The studies on municipal solid waste (MSW) management in Pakistan and its impacts on greenhouse gas (GHG) emissions are glaringly missing. Therefore, this study examines the effect of MSW management on GHG emissions in Pakistan and suggests the best suitable strategies for alleviating GHG emissions. The Intergovernmental Panel on Climate Change (IPCC) 2006 waste model (WM) was used to create inventory of GHG emissions from landfilling. The solid waste management GHG (SWM-GHG) calculator and strengths-weaknesses-opportunities-threat (SWOT) analyses were used as strategic planning tools to reduce GHG emissions by improving MSW management in Pakistan. The IPCC 2006 WM estimated 14,987,113 metric tonnes (Mt) carbon dioxide equivalents (CO2-eq) of GHG emissions in 2016. The SWM-GHG calculator, on the other hand, estimated 23,319,370 Mt CO2-eq of GHG emissions from management of 30,764,000 Mt of MSW in 2016, which included 8% recycling, 2% composting, and 90% disposal in open dumps. To reduce GHG emissions, two strategies including recycling-focused and incineration-focused were analysed. The recycling approach can reduce more GHG emissions than incineration, as it can reduce 36% of GHG emissions (as compared to GHG emission in 2016) by recycling 23% of MSW, anaerobically digesting 10% of MSW, and disposing of 67% of MSW in sanitary landfills (with energy recovery). Moreover, the SWOT analysis suggested integration of the informal sector, adoption of anaerobic digestion and formulation of explicit MSW regulations for improving the current management of MSW which will also result in lower GHG emissions.
This article aims to provide insights into the factors that contribute to the separation efficiency of solid particles. In this study, a pneumatic jigging technique was used to assess the separation of solid waste materials that consisted of copper, glass and rubber insulator. Several initial experiments were carried out to evaluate the strengths and limitations of the technique. It is found that despite some limitations of the technique, all the samples prepared for the experiments were successfully separated. The follow-up experiments were then carried out to further assess the separation of copper wire and rubber insulator. The effects of air flow and pulse rates on the separation process were examined. The data for these follow-up experiments were analysed using a sink float analysis technique. The analysis shows that the air flow rate was very important in determining the separation efficiency. However, the separation efficiency may be influenced by the type of materials used.
The management of end-of-life vehicles (ELVs) conserves natural resources, provides economic benefits, and reduces water, air, and soil pollution. In an effort to adequately manage flow of ELVs, modern infrastructure is considered a prerequisite. Thus, development of an effective performance evaluation tool for monitoring and continuous improvement of ELV management systems is strongly desired. In this paper, a performance evaluation tool is proposed for ELV management system implementation, based on the analytic hierarchy process. A real-life case study in Malaysia was conducted in order to demonstrate the potential and applicability of the presented methodology. The scores of eight key success factors in establishing an ELV management system (i.e., management responsibility, performance management, capacity management, resource management, stakeholders' responsibility, education and awareness, improvement and enforcement, and cost management) are presented. The overall score of the ELV management system implementation in Malaysia is equal to 2.13. Therefore, its performance level is average. The presented multi-criteria decision analysis tool can be of assistance not only to stakeholders in the Malaysian ELV management system, but also to vehicle recycling managers from other countries in order to monitor and continuously improve their ELV management systems.
The widespread distribution of persistent organic pollutants (POPs) in landfill leachate is problematic due to their acute toxicity, carcinogenicity and genotoxicity effects, which could be detrimental to public health and ecological systems. The objective of this study was to evaluate the effective removal of POPs - namely, p-tert-Butylphenol and Pyridine, 3-(1-methyl-2-pyrrolidinyl)-, (S)- - from landfill leachate using locust bean gum (LBG), and in comparison with commonly used alum. The response surface methodology coupled with a Box-Behnken design was employed to optimize the operating factors for optimal POPs removal. A quadratic polynomial model was fitted into the data with the R2 values of 0.97 and 0.96 for the removal of p-tert-Butylphenol and Pyridine, 3-(1-methyl-2-pyrrolidinyl), (S)-, respectively. The physicochemical characteristics of the flocs produced by LBG and alum were evaluated with Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM). The infrared spectra of LBG-treated floc were identical with LBG powder, but there was some variation in the peaks of the functional groups, signifying the chemical interactions between flocculants and pollutant particles resulting from POPs removal. The results showed that p-tert-Butylphenol and Pyridine, 3-(1-methyl-2-pyrrolidinyl)-, (S)- obtained 96% and 100% removal using 500 mg/L of LBG at pH 4. pH have a significant effect on POPs removal in leachate. It is estimated that treating one million gallons of leachate using alum (at 1 g/L dosage) would cost US$39, and using LBG (at 500 mg/L dosage) would cost US$2. LBG is eco-friendly, biodegradable and non-toxic and, hence, strongly recommended as an alternative to inorganic coagulants for the treatment of POPs in landfill leachate.
Landfill leachate contain persistent organic pollutants (POPs), namely, bisphenol A (BPA) and 2,4-Di-tert-butylphenol, which exceed the permissible limits. Thus, such landfill leachate must be treated before it is released into natural water courses. This article reports on investigations about the removal efficiency of POPs such as BPA and 2,4-Di-tert-butylphenol from leachate using locust bean gum (LBG) in comparison with alum. The vital experimental variables (pH, coagulant dosage and stirring speed) were optimised by applying response surface methodology equipped with the Box-Behnken design to reduce the POPs from leachate. An empirical quadratic polynomial model could accurately model the surface response with R2 values of 0.928 and 0.954 to reduce BPA and 2,4-Di-tert-butylphenol, respectively. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were performed on treated flocs for further understanding. FTIR analysis revealed that the bridging of pollutant particles could be due to the explicit adsorption and bridging via hydrogen bonding of a coagulation mechanism. SEM micrographs indicated that the flocs produced by LBG have a rough cloudy surface and numerous micro-pores compared with alum, which enabled the capture and removal of POPs from leachate. Results showed that the reduction efficiencies for BPA and 2,4-Di-tert-butylphenol at pH 7.5 were 76% and 84% at LBG dosage of 500 mg·L-1 and 400 mg·L-1, respectively. Coagulant dosage and pH variation have a significant effect on POPs reduction in leachate. Coagulation/flocculation using LBG could be applied for POPs reduction in leachate as a pre-treatment prior to advanced treatments.
Construction and demolition waste continues to sharply increase in step with the economic growth of less developed countries. Though the construction industry is large, it is composed of small firms with individual waste management practices, often leading to the deleterious environmental outcomes. Quantifying construction and demolition waste generation allows policy makers and stakeholders to understand the true internal and external costs of construction, providing a necessary foundation for waste management planning that may overcome deleterious environmental outcomes and may be both economically and environmentally optimal. This study offers a theoretical method for estimating the construction and demolition project waste generation rate by utilising available data, including waste disposal truck size and number, and waste volume and composition. This method is proposed as a less burdensome and more broadly applicable alternative, in contrast to waste estimation by on-site hand sorting and weighing. The developed method is applied to 11 projects across Malaysia as the case study. This study quantifies waste generation rate and illustrates the construction method in influencing the waste generation rate, estimating that the conventional construction method has a waste generation rate of 9.88 t 100 m(-2), the mixed-construction method has a waste generation rate of 3.29 t 100 m(-2), and demolition projects have a waste generation rate of 104.28 t 100 m(-2).
Rapid population growth of major urban centres in many developing countries has created massive landfills with extraordinary heights and steep side-slopes, which are frequently surrounded by illegal low-income residential settlements developed too close to landfills. These extraordinary landfills are facing high risks of catastrophic failure with potentially large numbers of fatalities. This study presents a novel method for risk assessment of landfill slope failure, using probabilistic analysis of potential failure scenarios and associated fatalities. The conceptual framework of the method includes selecting appropriate statistical distributions for the municipal solid waste (MSW) material shear strength and rheological properties for potential failure scenario analysis. The MSW material properties for a given scenario is then used to analyse the probability of slope failure and the resulting run-out length to calculate the potential risk of fatalities. In comparison with existing methods, which are solely based on the probability of slope failure, this method provides a more accurate estimate of the risk of fatalities associated with a given landfill slope failure. The application of the new risk assessment method is demonstrated with a case study for a landfill located within a heavily populated area of New Delhi, India.
The construction sector is among the fastest growing sectors in Malaysia; it consumes a vast amount of natural resources and produces a massive volume of construction and demolition waste. The waste is collected in a decentralised manner by sub-contracted companies. It is challenging to obtain reliable information on the amount of construction waste generated, because it is hard to determine its exact quantity and composition. Therefore, this study proposes a quantitative construction waste estimation model for residential buildings according to available data collected from the Construction Industry Development Board, Malaysia. In the development of this model, a theoretical investigation of the construction procedure and the construction waste generation process was conducted. The waste generated rate was determined as 25.79 kg m-2 for new residential constructions, which translates into about 553,406 t of anticipated waste annually.
The widespread occurrence of microplastic has invaded the environment to an extent that it appears to be present throughout the globe. This review investigated the global abundance and distribution of microplastics in marine and freshwater ecosystems. Furthermore, the issues and challenges have been addressed for better findings in microplastics studies. Findings revealed that the accumulation of microplastics varies geographically, with locations, hydrodynamic conditions, environmental pressure, and time. From this review, it is crucial that proper regulations are proposed and implemented in order to reduce the occurrence of microplastics in the aquatic environment. Without appropriate law and regulations, microplastic pollution will eventually threaten human livelihood.
Marine debris, defined as any persistent manufactured or processed solid material discarded, disposed of or abandoned in the marine and coastal environment, has been highlighted as a contaminant of global environmental and economic concern. The five main categories of marine debris comprise of plastic, paper, metal, textile, glass and rubber. Plastics is recognised as the major constituent of marine debris, representing between 50% and 90% of the total marine debris found globally. Between 4.8 and 12.7 million metric tonnes of consumer plastics end up in the world oceans annually, resulting in the presence of more than 100 million particles of macroplastics in only 12 regional seas worldwide, and with 51 trillion particles of microplastic floating on the ocean surface globally. The impacts of marine debris can be branched out into three categories; injury to or death of marine organisms, harm to marine environment and effects on human health and economy. Marine mammals often accidentally ingest marine debris because of its appearance that can easily be mistaken as food. Moreover, floating plastics may act as vehicles for chemicals and/or environmental contaminants, which may be absorbed on to their surface during their use and permanence into the environment. Additionally, floating plastics is a potential vector for the introduction of invasive species that get attached to it, into the marine environment. In addition, human beings are not excluded from the impact of marine debris as they become exposed to microplastics through seafood consumption. Moreover, landscape degradation owing to debris accumulation is an eyesore and aesthetically unpleasant, thus resulting in decreased tourism and subsequent income loss. There are a wide range of initiatives that have been taken to tackle the issue of marine debris. They may involve manual removal of marine debris from coastal and aquatic environment in form of programmes and projects organised, such as beach clean-ups by scientific communities, non-governmental organizations and the removal of marine litter from Europe's four regional seas, respectively. Other initiatives focus on assessment, reduction, prevention and management of marine debris under the umbrella of international (the United Nations Environment Programme/Mediterranean Action Plan, the Oslo/Paris Convention) and regional organisations - that is, the Helsinki Commission. There are also a number of international conventions and national regulations that encourage mitigation and management of marine debris. However, it is argued that these initiatives are short-term unsustainable solutions and the long-term sustainable solution would be adoption of circular economy. Similarly, four of the sustainable developmental goals have targets that promote mitigation of marine debris by efficient waste management and practice of 3R. As evident by the Ad Hoc Expert Group on Marine Litter and Microplastics meeting, tackling the marine debris crisis is not a straightforward, one-size-fits-all solution, but rather an integrated and continuous effort required at local, regional and global level.
Each year Bangladesh produces around 400,000 metric tonnes of e-waste. E-waste accumulation is expected to increase by 20% annually. In order to facilitate e-waste recycling, it is crucial to identify the factors. In this study, building on the stimulus-organism-response framework, we develop a research model to explore the effect of information publicity, ascription of responsibility and convenience of recycling on the recycling attitude, subjective norm, personal norm and perceived behaviour control which lead to recycling intention. Data were gathered from 127 small and medium electronics store managers. The structural equation modelling technique was used to test the paths. The result suggests a significant influence of the element of stimulus (S) on the element of organism (O). The relationship between the element of organism (O) and the element of response (R) is partial. This paper contributes to the body of work dedicated to helping us better understand the recycling behaviour from the stimulus-organism-response perspective. From the viewpoint of practice, this research sheds light on some of the challenges that the implementer might face when making strategy and policy for e-waste management in Bangladesh.
Biomass is considered as the largest renewable energy source in the world. However, some of its inherent properties such as hygroscopicity, lower energy content, low mass density and bio-degradation on storage hinder its extensive application in energy generation processes. Torrefaction, a thermochemical process carried out at 200-300°C in a non-oxidative environment, can address these inherent problems of the biomass. In this work, torrefaction of bagasse was performed in a bench-scale tubular reactor at 250°C and 275°C with residence times of 30, 60 and 90 mins. The effects of torrefaction conditions on the elemental composition, mass yield, energy yield, oxygen/carbon (O/C) and hydrogen/carbon (H/C) ratios, higher heating values and structural composition were investigated and compared with the commercially available 'Thar 6' and 'Tunnel C' coal. Based on the targeted mass and energy yields of 80% and 90% respectively, the optimal process conditions turned out to be 250°C and 30 mins. Torrefaction of the bagasse conducted at 275°C and 90 min raised the carbon content in bagasse to 58.14% and resulted in a high heating value of 23.84 MJ/kg. The structural and thermal analysis of the torrefied bagasse indicates that the moisture, non-structural carbohydrates and hemicellulose were reduced, which induced the hydrophobicity in the bagasse and enhanced its energy value. These findings showed that torrefaction can be a sustainable pre-treatment process to improve the fuel and structural properties of biomass as a feedstock for energy generation processes.
The removal of concentrated colour (around 5039 Pt-Co) and chemical oxygen demand (COD; around 4142 mg L-1) from matured landfill leachate through a novel combination of humic acid extraction and coagulation with natural oil palm trunk starch (OPTS) was investigated in this study. Central composite design from response surface methodology of Design Expert-10 software executed the experimental design to correlate experimental factors with desired responses. Analysis of variance developed the quadratic model for four factors (e.g. coagulant dosage, slow mixing speed and time and centrifugation duration) and two responses (% removal of colour, COD). The model confirmed the highest colour (84.96%) and COD (48.84%) removal with a desirability function of 0.836 at the optimum condition of 1.68 g L-1 coagulant dose, 19.11 rpm slow mixing speed, 16.43 minutes for mixing time and 35.75 minutes for centrifugation duration. Better results of correlation coefficient (R2 = 0.98 and 0.96) and predicted R2 (0.94 and 0.84) indicates the model significance. Electron microscopic images display the amalgamation of flocs through bridging. Fourier transforms infrared spectra confirmed the existence of selected organic groups in OPTS, which eventually signifies the applied method.
Management of waste is one of the major challenges faced by many developing countries. This study therefore attempts to develop a circular economy (CE) model to manage wastes and closing the loop and reducing the generation of residual wastes in Indian municipalities. Through extant literature review, the researchers found 30 success factors of CE implementation. Using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) SIMOS approach, the rating and weight of decision makers (DMs) for each factor were collected. A structured questionnaire has been developed incorporating all these 30 factors, to extract the most important factors. The data was collected from top 10 officials (DMs) from the Chennai municipality, who handle three regions (metropolitan, suburbia and industrial). Based on the TOPSIS SIMOS analysis, nine CE implementing factors (critical success factors (CSFs)) among the 30 variables that were significant based on the cut-off value was identified. A CE model has been proposed based on these nine CSFs for waste management in India.
The treatment of stabilized landfill leachate (SLL) by conventional biological treatment is often inefficient due to the presence of bio-recalcitrant substances. In this study, the feasibility of coagulation-flocculation coupled with the Fenton reaction in the treatment of SLL was evaluated. The efficiency of the selected treatment methods was evaluated through total organic carbon (TOC) removal from SLL. With ferric chloride as the coagulant, coagulation-flocculation was found to achieve the highest TOC removal of 71% at pH 6. Then, the pretreated SLL was subjected to the Fenton reaction. Nearly 50% of TOC removal was achieved when the reaction was carried out at pH 3, H2O2:Fe2+ ratio of 20:1, H2O2 dosage of 240 mM and 1 h of reaction time. By coupling the coagulation-flocculation with the Fenton reaction, the removal of TOC, COD (chemical oxygen demand) and turbidity of SLL were 85%, 84% and 100%, respectively. The ecotoxicity study performed using zebrafish revealed that 96 h LC50 for raw SLL was 1.40% (v/v). After coagulation-flocculation, the LC50 of the pretreated SLL was increased to 25.44%. However, after the Fenton reaction, the LC50 of the treated SLL was found to decrease to 10.96% due to the presence of H2O2 residue. In this study, H2O2 residue was removed using powdered activated charcoal. This method increased the LC50 of treated effluent to 34.48% and the removal of TOC and COD was further increased to 90%. This finding demonstrated that the combination of the selected treatment methods can be an efficient treatment method for SLL.
This research aims to analyse and understand recycling phenomena and competition between large-scale and small-scale enterprises under different public attention. It mainly emphasizes service-providing behaviours to the consumers in the recycling industry, where recyclers are struggling to enhance their profits. The government strives to protect the environment by promoting an efficient recycling industry. As fast-growing waste products, the recyclers should achieve the advantage of number and be equipped with service capability for the consumers. Thus, this study employs an evolutionary game model to analyse the competition for waste products acquisitions between large and small recyclers. Due to a significant association between the service and acquisition waste product price for the consumers and recycling quantity, there is a strong mutual influence between the acquisition price of waste products and the price strategy-taken rate of large and small recyclers. Results also reveal that the market acquisition price and processing cost play a crucial role in recyclers' decision-making on setting prices for acquiring waste products from consumers. Furthermore, it is also found that waste products acquisition price and recyclers' processing cost are the key factors that affect large and small recyclers' recycling quantity.
The coconut industry generates a relatively large amount of coconut shell and husk biomass, which can be utilized for industrial and environmental purposes. Immense potential for added value when coconut shell and husk biomass are turned into biochar and limited studies are available, making this review paper significant. This paper specifically presents the production and activation technology, economic and financial aspect and application of biochar from coconut shell and husk biomass. Pyrolysis, gasification and self-sustained carbonization are among the production technology discussed to convert this biomass into carbon-rich materials with distinctive characteristics. The surface characteristics of coconut-based biochar, that is, Brunauer-Emmett-Teller (BET) surface area (SBET), pore volume (Vp), pore diameter (dp) and surface functional group can be enhanced by physical and chemical activation and metal impregnation. Due to their favourable characteristics, coconut shell and husk-activated biochar exhibit their potential as valuable adsorption materials for industrial and environmental application including biodiesel production, capacitive deionization, soil amendment, water treatment and carbon sequestration. With the knowledge of the potential, the coconut industry can contribute to both the local and global biocircular economy by producing coconut shell and husk biochar for economic development and environmental remediation. The capital and operating cost for production and activation processes must be taken into account to ensure bioeconomy sustainability, hence coconut shell and husk biomass have a great potential for income generation.
End-of-life vehicles (ELV) management is becoming a global concern in the automotive industry. However, there is still limited study on supply chain optimisation that focusses on specific ELV treatments. Therefore, this mini-review article analyses the supply chain optimisation for recycling and remanufacturing sustainable management in ELV. A total of 51 papers were reviewed from the year 2016 to 2021. The key topics in each article were assessed and classified into various themes, followed by the content analysis. The percentage breakdown for the six main themes are ELV recovery management system (37.25%), reverse logistic network design (29.41%), ELV economy analysis (15.69%), government regulation or subsidies (7.84%), ELV quantity forecast (5.88%) and ELV part design (3.92%). It can be concluded that ELV recovery management and reverse logistic network design are the top two key focusses of supply chain optimisation priorities that have been extensively applied to improve ELV development. The literature gap has shown that the study on remanufacturing in the ELV supply chain is minimal compared to recycling. The classification of ELV recycling and remanufacturing supply chain optimisation in this study will be beneficial in supporting real-life problem-solving for industrial applications. This study serves as a valuable reference guide to identifying more sustainable solutions in ELV management and promoting the critical focus area for academicians and industry players.
Despite the government's policies and objectives, Malaysia lags behind in sustainable waste management techniques, particularly recycling. Bins should be located conveniently to encourage recycling and reduce waste. The current model of bin location-allocation is mostly determined by distance. However, it has been identified that previous studies excluded an important factor: litter pattern identification. Litter pattern is important to identify waste generation hotspots and litter distribution. Thus, we proposed the within cluster pattern identification (WCPI) approach to optimize the recycle point distribution. WCPI gathers the information on litter distribution using geotagged images and analyses the pattern distribution. The optimal location for recycle bin can be identified by incorporating k-means clustering to the pattern distribution. Since k-means faces the non-deterministic polynomial-time-hard challenge of selecting the ideal cluster and cluster centre, WCPI used the total within-cluster sum of square on top of k-means clustering. The proposed location by WCPI is validated in terms of accessibility and suitability. Furthermore, this study provides further analysis of carbon footprint that can be reduced by simulating the data from geotagged images. The results show that 10,323.55 kg of carbon emission can be reduced if the litter is sent for recycling. Thus, we believe that locating bins at an optimal location will embark on consumer motivation to dispose of recycled waste, reduce litter and lessen the carbon footprint. At the same time, these efforts could transform Malaysia into a clean and sustainable nation that aims to achieve Agenda 2030.
In recent years, the environmental pollution of microplastics (MPs) has increasingly drawn our attention. MPs are small fragments of plastics that are commonly dispersed in the environment. The accumulation of environmental MPs is due to population growth and urbanization, while natural disasters such as hurricanes, flooding and human activity may influence their distribution. The leaching of chemicals from MPs raises a significant safety problem and environmental approaches aimed at reducing the use and recycling of plastics, with the replacement by bioplastics and wastewater treatment developments are called for. This summary also helps in demonstrating the connection between terrestrial and freshwater MPs and wastewater treatment plants as the major contributors to environmental MPs by discharges of sludge and effluent. More research on the classification, detection, characterization and toxicity of MPs are essential to enable greater options and solutions. Control initiatives need to intensify the comprehensive study of MP waste control and management information programmes in the fields of institutional engagement, technological research and development, legislation and regulation. A comprehensive quantitative analysis approach for MPs should be created in the future, and more reliable traceability analysis methods should be built to examine further its environmental activity and existence, where this should be done to improve scientific research on MP pollution in terrestrial, freshwater and marine environments and hence, develop more scientific and rational control policies.