Waste, Volume 1, Issue 3 (September 2023) – 14 articles

This study systematically examined dredged materials from various aspects, including their sources, the volume generated annually, beneficial uses, and the management processes currently practiced. In addition, this paper presents the relevant policies governing the dredging, reuse, and disposal of dredged materials in the United States. A summary of various sources, types/classifications, and the physical and chemical properties of dredged materials used by various researchers are presented. This paper also summarizes the innovative techniques for the beneficial reuse of dredged materials in a wide range of applications in concrete materials, construction products, roadway construction, habitat building, landfill liner/cap, agriculture soil reconstruction, and beach nourishment. Further, limitations and corresponding solutions related to the beneficial use and management of dredged materials were provided in the end. Full article

This study investigated the recovery of polyphenolic compounds such as punicalagin, punicalin, and ellagic acid via solid-state fermentation (SSF)-assisted extraction from pomegranate peel (Punica granatum L.) using Aspergillus niger GH1 and Saccharomhyces cerevisiae. Food processing has contributed to the increase in agroindustrial wastes, which has become a global concern due to environmental protection. However, these wastes can be valorized via the extraction of high-value components such as bioactive compounds. Ellagitannins extracted during the bioprocesses were identified via the HPLC–MS technique and quantified via total polyphenols (hydrolyzable and condensed assays). Enzymatic activities were tested. HPLC–MS analysis showed a decrease in the levels of punicalagin, the formation of punicaline, and the accumulation of ellagic acid during fermentation kinetics. The present study compares two different bioprocesses in order to obtain, from agroindustrial wastes, high-added-value compounds using SSF-. Full article

Heavy metal contamination in wastewater is a significant concern for human health and the environment, prompting increased efforts to develop efficient and sustainable removal methods. Despite significant efforts in the last few decades, further research initiatives remain vital to comprehensively address the long-term performance and practical scalability of various adsorption methods and adsorbents for heavy metal remediation. This article aims to provide an overview of the mechanisms, kinetics, and applications of diverse adsorbents in remediating heavy metal-contaminated effluents. Physical and chemical processes, including ion exchange, complexation, electrostatic attraction, and surface precipitation, play essential roles in heavy metal adsorption. The kinetics of adsorption, influenced by factors such as contact time, temperature, and concentration, directly impact the rate and effectiveness of metal removal. This review presents an exhaustive analysis of the various adsorbents, categorized as activated carbon, biological adsorbents, agricultural waste-based materials, and nanomaterials, which possess distinct advantages and disadvantages that are linked to their surface area, porosity, surface chemistry, and metal ion concentration. To overcome challenges posed by heavy metal contamination, additional research is necessary to optimize adsorbent performance, explore novel materials, and devise cost-effective and sustainable solutions. This comprehensive overview of adsorption mechanisms, kinetics, and diverse adsorbents lays the foundation for further research and innovation in designing optimized adsorption systems and discovering new materials for sustainable heavy metal remediation in wastewater. Full article

The current project aimed at examining the effect of the enrichment of commercial seed oils with waste orange peel (WOP) extracts on their polyphenolic profiles and resistance against oxidation. Polyphenol-containing WOP extracts were produced using a novel combination of ethanol and triacetin, and they were incorporated into seed oils (sunflower, soybean, corn oil), at a level of 36.87 mg per kg of oil. The oils were then stored at 60 °C, for 58 days. By performing a Rancimat test, it was shown that enrichment of sunflower, soybean, and corn oils with WOP extracts did not provoke any prooxidant effects, but, to the contrary, exerted an antioxidant action, with protection factors varying from 1.01 to 1.61. Furthermore, in all cases examined, it was demonstrated that, during the storage period, the stabilizing effect of WOP extract against oxidation was comparable to that observed in oil samples containing 200 mg BHT per kg oil. This outcome was ascertained by measuring the onset of peroxide value, thiobarbituric-acid-reactive substances, and the TOTOX value. Furthermore, it was revealed that the Trolox-equivalent antiradical activity of the enriched oils exhibited a decline at the end of the examination period, a fact most probably attributed to the depletion of the antioxidants occurring in the oils. It was concluded that the method proposed might be a means of stabilizing commercial seed oils against oxidation, and of enhancing their nutritional value by enriching them with natural polyphenols. Full article

An option to reduce the exploitation and depletion of natural mineral resources is to repurpose current waste materials. Fillers are often added to polymers to improve the properties and lower the overall cost of the final product. Very few studies have assessed the use of waste brown eggshell powder (BESP) as filler in polylactic acid (PLA). The addition of mineral fillers in a polymer matrix can play an important role in the performance of a composite under load. Therefore, tailoring the amount of filler content can be a deciding factor as to which filler amount is best. The goal of this study was to investigate the effect of brown eggshells compared to conventional limestone (LS) powder on the mechanical properties of PLA composites. One-way analysis of variance (ANOVA) was used to carry out the statistical analysis on the average values of each composite mechanical property tested. Scanning electron microscopy (SEM) was used to view if there were any differences in the fractured surfaces. Overall, the LS performed marginally better than the BESP fillers. The highest ultimate tensile and ultimate flexural strengths for eggshell composites containing 32 µm fillers had values of 48 MPa (5–10 wt.% BESP) and 67 MPa (10 wt.%. BESP), respectively. Both the tensile and flexural modulus improved with filler contents and were highest at 20 wt.% with values of 4.5 GPa and 3.4 GPa, respectively. The Charpy impact strength decreased for all filler amounts. SEM micrographs identified changes in the fractured surfaces due to the additions of the filler materials. The ANOVA results showed statistically significant differences for the composite materials. After five weeks of soaking in distilled water, the composites containing 20 wt.% BESP fillers had the highest weight gain. The study demonstrated that waste brown eggshells in powdered form can be used as a filler in PLA composites. Full article

The improper disposal of PET bottle waste in Brazil jeopardizes the sustainability goals, impacting the social, economic, and environmental aspects. In order to tackle this issue, this study introduces a framework that was developed using a combination of environmental and social life cycle assessments (LCAs), along with a modified Analytic Hierarchy Process (AHP) methodology. Nine disposal scenarios were evaluated in Bauru, Brazil, including various combinations of landfills, sorting cooperatives, and incineration. Environmental (Env-LCA) and social (S-LCA) assessments followed the ISO 14040 standards, with the S-LCA incorporating the UNEP/SETAC guidelines. Scenario 9 was identified as the most sustainable option from the evaluated scenarios, with 100% of the waste sent to sorting cooperatives, with modified collection schemes. Conversely, Scenario 1, with a high landfill percentage, proved to be the least sustainable. Full article

Valorisation of wheat bran can be achieved by solid state fermentation (SSF), through application of this material as a growth substrate for a natural white rot fungal isolate, Trametes versicolor CM13, to produce lignin-degrading enzymes. One of the main challenges in optimising and upscaling (SSF) processes is the accurate adjustment and maintenance of moisture conditions. This factor was assessed in the scale up of microcosms and was evaluated over 28 days, under two slightly different moisture contents, reflecting minor differences in experimental conditions during set up and operation of the SSF process. In addition, the microcosms were processed differently from the initial trial using homogenisation of whole microcosms to create a homogeneous mixture prior to sampling. This appeared to result in less variation among the collected samples from the microcosms. Variation of measured parameters as a percentage of actual values measured ranged from 1.33% to 144% in the unmixed microcosms and from 0.77% to 36.0% in the pre-mixed microcosms. Decomposition in the more saturated microcosms progressed more quickly as hemicellulose content decreased and reached a steady state after 14 days, whereas hemicellulose content continued to decrease until 21 days in the less saturated microcosms. Lignin-degrading enzyme activities were not significantly different between either sets of experiments except for laccase on day 7. Laccase and manganese peroxidase activities were highest on day 21 and were similar in both sets of experiments. Enzyme activities on day 21 in the microcosms at moisture content of 42.9% and at 54.6% for laccase activities were 750 ± 30.5 and 820 ± 30.8 units, and for manganese peroxidase, activities were 23.3 ± 6.45 and 21.4 ± 21.4 units, respectively. These results revealed different decomposition rates during the early stage of solid-state fermentation as a function of the initial moisture content, whereas final enzyme activities and fibre content during the later stage were similar in microcosms having different moisture contents at the start. Full article

The amount of municipal solid waste (MSW) generation in Canada was 34 million tonnes in 2018. Responsible waste management is challenging, but essential to protect the environment and to prevent the contamination of the ecosystem on which we rely. Landfilling is the least desirable option, and diversion through thermo-chemical conversion to value-added products is a good option for difficult-to-recycle waste. In this study, the amounts, moisture contents, heating values, and compositions of municipally collected solid waste produced in Canada are reported, a classification that is suitable for conversion purposes is proposed, and the potential for thermo-chemical conversion is determined. Much of the waste generated in Canada is suitable for being converted, and its potential for heat or electricity generation was determined to be 193 PJ/yr and 37 TWh/y, respectively. The GHG emissions that are saved through diversion from the landfill, while assuming the generated heat or electricity offsets natural gas combustion, gives a GHG reduction of 10.6 MMTCO₂E/yr or 1.6% of Canada’s GHG emissions. The blending of waste in feedstocks can have varying effects on the amount of biogenic CO₂ produced per unit energy in the feedstock, which is an important consideration for new projects. Other considerations include the heating values, moisture contents, and contaminant levels in the waste. Full article

Second-generation (2G) ethanol production has been increasingly evaluated, and the use of sugarcane bagasse as feedstock has enabled the integration of this process with first-generation (1G) ethanol production from sugarcane. The pretreatment of bagasse generates pentose liquor as a by-product, which can be anaerobically processed to recover energy and value-added chemicals. The potential to produce biohydrogen and organic acids from pentose liquor was assessed using a mesophilic (25 °C) upflow anaerobic packed-bed bioreactor in this study. An average organic loading rate of 11.1 g COD·L⁻¹·d⁻¹ was applied in the reactor, resulting in a low biohydrogen production rate of 120 mL·L⁻¹ d⁻¹. Meanwhile, high lactate (38.6 g·d⁻¹), acetate (31.4 g·d⁻¹), propionate (50.1 g·d⁻¹), and butyrate (50.3 g·d⁻¹) production rates were concomitantly obtained. Preliminary analyses indicated that the full-scale application of this anaerobic acidogenic technology for hydrogen production in a medium-sized 2G ethanol distillery would have the potential to completely fuel 56 hydrogen-powered vehicles per day. An increase of 24.3% was estimated over the economic potential by means of chemical production, whereas an 8.1% increase was calculated if organic acids were converted into methane for cogeneration (806.73 MWh). In addition, 62.7 and 74.7% of excess organic matter from the 2G ethanol waste stream could be removed with the extraction of organic acid as chemical commodities or their utilization as a substrate for biomethane generation, respectively. Full article

Waste and resource management in Togo is expected to become more difficult due to increasing socioeconomic development, industrialization, and renewable energy investments. Although there are numerous elements that affect waste and resource management, legislation and policy frameworks are essential. In response to the growing demands for environmental protection, the legal provisions and regulatory frameworks of waste and resource management, as well as the legal implementation process, must be more and more comprehensive. Some actions have been taken in Togo to improve the incorporation of more sustainable industrial processes, which include restrictions and regulations on MSW generation, decentralization of MSW management, policies and incentive systems that promote waste reduction, reuse, and recycling, improvement of enforcement through investigation and treatment of violations, and encouragement of macro-socio-economies in the management of municipal solid waste. In spite of the presence of these policies, the sector is still plagued with numerous challenges, mostly in terms of implementation and the application of these policies to develop tailor made and locally feasible solutions. This research paper highlights relevant policies relating to MSW management in Togo as well as key international conventions and policies. It also discusses the contribution that “transition management” can make to such processes, emphasizes the role of governance for sustainable development, and it suggests solutions with a long-term transformation impact such as the incorporation of waste to energy systems into industrial processes. The paper further identifies some flaws and challenges with law implementation on MSW management and suggests solutions to improve the effectiveness of law implementation and the conditions and criteria for a safe and secure way to use waste-derived materials and fuels or by-products coming from society or other industries. These policy suggestions may also be applicable globally at an individual industry level to encourage the creation of more Green Industrial Companies (GICs). Full article

Every year in Australia, the household, commercial and industry sectors generate more than five million tonnes of food waste, with the majority of it ending up in landfills that are costly to run and diminishing in availability. There are urgent calls for effective waste management practices to better address the challenges related to increasing volumes of food waste. This study evaluates potential food waste collection and composting initiatives that will ensure the implementation of the appropriate policies and technologies, and best practice of utilizing food waste as a natural resource. A series of semi-structured interviews were conducted with practitioners from the Southeast Queensland waste industry to gain insights on the challenges and opportunities for implementing a Food Organics, Garden Organics (FOGO) system. The interviews revealed five key themes: levies and taxes, capital investment challenges, lack of capacity, contract inefficiencies, and separate waste streams. Organisations and companies in the waste industry heavily rely on funding in order to technologically advance. There is a divergence of attention between technology and policy. Advancement of technology grows faster than the policies that regulate the appropriate use and level of effectiveness of the introduced technology. Both policy and technological changes need to occur simultaneously for Queensland to evolve and develop a social-economic system that favours a non-wasteful and sustainable future. Full article

The winery sector represents one of the most important agricultural industries in Mediterranean country. Wine production processes generate a large amount of wastes and wastewaters that must be treated before their release in the environment. Among these wastes, wine lees, defined as the viscous material that settles on the bottom of fermenters, represent about 13% of the total wine production. The wine lees do not have applications within a circular economy approach, due to their low value; ethanol and tartaric acid are the only compounds recovered, while the rest is usually not valorized. The aim of this study is to explore the possible cultivation of microalgae on a liquid fraction of wine lees in a batch test at different substrate/inoculum dilutions. The results highlighted that Chlorella vulgaris can grow on wine lees at 1:10 and 1:5 dilutions, but a spontaneous yeast-microalgae consortium is observed (biomass production of 2 g l⁻¹). A high lipid and protein storage was detected in the yeast-microalgae consortium (34.56 ± 13.70% and 39.73 ± 4.49%, respectively), associated with a high sCOD and polyphenols removal (99.95 ± 0.01% and 92.31 ± 0.02%, respectively), encouraging biological wine lees treatment. Full article

More and more cities in Southern Africa are struggling to manage their waste in a context of rapid urbanisation and increasing poverty. In the Cameroon’s largest city, Yaoundé, managing household waste is a growing concern. The public and the authorities cast blame on each other, and the actions taken by each party far from guarantee an efficient management of household waste, which litters the streets. Considering the above, this paper analyses the socio-political practices of stakeholders and their influence on household waste management in Yaoundé. Based on a qualitative survey that combined both a literature review and interviews, the research analysed the challenges related to household waste management with regard to the economy, the environment, and public health. In addition, a cartographic survey using KoboToolbox was conducted in all seven municipalities to analyse the geographical distribution of the waste areas, their size, and their status within the city organizational framework. In total, 264 waste dumps were collected, of which 110 were formal waste using a waste bin of varying size. Social constructivism, stakeholder theory, and strategic analysis were mobilized to analyse the urban waste governance in Yaoundé. Thus, the poor quality of household waste management in Yaoundé was explained using political, economic, sociocultural, and environmental parameters. The social practices and dynamics of the stakeholders generate undesirable consequences that hinder the achievement of the Sustainable Development Goals (SDGs). By combining social science and engineering methods, this research aims to demonstrate that the shortcomings of waste governance in Yaoundé are both a collective (authorities/public powers) and individual (citizens) matter. Full article

Nowadays, the methodology aiming to achieve carbon neutrality and net zero energy on a large scale is known. Despite this, few specialists are mastering this technology globally. What new scenarios. applied at the neighbourhood scale. generate a significant reduction in the rate of CO₂ emissions and energy demand? In addition, a lack of massive, regular, and consistent data on carbon emissions and energy consumption has made it significantly difficult to understand the origins of climate change at the building and neighbourhood scales. This work has, as its main goal, the assessment of different strategies that facilitate reduction in the concentration of CO₂ and lower energy demands at the district level. The life cycle assessment of a new district has been carried out over 100 years during the four stages of the life cycle of the neighbourhood (construction, operation, demolition and end of life). The results showed that up to 93% of greenhouse gas (GHG) was produced during the operational stage. The energy demand due to transport and waste management represented 60% of the total energy demand of the district during the operational stage. There is still a possibility to maintain air temperature growth around 1.5 °C in the next decade by means of the following: Global warming + 100% of heavy renovation of all buildings + 100% of electric car − renewable energy. This strategy would facilitate a reduction of over 92% of the CO₂ produced at the district level. Full article