Metal-organic frameworks (MOFs) are widely investigated for water purification, yet conventional materials are often limited by saturated metal nodes that restrict active-site accessibility and by microporous channels that impede mass transport. Defect engineering provides a means to generate unsaturated metal sites and hierarchical porosity while preserving framework integrity. Quasi-MOFs occupy a distinct position within this landscape, retaining partial long-range order and local coordination environments of the parent MOF while incorporating controlled defects that yield high densities of coordinatively unsaturated sites and multimodal pore structures. In this review, we summarize synthetic strategies that enable precise control of defect type, density, and distribution in quasi-MOFs, including thermal activation, post-synthetic ligand exchange, and modulated coordination approaches. We examine advanced characterization techniques that reveal correlations between engineered defects and enhanced pollutant diffusion and catalytic activation. Applications in adsorptive removal and advanced oxidation/reduction processes are analyzed, highlighting performance advantages derived from improved site accessibility and transport kinetics relative to pristine MOFs. Finally, we discuss persisting challenges, including hydrolytic stability, scalable synthesis, and detailed structure-activity relationships, and outline future directions for translating quasi-MOFs into practical water-treatment technologies.

Wastewater-treatment plants (WWTPs) enable urban water reclamation but are significant sources of greenhouse-gas (GHG) emissions. Because GHG output scales with the volume and pollutant load of influent sewage, city-wide water-use patterns offer a direct yet under-examined lever for decarbonizing WWTP operations. The feedbacks linking demand-side water conservation to plant emissions remain poorly understood, obscuring important mitigation co-benefits. Here we show a domino-effect feedback between urban water-use patterns with WWTP carbon emissions. Our analysis demonstrates that optimized water management can improve average WWTP eco-efficiency by up to 189%, leading to an annual reduction in water consumption of 48.3 billion m³ and a decrease in GHG emissions by 1.67 million tons CO₂-equivalent. Under this synergistic water-carbon management scenario, the wastewater sector could achieve carbon neutrality by 2037, seven years ahead of schedules based solely on technological advancements. Our findings present a novel and replicable framework that simultaneously addresses water scarcity and climate change. Unlike costly and slow-to-implement technological innovations, leveraging cross-sectoral synergies in water-intensive industries such as agriculture and manufacturing offers a pragmatic pathway to meeting critical carbon-reduction targets.

The rapid expansion of both the global economy and the human population has led to a shortage of water resources suitable for direct human consumption. As a result, water remediation will inexorably become the primary focus on a global scale. Microalgae can be grown in various types of wastewaters (WW). They have a high potential to remove contaminants from the effluents of industries and urban areas. This review focuses on recent advances on WW remediation through microalgae cultivation. Attention has already been paid to microalgae-based wastewater treatment (WWT) due to its low energy requirements, the strong ability of microalgae to thrive under diverse environmental conditions, and the potential to transform WW nutrients into high-value compounds. It turned out that microalgae-based WWT is an economical and sustainable solution. Moreover, different types of toxins are removed by microalgae through biosorption, bioaccumulation, and biodegradation processes. Examples are toxins from agricultural runoffs and textile and pharmaceutical industrial effluents. Microalgae have the potential to mitigate carbon dioxide and make use of the micronutrients that are present in the effluents. This review paper highlights the application of microalgae in WW remediation and the remediation of diverse types of pollutants commonly present in WW through different mechanisms, simultaneous resource recovery, and efficient microalgae-based co-culturing systems along with bottlenecks and prospects.

Aquatic pollution caused by antibiotics poses a significant threat to human health and the ecosystem. Inspired from “Emmental Cheese” that owns lots of natural pores, we here fabricated a hierarchical cheese-like porous Spirulina residue biochar (KSBC) activated by KHCO₃ for efficiently boosting the removal of sulfathiazole (STZ). Through learning form nature that the CO₂ produced by bacteria can serve as the natural pore maker (like cheese-making), KHCO₃ was thus selected as the gas generating agent in this study. The effect of adding KHCO₃ on the surface properties of KSBC was comprehensively investigated. Benefiting from the activation, the KSBC with the mass ratio of 2:1 (2K-SBC) possessed the largest specific surface areas (1100 m² g⁻¹), which was approximately 81 times that of the original (not activated) Spirulina residue biochar (SBC) (13.56 m² g⁻¹). Moreover, 2K-SBC exhibited the maximum adsorption capacity for STZ (218.4 mg g⁻¹), dramatically higher than the SBC (25.78 mg g⁻¹). The adsorption kinetics and adsorption isotherms exhibited that the adsorption behavior of 2K-SBC for STZ was consistent with the pseudo-second-order and Langmuir models. Additionally, the adsorption thermodynamics revealed that the adsorption of STZ on 2K-SBC was spontaneous and exothermic. The pore-filling and electrostatic interaction were considered the main mechanism for the adsorption of STZ on 2K-SBC, whereas the π-π electron donor-acceptor (EDA) interaction and hydrogen bond would also partially contribute to the adsorption process.

The existence of continually increasing concentrations of antibiotics in the environment is a serious potential hazard due to their toxicity and persistence. Unfortunately, conventional treatment techniques, such as those utilized in wastewater treatment plants, are not efficient for the treatment of wastewater containing antibiotic. Recently, algae-based technologies have been found to be a sustainable and promising technique for antibiotic removal. Therefore, this review aims to provide a critical summary of algae-based technologies and their important role in antibiotic wastewater treatment. Algal removal mechanisms including bioadsorption, bioaccumulation, and biodegradation are discussed in detail, with using algae-bacteria consortia for antibiotic treatment, integration of algae with other microorganisms (fungi and multiple algal species), hybrid algae-based treatment and constructed wetlands, and the factors affecting algal antibiotic degradation comprehensively described and assessed. In addition, the use of algae as a precursor for the production of biochar is highlighted, along with the modification of biochar with other materials to improve its antibiotic removal capacity and hybrid algae-based treatment with advanced oxidation processes. Furthermore, recent novel approaches for enhancing antibiotic removal, such as the use of genetic engineering to enhance the antibiotic degradation capacity of algae and the integration of algal antibiotic removal with bioelectrochemical systems are discussed. Finally, some based on the critical review, key future research perspectives are proposed. Overall, this review systematically presents the current progress in algae-mediated antibiotic removal technologies, providing some novel insights for improved alleviation of antibiotic pollution in aquatic environments.