The acceleration of growth in the population in Saudi Arabia and the increase in municipal solid waste generation have caused a problem in Dammam city: an increase in solid waste production. Therefore, solid waste sorting is an important practice of municipal solid waste management. The main objectives in this research are understanding the effect of internal and external factors on household willingness in sorting waste in Dammam city and studying the attempts to construct a theoretical research model by adding market incentives, government facilitators, and awareness into the popular planned behaviour theory to explain residents' waste sorting intentions. The data collection and analysis are based on the questionnaire study, which is based on the questionnaire survey data from 450 households in Dammam. This study revealed that social influence significantly predicts households' willingness to sort and recycle, that is, to promote recycling. Additionally, the variable social influence has a significant but low influence on households' willingness to sort and recycle. The result of the structural equation model shows that perceived behavioural control significantly predicts households' willingness to sort and recycle waste. This finding is consistent with the theoretical expectation. Therefore, this research shows that attitude, social influence, perceived behavioural control, market incentives, government facilitators and awareness positively and significantly affect residents' waste sorting intentions. Additionally, this research corroborates the discrepancy between internal and external variables.
We report on a recycling project in which α-Al(2)O(3) was produced from aluminum cans because no such work has been reported in literature. Heated aluminum cans were mixed with 8.0 M of H(2)SO(4) solution to form an Al(2)(SO(4))(3) solution. The Al(2)(SO(4))(3) salt was contained in a white semi-liquid solution with excess H(2)SO(4); some unreacted aluminum pieces were also present. The solution was filtered and mixed with ethanol in a ratio of 2:3, to form a white solid of Al(2)(SO(4))(3)·18H(2)O. The Al(2)(SO(4))(3)·18H(2)O was calcined in an electrical furnace for 3 h at temperatures of 400-1400 °C. The heating and cooling rates were 10 °C /min. XRD was used to investigate the phase changes at different temperatures and XRF was used to determine the elemental composition in the alumina produced. A series of different alumina compositions, made by repeated dehydration and desulfonation of the Al(2)(SO(4))(3)·18H(2)O, is reported. All transitional alumina phases produced at low temperatures were converted to α-Al(2)O(3) at high temperatures. The X-ray diffraction results indicated that the α-Al(2)O(3) phase was realized when the calcination temperature was at 1200 °C or higher.
Solid-state recycling, which involves the direct recycling of scrap metal into bulk material using severe plastic deformation, has emerged as a potential alternative to the conventional remelting and recycling techniques. Hot press forging has been identified as a sustainable direct recycling technique that has fewer steps and maintains excellent material performance. An experimental investigation was conducted to explore the hardness and density of a recycled aluminum-based metal matrix composite by varying operating temperature and holding time. A mixture of recycled aluminum, AA6061, and aluminum oxide were simultaneously heated to 430, 480, and 530 °C and forged for 60, 90, and 120 min. We found a positive increase in microhardness and density for all composites. The hardness increased approximately 33.85%, while density improved by about 15.25% whenever the temperature or the holding time were increased. Based on qualitative analysis, the composite endures substantial plastic deformation due to the presence of hardness properties due to the aluminum oxide embedded in the aluminum matrix. These increases were significantly affected by the operating temperature; the holding time also had a subordinate role in enhancing the metal matrix composite properties. Furthermore, in an effort to curb the shortage of primary resources, this study reviewed the promising performance of secondary resources produced by using recycled aluminum and aluminum oxide as the base matrix and reinforcement constituent, respectively. This study is an outline for machining practitioners and the manufacturing industry to help increase industry sustainability with the aim of preserving the Earth for our community in the future.
The rapid increase in urbanization has given rise to the need of proper waste management. Within municipal waste, the plastic waste is a growing concern which is causing severe harm to our ecosystem. If ignored, this problem will have harmful effects on both human and wildlife. Therefore, this study aims to find out the factors that influence the recycling behavior patterns of consumers regarding plastic waste. The variables from the theory of planned behavior were adopted to study the behavior of consumers toward recycling plastic waste. The data was collected from 243 residents of Karachi-metropolitan city of Pakistan. The partial least square-structural equation modelling was applied to analyze the data. The findings of the current study reveal that different consumers' attributes and attitudes trigger different types of recycling behavior when it comes to waste disposal. Pressure from family and friends and perceived behavioral control trigger the behavior of reselling the waste plastic products while consumer's awareness of consequences and personal attitude toward proper waste disposal leads to reuse or donating that product to someone who can use that plastic product. The understanding of these consumer attributes may help to shape the behavioral outcomes in order to manage waste disposal. This study will be beneficial for business managers looking to improve reverse logistics as well as government/municipal policy makers and academics/researchers who are interested in a solution-oriented study.
In this paper, optimum routing was developed based on the travel salesman method and integrated in ArcInfo GIS using linear programming. The results of the optimized travel distances and times for residential waste collection and routing to disposal site were used to calculate the number and type of required track collection, labour requirement, costing of waste collection and to determine the overall solid waste management efficiency through waste management operation research methods. The objective of the study was to optimize residential collection and hauling to disposal site through operation cost minimization for Petaling Jaya Municipality in the state of Selangor, Malaysia. The study determined that with optimized routes and recycling possibilities, the total cost of waste collections could be reduced from RM90,372 to RM20,967, with a reduction of 76.8%. It was also revealed that optimum routes might not necessarily be the shortest distance from point A to point B as travel time maybe high on short distances due to traffic congestion and the presence of many traffic lights. Techniques and methods developed using general GIS have proven effective in route optimization and allowed management of data to suit local conditions and limitations of waste management for the studied area. Thus, scenarios of travel distances, time and waste quantity value generated from the GIS enabled appropriate determination of the number of waste trucks and labour requirements for the operation and the overall calculation of costs of waste management based on the operation research methods used in the study.
There is an interest in the sustainable utilization of waste cotton cloths because of their enormous volume of generation and high cellulose content. Waste cotton cloths generated are disposed of in a landfill, which causes environmental pollution and leads to the waste of useful resources. In the present study, cellulose nanocrystals (CNCs) were isolated from waste cotton cloths collected from a landfill. The waste cotton cloths collected from the landfill were sterilized and cleaned using supercritical CO2 (scCO2) technology. The cellulose was extracted from scCO2-treated waste cotton cloths using alkaline pulping and bleaching processes. Subsequently, the CNCs were isolated using the H2SO4 hydrolysis of cellulose. The isolated CNCs were analyzed to determine the morphological, chemical, thermal, and physical properties with various analytical methods, including attenuated total reflection-Fourier transform-infrared spectroscopy (ATR-FTIR), field-emission scanning electron microscopy (FE-SEM), energy-filtered transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results showed that the isolated CNCs had a needle-like structure with a length and diameter of 10-30 and 2-6 nm, respectively, and an aspect ratio of 5-15, respectively. Additionally, the isolated CNCs had a high crystallinity index with a good thermal stability. The findings of the present study revealed the potential of recycling waste cotton cloths to produce a value-added product.
Consumption of natural resources and waste generation continues to rise as the human population increases. Ever since the industrial revolution, consumers have been adopting a linear economy model based on the 'take-make-dispose' approach. Raw materials are extracted to be converted into products and finally discarded as wastes. Consequently, this practice is unsustainable because it causes a massive increase in waste production. The root problems of the linear system can be addressed by transitioning to a circular economy. Circular economy is an economic model in which wastes from one product are recycled and used as resources for other processes. This literature review discovers the potential of vermicompost as a sustainable strategy in circular economy and highlights the benefits of vermicompost in ensuring food security, particularly in improving agricultural yield and quality, as well as boosting crop's nutritional quality. Vermicompost has the potential to be used in a variety of ways in the circular economy, including for agricultural sustainability, managing waste, pollutant remediation, biogas production and animal feed production. The recycling of organic wastes to produce vermicompost can benefit both the consumers and environment, thus paving the way towards a more sustainable agriculture for the future.
There is an urgent need globally to find alternative sustainable steps to treat municipal solid wastes (MSW) originated from mismanagement of urban wastes with increasing disposal cost. Furthermore, a conglomeration of ever-increasing population and consumerist lifestyle is contributing towards the generation of more MSW. In this context, vermicomposting offers excellent potential to promote safe, hygienic and sustainable management of biodegradable MSW. It has been demonstrated that, through vermicomposting, MSW such as city garbage, household and kitchen wastes, vegetable wastes, paper wastes, human faeces and others could be sustainably transformed into organic fertiliser or vermicompost that provides great benefits to agricultural soil and plants. Generally, earthworms are sensitive to their environment and require temperature, moisture content, pH and sometimes ventilation at proper levels for the optimum vermicomposting process. Apart from setting the optimum operational conditions for the vermicomposting process, other approaches such as pre-composting, inoculating micro-organisms into MSW and redesigning the conventional vermireactor could be introduced to further enhance the vermicomposting of MSW. Thus the present mini-review discusses the potential of introducing vermicomposting in MSW management, the benefits of vermicomposted MSW to plants, suggestions on how to enhance the vermicomposting of MSW as well as risk management in the vermicomposting of MSW.
The aim of this study is to identify and highlight the positive and negative indirect environmental impacts of COVID-19, with a particular focus on the most affected economies (USA, China, Spain, and Italy). In this respect, the empirical and theoretical dimensions of the contents of those impacts are analyzed. Research findings reveal a significant relationship between contingency actions and positive indirect impacts such as air quality improvements, clean beaches, and the decline in environmental noise. Besides, negative indirect impacts also exist, such as the rise in waste level and curtailment in recycling, further threatening the physical spaces (land and water), besides air. It is expected that global businesses will revive in the near future (though slowly), but the reduction in greenhouse gas emissions during this short time span is not a sustainable way of environmental mitigation. Thus, long-term mitigation policies should be strengthened to cope with the undesirable deterioration of the environment. Research findings provide an up-to-date glimpse of the pandemic from the perspectives of current and future indirect environmental impacts and the post-pandemic situation. Finally, it is suggested to invent and prepare action plans to induce a sustainable economic and environmental future in the post-pandemic world scenario.
Plastics are a wide range of synthetic or semi-synthetic materials, mainly consisting of polymers. The use of plastics has increased to over 300 million metric tonnes in recent years, and by 2050, it is expected to grow to 800 million. Presently, a mere 10% of plastic waste is recycled, with approximately 75% ended up in landfills. Inappropriate disposal of plastic waste into the environment poses a threat to human lives and marine species. Therefore, this review article highlights potential routes for converting plastic/microplastic waste into valuable resources to promote a greener and more sustainable environment. The literature review revealed that plastics/microplastics (P/MP) could be recycled or upcycled into various products or materials via several innovative processes. For example, P/MP are recycled and utilized as anodes in lithium-ion (Li-ion) and sodium-ion (Na-ion) batteries. The anode in Na-ion batteries comprising PP carbon powder exhibits a high reversible capacity of ∼340 mAh/g at 0.01 A/g current state. In contrast, integrating Fe3O4 and PE into a Li-ion battery yielded an excellent capacity of 1123 mAh/g at 0.5 A/g current state. Additionally, recycled Nylon displayed high physical and mechanical properties necessary for excellent application as 3D printing material. Induction heating is considered a revolutionary pyrolysis technique with improved yield, efficiency, and lower energy utilization. Overall, P/MPs are highlighted as abundant resources for the sustainable production of valuable products and materials such as batteries, nanomaterials, graphene, and membranes for future applications.
After twenty-four years of government efforts, the latest national recycling rate in Malaysia rose from 5% in 1993 to approximately 24.6% in 2017. However, the practice of solid waste recycling in developing countries is still challenging compared to developing countries. Especially in Malaysia, a multi-ethnic country where people with different ethics have different living lifestyles. Still, Malaysia faces rapidly increasing solid waste and management costs, lacks appropriate data on solid waste management and recycling, lacks awareness of the 3R's (reduce, reuse and recycle) culture and lacks policies to promote 3R's culture. In addition, prior to the enforcement of ACT 672, information and networks between stakeholders have been limited for more than 20 years. Some scholars believe that the success of recycling practices is mainly influenced by community recycling behaviours. Therefore, in order to improve and evaluate the effectiveness of current national solid waste recycling management systems, research and assessment of community recycling behaviours are essential. This paper aims to evaluate the factors that attract communities to implement recycling in their daily lives and to obtain data through quantitative survey methods. Face-to-face questionnaires are conducted through purposive sampling and collected data is further analysed by PASW statistical tools. The comparison between recyclers and non-recyclers are presented in terms of frequency, means scores and radar chart. The results indicate that policy makers involved in the planning, organisation, and implementation of community recycling programs have to focus on strategies that engage community members and adopt recycling practices to improve environmental impact by changing their attitudes. Based on the results of means scores, the type of age, occupation and place of life must be taken into consideration in order to organize future recycling campaigns or awareness programs. In conclusion, the information will help policymakers make better solid waste recycling management to meet the needs of the public.
Agro-waste from the bark of Metroxylon sagu (sago) was studied as a low cost and effective oil sorbent in dry and aqueous environments. Sorption study was conducted using untreated sago bark (SB) and esterified sago bark (ESB) in used engine oil. Characterization study showed that esterification has successfully improved the hydrophobicity, buoyancy, surface roughness and oil sorption capacity of ESB. Sorption study revealed that water uptake of SB is higher (30 min static: 2.46 g/g, dynamic: 2.67 g/g) compared with ESB (30 min static: 0.18 g/g, dynamic: 0.14 g/g). ESB, however, showed higher oil sorption capacity in aqueous environment (30 min static: 2.30 g/g, dynamic: 2.14) compared with SB (30 min static: 0 g/g, dynamic: 0 g/g). ESB has shown great poTENTial as effective oil sorbent in aqueous environment due to its high oil sorption capacity, low water uptake and high buoyancy.
Source-separating sanitation systems offer the possibility of recycling nutrients present in wastewater as crop fertilisers. Thereby, they can reduce agriculture's impacts on global sources, sinks, and cycles for nitrogen and phosphorous, as well as their associated environmental costs. However, it has been broadly assumed that people would be reluctant to perform the new sanitation behaviours that are necessary for implementing such systems in practice. Yet, few studies have tried to systematically gather evidence in support of this assumption. To address this gap, we surveyed 3763 people at 20 universities in 16 countries using a standardised questionnaire. We identified and systematically assessed cross-cultural and country-level explanatory factors that were strongly associated with people's willingness to consume food grown using human urine as fertiliser. Overall, 68% of the respondents favoured recycling human urine, 59% stated a willingness to eat urine-fertilised food, and only 11% believed that urine posed health risks that could not be mitigated by treatment. Most people did not expect to pay less for urine-fertilised food, but only 15% were willing to pay a price premium. Consumer perceptions were found to differ greatly by country and the strongest predictive factors for acceptance overall were cognitive factors (perceptions of risks and benefits) and social norms. Increasing awareness and building trust among consumers about the effectiveness of new sanitation systems via cognitive and normative messaging can help increase acceptance. Based on our findings, we believe that in many countries, acceptance by food consumers will not be the major social barrier to closing the loop on human urine. That a potential market exists for urine-fertilised food, however, needs to be communicated to other stakeholders in the sanitation service chain.
This study identifies the potential greenhouse gas (GHG) reductions, which can be achieved by optimizing the use of residues in the life cycle of palm oil derived biodiesel. This is done through compilation of data on existing and prospective treatment technologies as well as practical experiments on methane potentials from empty fruit bunches. Methane capture from the anaerobic digestion of palm oil mill effluent was found to result in the highest GHG reductions. Among the solid residues, energy extraction from shells was found to constitute the biggest GHG savings per ton of residue, whereas energy extraction from empty fruit bunches was found to be the most significant in the biodiesel production life cycle. All the studied waste treatment technologies performed significantly better than the conventional practices and with dedicated efforts of optimized use in the palm oil industry, the production of palm oil derived biodiesel can be almost carbon neutral.
Nickel (Ni), cobalt (Co), and zinc (Zn) loaded on fibrous silica KCC-1 was investigated for CO2 methanation reactions. Ni/KCC-1 exhibits the highest catalyst performance with a CH4 formation rate of 33.02 × 10-2 molCH4 molmetal-1 s-1, 1.77 times higher than that of Co/KCC-1 followed by Zn/KCC-1 and finally the parent KCC-1. A pyrrole adsorption FTIR study reveals shifting of perturbed N-H stretching decreasing slightly with the addition of metal oxide, suggesting that the basic sites of catalyst were inaccessible due to metal oxide deposition. The strengths of basicity were found to follow sthe equence KCC-1, Ni/KCC-1, Zn/KCC-1, and Co/KCC-1. The data were supported by N2 adsorption desorption analysis, where Co/KCC-1 displayed the greatest reduction in total surface area whereas Ni/KCC-1 displayed the least reduction. The elucidation of difference mechanism pathways has also been studied by in situ IR spectroscopy studies to determine the role of different metal oxides in CO2 methanation. It was discovered that Ni/KCC-1 and Co/KCC-1 follow a dissociative mechanism of CO2 methanation in which the CO2 molecule was dissociated on the surface of the metal oxide before migration onto the catalyst surface. This was confirmed by the evolution of a peak corresponding to carbonyl species (COads) on a metal oxide surface in FTIR spectra. Zn/KCC-1, on the other hand, showed no such peak, indicating associative methanation pathways where a hydrogen molecule interacts with an O atom in CO2 to form COads and OH. These results offers a better understanding for catalytic studies, particularly in the field of CO2 recycling.
To tackle the crisis associated with the rising commercial food waste generation, it is imperative to comprehend how corporates' recycling behaviour is influenced by different industry structures and economies. This study aims to fill in the information gap that various factors might be affecting corporates' recycling behaviour in two different economies due to environmental inequality by comparing upper-middle-income region (Malaysia) and high-income region (Hong Kong), respectively. A questionnaire survey regarding food waste management according to the Theory of Planned Behaviour was conducted with representatives coming from diverse industries of the hotel, food and beverage, and property management. The questionnaire responses were evaluated based on quantitative structural equation modelling and correlation analysis. The analysis results showed that the model fit the data well, explaining 78% of the variance in recycling behaviour. The findings demonstrated that the most substantial factor on individual's recycling intention by Malaysian commercial food waste generators was perceived behavioural control, and logistics and management incentives. Subjective norms demonstrated significant and adverse effects on the behaviour of food waste recycling. The variable of administrative incentives and corporate support presented strong positive correlations with moral attitudes as well as logistics and management incentives. Hotel industries from both Hong Kong and Malaysia have a higher acceptance level on human resources regarding food waste recycling. In comparison, food and beverage industries from both regions have a lower acceptance level. These findings could enrich our knowledge of the concerns in establishing regional policy strategies to encourage economic behavioural changes for sustainable development.
This study evaluated the use of alginate-immobilized bentonite to remove Cu(II) as an alternative to mitigate clogging problems. The adsorption efficacy (under the influence of time, pH and initial Cu(II) concentration) and reusability of immobilized-bentonite (1% w/v bentonite) was tested against plain alginate beads. Results revealed that immobilized bentonite demonstrated significantly higher sorption efficacy compared to plain alginate beads with 114.70 and 94.04 mg Cu(II) adsorbed g(-1) adsorbent, respectively. Both sorbents were comparable in other aspects where sorption equilibrium was achieved within 6 h, with optimum pH between pH 4 and 5 for adsorption, displayed maximum adsorption capacity at initial Cu(II) concentrations of 400 mg l(-1), and demonstrated excellent reusability potential with desorption greater than 90% throughout three consecutive adsorption-desorption cycles. Both sorbents also conformed to Langmuir isotherm and pseudo-second order kinetic model. Immobilized bentonite is therefore recommended for use in water treatments to remove Cu(II) without clogging the system.
Cu(II) removal efficacies of alginate-immobilized Trichoderma asperellum using viable and non-viable forms were investigated with respect to time, pH, and initial Cu(II) concentrations. The reusability potential of the biomass was determined based on sorption/desorption tests. Cu(II) biosorption by immobilized heat-inactivated T. asperellum cells was the most efficient, with 134.22mg Cu(II) removed g(-1) adsorbent, compared to immobilized viable cells and plain alginate beads (control) with 105.96 and 94.04mg Cu(II) adsorbed g(-1) adsorbent, respectively. Immobilized non-viable cells achieved equilibrium more rapidly within 4h. For all biosorbents, optimum pH for Cu(II) removal was between pH 4 and 5. Reusability of all biosorbents were similar, with more than 90% Cu(II) desorbed with HCl. These alginate-immobilized cells can be applied to reduce clogging and post-separation process incurred from use of suspended biomass.
This study analyzes the regional implications of China's 2017 import ban on plastic waste by examining U.S. census data. A statistically significant decrease in total U.S. plastic waste exports was found, dropping from about 1.4 million tons to 0.6 million tons in the post-ban period. California remained the top exporter, throughout both pre- and post-ban periods, while South Carolina exhibited the highest per capita exports. Malaysia emerged as the largest importer of U.S. plastic waste, followed by Vietnam, Indonesia, and Thailand. The ban also led to a change in the composition of the exported plastic waste. Ethylene polymers increased from 32.6% of total exports in the pre-ban period to 46.9% in the post-ban period. Other plastics (vinyl chloride polymers, styrene polymers, and for plastics not elsewhere specified or included) decreased from 67.4% of total exports in the pre-ban period to 53.1% in the post-ban period. Moreover, we found that exporting plastic waste has significant environmental and human health impacts. For example, the Global Warming Potential (GWP) decreased from 20 million tons CO2-eq in the scenario where 100% of plastics are exported, or 25 million tons exported from the U.S. since 2002, to -11.1 million tons CO2-eq in the scenario where 100% of plastics are treated domestically. Transportation exacerbates these impacts for exported waste scenarios, increasing to 5.4 million tons CO2-eq when plastics are exported by ship while decreasing to 0.9 million tons CO2-eq for domestic treatment. Although exporting plastic waste is initially cost-effective, our study highlights that investing in domestic waste management can yield significant long-term benefits, considering the environmental and public health impacts. Therefore, it is crucial to prioritize context-specific solutions to address the challenges of the evolving global plastic waste landscape.