This study evaluated the dark-fermentative hydrogen (H2) production potential of isolated and identified Shigella flexneri SPD1 from various pure (glucose, fructose, sucrose, lactose, and galactose) and biowastes (coconut coir, cotton fiber, groundnut shells, rice-, and wheat-straws)-derived sugars. Among sugars, S. flexneri SPD1 exhibited high H2 production of up to 3.20 mol/mole of hexose using glucose (5.0 g/L). The pre-treatment of various biowastes using green solvents (choline chloride and lactic acid mixture) and enzymatic hydrolysis resulted in the generation of up to 36.0 g/L of sugars. The maximum H2 production is achieved up to 2.92 mol/mol of hexose using cotton-hydrolysate. Further, the upscaling of bioprocess up to 5 L of capacity resulted in a maximum yield of up to 3.06 mol/mol of hexose. These findings suggested that S. flexneri SPD1, a novel H2-producer, can be employed to develop a circular economy-based approach to produce clean energy.

The present study used bench scale columns filled with biochar for phosphorous (P) recovery from real ultrafiltered wastewater. No studies are available about the potentiality of biochar using ultrafiltered real wastewater. Therefore, this study aimed to assess phosphate (PO4 3-) recovery by biochar-packed columns employing real treated wastewater from an ultrafiltration process. Three flow rates were tested, specifically 0.7, 1.7 and 2.3 L h-1, to gain insights into the optimal working conditions. Results revealed that the maximum amount of PO4 3- recovery (namely, 3.43 mg g-1 biochar) can be achieved after 7 h by employing the highest tested flow rate. Furthermore, the phosphorus exchange capacity (PEC) was inversely correlated with the feeding flow rate (FFR), with PEC values equal to 35, 25 and 9 % for FFR of 0.67, 1.7 and 2.3 L h-1, respectively. The pseudo-first order model best approximated the adsorption kinetics, thus suggesting that the adsorption of phosphate by biochar depends on its concentrations (i.e. physiosorption mechanism).

Despite the global focus on sustainability, transitioning from linear to circular production systems is slow in the mining sector of most developing economies like Namibia. However, mining plays a crucial role in supporting the livelihoods of local communities. Furthermore, existing literature indicates that the potential for regenerative production systems using the remanufacture and recycle approach remains low and limited within the mining and developing economies. Institutional theory can help reveal the reasons for the slow take-up of the regenerative circular economy models in mining. This study uses a unique dataset of 40 semi-structured interviews with key players in the mining sector of Namibia to understand the current phase of circular economy adoption and the role played by institutional pressures in the process of institutional isomorphism, when companies would display a similar level of practices within a shared institutional environment. The findings reveal: (1) 72.5% of participants believe that Namibian mines are adoption-decision phase-a beginning stage of circular economy adoption; (2) companies are reliant on heavy government participation through policy/legislation and tax incentives is recommended; (3) the ranked order-coercive, normative, and mimetic pressures-describes their significance among key actors, for the successful adoption; and (4) proactive implementation and a mindset shift towards circularity is needed to meet emerging expectations on social and environmental concerns in mining.

An innovative circular economy (CE) system was implemented at the wastewater treatment plant (WWTP) in Brunswick. The performance of the CE system was evaluated for 4 years: the thermal pressure hydrolysis enhanced the methane production by 18% and increased the digestate dewaterability by 14%. Refractory COD formed in thermal hydrolysis and increased the COD concentration in the WWTP effluent by 4 mg L-1 while still complying with the legal threshold. Struvite production reached high phosphorus recovery rates of >80% with a Mg:P molar ratio ≥0.8. Nitrogen was successfully recovered as ammonium sulfate with high recovery rates of 85-97%. The chemical analyses of secondary fertilizers showed a low pollutant content, posing low risks to soil and groundwater ecosystems. The total carbon footprint of the WWTP decreased due to enhanced biogas production, the recovery of renewable fertilizers and a further reduction of nitrous oxide emissions. Using green energy will be crucial to reach carbon neutrality for the entire WWTP.

Plastic products are now essential commodities, yet their widespread disposal leads to environmental and human health effects, particularly in developing nations. Therefore, developing nations require comprehensive studies to assess the current state of plastic and plastic waste production to enhance plastic waste management practices. This review analyzes the import and export of plastic and the production of plastic waste in Rwanda, aiming to improve waste management practices. This review used open-access papers, reports, and websites dealing with plastic waste management. In this review, 58 articles from the Web of Science and 86 from other search engines were consulted to write this review. The findings revealed that the daily estimated plastic waste produced per person ranges between 0.012 and 0.056 kg. The estimated amount of plastic waste generated per person per year in Rwanda could be between 4.38 and 20.44 kg. Plastic waste accounts for between 1 and 8% of the total municipal solid waste produced per person per day in the country, which ranges from 219 to 255.5 kg. The average annual amount of imported plastics could reach 568.2881 tons, whereas the average quantity of exported plastics could reach 103.7414 tons. This shows that plastic management practices have not yet adopted technically advanced or improved practices, which should concern efforts to protect our environment. This study suggests approaches that can vastly improve plastic waste management and potentially open massive opportunities for the people of Rwanda.

Protein-based fish adhesives have historically been used in various bonding applications; however, due to the protein\'s high affinity for water absorption, these adhesives become destabilized in high-moisture environments, resulting in reduced bondline strength and early failure. This limitation makes them unsuitable for industrial applications with higher demands. To address this issue, water-insoluble raw powder materials such as iron, copper, or zeolite were incorporated into natural fish adhesives. In this study, the hygroscopicity, dry matter content, thermal analysis (TGA/DSC), FT-IR spectroscopy, surface tension measurements, vapour permeability, and scanning electron microscope (SEM) of the modified adhesives were determined. In addition, the bonding properties of the modified adhesives were evaluated by the tensile shear strength of the lap joints, and mould growth was visually inspected. The resulting modified protein-based adhesives demonstrated improved stability in high humidity environments. Enhancing the hygroscopic properties of protein-based fish adhesives has the potential to unlock new opportunities and applications, providing a healthier and more environmentally sustainable alternative to petroleum-based adhesives.

Acid mine drainage (AMD) is one of the main environmental problems associated with mining activity, whether the mine is operational or abandoned. In this work, several precipitates from this mine drainage generated by the oxidation of sulfide minerals, when exposed to weathering, were used as adsorbents. Such AMD precipitates from abandoned Portuguese mines (AGO, AGO-1, CF, and V9) were compared with two raw materials from Morocco (ClayMA and pyrophyllite) in terms of their efficiency in wastewater treatment. Different analytical techniques, such as XRD diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), N2 adsorption isotherms, and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) were used to characterize these natural materials. The adsorption properties were studied by optimizing different experimental factors, such as type of adsorbent, adsorbent mass, and dye concentration by the Box-Behnken Design model, using methylene blue (MB) and crystal violet (CV) compounds as organic pollutants. The obtained kinetic data were examined using the pseudo-first and pseudo-second order equations, and the equilibrium adsorption data were studied using the Freundlich and Langmuir models. The adsorption behavior of the different adsorbents was perfectly fitted by the pseudo-second order kinetic model and the Langmuir isotherm. The most efficient adsorbent for both dyes was AGO-1 due to the presence of the cellulose molecules, with qm equal to 40.5 and 16.0 mg/g for CV and MB, respectively. This study confirms the possibility of employing AMD precipitates to adsorb organic pollutants in water, providing valuable information for developing future affordable solutions to reduce the wastes associated with mining activity.

Reuse in new buildings of structural concrete components from demolitions holds the potential for avoiding the use of raw materials to produce new components, including cement for new castings. Reuse rates are high in the circular economy; however, reusing structural components requires documentation of the properties to equate the safety of using reused and new components. Yet, there is no structured or recognized way to perform the documentation. This paper discusses a framework for the documentation requirements for structural concrete, stating the need for documenting the mechanical properties, concrete heterogeneity, and corrosion status of the reinforcement. The possibility is explored for documenting the required properties while the components are in the donor building by use of non-destructive test (NDT) methods. Such use of NDT methods is new. A comprehensive literature survey on the indirect literature, where NDT methods are used to demonstrate similar concrete properties though related to other purposes, is conducted. The overall conclusion is that the use of NDT methods has the potential to document the requested properties before reuse. The next steps towards implementation of NDT for documenting the properties of structural concrete components for reuse involve research in combined NDT methods and the development of AI systems for data interpretation.

Listeria monocytogenes is a foodborne pathogen that represents a serious concern for ready-to-eat (RTE) meat products due to its persistence in production facilities. Among the different strategies for the control of this pathogen, the use of antimicrobial peptides derived from food by-products, such as slaughterhouse blood proteins, has emerged as a promising biocontrol strategy. This study evaluated for the first time the use of peptic hydrolysates of porcine hemoglobin as a biocontrol strategy of L. monocytogenes in RTE pork cooked ham. Pure porcine hemoglobin (Hb-P) and porcine cruor (P-Cru) were hydrolyzed using pepsin at different temperatures (37 °C for Hb-P and 23 °C for P-Cru) for 3 h. Then, the hydrolysates were characterized in terms of their degree of hydrolysis (DH), peptide population, color, and antimicrobial activity (in vitro and in situ) against three different serotypes of L. monocytogenes. Reducing the hydrolysis temperature of P-Cru by 14 °C resulted in a 2 percentage unit decrease in DH and some differences in the peptide composition. Nevertheless, the antimicrobial activity (in situ) was not significantly impacted, decreasing the viable count of L. monocytogenes by ~1-log and retarding their growth for 21 days at 4 °C. Although the color of the product was visibly altered, leading to more saturated reddish and yellowish tones and reduced brightness, the discoloration of the hydrolysates can be addressed. This biopreservation approach holds promise for other meat products and contributes to the circular economy concept of the meat industry by valorizing slaughterhouse blood and producing new antilisterial compounds.

In this study, the generation of domestic waste electrical and electronic equipment (WEEE) and waste printed circuit board (WPCB) were estimated, from 2015 to 2030. Based on the number of EEE put on the Brazilian market, the possession rate in the Brazilian households and obsolescence amounts of five EEE types were estimated using time series. The results show that, between 2015 and 2030, the quantity of WEEE generated per year will increase from 131.87 kt to 195.22 kt. In this period, WPCB generation will stay around 10% of WEEE generation. Additionally, this study shows that the urban mining potential of the materials recoverable from WPCB can be an important revenue source, with environmental benefits deriving from energy savings and a reduction in CO2 emissions. The results of this study provide a quantitative basis that may help decision makers develop strategic policies for WEEE management, considering material circularity.