy measures (financial subsidies or tax reductions) and infrastructure improvements (delivery access and material storage). In sum, this study employs a novel analytical framework combining original qualitative and quantitative evidence to provide policy innovation towards circular, GHG emission-saving waste paper management.

Environmental and economic assessment of rural domestic waste gasification models in China

The dispersed sources and inconvenient transportation of rural domestic waste (RDW) lead to difficult centralized treatment. Gasification is suitable for decentralized waste treatment, which can effectively avoid RDW long-distance transportation and reduce dioxin emissions compared with small-scale incineration. Hence, economically-affordable and environmentally-friendly RDW treatment models with different gasification scales are required, and village, town and county models were compared via life cycle assessment (LCA) and life cycle cost (LCC) methods in this study. Furthermore, scenario analysis investigated waste sorting based on two food waste (FW) treatment technologies, different FW separate collection efficiency, and electricity recovery to explore the environmental and economic improvement potentials of three models. LCA results show that electricity consumption and direct emissions are significant contributors to environmental impacts, and the county model outperforms village and town models. Moreover, transportation accounts for 6% of the overall environmental impact in the county model. Scenario analysis reveals that waste sorting and electricity recovery can reduce the overall environmental impact by 29% to 146% for three models. LCC results demonstrate that the town model delivers the lowest economic cost, while the village model is the highest. In scenario analysis, resource utilization of FW and electricity recovery of other waste exhibit promising economic benefits. The findings provide comprehensive references for sustainable RDW treatment.

Electricity Generation from Municipal Solid Waste in Nigeria: A Prospective LCA Study

Diverse opportunities and environmental impacts could occur from a potential move towards waste-to-energy (WtE) systems for electricity generation from municipal solid waste (MSW) in Lagos and Abuja, Nigeria. Given this, the purpose of this study is to use life cycle assessment (LCA) as a primary analytical approach in order to undertake a comparative analysis from an environmental impact perspective of different WtE scenarios, along with diesel backup generators (DBGs) and grid electricity. A functional unit of 1 kilowatt-hour of electricity produced was used in assessing the following environmental impact categories: abiotic depletion (fossil fuels) potential (ADP), global warming potential (GWP 100a), human toxicity potential (HTP), photochemical oxidation potential (POCP), acidification potential (AP), and eutrophication potential (EP). The overall result indicated that anaerobic digestion (AD) had the highest energy generated per one tonne of MSW processed for both Lagos (683 kWh/t) and Abuja (667 kWh/t), while landfill gas to energy (LFGTE) had the lowest for both (Lagos 171 kWh/t, Abuja 135 kWh/t). AD also had the lowest environmental impacts amongst the four WtE systems for both cities based on all the impact categories except for POCP. In contrast, LFGTE had the highest impact in all the categories except ADP and HTP. Extending the analysis to include diesel-based generators (DBG) and grid electricity saw the DBGs having the highest impact overall in ADP (14.1 MJ), HTP (0.0732 Kg, 1.4 DB eq), AP (0.0129 Kg SO2 eq), and EP (0.00313 Kg PO4 eq) and grid electricity having the lowest impact in GWP (0.497 Kg CO2 eq), AP (0.000296 Kg SO2 eq), and EP (0.000061 Kg PO4 eq). It was concluded that additional electricity supply from AD to the grid, with its potential to reduce the reliance on DBGs (worst scenario overall), would be a positive action in environmental impact terms.

Analysis of the effects of domestic waste disposal methods on mucilage with life cycle assessment

Mucilage has been observed surface and water column of the Sea of Marmara since 2021 and the domestic and industrial based organic waste is accepted as one of the major sources for the mucilage. In this study, in order to measure the impacts of the wastes to mucilage, seven different waste disposal scenarios, which are determined according to EU directives, are applied to the waste composition of municipalities located near the Sea of Marmara. Then, the environmental impacts of these scenarios are calculated in life cycle perspective. Results show that composting has the greatest positive impact via reducing the deleterious impacts of organic wastes, which are the major source for nutritious groundwater. As to the authors knowledge, this is the first study to integrate life cycle assessment, waste management, and mucilage. The results can be used to guide municipalities around the Sea of Marmara on the prevention of mucilage.

A waste to energy technology for Enrichment of biomethane generation: A review on operating parameters, types of biodigesters, solar assisted heating systems, socio economic benefits and challenges

Anaerobic Digestion (AD) is one of the promising wastestoenergy (WtE) technologies that convert organic wastes to useful gaseous fuel (biogas). In this process methane is produced in the presence of methanogens (bacteria). The survival and activities of methanogens are based on several parameters such as pH, temperature, organic loading rate, types of biodigester. Moreover, these parameters influence the production of biogas in terms of yield and composition. Maintaining an appropriate temperaturefor AD is highly critical and energy intensive. This study reviews the various hybrid technologies assistedbio gas production schemes particularly from renewable energy sources. Also discuss the direct and indirect solar assisted bio-digester impacts and recommendation to improve its performance. In addition, the performance analysis Solar Photovoltaic (PV) and thermal collector assisted bio gas plants; besides their impact on the performance of anaerobic digesters. Since opportunities of solar energy are attractive, the effective utilization of the same is selected for the discussion. Besides, the various constraints that affect the yield and composition of biogas are also evaluated along with the current biogas technologies and the biodigesters. The environmental benefits, challenges and socio-economic factors are also discussed for the successful implementation of various technologies.

Environmental impacts of hazardous waste, and management strategies to reconcile circular economy and eco-sustainability

The rise in living standards and the continuous development in the global economy led to the depletion of resources and increased waste generation per capita. This waste might posture a significant threat to human health or the environmental matrices (water, air, soil) when inadequately treated, transported, stored, or managed/disposed of. Therefore, effective waste management in an economically viable and environmentally friendly way has become meaningful. Prominent technology is the need of the day for circular economy and sustainable development to reduce the speed of depletion in resources and produce an alternative means for the future demands in the different sectors of science and technology. In order to meet the potential requirements for energy production or producing secondary raw material, solid waste may be the prime source. The activities of living organisms convert waste products in one form or another in which electronic waste (e-waste) is a modern-day problem that is growing by leaps and bounds. The disposal protocols of the e-waste management need to be given proper attention to avoid its hazardous impacts. The e-waste is obtained from any equipment or devices that run by electricity or batteries like laptops, palmtops, computers, televisions, mobile phones, digital video discs (DVD), and many more. E-waste is one of the rapidly growing causes of world pollution today. Plenty of research is available in the scientific literature, which shows different approaches being set up and followed to manage and dispose of waste products. These strategies to manage waste products designed by the states all over the globe revolves around minimal production, authentic techniques for the management of waste produced, reuse and recycling, etc. The virtual survey of the available literature on waste management shows that it lacks specificity regarding the management of waste products parallel to ecological sustainability. The presented review covers the sources, potential environmental impacts, and highlights the importance of waste management strategies to provide the latest and updated knowledge. The review also put forward the countermeasures that need to be taken on national and International levels addressing the sensitive issue of waste management.

Comparative Life Cycle Assessment of Gasification and Landfilling for Disposal of Municipal Solid Wastes

Disposal of municipal solid wastes (MSW) remains a challenge to minimize its impacts on the environment and human health. Landfilling, currently the most common method used for MSW disposal, occupies land space and leads to soil and air emissions. Gasification, an alternative MSW disposal method, can convert waste to energy, but can also lead to soil and air emissions and is a more extensive operation. In this study, life cycle assessments (LCA) of the two disposal methods (landfilling without energy recovery and gasification) were compared to understand impacts on environment and health. The LCA was conducted following the ISO 14040 standards with one ton of MSW as the functional unit. The life cycle inventory was obtained from published journals, technical reports, LandGEM, HELP and GREET database. The impact assessment was done using TRACI 2.1 and categorized into eight groups. The LCA revealed that landfilling is a higher contributor in global warming, acidification, smog formation, eutrophication, ecotoxicity and human health cancer and non-cancer categories. The negative environmental impacts of MSW landfilling can be primarily attributed to the fate of leachate loss and landfill gas, while those of the MSW gasification can be attributed to the disposal of its solid residues.

Combining Coagulation and Electrocoagulation with UVA-LED Photo-Fenton to Improve the Efficiency and Reduce the Cost of Mature Landfill Leachate Treatment

This study focused on the reduction of the treatment cost of mature landfill leachate (LL) by enhancing the coagulation pre-treatment before a UVA-LED photo-Fenton process. A more efficient advanced coagulation pretreatment was designed by combining conventional coagulation (CC) and electro-coagulation (EC). Regardless of the order in which the two coagulations were applied, the combination achieved more than 73% color removal, 80% COD removal, and 27% SUVA removal. However, the coagulation order had a great influence on both final pH and total dissolved iron, which were key parameters for the UVA-LED photo-Fenton post-treatment. CC (pH = 5; 2 g L^-1 of FeCl₃6H₂O) followed by EC (pH = 5; 10 mA cm^-2) resulted in a pH of 6.4 and 100 mg L^-1 of dissolved iron, whereas EC (pH = 4; 10 mA cm^-2) followed by CC (pH = 6; 1 g L^-1 FeCl₃6H₂O) led to a final pH of 3.4 and 210 mg L^-1 dissolved iron. This last combination was therefore considered better for the posterior photo-Fenton treatment. Results at the best cost-efficient [H₂O₂]:COD ratio of 1.063 showed a high treatment efficiency, namely the removal of 99% of the color, 89% of the COD, and 60% of the SUVA. Conductivity was reduced by 17%, and biodegradability increased to BOD₅:COD = 0.40. With this proposed treatment, a final COD of only 453 mg O₂ L^-1 was obtained at a treatment cost of EUR 3.42 kg COD^-1.

Research on High- and Low-Temperature Characteristics of Bitumen Blended with Waste Eggshell Powder

The sustainability of resources is presently a major global concern. Sustainable construction materials can be produced by applying biological waste to engineering. Eggshells, as biological waste, are usually dumped in landfills or discarded. This causes many environmental problems including malodor, noise pollution, and serious waste of resources. To solve these problems, this study combined eggshell waste with bitumen materials for bio-roads construction. This paper investigated the impact of biological waste eggshell powder on the high- and low-temperature characteristics of bitumen materials. Scanning electron microscopy (SEM) revealed the microstructure of eggshell powder. The interaction between eggshell powder and asphalt was analyzed using Fourier transform infrared spectroscopy (FT-IR). The high- and low-temperature characteristics were investigated using conventional performance tests, and dynamic shear rheometer (DSR) and bending beam rheometer (BBR) experiments. These results indicate that eggshell powder (1) has a rough and porous microstructure; (2) has no apparent chemical reaction with asphalt; and (3) improves the consistency, hardness, and high-temperature characteristics. However, it reduces the plastic deformation capacity of asphalt, and the low-temperature crack resistance of asphalt cannot be improved. The research demonstrated that the application of eggshell powder in asphalt is feasible and has long-term resource and environmental advantages.