In recent years, various institutions around the world have emphasised the need to change the economic paradigm from linear to circular. In this framework, waste - particularly organic waste - has become a source of opportunities for converting a wide range of organic waste types into bioproducts or bioenergy. This strategy gives rise to the concept of a biorefinery: a multi-product facility combining technologies and processes to maximise the potential of organic waste, going beyond the traditional waste treatment plant. In this context, chemical engineering (CE) is the most suitable discipline for studying the bioeconomy based on organic waste. By its very nature, CE is multidisciplinary and flexible, and is based on mass and heat balances. Thus, it has powerful tools with which to address the technical challenges of organic transformation. Furthermore, Life Cycle assessment (LCA) and Techno-Economical Analysis (TEA) should be based on CE. In turn, LCA and TEA are the main tools that different stakeholders use to successfully implement an organic waste-circular bioeconomy. This perspective paper explores how CE has already helped and could help in the future with the development of a bioeconomy based on organic waste, using both classical and newly developed CE principles and techniques.

Additive manufacturing has rapidly emerged as a transformative and inherently sustainable technology in engineering. It enables the fabrication of components with minimal or near-zero material wastage. While additive manufacturing was initially focused on metals, it now includes polymers, ceramics, composites, and biomaterials, providing an efficient platform to produce sustainable materials. This review provides a comprehensive overview of additive manufacturing techniques for non-metal materials and emphasises their potential to minimise waste, promote resource circularity, and support sustainable production. Particular attention is given to polymer-based techniques such as fused deposition modelling, stereolithography, and selective laser sintering. These techniques offer design flexibility, reduced material wastage, and compatibility with recycled and bio-based feedstocks. This review highlights the major advantages and practical applications of polymer-based materials in biomedical engineering, microelectronics, flame-retardant and conductive systems, and multifunctional composites. While most limitations are presently observed in flame-retardant systems, a comparative discussion is also provided for the other application domains to maintain balance across the sections. Additionally, emerging research on sustainable and bio-derived polymers such as PLA and PHB reinforced with carbonised biomass or eco-friendly conductive fillers is introduced to emphasise environmentally responsible pathways for developing next-generation conductive materials. Overall, this review highlights additive manufacturing as a sustainable pathway for material valorisation and innovation within waste-to-material and waste-to-energy frameworks.

Energy efficiency is a critical factor in the transition toward sustainable energy systems and the decarbonization of industrial processes. In this context, the recovery of residual process energy represents a key strategy. This study presents a case analysis of a Brazilian carbo-chemical plant, where calcination furnaces release exhaust gases containing both thermal and chemical energy. These gases, generated by six furnaces, have a total flow rate of 1.36 kg/s at 800 °C and a volumetric composition of 26% H 2 , 4.2% CH 4 , and 5% CO, among other components, resulting in a total energy potential of 8.30 MW—comprising 1.63 MW of thermal and 6.67 MW of chemical energy. The main objective of this study is to assess the potential for recovering this energy through various cogeneration system configurations based on steam cycles, aimed at process thermal oil heating and electricity generation. Simulations were conducted using IPSEpro 8.0, and system performance was evaluated according to the First and Second Laws of Thermodynamics to identify opportunities for optimization. The results show that, in addition to providing 70 kW of useful heat for oil heating, the system can deliver up to 2.65 MW of electrical power. The energy and exergy efficiencies of the steam cycles reach 43.35% and 80.45%, respectively, while the overall system achieves energy and exergy efficiencies of 32.8% and 32.03%. Exergy analysis highlights areas for improvement, particularly in combustion and heat exchange, due to high irreversibilities in combustion chambers and boilers (up to 821.50 kW and 3384.29 kW, respectively) and recoverable heat present in boiler exhaust gases. Environmental analysis indicates a significant reduction in stack gas temperatures (66%–77% relative to the initial 800 °C) and the combustion of residual fuel components, especially CH 4 , which markedly decreases thermal and chemical pollution. Quantitatively, electricity generation reduces grid dependency, preventing up to 3234 tons of CO 2 emissions per year. These findings demonstrate a considerable theoretical estimable potential for residual energy recovery, yielding substantial improvements in efficiency and environmental impact mitigation. Furthermore, an optimized technological approach could achieve energy efficiencies of up to 50%, producing 40% more electricity. These results highlight the importance of further studies, particularly to evaluate economic feasibility and potential integration into carbon markets.

Hydrothermal liquefaction (HTL) is a developing alternative for municipal wastewater sludge management that converts sludge into biocrude oil that can be refined into a liquid transportation fuel for the road, marine, and aviation sectors. A major byproduct of HTL is an aqueous phase (AP) high in ammonia, organic carbon, and potentially toxic compounds. This study investigated the feasibility of disposing AP through discharge into the headworks of conventional activated sludge water resource recovery facilities (WRRFs). Bench-scale, acute inhibition experiments using non-nitrifying mixed liquor indicated that a single AP exposure did not inhibit the specific oxygen uptake rates (SOUR) at pilot- and full-scale dilutions (0.03%–0.4% v/v). In contrast, post-secondary nitrifying mixed liquor showed that SOUR inhibition was linearly correlated to the AP concentration. Chronic AP exposure studies (121 days of operation) in continuous-flow, 2.25-L, non-nitrifying activated sludge reactors also indicated that SOUR was unaffected at the pilot- and full-scale AP dilutions in synthetic wastewater feed. However, repeated-measure linear-mixed models showed statistically significant lower specific dissolved organic carbon (DOC) removal rates and percentage DOC removal associated with higher AP concentration in the influent. At the full-scale AP concentration, removal rates were 25 mg DOC/g TSS-hr less and mean percent DOC removal was 40% lower than controls, despite higher DOC loading to the +AP reactors. Furthermore, ultraviolet transmittance (UVT) in the effluent of these reactors was 93% less than in the controls. The results of this study suggest that while headworks discharge of AP at pilot scale might be feasible, full-scale would require pretreatment of the AP, especially at WRRFs that use ultraviolet disinfection. The lack of detectable inhibition in non-nitrifying activated sludge via batch SOUR tests contrasted with the reduction in DOC removal detected in the continuous reactor studies. This result indicates the value of continuous studies to adequately understand the implications of AP headworks discharge on activated sludge processes. To our knowledge, this study is the first to characterize the effects of chronic exposure of mixed liquor to AP in continuous-flow activated sludge reactors.

Nanofiltration (NF) membranes are a pressure-driven membrane separation technology that lies between reverse osmosis (RO) and ultrafiltration (UF), featuring selective separation of low-molecular-weight organic compounds, divalent ions, and some monovalent ions. Due to their low operating pressure, low energy consumption, and ability to efficiently desalinate while retaining some beneficial minerals, NF membranes have shown broad application prospects in drinking water purification, wastewater treatment, food and pharmaceutical industries, and resource recovery. This article systematically reviews the existing challenges (including trade-off effect between selectivity and flux, membrane fouling and insufficient chemical stability) and the corresponding countermeasures from the perspectives of material modification and structural design, etc., with the aim of providing references for further research and industrial application of NF membranes.

IntroductionA type of batch electrolysis system comprising a platinum anode and stainless-steel cathode was investigated for the removal of hexavalent chromium (Cr6+) from synthetic wastewater.MethodsElectrochemical treatment was conducted at a constant current of 0.25 A with NaCl of 1 g/L as the supporting electrolyte.ResultsThe highest Cr6+ removal efficiencies achieved were at 100 mg/L metal ion dosage and an initial Cr6+ concentration of 5 mg/L, yielding removal rates of 56.80% for Fe3+, 49.62% for Al3+, and 30.05% for Mg2+.DiscussionRemoval was attributed to the in-situ formation of metal hydroxides (Al(OH)3, Fe(OH)3, Mg(OH)2), which subsequently enhanced the reduction and immobilization of Cr6+ through co-precipitation, Coulomb forces, and electrostatic adsorption. Further increase in Cr6+ removal efficiency was inhibited at higher initial Cr6+ concentrations due to the saturation of hydroxides, which also exhibited competitive behaviour toward ion adsorption. These results confirm the significant role of multivalent cation additives in increasing the remediation of Cr6+ in the electrochemical system, thus lending support to the theory behind the development of scalable additive-assisted electrochemical water treatment technique.

Cell manufacturing processes play a crucial role in cell-based tissue engineering by isolating, purifying, culturing, expanding, modifying, cryopreserving, and formulating patient-derived cells in vitro before utilizing them for tissue regeneration. Currently, researchers apply various methods for cell manufacturing, including bioreactors, defined chemical cues, and substrate modifications. However, factors such as loss of cell potency and heterogeneity are critical challenges when engineering tissues for regenerative medicine. In particular, neglecting cellular heterogeneity during cell expansion prevents the formation of tissues that recapitulate the structural and cellular heterogeneity of our native tissues. This review discusses current and emerging approaches for cell manufacturing, with a focus on biomanufacturing for vascularized, skeletal muscle tissue engineering. Specifically, this review highlights 1) the U.S. Food and Drug Administration’s regulation of manufacturing for cell therapies, 2) state-of-the-art approaches for manufacturing endothelial cells and muscle stem cells that maintain cellular identity and potency, and 3) emerging tools and methods for measuring and manipulating cellular heterogeneities. Ultimately, these approaches can be leveraged to manufacture and formulate tissue-engineered products that mimic the heterogeneous form and function of our native tissues.

PEGylation is widely used in biopharmaceuticals to enhance protein stability and half-life, but the resulting mixtures typically contain multiple PEGylated derivatives alongside unmodified proteins, complicating purification. In this study, we developed a novel aqueous two-phase separation (ATPS) strategy for selectively purifying mono-PEGylated human serum albumin (HSA). HSA was PEGylated using polyethylene glycol (PEG) reagents of different molecular weights (20 kDa and 40 kDa) and subsequently purified using ATPS. Our results demonstrated that ATPS effectively isolated PEGylated HSA with purity >99% and extremely high selectivity in the top phase. Tie-line length (TLL) significantly influenced yield and purity, whereas the volume ratio (Vr) had a minimal effect. Optimal conditions for the separation of 20 kDa PEGylated HSA were identified at a TLL of 29% (w/w) and a Vr of 2.5, achieving a yield of 50% and an equilibrium constant of 1.6. Under identical conditions, the yield and equilibrium constants for 40 kDa PEGylated HSA increased to 58% and 18, respectively, attributed to enhanced hydrophobic interactions from the larger PEG reagent. Furthermore, ATPS reached equilibrium rapidly within 30 min, resulting in high productivity levels of 1.3 and 1.5 g/L/h for 20 and 40 kDa PEGylated HSA, respectively. These findings illustrate the high efficiency and industrial potential of ATPS as an effective purification strategy for PEGylated therapeutic proteins.

This paper analyzes the structural challenges faced by South Africa, such as high dependence on coal power, low penetration rate of clean energy and lagging power grid infrastructure. Combined with the basis and bottlenecks of energy cooperation between China and South Africa, it proposes a multi-dimensional cooperation path centered on technological synergy, financial innovation and institutional adaptation. This path requires both sides to focus on joint research and development of clean energy technologies, cultivation of localized industrial chains and upgrading of smart grids. By innovating hybrid financing tools and risk hedging mechanisms, they can break through capital constraints and promote the reform of South Africa’s energy policy to activate market vitality. At the same time, it is emphasized to deeply integrate China’s advantages in the clean energy industry with South Africa’s resource endowments, establish a mutual recognition system for technical standards and a long-term mechanism for talent cultivation, and ultimately achieve the dual goals of optimizing South Africa’s energy structure and regionalizing the application of China’s technical standards. Clean energy cooperation between China and South Africa is not only about capacity matching, but also requires the establishment of a sustainable collaborative innovation ecosystem to provide a replicable regional cooperation model for the energy transition of emerging economies.

The growing interest in hydrogen as an alternative fuel has stimulated research into methods that enable the global shift to sustainable, green energy. One promising pathway is the production of green hydrogen via electrolysis, particularly when coupled with renewable energy sources like solar power. Integrating a proton exchange membrane (PEM) electrolyzer with solar energy can aid this transition. Using treated sewage effluent, instead of deionized water, can make the process more economical and sustainable. Thus, the objective of this research is to demonstrate that an integrated electrolysis-water treatment-solar energy system can be a viable candidate for producing green hydrogen in a sustainable manner. This study assesses different combinations of water pretreatment (RO and UF) and solar energy input (PV, ST, and PTC), evaluating their techno-economic feasibility, efficiencies, environmental impact, and sustainability. The study shows that CSP scenarios have the highest CAPEX, roughly fourfold that of PV cases and sevenfold that of national grid cases. Using solar energy sources like PV, ST, and PTC results in high material efficiency (94.87%) and environmental efficiency (98.34%), while also reducing CO2 emissions by approximately 88% compared to the national grid. The process’s economic sustainability averages 57%, but it could reach 90% if hydrogen production costs fall to $2.08-$2.27 per kg. The outcome of this study is to provide a green hydrogen production pathway that is technically feasible, environmentally sustainable, and economically viable.