Potential application of bioelectrochemical systems in cold environments

Globally, more than half of the world's regions and populations inhabit psychrophilic and seasonally cold environments. Lower temperatures can inhibit the metabolic activity of microorganisms, thereby restricting the application of traditional biological treatment technologies. Bioelectrochemical systems (BES), which combine electrochemistry and biocatalysis, can enhance the resistance of microorganisms to unfavorable environments through electrical stimulation, thus showing promising applications in low-temperature environments. In this review, we focus on the potential application of BES in such environments, given the relatively limited research in this area due to temperature limitations. We select microbial fuel cells (MFC), microbial electrolytic cells (MEC), and microbial electrosynthesis cells (MES) as the objects of analysis and compare their operational mechanisms and application fields. MFC mainly utilizes the redox potential of microorganisms during substance metabolism to generate electricity, while MEC and MES promote the degradation of refractory substances by augmenting the electrode potential with an applied voltage. Subsequently, we summarize and discuss the application of these three types of BES in low-temperature environments. MFC can be employed for environmental remediation as well as for biosensors to monitor environmental quality, while MEC and MES are primarily intended for hydrogen and methane production. Additionally, we explore the influencing factors for the application of BES in low-temperature environments, including operational parameters, electrodes and membranes, external voltage, oxygen intervention, and reaction devices. Finally, the technical, economic, and environmental feasibility analyses reveal that the application of BES in low-temperature environments has great potential for development.

Municipal solid waste management challenges in developing regions: A comprehensive review and future perspectives for Asia and Africa

The rapid urbanization witnessed in developing countries in Asia and Africa has led to a substantial increase in municipal solid waste (MSW) generation. However, the corresponding disposal strategies, along with constraints in land resources and finances, compounded by unorganized public behaviour, have resulted in ineffective policy implementation and monitoring. This lack of systematic and targeted orientation, combined with blind mapping, has led to inefficient development in many areas. This review examines the key challenges of MSW management in developing countries in Asia and Africa from 2013 to 2023, drawing insights from 170 academic papers. Rather than solely focusing on recycling, the study proposes waste sorting at the source, optimization of landfill practices, thermal treatment measures, and strategies to capitalize on the value of waste as more pertinent solutions aligned with local realities. Barriers to optimizing management systems arise from socio-economic factors, infrastructural limitations, and cultural considerations. The review emphasizes the importance of integrating the study area into the circular economy framework, with a focus on enhancing citizen participation in solid waste reduction and promoting recycling initiatives, along with seeking economic assistance from international organizations.

Overview of municipal solid waste management in sub-tropical climatic region of North Eastern India

Municipal solid waste management (MSWM) is perceived as a global issue regardless of the place of waste generation. The amount of unmanaged waste is increasing rapidly, along with its impact on the environment and human health. In hilly areas, specifically the North Eastern Region (NER) states of India, due to the unique topography coupled with socio-economic factors, there are inadequate waste management practices marked by insufficient infrastructure, minimal research studies, and limited data availability. This paper comprehensively reviews the existing status of MSWM practices and waste treatment technologies, identifies the challenges, and discusses the prospective approaches for MSWM in NER states of India. NER, is characterized by its hilly terrain and has the most diverse demographic profile in the country. The study highlights the notable increase in waste generation in the urban population in NER. The total amount of waste generated in NER is about 2907 tons per day, with a collection rate of 86.96%, treatment at 31.09%, and landfilling at 33.67%. The biodegradable fraction makes up the majority of waste composition (more than 50%) in NER, followed by recyclables and inert. The existing MSWM consists of waste collection, transportation, and disposal with limited source segregation and treatment. All the states of NER practice open dumping and burning as the primary waste treatment and disposal system. The study discusses the challenges and prospects to ensure effective MSWM in NER. This review is a region-specific study that considers cultural diversity, topography, and socio-economic dynamics. The outcome of this review will be helpful to the researchers and policymakers in making appropriate waste management plans and improve the MSWM system in NER.

Aqueous-phase product treatment and monetization options of wet waste hydrothermal liquefaction: Comprehensive techno-economic and life-cycle GHG emission assessment unveiling research opportunities

While wet waste hydrothermal liquefaction technology has a high biofuel yield, a significant amount of the carbon and nitrogen in the feedstock reports to the aqueous-phase product. Pretreatment of this stream before sending to a conventional wastewater plant is essential or at the very least, advisable. In this work, techno-economic and life-cycle assessments were conducted for the state-of-technology baseline and four aqueous-phase product treatment and monetization options based on experimental data. These options can cut minimum fuel selling prices by up to 13 % and life-cycle greenhouse gas emissions by up to 39 % compared to the baseline. These findings highlight the substantial influence of aqueous produce treatment strategies on the entire wet waste hydrothermal liquefaction process, demonstrating the potential for optimizing economic viability and environmental impact through further research and development of milder treatment methods and diversified by-product valorization pathways.

Recovery of non-metallic useable materials from e-waste

Tremendous amounts of electric and electronic wastes (e-waste) are generated daily, and their indiscriminate disposal may cause serious environmental pollution. The recovery of non-metallic materials from e-waste is a strategy to not only reduce the volume of e-waste but also avoid pollutant emissions produced by indiscriminate disposal of e-waste. Pyrolysis, sub/supercritical water treatment, chemical dissolution, and physical treatment (e.g., ball milling, flotation, and electrostatic separation) are available methods to recover useable non-metallic materials (e.g., resins, fibers, and various kinds of polymers) from e-waste. The e-waste-derived materials can be used to manufacture a large variety of industrial and consumer products. In this regard, this work attempts to compile relevant knowledge on the technologies that derive utilizable materials from different classes of e-waste. Moreover, this work highlights the potential of the e-waste-derived materials for various applications. Current challenges and perspectives on e-waste upcycling to useable materials are also discussed.

Acidithiobacillus species drive the formation of ferric-silica cemented microstructure: Insights into early hardpan development for mine site rehabilitation

Hardpan-based profiles naturally formed under semi-arid climatic conditions have substantial potential in rehabilitating sulfidic tailings, resulting from their aggregation microstructure regulated by Fe-Si cements. Nevertheless, eco-engineered approaches for accelerating the formation of complex cementation structure remain unclear. The present study aims to investigate the microbial functions of extremophiles on mineral dissolution, oxidation, and aggregation (cementation) through a microcosm experiment containing pyrites and polysilicates, of which are dominant components in typical sulfidic tailings. Microspectroscopic analysis revealed that pyrite was rapidly dissolved and massive microbial corrosion pits were displayed on pyrite surfaces. Synchrotron-based X-ray absorption spectroscopy demonstrated that approximately 30 % pyrites were oxidized to jarosite-like (ca. 14 %) and ferrihydrite-like minerals (ca. 16 %) in talc group, leading to the formation of secondary Fe precipitates. The Si ions co-dissolved from polysilicates may be embedded into secondary Fe precipitates, while these clustered Fe-Si precipitates displayed distinct morphology (e.g., "circular" shaped in the talc group, "fine-grained" shaped in the chlorite group, and "donut" shaped in the muscovite group). Moreover, the precipitates could join together and act as cementing agents aggregating mineral particles together, forming macroaggregates in talc and chlorite groups. The present findings revealed critical microbial functions on accelerating mineral dissolution, oxidation, and aggregation of pyrite and various silicates, which provided the eco-engineered feasibility of hardpan-based technology for mine site rehabilitation.

Trends in research on characterization, treatment and valorization of hazardous red mud: A systematic review

Meta-analysis of red mud-related literature in English published from 1976 to 2022 and in Chinese from 1990 to 2022 was performed to support critical analysis and evaluation of the available literature based on the following aspects of red mud research: (a) characterization, (b) treatment for harmfulness minimization, (c) recovery of valuable metals, (d) environmental applications, and (e) uses as construction materials. It was found that (a) sinter red mud tended to contain more silica and calcium, and less iron, sodium and aluminium compared to Bayer red mud; (b) gypsum was the most frequently used agent for harmfulness reduction treatment of red mud, followed by flue gas/CO2; (c) the mean optimal pH for adsorption of major anionic pollutants was 8.42 ± 1.13 (arsenite), 3.73 ± 0.68 (arsenate), 3.50 ± 2.38 (phosphate), 4.43 ± 1.04 (fluoride) and 3.80 ± 1.54 (chromate); (d) wastewater treatment has attracted more attention compared to contaminated soils and waste gases; (e) recovery of iron and scandium has attracted more attention compared to other metals; (f) cement making has been the focus in construction uses. Most of the research findings were based on laboratory-scale experiments that focused on efficacy rather than efficiency. There was a lack of integrated approaches for research in red mud valorization.

Effects of Fe-N co-modified biochar on methanogenesis performance, microbial community, and metabolic pathway during anaerobic co-digestion of alternanthera philoxeroides and cow manure

The performance of anaerobic digestion (AD) is susceptible to disturbances in feedstock degradation, intermediates accumulation, and methanogenic archaea activity. To improve the methanogenesis performance of the AD system, Fe-N co-modified biochar was prepared under different pyrolysis temperatures (300,500, and 700 °C). Meanwhile, pristine and Fe-modified biochar were also derived from alternanthera philoxeroides (AP). The aim was to compare the effects of Fe-N co-modification, Fe modification, and pristine biochar on the methanogenic performance and explicit the responding mechanism of the microbial community in anaerobic co-digestion (coAD) of AP and cow manure (CM). The highest cumulative methane production was obtained with the addition of Fe-N-BC500 (260.38 mL/gVS), which was 42.37 % higher than the control, while the acetic acid, propionic acid, and butyric acid concentration of Fe-N-BC were increased by 147.58 %, 44.25 %, and 194.06 % compared with the control, respectively. The co-modified biochar enhanced the abundance of Chloroflexi and Methanosarcina in the AD system. Metabolic pathway analysis revealed that the increased methane production was related to the formation and metabolism of volatile fatty acids and that Fe-N-BC500 enhanced the biosynthesis of coenzyme A and the cell activity of microorganisms, accelerating the degradation of propionic acid and enhancing the hydrogenotrophic methanogenesis pathway. Overall, Fe-N co-modified biochar was proved to be an effective promoter for accelerated methane production during AD.

Focus on Co-digestion of waste activated sludge and food waste via yeast pre-fermentation and biochar supplementation: The optimization and mechanism

Anaerobic digestion is a promising method to recover energy from waste, but the slow rate of fermentation hinders its application. Yeast pre-fermentation has been reported to enhance organic matter solubilization and ethanol production to promote syntrophic metabolism and methanogenesis. However, the pre-fermentation with yeast has not been optimized so far. In this study, the lab-scale experiment was conducted to optimize operational conditions, and a pilot-scale study was conducted to evaluate the combined strategy of yeast pre-fermentation and biochar supplementation. Results demonstrated that at a fermentation time of 6 h, temperature of 30 °C, and dry yeast dosage of 2‰, the highest ethanol production was achieved, which accounted for 6.2% of the total COD of pre-fermentation effluent of a mixture of waste-activated sludge and food waste. The methane yield of the pre-fermented waste averaged 161.3 mL/g VS/d, which was 18.7% higher than that of the control group without the yeast inoculation (135.8 mL/g VS/d). With supplementing biochar of 0.5 and 1 g/L, the average methane production was 27.8% and 36.4% higher than the control group, respectively. The volatile solid removal rate was over 10% higher than the control (58.2 ± 3.12%). Consistently, the electrochemical properties of sludge with biochar were significantly improved. A pilot-scale experiment further showed that the methane production with the yeast pre-fermentation and biochar supplementation reached 227 mL/g VS/d, 54.3% higher than that without yeast pre-fermentation and biochar. This study provided a feasible method to combine yeast pre-fermentation and biochar supplementation under optimal conditions, which effectively increased methane production during anaerobic digestion of organic waste.

Life cycle environmental benefits of recycling waste liquor and chemicals in production of lignocellulosic bioethanol

In recent decades, numerous bioconversion processes and techniques have been developed to utilize lignocellulosic biomass as feedstock in the production of bio-based fuels and materials. However, waste treatment, an important sub-system, is seldom considered in the life cycle assessment of lignocellulose derived products. This study comprehensively investigated the environmental impacts of bioethanol and electricity cogeneration from sugarcane bagasse, with a focus on recycling techniques adopted in waste treatment. A life cycle assessment indicated that high recycle rate of black liquor, acid and waste washing water can substantially reduce the consumption of fresh water, related chemicals and energy by 70-80%. Environmental impacts relating to global warming, acidification potential and primary energy demand can be decreased by 5-10 times or even entirely eliminated. These study outcomes demonstrate significant environmental benefits of integrating waste recycling techniques into lignocellulose biorefinery process, providing a solid foundation for future industrial development.

In-depth analysis of the effect of catalysts on plasma technologies for treatment of various wastes

Energy security and waste management are gaining global attention. The modern world is producing a large amount of liquid and solid waste as a result of the increasing population and industrialization. A circular economy encourages the conversion of waste to energy and other value-added products. Waste processing requires a sustainable route for a healthy society and clean environment. One of the emerging solutions for waste treatment is plasma technology. It converts waste into syngas, oil, and char/slag depending on the thermal/non-thermal processes. Most of all the types of carbonaceous wastes can be treated by plasma processes. The addition of a catalyst to the plasma process is a developing field as plasma processes are energy intensive. This paper covers the detailed concept of plasma and catalysis. It comprises various types of plasma (non-thermal and thermal) and catalysts (zeolites, oxides, and salts) which have been used for waste treatment. Catalyst addition improves gas yield and hydrogen selectivity at moderate temperatures. Depending on the properties of the catalyst and type of plasma, comprehensive points are listed for the selection of the right catalyst for a plasma process. This review offers an in-depth analysis of the research in the field of waste-to-energy using plasma-catalytic processes.

ZnO-based heterojunction catalysts for the photocatalytic degradation of methyl orange dye

In this study, a variety of ZnO-based heterojunctions with disparate wt.% doping of WO3 and BiOI have been prepared for the photodestruction of methyl orange (MO) dye in aqueous solution. The composites were analysed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, optical studies, and nitrogen adsorption-desorption isotherms. The SEM images revealed non-uniform surfaces of the ZnO-BiOI based composites while mostly nodular morphology was observed for all three samples of ZnO-WO3. As the WO3 loading increased, more clustering was detected. The analysed samples exhibited characteristic peaks representative of the triclinic phase of WO3 and the hexagonal wurtzite structure of ZnO, while the diffractogram observed from the materials displayed distinct peaks corresponding to the crystalline phases of both BiOI and ZnO in their pure forms. Further evidence of the samples' characteristics includes the presence of distinct crystalline patterns without any impurity peaks, a red shift in the absorption spectra of the heterostructure, the detection of only the reference elements, and mostly Type IV isotherm adsorption. This study identified the ZnO-[10%]BiOI and ZnO-[10%]WO3 heterojunctions as the best performing photocatalysts, as MO was completely destroyed in 120 and 90 min, respectively. Thus, confirming 10% wt. as the optimal doping concentration for the best photo-activity in this study. The impact of varying process parameters demonstrates that at an elevated photocatalyst mass of 40 mg, both heterojunctions effectively degraded MO. The photodegradation efficiency of MO was more pronounced in strong acidic conditions (pH 2) when compared to high alkaline conditions (pH 11) for the ZnO-[10%]BiOI heterostructure. However, a decrease in performance was observed for both strong acidic and high alkaline pH values when the ZnO-[10%]WO3 heterostructure was applied. The kinetic analysis of the photodegradation study reveals that all the photodegradation experiments can be represented by the pseudo-first-order kinetic model. The findings from this investigation propose that the ZnO-[10%]BiOI heterojunction photocatalyst holds significant potential for the effective treatment of dye-contaminated wastewater.

Dual Role of Silicon-based Matrices in Electron Exchange Matrices for Waste Treatment

Para chloro aniline (PCA) is a common toxic pollutant found in pharmaceutical wastewater. Our study suggests a novel PCA treatment method based on a heterogeneous advanced oxidation process (AOP) that proceeds in an electron exchange matrix (EEM) prepared by the incorporation of redox-active specie in silica matrices using the sol-gel synthesis route. The results, which are supported by DFT calculations, show that the silicon skeleton of the EEM has two important roles, both as a porous matrix that hosts the redox species and as an oxidant species involved in the AOP. The calculations indicate that the formation of a radical on the nitrogen is favored. The suggested mechanism could shed light on the AOP, which proceeds in a heterogenous system, and on its application inside the understudied EEMs that, until now, have been a virtual black box. A better understanding of the mechanism could lead to improved control over the heterogeneous processes that can play a critical role in industries with the need to treat small amounts of toxic compounds at low concentrations, such as in the pharmaceutical industry.

Application of q-rung orthopair fuzzy based SWARA-COPRAS model for municipal waste treatment technology selection

Despite several methods available for the treatment of solid wastes, the management of municipal solid waste is still a crucial and complex process. The available methods for waste treatment range from advanced to conventional techniques. The identification of a proper method for municipal solid waste management involves several techno-eco and environmental considerations. To solve the real-world problems of municipal waste management, the research proposed an integrated q-rung orthopair fuzzy number-based stepwise weight assessment ratio analysis-complex proportional assessment (SWARA-COPRAS) mathematical model to rank the waste treatment techniques. The research aimed to develop a systematic approach for a suitable selection of waste treatment methods. Ten (10) different alternatives for waste treatments were ranked against seven (07) different techno-eco and environmental criteria. The ambiguity in the decision was handled by the q-rung orthopair fuzzy numbers. The proposed integrated model has identified upcycling and recycling of waste having priority values of 100% and 99.9%, respectively, as the suitable practices for the successful management of generated solid wastes, whereas landfilling has obtained a minimum priority value of 66.782% and, therefore, is least preferable for waste management. The ranking of the alternatives followed the sequence as upcycling > recycling > pyrolysis > hydrolysis > biotechnological > core plasma pyrolysis > incineration > composting > gasification > landfilling. The comparison between the rankings of the proposed model with other techniques has revealed that the values of Spearman's rank correlation coefficient are in the range of 0.8545 to 0.9272; thereby, the robustness of the proposed model is verified. Sensitivity analysis for the criteria weight has showed that the ranking results are influenced significantly by the change in criteria weights and suggested that an accurate estimation of the criteria weight is decisive in determining the overall ranking of the alternative. The study has provided a framework for decision-making in the technology selection for solid waste management.

Pollution characteristics and microbial community succession of a rural informal landfill in an arid climate

Informal landfills pose potential threats to the environment and human health due to the lack of anti-seepage measures. However, little research has been conducted on the distribution of pollutants in informal landfill sites situated in arid climates, as well as the underlying interaction mechanisms between environmental factors and microbial structure. In this study, we sought to investigate the pollution characteristics and microbial community succession of the landfill in northern China. The results revealed that heavy metals in the landfill showed poor mobility and migration. The lower layers of the garbage samples had higher water-soluble contents of heavy metals compared to the upper layers. The landfill-derived dissolved organic matter (DOM) was found to originate from microbial production, and four fluorescent components were identified, including fulvic acid-like substances, humus-like substances, and protein-like components. Fluorescence intensity and humification degree increased with increasing depth. The microbial diversity and richness decreased with sampling depth. The most abundant phyla in the samples were Proteobacteria, unidentified_Bacteria, Bacteroidota, Firmicutes, Myxococcota, Gemmatimonadota, Actinobacteria, and Deinococcota. As the sampling depth increased, Proteobacteria decreased, while Bacteroidota and Firmicutes showed a remarkable increase, with little variation observed in the other phyla. The partial least-squares path model (PLS-PM) results indicated that pH had the most significant effect on microbial abundance and diversity (direct effect value = -5.560), while DOM and heavy metals had the opposite effect, with direct effects of 1.838 and 3.231, respectively. DOM was identified as the driving factor for the variation in other environmental factors. The redundancy analysis (RDA) showed that the dominant genera were greatly influenced by Cu, humic-like substances, and protein-like substances. Among them, Bacillus, Alcanivorax, Devosia, and Chryseolinea may play important roles in the remediation of landfills. Our study not only gains a deeper understanding of the pollution risk of informal landfills in arid climates, but also provides a scientific basis for the future treatment and restoration of contaminated sites associated with landfills.

Screening and characterization of agarolytic bacteria from different sources

According to the results of our investigation distinct bacterial isolates capable of breaking down agar were found in various non-marine environments. The deficiency of reducing sugar in the control media demonstrates that the agar in the experiment is broken down by the bacteria to produce various oligosaccharides because the viscosity of the medium containing the agar was found to have been extremely high before inoculation, reducing with incubation duration and attaining a maximum after 48 hours. These isolates were subsequently used in tests along with additional investigation since they could create reducing sugar. Interestingly, the deterioration of agar appears to be mainly caused by gram-negative bacteria. In order to study the agarase properties, the relative quantity of the enzyme secreted by the bacteria that hydrolyze the agar was used. The detection of extracellular agarase surrounding the colonies and the absence of stained halos on iodine-treated agar plates show that the agarase diffusing from the bacteria impacted the characteristics of the gel. Inconclusion, these agarsase-producing bacteria can be exploited for industrial applications. Waste agar from the plant tissue culture business can be utilised for a range of applications and this degraded agar can be explored for reliable and ecologically safe alternatives.

The investigation of batch-to-batch variabilities in the composition of isolates from fish and mammalian species using different protocols

The aim of this study was to investigate batch-to-batch inconsistencies in the processing of pig and fish collagen isolates processed using two protocols that differed in terms of the acetic acid concentrations applied and the pre- and post-extraction steps, and which were previously tested in our laboratory with the intention of preserving the biological structures and functions of the collagen isolates for biomedical purposes. Both the major and minor components such as the amino acids, lipids, water, glycosaminoglycan and ash contents and elemental content, as well as the structure and morphology of the raw sources and the resulting batches of isolates were subsequently examined in detail applying standardized analytical methods including high perfomance liquid chromatography, ultraviolet-visible and infrared spectrometry, polyacrylamide gel electrophoresis, energy dispersive spectroscopy and scanning electron microscopy. All the fish isolates provided severalfold higher yields (8-45 wt%) than did the pig isolates (3-9 wt%). In addition, the variability of the fish isolate yields (the coefficient of variation for processing A: 16.4-32.9 % and B: 6.8-17.4 %) was significantly lower (p ≤ 0.05, n = 5) than that of the pig isolates (A: 27.7-69.8 %; B: 35.3-87.9 %). In general, the fish skin batches had significantly higher protein contents (˃60 wt%) and lower lipid contents (<10 wt%) than the pig skin batches (<55 wt% protein and up to 66 wt% lipid). In addition, the fish skin batches did not differ significantly in terms of their composition applying the same processing method, whereas the pig skin batches exhibited considerable variations in terms of their compositions, particularly regarding the protein and lipid contents. It can be stated that, concerning the fish isolates, processing B was, in most cases, slightly more efficient and reproducible than processing A. However, concerning the pig isolates, although processing A appeared to be more efficient than processing B in terms of the yield, it resulted in the production of isolates that contained a certain level of contaminants. The study provides a comprehensive discussion on the suitability of the processing protocol in terms of producing batches of reproducible quality according to the specific type of biomaterial processed from different animal species.

Landfill: An eclectic review on structure, reactions and remediation approach

Since the enactment of the Clean Water Act (1972), which was supplemented by increased accountability under Resource Conservation and Recovery Act (RCRA) Subtitle D (1991) and the Clean Air Act Amendments (1996), landfills have indeed been widely used all around the world for treating various wastes. The landfill's biological and biogeochemical processes are believed to be originated about 2 to 4 decades ago. Scopus and web of Science based bibliometric study reveals that there are few papers available in scientific domain. Further, till today not a single paper demonstrated the detailed landfills heterogenicity, chemistry and microbiological processes and their associated dynamics in a combined approach. Accordingly, the paper addresses the recent applications of cutting-edge biogeochemical and biological methods adopted by different countries to sketch an emerging perspective of landfill biological and biogeochemical reactions and dynamics. Additionally, the significance of several regulatory factors controlling the landfill's biogeochemical and biological processes is highlighted. Finally, this article emphasizes the future opportunities for integrating advanced techniques to explain landfill chemistry explicitly. In conclusion, this paper will provide a comprehensive vision of the diverse dimensions of landfill biological and biogeochemical reactions and dynamics to the scientific world and policymakers.

Destruction and defluorination of PFAS matrix in continuous-flow supercritical water oxidation reactor: Effect of operating temperature

Cleanup and disposal of stockpiles and waste streams containing per- and polyfluoroalkyl substances (PFAS) require effective end-of-life destruction/mineralization technologies. Two classes of PFAS, perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs), are commonly found in legacy stockpiles, industrial waste streams, and as environmental pollutants. Continuous flow supercritical water oxidation (SCWO) reactors have been shown to destroy several PFAS and aqueous film-forming foams. However, a direct comparison of the SCWO efficacy for PFSAs and PFCAs has not been reported. We show the effectiveness of continuous flow SCWO treatment for a matrix of model PFCAs and PFSAs as a function of operating temperature. PFSAs appear to be significantly more recalcitrant than PFCAs in the SCWO environment. The SCWO treatment results in a destruction and removal efficiency of 99.999% at a T > 610 °C and at a residence time of ∼30 s. Fluoride recovery lags destruction PFAS at 510 °C and reaches >100% above 610 °C, confirming the formation of liquid and gaseous phase intermediate product during lower temperature oxidation. This paper establishes the threshold for destroying PFAS-containing liquids under SCWO conditions.

Environmental assessment of a novel ionic-liquid based method for recycling of PVC in composite materials

Waste PVC is scarcely recycled due to its high chlorine content and its use in composite materials, which reduces the applicability of conventional waste treatment methods, including thermal, mechanical and chemical recycling. For this reason, alternative treatment options are being developed to increase the recyclability of waste PVC. This paper focuses on one such option which utilises ionic liquids (ILs) for material separation and dehydrochlorination of PVC contained in composite materials. Taking blisterpacks used as a packaging for medicines as an example of a composite material, the paper presents for the first time the life cycle environmental impacts of this novel PVC recycling method, in comparison with thermal treatment (low-temperature pyrolytic degradation of PVC). Three ILs were considered for the PVC recycling process: trihexyl(tetradecyl)phosphonium chloride, bromide and hexanoate. The results suggested that the impacts of the process using the first two ILs were comparable, while the system with hexanoate-based IL had 7-229 % higher impacts. Compared to the thermal treatment of waste blisterpacks, the IL assisted process had significantly higher impacts (22-819 %) in all 18 categories considered due to the greater heat requirements and the IL losses. Reducing the latter would lower most impacts by 8-41 %, while optimising the energy requirements would reduce the impacts by 10-58 %. Moreover, recovering HCl would increase significantly the environmental sustainability of the process, resulting in net-negative impacts (savings) in most categories. Overall, these improvements would lead to lower or comparable impacts to those of the thermal treatment. The findings of this study will be of interest to the polymer, recycling and related industries, as well as to process developers.

Implementation of life cycle analysis on green tea process

This study examines the life cycle analysis of the manufacturing of 1 kg of green tea using various disposal techniques, including landfill procedure, incineration, and modification of green tea waste as an adsorbent for heavy metal removal. OpenLCA is used to produce the evaluation. To identify the objectives and scope, inventory analysis, effect, and interpretation, the assessment process corresponds to ISO 14044 of 2006. AGRIBALYSE version 3 is the database used to evaluate the environmental effects. A reference unit called a DALY is used to study the environmental impact. For the LCA of green tea, there were four main effect categories that were taken into consideration: human carcinogenic toxicity, human non-carcinogenic toxicity, global warming (human health), and fine particle creation. The outcome demonstrates that processing 1 kg of green tea waste has an environmental effect that is around 63% greater than incinerating it and roughly 58% higher than dumping it in a landfill. However the ecology is more affected by the adsorption process than by landfill and incineration of green tea waste. Even yet, if the preparation is done in bulk, the process can be improved by altering the adsorption of green tea waste.

Size-resolved characterization of particles >10 nm emitted to air during metal recycling

BACKGROUND

In the strive towards a circular economy, metal waste recycling is a growing industry. During the recycling process, particulate matter containing toxic and allergenic metals will be emitted to the air causing unintentional exposure to humans and environment.

OBJECTIVE

In this study detailed characterization of particle emissions and workplace exposures were performed, covering the full size range from 10 nm to 10 µm, during recycling of three different material flows: Waste of electrical and electronic equipment (WEEE), metal scrap, and cables.

METHODS

Both direct-reading instruments (minute resolution), and time-integrated filter measurements for gravimetric and chemical analysis were used. Additionally, optical sensors were applied and evaluated for long-term online monitoring of air quality in industrial settings.

RESULTS

The highest concentrations, in all particle sizes, and with respect both to particle mass and number, were measured in the WEEE flow, followed by the metal scrap flow. The number fraction of nanoparticles was high for all material flows (0.66-0.86). The most abundant metals were Fe, Al, Zn, Pb and Cu. Other elements of toxicological interest were Mn, Ba and Co.

SIGNIFICANCE

The large fraction of nanoparticles, and the fact that their chemical composition deviate from that of the coarse particles, raises questions that needs to be further addressed including toxicological implications, both for humans and for the environment.

Does the initial C/N ratio interfere with the performance of sewage sludge composting and cotton waste?

The effects of the initial C/N ratio on the composting of sewage sludge and cotton residues are not reported in the literature. Understanding the main composting control parameters is essential for the good stabilization of these wastes. Therefore, this study sought to evaluate different initial C/N ratios for the composting of sewage sludge and cotton waste, aiming to find the ranges with the best performance for the process and quality of the final organic compost. In this sense, five mixtures of sewage sludge (S) and cotton residues (C) were prepared and composted with three replications for each treatment in a completely randomized design. Physicochemical parameters were evaluated during composting and in the final organic compounds. A Multivariate Principal Component Analysis (PCA) was applied to evaluate the agronomic quality of organic compounds. The thermal behaviour of the mixtures presented differences. The treatments 90C10S, 80C20S and 67C33S showed the highest EXI² index (3566.64, 3448.39 and 2738.89), longer duration of thermophilic phase (12 and 13 days) and better potential for maximum degradation (A) of organic matter (67.5, 61.2 and 65.6%C). The final compounds of 90C10S and 80C20S showed higher pH values (7.9 and 7.5) and higher CEC (123.6 and 114.0 meq/100 g OM). PCA showed similarity in the agronomic quality of organic compounds for 90C10S, 80C20S and 67C33S. The treatment 28C72S (initial C/N ratio of 16.6) presented final pH of 5.3 and did not meet the minimum limit required by Brazilian regulations. Initial C/N relations between 24.9 and 35.2 showed better stabilization of waste and final organic compound with better agronomic quality.

Reuse of waste cooking oil (WCO) as diluent in green emulsion liquid membrane (GELM) for zinc extraction

Zinc (Zn) was identified as one of the most toxic heavy metals and often found contaminating the water sources as a result of inefficient treatment of industrial effluent. A green emulsion liquid membrane (GELM) was proposed in this study as a method to minimize the concentration of Zn ions in an aqueous solution. Instead of the common petroleum-based diluent, the emulsion is reformulated with untreated waste cooking oil (WCO) collected from the food industry as a sustainable and cheaper diluent. It also includes Bis(2-ethylhexyl) phosphate (D2EHPA) as a carrier, Span 80 as a surfactant, sulfuric acid (H2SO4) as an internal phase, and ZnSO4 solution as an external phase. Such formulation requires a thorough understanding of the oil characteristics as well as the interaction of the components in the membrane phase. The compatibility of WCO and D2EHPA, as well as the external phase pH, was confirmed via a liquid-liquid extraction (LLE) method. To obtain the best operating conditions for Zn extraction using GELM, the extraction time and speed, carrier, surfactant and internal phase concentrations, and W/O ratio were varied. 95.17% of Zn ions were removed under the following conditions; 0.001 M of H2SO4 in external phase, 700 rpm extraction speed for 10 min, 8 wt% of carrier and 4 wt% of surfactant concentrations, 1:4 of W/O ratio, and 1 M of internal phase concentration.

A bi-level optimized approach for promoting the mixed treatment of municipal sludge and food waste

The mixed treatment of municipal sludge and food waste can generate renewable energy, solve the environmental and economic challenges caused by this waste, and has attracted significant research attention. Using environmentally friendly anaerobic co-digestion of municipal sludge and food waste can improve the effects of anaerobic mono-digestion and produce more biogas. However, as the municipal sludge and food waste managers are different, balancing the interests of both managers is needed to encourage anaerobic co-digestion development. By fully considering the interests of the local authority, the waste water treatment plants, and the food waste anaerobic digestion treatment plants, this paper developed a bi-level optimization approach based on Stackelberg equilibrium theory to resolve the conflicts between the different stakeholders, in which uncertain parameters were used to describe the uncertainties. The proposed model was then applied to a real case in Chongqing, China, to test its practicality, and scenario analyses under different policy parameter values were conducted to provide guidance for local authorities, waste water treatment plants, and food waste treatment plants. The proposed approach was found to provide balanced strategies for all three stakeholders, increase the renewable energy output of municipal sludge and food waste treatment 14.2 times, and reduce carbon emissions by 50%, thereby protecting the environment and achieving a circular economy.

Upcycling textile waste using pyrolysis process

Rapidly changing fashion trends have generated tremendous amounts of textile waste globally. Textile waste is composed of a variety of substances (natural, synthetic, organic, and inorganic fibers). The inhomogeneity and complex nature of textile waste makes recycling economically challenging. Pyrolysis is a thermochemical process that transforms waste feedstocks of an inhomogeneous and complex nature into value added products (i.e., waste upcycling). This article provides a systematic review of the currently available and investigated pyrolysis processes to upcycle textile waste (e.g., material and energy recovery). The challenges in the pyrolysis process of textile waste are discussed, and relevant future research needs are recommended. Despite these challenges, pyrolysis will be an effective end-of-life option for textile waste if continuous research and development activities are conducted.

Design of a modular controlled unit for the study of bioprocesses: Towards solutions for Bioregenerative Life Support Systems in space

Space exploration beyond the Low Earth Orbit requires the establishment of Bioregenerative Life Support Systems (BLSSs), which, through bioprocesses for primary resource recycling, ensure crew survival. However, the introduction of new organisms in confined space habitats must be carefully evaluated in advance to avoid unforeseen events that could compromise the mission. In this work, we have designed and built an experimental chamber, named Growing/Rearing Module (GRM), completely isolated and equipped with micro-environmental monitoring and control systems. This unit is specially intended for the study of single bioprocesses, which can be composed to design functional BLSSs. GRM can be implemented with specific devices for the biological system under study and the control of environmental parameters such as temperature, humidity, lighting and if required, pressure of gaseous components. GRM was validated in experiments of both microgreen cultivation, as a source of fresh food for astronauts, and rearing of the decomposer insect Hermetia illucens for bioconversion of organic waste. During the study of each bioprocess, the environmental and biological data were recorded, allowing to make preliminary assessments of the system efficiency. The GRM, as a completely confined environment, represents the first self-consistent unit that allows to fine-tune the optimal parameters for the operability of different bioprocesses. Furthermore, the upgradability according to the mission needs and the functional integrability of modules differently equipped are the keys to GRM versatility, representing a valuable tool for BLSSs' design.

Recent achievements in platform chemical production from food waste

Food waste conversion/valorization to produce bio-based chemicals plays a key role toward achieving carbon neutrality by 2050. Food waste valorization to renewable chemicals is thus an attractive and eco-friendly approach to handling food waste. The production of platform chemicals from food waste is crucial for making highly value-added renewable chemicals. However, earlier reviews dealing with food waste valorization to produce value-added chemicals have emphasized the enhancement of methane, hydrogen, and ethanol production. Along these lines, the existing methods of food waste to produce platform chemicals (e.g., volatile fatty acids, glucose, hydroxymethylfurfural, levulinic acid, lactic acid, and succinic acid) through physical, chemical, and enzymatic pretreatments, hydrolysis, fermentation, and hydrothermal conversion are extensively reviewed. Finally, the challenges faced under these methods are discussed, along with suggestions for future research on platform chemical production from food waste.

The occurrence, distribution and removal of adsorbable organic halogens (AOX) in a typical fine chemical industrial park

Coastal water quality in China has been impacted by direct discharge of industrial wastewater, and various kinds of AOX pollutants have been detected in the seawater and sediment. As the dominant pollution source of Hangzhou Bay, a typical fine chemical industry park "HSEDA" was selected as the study area in this research. The AOX in both wastewater and sludge phases from 22 large-scaled enterprises were simultaneously investigated. The results quantitatively illustrated the AOX flows from engineered wastewater and sludge treatment systems to natural environment. It can be seen that industrial enterprises discharged at least 160 t AOX every year, and about 105.4 t/a AOX eventually entered the natural environment. The dye manufacturing industry, which accounted for more than 60% of the total AOX emission load in HSEDA, was identified as the AOX pollution-intensive sector. The occurrence, characteristic pollutants and fate of AOX in dye wastewater were discussed, on the basis of which the improvements of cleaner production and wastewater treatment technologies have been put forward.

The study of the performance of a microbial fuel cell: a progress towards the improvement of low electrical bioenergy output by using an amplification system

OBJECTIVE

A microbial fuel cell (MFC) has been conceived and constructed for the treatment of the sheep manure wastes and their conversion into clean sustainable renewable energy. The aim of the present investigation was to examine the performance of this bioelectrochemical device, in breaking down the organic matter (pollutant removal) and simultaneously producing electricity. Furthermore, the objective was to enhance the low electric energy by using an adequate amplification system.

RESULTS

So, the chemical oxygen demand (COD) removal was increased by 58.7% with the MFC running for 10 days. However, this technology faces practical barriers as it produces low electrical energy. A power management system was therefore elaborated in this respect. It included the MFC, operational amplifier (OA), solar photovoltaic panel and a boost DC/DC converter. The low voltage output obtained was thus increased substantially using the OA prior to its polarization by the solar photovoltaic module. The amplified voltage was sufficiently enough and in consequence, utilized to feed a light emitting diode. The low output voltage 0.5 V was simply harvested, successfully boosted up to approximately 2 V (i.e. 4 times higher) and finally harnessed as a power supply.

CONCLUSIONS

The MFCs association shows the positive stacking effect successfully, when the cells were connected in parallel. This novel application is very interesting to utilize the natural bioenergy contained in wastes to supply small electronic devices.

Briquette production from a mixture of biomass: poultry slaughterhouse sludge and sawdust

This study refers to the development of hybrid briquettes using centrifuged sludge from the wastewater treatment of poultry and sawdust from furniture industry. The aim was to evaluate the performance of briquettes as a source of thermal energy, mitigating the risks of the current elimination and reducing the operational costs of their destination. To know the oxidizing characteristics of the briquettes and their mechanical resistance, superior calorific power, ash content, volatile materials, fixed carbon, and resistance to axial compression were evaluated. Thermogravimetric and differential exploratory calorimetry analyses were performed. Statistical treatments were carried out to verify the most significant factors to produce briquettes, the best proportions of the raw materials, and to evaluate whether there is interference from moisture and glue flour used as a binder. The best condition of the sludge-sawdust mixture was 15% and 85%, respectively, with 6.0% moisture. The best-case treatment had 23.82-MPa mechanical resistance, a calorific value of 17.20 MJ kg^-1, and a density of 1374.15 kg m^-3.

Correlation of microbial dynamics to odor production and emission in full-scale sewage sludge composting

Odor is inevitably produced during sewage sludge composting, and the subsequent pollution hinders the further development of composting technologies. Third-generation high-throughput sequencing was used to analyze microbial community succession, and the correlations between odor and microbial communities were evaluated. Hydrogen sulfide (47.5-87.9 %) and ammonia (9.4-49.9 %) contributed majorly to odor emissions, accounting for 93.7-98.5 % of the emissions. Volatile sulfur compounds were mainly produced in the mesophilic and pre-thermophilic phases (43.0-83.4 %), whereas ammonia was mainly produced in the thermophilic phase (52.1-59.4 %). Microorganisms dominant in the mesophilic and thermophilic phases correlated positively with odor production in the following order: Rhodocyclaceae > Clostridiaceae_1 > Hyphomicrobiaceae > Acidimicrobiales > Family_XI, whereas those dominant in the cooling phase showed negative correlations with odor production in the following order: Bacillus > Sphingobacteriaceae > Pseudomonadaceae > DSSF69 > Chitinophagaceae. The back mixing of mature compost is expected to serve as an economical measure for controlling odor during sewage sludge composting.

Improving the quality of organic compost of sewage sludge using grass cultivation followed by composting

Composting is one of the main processes of stabilization of sewage sludge and its association with cultivation in this residue has a great potential to produce stabilized organic fertilizer and, or substrate for plant development. The aim of this work was to evaluate the physical, chemical, and microbial attributes of sewage sludge (SS) aerated and cultivated with Pennisetum purpureum or Urochloa brizantha and, later, composted. The study was installed in a 2x2+2 factorial scheme, with four replications. The factors consisted of cultivation of P. purpureum or U. brizantha in SS for 90 days, with or without intermittent aeration for 60 days. The control treatments were SS without cultivation, with the presence or absence of aeration. After 90 days of cultivation, the grass was cut, crushed, and incorporated into the SS for composting for 60 days. The composted sewage sludge showed an increase of 26, 24, 17, 123, 19, 32, and 7.7% in the levels of P, Ca, Cu, Fe, Mn, Zn, and Pb; and a reduction of 22, 5.2, 26, 30, 8.8, and 70% in the levels of C, N, K, Mg, Ni, and Na, respectively. The levels of Cu, Ni, Zn, and Pb remained below the maximum limit allowed by environmental resolution. The degradation of SS decreased the particle diameter, increasing the bulk density and total porosity, improving the physical properties of the compost. The SS cultivation and composting, regardless of the grass, led to a reduction in pH, basal and accumulated respiration, nitrification index, and C/N ratio and an increase in the CEC/C ratio, showing adequate maturation of the compost produced. Thus, the SS cultivation and composting with grasses were effective for producing matured and quality organic compost with low risk of environmental contamination.

Integration of steam gasification and catalytic reforming of lignocellulosic biomass as a strategy to improve syngas quality and pollutants removal

Residual biomass gasification is a promising route for the production of H₂-rich syngas. However, the simultaneous formation of pollutants such as light hydrocarbons (HCs), benzene, toluene and xylenes (BTEX), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during gasification must be controlled. As a result, this study evaluated the effect of temperature and catalytic reforming over a Rh-Pt/CeO₂-SiO₂ catalyst during steam gasification of sugarcane residual biomass on syngas composition and pollutant removal. The above was carried out in a horizontal moving reactor, an Amberlite XAD-2 polyaromatic resin was used to collect the contaminants and characterization of the catalyst was performed. In this study, a concentration of up to 37 mol% of H₂, a yield of 23.1 g H₂ kg^-1_biomass, and a H₂/CO ratio ≥2 were achieved when gasification and reforming were integrated. In addition, the catalyst characterization showed that Rh-Pt/CeO₂-SiO₂ was not susceptible to sintering and favored the formation of hydroxyl groups that promoted CO oxidation, thereby increasing the H₂/CO ratio, as confirmed by in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). At 800 °C, where a high H₂ yield was obtained, 209 g Nm^-3 of light HCs and BTEX, 10.9 g Nm^-3 of PAHs, and 32.5 ng WHO-TEQ Nm^-3 of PCDD/Fs were formed after gasification. Interestingly, after catalytic reforming, 62% of light HCs and BTEX, 60% of PAHs, and 94% of PCDD/Fs were removed, leading to cleaner syngas with properties that allow it to be used in a wide range of energy applications.

Designing a fuzzy decision support framework for assessing solid waste management in the South European region

The environmental planning of cities and rural regions is associated with monitoring the performance of several services, including solid waste management. This study proposes a new framework for the comparative assessment of the performance of integrated municipal solid waste management. The framework includes the fuzzy MACBETH multi-criteria decision-making model used to investigate the uncertainties and inefficiencies associated with solid waste management systems. The model consists of all major stages in solid waste management and its environmental impact. The applicability of the model was examined in the South European region. According to the global fuzzy values of the criteria weights, the most influential reported criteria were GHG emission (0.113,0.157,0.202), the waste generation growth rate (0.034,0.063,0.141), and waste generation (0.034,0.054,0.127). The other results indicated that Italy (47.26) and France (42.67) had shown a better performance, only to be followed by Spain (37.68), whereas Greece (15.77) and Portugal (12.85) had received the lowest score. In the context of promoting the circular economy in Europe, having a higher recycling rate and less landfilling is beneficial for Greece and Portugal. In addition to this, all these countries should make efforts on decoupling the waste generation-GDP correlation. Furthermore, the applicability of the model depends on an appropriate scale and criteria. The model can be replicated to other developed societies with a few modifications. However, it is necessary to modify the criteria for assessing developing societies based on local conditions.

The role of (bio)degradability on the management of petrochemical and bio-based plastic waste

In order to mitigate the social and ecological impacts of post-consumer plastic made of conventional petrochemical polymers, the market of (bio)degradable plastics have recently become more widespread. Although (bio)degradable plastics could be an environmentally friendly substitute of petrochemical ones, the consequences of their presence in the waste management system and in the environment (if not correctly disposed) are not always positive and plastic pollution is not automatically solved. Consequently, this work aims to review how plastic (bio)degradability affects the municipal solid waste management cycle. To this end, the state-of-the-art of the intrinsic (bio)degradability of conventional and unconventional petrochemical and bio-based polymers has been discussed, focusing on the environment related to the waste management system. Then, the focus was on strategies to improve polymer (bio)degradability: different types of eco-design and pre-treatment approach for plastics has been investigated, differently from other works that focused only on specific topics. The information gathered was used to discuss three typical disposal/treatment routes for plastic waste. Despite many of the proposed materials in eco-design have increased the plastics (bio)degradability and pre-treatments have showed interesting results, these achievements are not always positive in the current MSW management system. The effect on mechanical recycling is negative in several cases but the enhanced (bio)degradability can help the treatment with organic waste. On the other hand, the current waste treatment facility is not capable to manage this waste, leading to the incineration the most promising options. In this way, the consumption of raw materials will persist even by using (bio)degradable plastics, which strength the doubt if the solution of plastic pollution leads really on these materials. The review also highlighted the need for further research on this topic that is currently limited by the still scarce amount of (bio)degradable plastics in input to full-scale waste treatment plants.

Mechanism of pH sensitive flocculation for organic load and colour reduction in landfill leachate

Landfill leachate has an important fraction of humic substances, mainly humic acids (HAs), which often represent more than half value of COD, specially in liquids proceeded from composting processes of organic fraction of solid wastes. We propose in this article a new method of pH sensitive flocculation for COD and colour reduction in landfill leachate based on the chemical properties of HAs. Landfill leachate with a high content of humic acids can be efficiently treated by pH sensitive flocculation at pH 2.0, reducing COD value in 86.1% and colour in 84.7%. Mechanism of pH sensitive flocculation is based in protonation first of phenolic groups and later of carboxylic acid groups in the HAs molecules, resulting in a reduction of Zeta potential value. For pH over neutrality, carboxylic acid and phenolic groups are ionized and Zeta potential increases in absolute value, maintaining HAs in suspension as colloids and conducting flocculation to be obstructed. Ionized anionic groups (carboxylates) can interact electrostatically with cations abundant in leachate (site binding) aiding to maintain HAs in suspension. Simulation of this situation and ideal visualization of Zeta potential behavior is described in the paper and aggregation of molecules by H-bonds is proposed as the main step in separation of HAs from leachate and reduction of COD value in this complex liquid. CHNS analysis, FT-IR spectrometry and UV-VIS spectrophotometry show chemical elements content in the range of natural and commercial HAs, clear aromaticity and carboxylic acids and phenolic groups presence in the precipitate from landfill leachate.

Chemical looping gasification using Nickel-containing electroplating sludge and dyeing sludge as oxygen carrier

Nickel-containing electroplating sludge (NiES) and dyeing sludge (DS) were used to prepare oxygen carriers (OCs) for chemical looping gasification (CLG) of DS. X-ray diffraction (XRD), surface area and porosity analysis were employed to investigate the crystal structure and pore structure of NiES and DS ash OCs. It was found that OCs prepared at 850 ℃ for 8 h (850NiES8, 850DS8) exhibited good characteristics in terms of pore structure. X-ray fluorescence (XRF), hydrogen temperature programmed reduction (H2-TPR) and thermo-gravimetric (TG) were employed to explore the elemental composition, reactivity, redox behavior and their effect on DS pyrolysis of the two selected OCs. The influence of mass ratio of 850NiES8, 850DS8 to DS (850NiES8/DS, 850DS8/DS) and reaction temperature on DS CLG were investigated. It showed that the addition of two OCs significantly promoted the gas yield of DS while accelerating the gasification process. It showed a better performance of 850NiES8 than that of 850DS8 when it was below 900 ℃. On the other side, 850DS8 showed more advantage between 900 and 950 ℃. And high carbon conversion (ηC) of 80.94%,77.59% and acceptable valid gas yield (Vg) of 0.192,0.190 Nm3/kg could be obtained at 850 ℃ when 850NiES8/DS, 850DS8/DS were 1, respectively. In this process, the reduction and energy recovery of dyeing sludge were implemented, and two promising OCs (850NiES8, 850DS8) were developed. In addition, a new harmless method of NiES recycle treatment was also provided.

Environmental and economic benefits of electric, hybrid and conventional vehicle treatment: A case study of Lithuania

Reuse, recovery, and recycling of end-of-life vehicles (ELVs) are encouraged owing to various economic and environmental benefits. Automotive remanufacturing serves as a specific circular marketing system for the reuse of recovered parts that can bring economic benefits for both dismantling companies and consumers. This study aimed to reveal the economic and environmental benefits of the end-of-life treatment of electric, hybrid, and conventional passenger cars. This research presents an economic assessment of the reuse of ELV parts based on a material flow analysis (MFA) and a practical analysis of the prices of these parts in the Lithuanian market. The environmental assessment of the reuse of ELV parts was performed using an MFA, the CO₂ equivalents for the production of different materials, and a life cycle assessment methodology. The results showed that 38% of all electric and hybrid ELV parts, and 27% and 28% of diesel- and petrol-powered ELV parts, respectively, can be sold (reused). The economic benefit across all four types of ELVs could amount to savings of up to 12,739 Eur and 51,281 Eur for the dismantlers and passenger car consumers, respectively. The greatest CO₂ savings result from reusing the parts of electric ELVs, whilst the lowest savings come from petrol ELVs.

Assessing the externalities of a waste management system via life cycle costing: The case study of the Emilia-Romagna Region (Italy)

Effective and efficient urban waste management systems (WMSs) are a cornerstone for a sustainable society. Life cycle costing (LCC) provides a useful framework for the joint analysis of economic and environmental impacts of a WMS, by considering both financial and external costs. The present study applies the methodology of societal LCC to the WMS of the Italian region of Emilia-Romagna to provide a case study on how the available information on waste flows and budget costs of a real WMS can be used to obtain an estimate of the total cost of waste management, including externalities. The results evidence that the main source of negative externality in the analyzed WMS is the transportation of waste, with only a minor role of external burdens due to incinerators and landfills. However, the positive externality resulting from recycling more than compensates those impacts, leading to a net external benefit associated to the WMS. The contribution of both uncertain unit external costs and environmental benefits imputable to recycled materials to the overall uncertainty of the result is systematically investigated by parametric uncertainty analysis. The most critical parameters in determining the sensitivity of the result are the monetary values attributed to primary energy consumption and CO2 emissions, together with assumptions on energy savings related to recycling. Eventually, it is shown how the developed LCC model can be used as decision-support tool to preliminarily investigate the implications of alternative management options on the financial and external costs of the WMS.

Enhanced solar light photocatalytic performance of Fe-ZnO in the presence of H2O2, S2O82-, and HSO5- for degradation of chlorpyrifos from agricultural wastes: Toxicities investigation

This study reported Fe doped zinc oxide (Fe-ZnO) synthesis to degrade chlorpyrifos (CPY), a highly toxic organophosphate pesticide and important sources of agricultural wastes. Fourier transform infrared, X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectroscopic analyses showed successful formation of the Fe-ZnO with highly crystalline and amorphous nature. Water collected from agricultural wastes were treated with Fe-ZnO and the results showed 67% degradation of CPY by Fe-ZnO versus 39% by ZnO at 140 min treatment time. Detail mechanism involving reactive oxygen species production from solar light activated Fe-ZnO and their role in degradation of CPY was assessed. Use of H₂O₂, peroxydisulfate (S₂O₈^2-) and peroxymonosulfate (HSO₅^-) with Fe-ZnO under solar irradiation promoted removal of CPY. The peroxides yielded hydroxyl (OH) and sulfate radical () under solar irradiation mediated by Fe-ZnO. Effects of several parameters including concentration of pollutant and oxidants, pH, co-existing ions, and presence of natural organic matter on CPY degradation were studied. Among peroxides, HSO₅^- revealed to provide better performance. The prepared Fe-ZnO showed high reusability and greater mineralization of CPY. The GC-MS analysis showed degradation of CPY resulted into several transformation products (TPs). Toxicity analysis of CPY as well as its TPs was performed and the formation of non-toxic acetate imply greater capability of the treatment technology.

Diffusion simulation, health risks, ozone and secondary organic aerosol formation potential of gaseous pollutants from rural comprehensive waste treatment plant

Comprehensive waste treatment plants (CWTPs) are significant sources of gaseous pollutants such as odors, volatile organic compounds (VOCs) and nitrogen oxides (NOx), polluting the environment and endangering human health. This study conducted on-site investigations on gaseous pollutants emissions from different areas of a CWTP. A total of 10 pollutants were identified of which ammonia (11.32 mg/m³ in average) was the main odorous substance, and benzene (19.51 mg/m³ in average) and toluene (42.07 mg/m³ in average) were the main VOCs. The feeding workshop (FW) was considered the main source of gaseous pollutants. The Gaussian plume model demonstrated that the pollution became more serious after spreading in the southeast downwind direction. Occupational exposure risks of on-site workers were mainly attributed to hydrogen sulfide, ammonia, benzene, and toluene, as their hazard index (HI) and lifetime cancer risk (CR) exceeded the recommended occupational safety limits. The gaseous pollutants diffused from CWTP may still pose a potential health risk to residents within a range of up to 7.5 km. The emulation and quantification of ozone formation potential by methods of Propyl-Equiv and MIR demonstrated that the contribution rate of toluene presented in each stage of CWTP exceed 80 %. Toluene was also the largest contributor to secondary organic aerosol with the contribution rate reached 56.34-85.14 %, followed by benzene (14.72-38.52 %). This research provides a basis for the reduction and control of gaseous pollutants in the treatment and disposal of rural domestic waste.

Selective and highly efficient removal of uranium from radioactive effluents by activated carbon functionalized with 2-aminobenzoic acid as a new sorbent

The purpose of this study was modification of activated carbon (AC) to prepare a new selective sorbent for removal of uranium ion. The modification was performed by introducing carboxyl groups onto AC using ammonium persulfate (APS) in sulfuric acid solution followed by functionalization with 2-aminobenzoic acid (ABA) as a selective ligand for U (VI) ion (UO₂²⁺) adsorption. The characterization of the synthetized sorbent (AC-ABA) was carried out through several methods including potentiometry, scanning electron microscopy, energy dispersive spectroscopy, x-ray diffraction and FT-IR to confirm successful functionalization of the sorbent surface with oxygen and amine groups. The sorption of U (VI) on the unmodified AC and AC-ABA was investigated as a function of contact time, sorbent content, initial uranium concentration, solution pH, and temperature using batch sorption technique. In addition, the effect of various parameters on the U (VI) sorption capacity was optimized by the response surface methodology as a potent experimental design method. The results indicated that sorption of U (VI) under the optimal conditions was significantly improved onto AC-ABA compared to AC. Kinetic studies displayed that the sorption process reached equilibrium after 100 min and followed the pseudo-second-order rate equation. The isothermal data fitted better with the Langmuir model than the Freundlich model. The maximum sorption capacity of AC-ABA for U(VI) was obtained to be 194.2 mg g^-1 by the Langmuir model under optimum conditions, which demonstrates the sorption capacity has been improved by the modification process. The thermodynamic parameters (ΔH, ΔS and ΔG) indicated that sorption of uranium onto AC-ABA was an endothermic and spontaneous process. The sorption studies on radioactive effluents of the nuclear fuel plant represented high selectivity of AC-ABA for removal of uranium in the presence of other metal ions, and the selectivity coefficients significantly improved after modification of the sorbent. Application of AC-ABA for treatment of industrial effluents containing heavy and radioactive metal ions show high potential and capability of the proposed method.

Application of biodegradable cellulose-based biomass materials in wastewater treatment

Water bodies contain a large number of harmful environmental pollutants, including oil, heavy metal ions and dyes, which has become a major global problem. The current work focusses on the development and future prospect of sustainable application of biodegradable cellulose-biomass materials in water treatment, considering that they show an important prospect in wastewater treatment. This paper summarizes the advantages and disadvantages of cellulose-biomass materials in removing harmful substances and pollutants from water and the key problems the technology faces. Cellulose-biomass material has unique structure, is environment friendly, degradable, renewable and provides low energy cost benefits, among other advantages. In this paper, the research progress of wastewater treatment in recent years is reviewed from the following three aspects: oil-water separation, heavy metal ions in water, and dye adsorption. The future research direction is also discussed.

Achievements in pyrolysis process in E-waste management sector

Many aspects of modern life of our civilization are associated with using electrical and electronic devices (EEE). Ever-increasing demand for high-performance EEE and accelerated technological development make the replacement of EEE become frequent. This leads to the generation of a tremendous amount of electronic waste (E-waste). Challenges of the management of E-waste have recently arisen out of a dearth of proper technologies to treat E-waste. Pyrolysis process can thermochemically treat waste materials that have a complicated nature and inhomogeneity. This article gives a systematic review as an effort to tackle the challenges in the context of achievements in pyrolysis process in E-waste management sector. Pyrolysis mechanism and types of pyrolysis processes and pyrolysis reactors are first discussed. Various pyrolysis technologies applied to the E-waste treatment are then summarized and compared to each other. Points to be considered for further research and pending challenges of E-waste pyrolysis are also discussed. The pyrolysis treatment of E-waste is not yet fully industrialized mostly because of high costs. However, there should be much room for further developing the E-waste pyrolysis; hence, its industrialization and commercialization is just a matter of time.

Production of value-added aromatics from wasted COVID-19 mask via catalytic pyrolysis

In this study, wasted mask is chosen as a pyrolysis feedstock whose generation has incredibly increased these days due to COVID-19. We suggest a way to produce value-added chemicals (e.g., aromatic compounds) from the mask with high amounts through catalytic fast pyrolysis (CFP). To this end, the effects of zeolite catalyst properties on the upgradation efficiency of pyrolytic products produced from pyrolysis of wasted mask were investigated. The compositions and yields of pyrolytic gases and oils were characterized as functions of pyrolysis temperature and the type of zeolite catalyst (HBeta, HY, and HZSM-5), including the mesoporous catalyst of Al-MCM-41. The mask was pyrolyzed in a fixed bed reactor, and the pyrolysis gases evolved in the reactor was routed to a secondary reactor inside which the zeolite catalyst was loaded. It was chosen 550 °C as the CFP temperature to compare the catalyst performance for the production of benzene, toluene, ethylbenzene, and xylene (BTEX) because this temperature gave the highest oil yield (80.7 wt%) during the non-catalytic pyrolysis process. The large pore zeolite group of HBeta and HY led to 134% and 67% higher BTEX concentrations than HZSM-5, respectively, likely because they had larger pores, higher surface areas, and higher acid site density than the HZSM-5. This is the first report of the effect of zeolite characteristics on BTEX production via CFP.

Characterization of the separately collected organic fraction of municipal solid waste (OFMSW) from rural and urban districts for a one-year period in Germany

Knowledge on material properties is beneficial to fully exploit inherent utilization potentials of the organic fraction of municipal solid waste (OFMSW). The objective of this study was to analyze and compare the physico-chemical characteristics of separately collected OFMSW (biowaste bin) originating in southwestern Germany. Therefore, 22 rural and 20 urban OFMSW samples, each from the same location were analyzed in the course of one year. Next to the basic characteristics such as the impurity, dry matter (DM) and organic dry matter (oDM) contents, this study focused on the analysis of 37 major, minor and trace elements. In addition, stoichiometric CH₄ potentials for the anaerobic digestion were calculated. The fresh mass (FM) based DM contents were significantly (p = 0.001) higher in rural OFMSW (32.86 ± 2.35% vs. 30.50 ± 1.75%) while the DM based oDM content was higher (p = 0.07) in urban OFMSW (84.59 ± 3.90% vs. 82.22 ± 4.16%). The impurities in rural OFMSW were significantly lower (2.83 ± 1.67% DM vs. 5.07 ± 2.71% DM with p = 0.004) while oDM based CH₄ potentials were higher for urban OFMSW (533 ± 22 L/kg vs. 519 ± 26L/kg). For both OFMSW types, contents >1000 mg/kgDM were detected for Ca, K, Si, Na, Al, Fe, Mg, P and S while Ti, Mn, Ba, Zn, Sr, Cr, Cu, V, Ni, Li, Pb and B were measured between 1 and 1000 mg/kgDM. The determined element concentrations are useful for an improved classification of OFMSW as a biorefinery resource.

Regional waste footprint and waste treatments analysis

This paper provides a detailed analysis of the waste footprint and waste treatments at subnational level, for Brussels, Flanders, and Wallonia. The paper details the waste footprint components into direct waste from households (disposed in bins), indirect waste generated upstream in the supply chains and induced by household consumption and waste materials from the degradation of in-use stocks. For each component, we analysed the contribution of waste types, products consumed and location where the waste was generated, as well as the associated treatments. The results show that Flanders had the highest total waste footprint in absolute terms; Brussels the highest direct waste in capita terms and Wallonia the highest indirect waste and stock depletion in capita terms. In each region, almost 78 ± 2% of the regional waste footprints were attributed to the consumption of food products, manufactured products and restaurants and accommodation services. For each region, around 45 ± 4% of the indirect waste was generated within its boundaries, 16 ± 9% in other regions and 39 ± 5% out of Belgium. Incineration was the predominant waste treatment type of the regional waste footprint, followed by recycling. Landfill was the second widely applied treatment for indirect waste. Results constitute key information relevant to enhance the waste data monitoring practices at regional level with effects at national level. We unveiled the waste footprint and associated treatments inherent to the interregional and international linkages. Results are also useful resources to substantiate waste management and circular economy policies, enacting on waste prevention and reduction, ecodesign and product lifetime extension.

Occurrence and risk assessment of pharmaceuticals and cocaine around the coastal submarine sewage outfall in Guarujá, São Paulo State, Brazil

The aim of this study was to screen and quantify 23 pharmaceutical compounds (including illicit drugs), at two sampling points near the diffusers of the Guarujá submarine outfall, State of São Paulo, Brazil. Samples were collected in triplicate during the high (January 2018) and low (April 2018) seasons at two different water column depths (surface and bottom). A total of 10 compounds were detected using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Caffeine (42.3-141.0 ng/L), diclofenac (3.6-85.7 ng/L), valsartan (4.7-14.3 ng/L), benzoylecgonine (0.3-1.7 ng/L), and cocaine (0.3-0.6 ng/L) were frequently detected (75% occurrence). Orphenadrine (0.6-3.0 ng/L) and atenolol (0.1-0.3 ng/L), and acetaminophen (1.2-1.4 ng/L) and losartan (0.7-3.4 ng/L), were detected in 50% and 25% of the samples, respectively. Only one sample (12.5%) detected the presence of carbamazepine (< 0.001-0.1 ng/L). Unexpectedly a lower frequency of occurrence and concentration of these compounds occurred during the summer season, suggesting that other factors, such as the oceanographic and hydrodynamic regimes of the study area, besides the population rise, should be taken into account. Caffeine presented concentrations above the surface water safety limits (0.01 μg/L). For almost all compounds, the observed concentrations indicate nonenvironmental risk for the aquatic biota, except for caffeine, diclofenac, and acetaminophen that showed low to moderate ecological risk for the three trophic levels tested.

Compliance with the EU waste hierarchy: A matter of stringency, enforcement, and time

The aim of this paper is to assess whether and to what extent income and the stringency and enforcement (S&E) of environmental regulation influence compliance with the EU Waste Hierarchy (EWH), i.e., how EU member states treat waste. The EWH prioritizes waste prevention and re-use over recycling, which is ranked above waste to energy (WtE), while incineration and landfilling are the least preferred options. Biennial panel data for the period 2010-2016 is used to create a compliance index based on the waste treatment alternatives in the EWH. Waste (excluding major mineral waste) of 26 European Union countries is examined. This study is the first of its kind to regress an EWH compliance index on income, stringency and enforcement of environmental regulation, and other variables that are also expected to affect the relative benefits and costs of waste treatment, such as population density, heating demand, and electricity prices. The shares of landfilling, incineration, WtE, and recycling are also modeled to capture the effect of these variables in the waste treatment mix. The stringency and enforcement of environmental regulation are found to have a positive effect on compliance with the EWH, which has increased over time.