Waste Streams Research Articles

Using eDNA to play whack-a-mole with invasive species in green yard waste.

As large cities begin to overrun their landfill capacities, they begin to look for alternative locations to handle the waste stream. Seeing an opportunity to bring in revenue, rural communities offer to handle municipal waste in their landfills. However, many rural communities are also places of agricultural production, which are vulnerable to attacks by invasive insect species, which could be present in green yard waste, the component of municipal waste most likely to contain agriculturally harmful insect species. We used environmental DNA (eDNA) to determine whether green yard waste could be a pathway for invasive insect species to enter and establish in the landfill-receiving agricultural community. We identified several target species that could be in green yard waste coming from Vancouver, BC, Canada, to Central Washington State, USA. We sampled green yard waste from 3 sites every 2 weeks from June to October in 2019 and 2020. DNA was extracted from the nearly 400 samples and subjected to amplification with COI barcoding primers followed by sequencing to identify target insects in the samples. Sequence analyses identified 3 species from the target list: 2 species that are pests of deciduous tree fruits and a generalist root-feeding crop pest. This eDNA technique was useful in identifying potential invasive species in green yard waste and may prove to be an important tool informing policy on the movement of biological material across borders and stemming the spread of invasive species.

Self-nucleation (SN) and successive self-nucleation and annealing (SSA) as powerful tools to determine the composition of polyolefin post-consumer recycled blends

AbstractFor the incorporation of post-consumer recycled (PCR) resins in mechanical recycling processes, it is crucial to determine their composition accurately. The blends of linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE) in PCR film resins pose a challenge due to their varying ratios. This study introduces a quantitative method that employs the successive self-nucleation and annealing (SSA) technique to analyze commercial PCR LLDPE/LDPE blend compositions. Our method is an efficient way to assess these blend compositions, offering an improved analysis compared with traditional methods. We established a series of calibration curves based on the SSA final melting trace to validate our approach. The SSA technique's efficacy was compared with the robust NMR method, showing that SSA can predict LLDPE contents in the blends with comparable accuracy. We demonstrate that the SSA methodology is an accurate and reliable technique for assessing complex waste streams, thereby facilitating the optimization of recycling processes and advancing the goals of sustainable materials management.

Ion Exchange Processes for CO2 Mineralization Using Industrial Waste Streams: Pilot Plant Demonstration and Life Cycle Assessment

AbstractAn attractive technique for removing CO2 from the environment is sequestration within stable carbonate solids (e. g., calcite). However, continuous addition of alkalinity is required to achieve favorable conditions for carbonate precipitation (pH>8) from aqueous streams containing dissolved CO2 (pH<4.5) and Ca2+ ions. In this study, a pH‐swing process using ion exchange was demonstrated to process 300 L of produced water brine per day for CO2 mineralization. Proton titration capacities were quantified for aqueous streams in equilibrium with gas streams at various concentrations of CO2 (pCO2=0.03–0.20 atm) and at various flow rates (0.5–2.0 L min−1). Energy intensities for the process were determined to be between 30 and 65 kWh per tonne of CO2 sequestered depending on the composition of the brine stream. A life cycle assessment was performed to analyze the net carbon emissions of the technology which indicated a net CO2 reduction for pCO2≥0.12 atm (−0.06–−0.39 kg CO2e per kg precipitated CaCO3) utilizing calcium‐rich brines. The results from this study indicate the ion exchange process can be used as a scalable method to provide alkalinity necessary for the capture and storage of CO2 in Ca‐rich waste streams.

Environmental and Technological Aspects of the Functioning of Municipal Solid Waste Recycling Complexes (on the Example of the Moscow Region)

The existing scheme, key operations and technologies used in the company for sorting and processing municipal solid waste in the Moscow region have been considered. The features of waste streams entering the waste processing system have been studied, quantitative and qualitative characteristics of the morphological composition have been presented, actual data on the composition of pollutant emissions generated at different stages of waste sorting and processing have been analyzed, the most problematic areas and priority eco-toxicants have been identified.

Double-layered cellulosic interfacial evaporator via upcycling of waste cotton fabrics for efficient solar desalination

Constructing efficient solar-driven interfacial evaporators (SDIEs) derived from biomass or waste stream materials (e.g., cellulose) is still challenging due to their less elaborate porous structure. Herein, we showed waste cotton fabrics could be dissolved and regenerated into aerogels with tunable channels suitable for constructing a double-layered SDIE. The evaporator consists of a polypyrrol-coated top layer featuring vertical channels with larger pores and a hydrophilic bottom layer featuring smaller pores. With such design, the photothermal and pro-evaporative capabilities of the top layer was coupled with the strong capillary effect of the bottom layer to drive effective evaporation. A desirable evaporation rate of 3.20 kg m−2h−1, 80.0% solar-to-vapor conversion efficiency under 1 sun irradiation, and a reduced evaporation enthalpy of 962 J g−1 was achieved. The SDIE also exhibits high purification efficiency (exceeding 99%) during long-term operation of seawater desalination and shows great potential in treatment of waste streams of high salinity dyeing effluent. In summary, this work demonstrates a case of upcycling waste cotton fabrics for water desalination.

A prototype system for the removal of 137Cs from liquid radioactive waste using reverse osmosis membrane.

Cesium removal from aqueous solutions of radioactive waste streams is a challenge in the field of radioactive waste management; this is due to the small atomic radii of Cs+ metal ions and their high migration ability. So, the development of a withstand system for the removal of Cs+ is crucial. In the current study, the removal of radioactive cesium from aqueous solutions using an RO-TLC membrane was studied. Two modifications were conducted; the first is to enlarge the cesium metal ion radii by interacting with mono- and dibasic acids, namely, stearic acid, tartaric acid, citric acid, and EDTA, and the second is the modification of the RO membrane pore size via reaction with the same acids. The modification was confirmed using SEM, FTIR, and EDX analysis techniques. The Cs+ and K+ rejection capacities and water permeability across the membrane at 1.5 bars were evaluated. Along with using the above-mentioned acids, the Cs+ metal ion retention index (RCs) was also obtained. It was found that employing EDTA as a chelating agent in an amount of 1.5g/L in conjunction with the variation of feed content since it provided the highest value of RCs ~ 98% when used. Moreover, the elution of Cs+ using water, EDTA, ammonia, and HCl is also investigated. The optimal value of the eluent concentration was (0.25M) HCl. Finally, Langmuir and Freundlich isotherm models were applied for a better understanding of the sorption process. The results of the present work more closely match the Langmuir isotherm model to determine the dominance of the chemical sorption mechanism.

Synergistic microwave and acidic deep eutectic solvent-based pretreatment of Theobroma cacao pod husk biomass for xylooligosaccharides production

The bioconversion of lignocellulosic biomass into novel bioproducts is crucial for sustainable biorefineries, providing an integrated solution for circular economy objectives. The current study investigated a novel microwave-assisted acidic deep eutectic solvent (DES) pretreatment of waste cocoa pod husk (CPH) biomass to extract xylooligosaccharides (XOS). The sequential DES (choline chloride/citric acid, molar ratio 1:1) and microwave (450W) pretreatment of CPH biomass was effective in 67.3% xylan removal with a 52% XOS yield from total xylan. Among different XOS of varying degrees of polymerization, a higher xylobiose content corresponding to 69.3% of the total XOS (68.22 mg/g CPH) from liquid fraction was observed. Enzymatic hydrolysis of residual xylan from pretreated CPH biomass with low commercial xylanase (10 IU/g) concentration yielded 24.2% XOS. The MW-ChCl/citric acid synergistic pretreatment approach holds great promise for developing a cost-effective and environmentally friendly method contributing to the sustainable production of XOS from agricultural waste streams.

Effects of aflatoxin B1 on metabolism- and immunity-related gene expression in Hermetia illucens L. (Diptera: Stratiomyidae)

Contamination of food products with mycotoxins such as aflatoxin B1 (AFB1) poses a severe risk to human health. Larvae of the black soldier fly (BSFL), Hermetia illucens (Diptera: Stratiomyidae), can successfully metabolize AFB1 without any negative consequences on their survival or growth. Organic waste streams contaminated with mycotoxins can be upcycled into protein-rich BSFL as an alternative feed for livestock and the left-over feed residue into nutrient-rich crop fertilizers. However, the underlying mechanisms that allow BSFL to metabolize AFB1 are unknown. In this study, five-day-old BSFL were fed with either a control or an AFB1-spiked (20 μg/kg) diet to elucidate the underlying mechanisms. Larval samples were collected at three timepoints and subjected to RNA-Seq analysis to determine gene expression patterns. Provision of an AFB1-spiked diet resulted in an up-regulation of 357 and a down-regulation of 929 unique genes. Upregulated genes include multiple genes involved in AFB1 metabolism in other (insect) species. Downregulated genes were generally involved in the insects' growth, development, and immunity. BSFL possesses a diverse genetic arsenal that encodes for enzymes capable of metabolizing AFB1 without trade-offs on larval survival. In conclusion, the adverse impact of AFB1 exposure on immunity-related processes is observed in the transcriptomic response, and is indicative of a trade-off between detoxification and immune responses.

Towards zero waste: A comprehensive framework for categorizing household food waste

One-third of food produced for humans, approximately 1.3 billion tonnes annually, is wasted, with households contributing over 60 % of this waste. This waste has significant environmental, social, and economic impacts. Previous studies have examined the problem of household food waste but lacked sufficient specificity in categorizing waste streams, hindering the development of targeted interventions. This paper addresses this issue by systematically developing a novel household food waste categorization framework that enables a more targeted and potentially effective approach to intervention design aimed at reducing household food waste. Specifically, it revolutionises existing classification systems and introduces a novel, practical nine-stage categorization framework, rigorously validated with 190 household food waste occurrence descriptions and expert feedback. Users of the framework correctly categorized 92 % of household food waste samples identifying 165 as edible, with 92 as eatable and 73 as not eatable. Domestic food preparation and consumption stages showed the highest waste instances (91), followed by planning and purchasing (77), emphasizing the framework's effectiveness in identifying key areas of focus for reducing food waste within households. The role of the framework for developing future interventions to reduce household food waste is discussed.

Bone cement in total hip arthroplasty – Is it really green?

BackgroundTotal hip replacement (THR)is typically cemented, cementless or hybrid depending on patient factors and surgeon preference. To date no studies have evaluated waste generated with each of these procedures in relation to implant choice, and particularly waste related to consumables. We aimed to quantify the volume; type and ability to recycle this waste and suggest potential strategies for reducing the overall waste related to consumables in THR. MethodThis was a prospective review of all waste related to consumables in THR. The waste was weighed using a Salter 1066 BKDR15 scale, accurate to the nearest 1 ​g. The primary outcome was the amount of waste generated per case depending on implant choice (cemented vs. uncemented). Secondary outcomes included: proportion of clinical waste and proportion of recyclable waste. ResultsCemented THR generated a total of 1.89 ​kg of waste compared to 775 ​g for an uncemented THR. Cemented THR generated significantly more sterile (hazardous) waste than uncemented THR both as overall volume and as a proportion 763 ​g (40%) vs 76 ​g (10%). Significantly more of the waste related to uncemented THR was amenable to being recycled through conventional waste streams with simple changes in theatre 672 ​g (86%) compared to 989 ​g (52%) with cemented THR. Between 20 and 30% of waste packaging for both types of surgery compromised information booklets. ConclusionCemented hip replacement generates significantly more waste from consumables than uncemented and a greater amount of this waste is hazardous requiring intensive processing. For both implants a significant proportion of waste can be recycled with simple process changes in theatre. Industry partners have a responsibility to minimise unnecessary packaging and work with surgeons to improve sustainability.

Synergistic effect on simultaneous treatment of Cr(VI) and chloramphenicol using a non-thermal plasma technology

Toxic organic and heavy metal contaminants commonly exist in industrial waste stream and the treatment is of great challenge. In this study, a dielectric barrier discharge (DBD) non-thermal plasma was employed for the simultaneous treatment of two important contaminants, chloramphenicol (CAP) and Cr(VI) in an aqueous solution through redox transformations. More than 70% of CAP and 20% of TOC were degraded in 60 min, while Cr(VI) was completely removed in 10 min. The hydroxyl radicals could be the main active species for the degradation. Meanwhile, the consumption of hydroxyl radicals was beneficial to the reduction of Cr(VI). The synergistic effect was investigated between CAP degradation and Cr(VI) reduction. The reduction of Cr(VI) would be enhanced in the presence of CAP with a low concentration and could be inhibited under a high concentration of CAP, because part of hydroxyl radicals could be consumed by a low concentration of CAP and the obtained intermediates with a higher kinetic rate. However, CAP with a high concentration could also react with some reductive species, such as eaq- and •H, which could compete with Cr(VI) and inhibit the reduction of Cr(VI). In addition, the presence of Cr(VI) could enhance the degradation and mineralization of CAP, and the identification of obtained intermediates indicated that the presence of Cr(VI) could change the degradation path of CAP as Cr(VI) would react with reductive species and enhance the generation of hydroxyl radicals, leading to more hydroxylation reactions. Moreover, the mechanism for the simultaneous redox transformations of CAP and Cr(VI) was illustrated. This study indicates that the DBD non-thermal plasma technology could be one of better solutions for simultaneous elimination of heavy metal and organic contaminants in aquatic environment.

Dynamic simulation and analysis of dichloromethane-acetone, dichloromethane-trichloromethane and dichloromethane-toluene VOC mixture abatement systems under transient feed conditions

Minimisation of environmental footprint in line with sustainability goals rests at the top of the agenda of the pharmaceutical industry. Volatile Organic Compounds (VOCs), while essential to primary pharmaceutical manufacturing, are solvents whose emissions pose a risk to human health and ecosystems. Adsorption on activated carbon beds is an established technology for end of pipe emissions control, which, however, faces efficiency limitations by quick and irregular bed saturation due to complex, transient feeds. This study employs a validated nonisothermal, multicomponent adsorption model to quantitatively assess the exact effect and potential value of waste stream feed sequencing towards activated carbon bed utilisation optimisation. Our results indicate that gradual increase of dichloromethane feed concentration in combination with a low, constant inlet concentration of the strongly adsorbing component leads to the latest breakthrough onset for the dichloromethane-acetone, dichloromethane-chloroform and dichloromethane-toluene mixtures, paving the way to industrial VOC emission abatement scheduling and process optimisation.

Valorizing inherent resources from waste streams for in-situ CO2 capture and sequestration in the steel industry

The imperative need for decarbonization within the energy-intensive steel industry, a pivotal sector for meeting global warming mitigation targets, underscores the significance of deploying cost-effective CO2 capture and sequestration (CCS) measures. The substantial external costs and resource consumption associated with traditional CCS methods present practical challenges. Here, we proposed a pragmatic strategy to integrate CCS into the steel industry through recycling inherent resources from steelmaking waste streams for in-situ CCS (ICCS). The composites prepared from blast furnace slag (BFS) and steel slag (SS) demonstrated the capacity to capture a maximum of 2.77 mol/kg of CO2 from the simulated flowing flue gas at 75 °C, and the energy required could be sourced from steelmaking waste heat. Comprehensive characterizations revealed the evolution of phase compositions and pore structures in different BFS/SS-incorporated composites, providing insights into accelerating the carbonation by elevating temperatures and SS dosages. Notably, ICCS strategy was validated to offer significant potential in CO2 emission reduction (up to −570.0 kg CO2e/t) normalized by compressive strength of the conventional construction materials. Overall, ICCS strategy can minimize the external resource consumption and additional units for implementing collaborative waste recycling in the steel industry with significant environmental benefits.

Effect of Sample Presentation on the Classification of Black Soldier Fly Larvae Using Near-Infrared Spectroscopy

Black soldier fly larvae (BSFL) (Hermetia illucens) reared on food waste streams are considered a sustainable source of protein in feed livestock diets. Recently, portable near-infrared spectroscopy (NIR) instruments have been assessed to monitor the consistency and quality of food waste streams used to feed black soldier fly larvae. During the application of NIR spectroscopy, sample presentation (e.g., drying, processing, particle size) plays an important role in the accuracy of the models developed (quantitative or qualitative analysis). The objective of this study was to evaluate the effect of sample presentation (number of larvae used during the scanning of BSFL) on the accuracy of classification models developed to trace the food waste stream (e.g., supermarket of childcare) used to feed the larvae. BSFL samples were sourced from two waste streams and scanned as half, 1, 2, or 3 larvae using an NIR portable instrument (MicroNIR, Viavi, Milpitas, California, USA). Principal component analysis (PCA) and linear discriminant analysis (LDA) were used to analyze the NIR data and to classify the samples according to the waste stream. The main differences in the NIR spectra of the BSFL samples associated with the number of larvae scanned were observed around 1200 nm, mainly associated with the C-H overtones (lipids). The classification results showed that high classification rates (>93%) were obtained regardless of the number of larvae scanned, ranging from 93% (using 0.5 larvae) to 100% (using 1, 2, or 3 larvae samples). Overall, the number of larvae scanned had minimal to no effect on the accuracy of the LDA classification models. The present study demonstrated that a portable NIR instrument can be suitable for an initial rapid classification or determination of the origin of the waste stream used to feed the BSFL.

The Application of Microbially Induced Calcium Carbonate Precipitation (MICP) Technology in Building Materials and its Contribution to Waste Resource Utilization

Abstract: In many countries around the world, waste generation has become an increasingly pressing issue, particularly in urban areas experiencing rapid population growth and industrialization. The volume of waste produced by human activities continues to rise, posing significant challenges to the environment, economy, and public health. Improper waste management can lead to air and water pollution, soil degradation, and the spread of diseases. Additionally, waste generation consumes substantial natural resources and energy, exacerbating resource depletion and contributing to greenhouse gas emissions.To address these challenges, sustainable waste management practices are essential to reduce waste generation and promote resource recovery and recycling. In this context, the development of innovative technologies, such as Microbially Induced Calcium Carbonate Precipitation (MICP) in building materials, offers an effective means of converting waste into valuable and sustainable applications. MICP is an environmentally friendly biogeochemical technique that employs microorganisms and chemical agents in biological processes to produce carbonate minerals, providing an energy-efficient, cost-effective, and sustainable solution to environmental and engineering challenges.Recent research indicates that waste streams can substitute for several MICP chemical components in microbial and cementitious agent growth media. MICP technology has been found not only to be effective in handling hazardous waste streams but also to be a cost-effective and sustainable solution applicable to various waste media. This comprehensive review aims to provide insights into the environmental advantages and engineering applications of MICP technology, with a particular focus on the potential contributions of waste streams. It also offers guidance for researchers on identifying and overcoming challenges associated with using waste streams for MICP technology applications.

Distribution of Per- and Polyfluoroalkyl Substances (PFASs) in a Waste-to-Energy Plant─Tracking PFASs in Internal Residual Streams.

Per- and polyfluoroalkyl substances (PFASs) constitute a diverse group of man-made chemicals characterized by their water- and oil-repellent properties and persistency. Given their widespread use in consumer products, PFASs will inevitably be present in waste streams sent to Waste-to-Energy (WtE) plants. We have previously observed a subset of PFASs in residual streams (ashes, treated process water, and flue gas) from a WtE plant. However, the transport and distribution of PFASs inside the WtE plant have remained unaddressed. This study is part of a comprehensive investigation to create a synoptic overview of the distribution of PFASs in WtE residues. PFASs were found in all sample types except for boiler ash. The total levels of 18 individual PFASs (Σ18PFASs) in untreated flue gas ranged from 5.2 to 9.5 ng m-3, decreasing with 35% ± 10% after wet flue gas treatment. Σ18PFASs in the condensate ranged from 46 to 50 ng L-1, of which perfluorohexanoic acid (PFHxA) made up 90% on a ng L-1 basis. PFHxA was also dominant in filter ash, where Σ18PFASs ranged from 0.28 to 0.79 ng g-1. This study shows that flue gas treatment can capture some PFASs and transfer them into WtE residues.

Assessing the Potential Climate Impacts and Benefits of Waste Prevention and Management: A Case Study of Sweden

This study employs a life cycle perspective to analyze the carbon footprints of various waste streams, evaluating 52 cases across 26 types of household waste in Sweden, with a focus on waste prevention and management. It demonstrates that while recycling can reduce carbon emissions, prevention could significantly enhance these benefits, with savings ranging from −36.5 to −0.01 kg-CO2-eq per kg of waste. Notably, Waste Electrical and Electronic Equipment (WEEE), textiles, tires, residual household, and plastic waste are the top five fractions most amenable to prevention on a per mass basis. Further analysis, considering waste volumes, shows that targeted recycling of materials like WEEE, metals, and paper could account for over 80% of potential carbon savings. However, the majority of potential climate impact is attributed to the energy recovery of unsorted (mixed) waste, contributing to more than 90% of total impacts. Redirecting all mixed waste to recycling could triple carbon savings, but focusing on prevention could potentially increase benefits twenty-sevenfold, particularly for waste like WEEE, food, and textiles. This research provides a valuable tool for identifying key areas in waste management to optimize climate benefits and enhance public awareness. However, it advises using local data for precise planning due to inherent uncertainties.

Phosphorus Release Dynamics from Ashes during a Soil Incubation Study: Effect of Feedstock Characteristics and Combustion Conditions

Recovering phosphorus (P) through combustion from waste streams, like wastewater sludge and animal manure, offers a promising solution. This research explores the P release patterns in different ashes derived from secondary raw materials, using a long-term soil incubation lasting 160 days. The study evaluated the P release dynamics in five types of ashes from enhanced biological phosphorus removal (EBPR) systems and pig slurry burned at different temperatures. According to the results, a primary effect was observed on P bioavailability during the initial incubation period. All tested ashes release more than 50% of the total P applied between days 5 and 10. Ashes from EBPR exhibited higher P release than those from pig manure, indicating ash origin as a key factor in P release. Additionally, combustion temperature was crucial, with higher temperatures resulting in increased P release rates. Furthermore, the Pearson correlation revealed a strong relationship between the characteristics of the ashes and the amount of P release. Overall, these findings suggest that ashes could be a valuable P-source for agriculture avoiding the process of wet chemical P extraction, thus reducing both economic and environmental costs.

Deep Learning Approaches for Automated Waste Classification and Sorting

Abstract: Effective waste management is critical for environmental sustainability in modern societies. Manual classification and sorting of waste streams is labour-intensive, error-prone, and poses health hazards. Recent advancements in deep neural networks provide new opportunities for automated waste characterization and segregation. This work develops a deep convolutional neural network architecture for classifying various materials commonly found in municipal solid waste. The model achieves over 93% accuracy in categorizing plastics, paper, metals, and glass items from images. The system is designed for edge deployment on low-cost hardware at waste sorting facilities. We implement a closed-loop simulation environment using robotic arms and conveyor belts to demonstrate automated segregation based on predicted waste categories. Results highlight viability for improved waste processing via integration of deep learning-enabled automation. Broader adoption could lead to reduced costs and environmental impact while increasing recycling rates

Improving waste management strategies in the food sector: case studies from Spain, Tunisia and Hong Kong

AbstractAppropriate waste generation and management is becoming increasingly important in making food systems more sustainable. It is, therefore, imperative to both reduce waste generation and sustainably manage the waste that cannot be reduced. However, this is challenging due to the heterogeneity of waste materials, the high economic costs of optimizing food systems and the low awareness of the issue in some societies. This article analyzes three case studies that explore improvements in waste management in the food sector in Europe, Africa and Asia. The case studies focus on a horticultural cooperative in Spain, a seafood company in Tunisia and municipal waste management in Hong Kong, highlighting different challenges and approaches. Key factors for horticultural waste management include a consistent regulatory framework, appropriate management systems and waste traceability. The article also highlights the potential for valorisation of waste products, such as blue crab by-products, which can be used to obtain polysaccharides, proteins, lipids, antioxidants, flavonoids, vitamins and minerals. A shift from landfill to anaerobic digestion is also recommended for a more sustainable waste management. By identifying and quantifying waste streams and problematic waste types, alternative solutions can be developed to improve the sustainability of the global food supply chain.