In wastewater treatment processes, there exists a typical conflict between the objectives of energy consumption (EC) and effluent quality (EQ). Achieving energy savings while ensuring effluent compliance remains a critical challenge. This article proposes a dynamic optimal control method to reconcile this trade-off. The approach integrates intelligent modeling, multiobjective optimization, and advanced control techniques. First, a hybrid optimization strategy combining Bayesian optimization (BO) and the multiobjective evolutionary algorithm based on decomposition (MOEA/D) is developed to efficiently search the Pareto front on the Gaussian process regression model. This strategy dynamically generates optimal setpoints for control variables while balancing exploration and evaluation efficiency. Second, a nonlinear model predictive controller (NMPC) enhanced by an extended state observer (ESO) is designed to precisely track these optimal setpoints. The ESO estimates and compensates for internal and external disturbances in real time, thereby improving control robustness. Last, a dynamic multiobjective optimal control strategy is presented, where BO-MOEA/D is utilized to determine the controller setpoints, and NMPC-ESO is employed to execute tracking control. The proposed method is validated on the Benchmark Simulation Model No. 1. Simulation results demonstrate that, compared with conventional strategies, the proposed approach can more effectively identify and track optimal operating points. It significantly reduces overall EC while consistently meeting EQ standards, thereby verifying its effectiveness and superiority for the optimization of complex, nonlinear processes.
Nitrate pollution in groundwater is a global issue with far-reaching effects on ecological balance and human health. Stimulation of indigenous denitrifying populations using emulsified vegetable oil (EVO) has shown promise for treating nitrate plumes, but the potential for secondary effects, such as release of nitrous oxide and discharge of dissolved carbon, are not yet well understood. This study adapts an electron competition model for use in flow and transport modeling to better understand those potential secondary effects as the electron competition framework has been shown to better describe the dynamics of nitrogen intermediates, when applied in the context of wastewater treatment. The model decouples the description of carbon oxidation and nitrogen reduction to describe nitrogen and carbon emissions over the duration of treatment following the introduction of EVO as a permeable reactive barrier. Model simulations indicate that nitrous oxide emissions may be influenced by the balance between oxidized and reduced electron carriers, modulated by biomass activity and carbon substrate availability. The hydrolysis of EVO is identified as the rate-limiting step in sustaining denitrification, but incomplete denitrification can occur even at high carbon availability. This research advances the understanding of microbially mediated denitrification mechanisms and provides model-based insights for managing nitrate-containing groundwater in ways that minimize nitrogen oxide emissions and downstream impacts by limiting carbon discharge.
Simultaneous nitrification and denitrification (SND) in one reactor has been realized with different methods in previous research. In this study, porous polymer biofilm carriers together with suspended biomass were fluidized in an airlift membrane bioreactor reactor. Limited filamentous bulking (LFB) was used to enhance SND, synthetic wastewater with mean ammonium-nitrogen concentrations of 50 mg/L was treated in the system, achieving 70% nitrogen removal. Batch experiments clearly demonstrated that nitrification was localized in the suspended biomass and attached on the carriers, while denitrification was confined within the bioparticles of the slowly degrading biocompounds. High-throughput sequencing analyses confirmed that heterotrophic nitrifying bacteria were the nitrogen-transforming functional bacteria in both the sludge and biofilm of the integrated fixed-film activated system, with Rhodobacter being the dominant genus. The LFB state-causing agent was identified as Thiothrix , which was present in the integrated fixed-film activated.
The removal of phenol from wastewater is crucial due to its harmful effects on human health and the environment. This study investigates phenol removal using a sulfuric acid-activated coal-based adsorbent in fixed- and fluidized-bed columns, evaluating the effects of initial phenol concentration, flow rate, and bed height. In the fixed-bed adsorption, the optimum operating conditions were determined to be a bed height of 3.2 cm, a flow rate of 1.75 mL/min, and an initial phenol concentration of 100 mg/L based on the analysis of the mass transfer zone heights and removal efficiencies. While higher removal efficiencies were observed at lower flow rates and higher initial phenol concentrations, increasing the bed height did not improve removal efficiency due to increases in the unused bed heights. In the fluidized-bed column, higher phenol removal efficiencies were achieved with increased contact time at lower flow rates. The optimum operating flow rate was determined to be 18.38 mL/min depending on the minimum fluidization velocity. In contrast to fixed bed, it was determined that the initial phenol concentration did not have a significant effect on removal efficiency in the fluidized-bed column due to the presence of mixing. When the bed heights were equal, the fluidized bed reached saturation faster at higher flow rates compared with the fixed bed, allowing for the treatment of larger volumes of water in shorter periods. In the modeling studies, the Adams–Bohart, Wolborska, Thomas, and Yoon–Nelson models were fitted to the experimental data, and the model predictions were compared with breakthrough curves. Thomas and Yoon–Nelson models showed the best fit to the experimental data, but the predicted removal efficiencies were lower than those of the experimental data. The discrepancy was attributed to neglecting diffusion mass transfer in the models.
Pharmaceuticals and personal care products (PPCPs) have emerged as pseudo-persistent contaminants of global concern due to continuous discharge, incomplete removal in conventional treatment systems, and inherent bioactivity. Their widespread occurrence in effluents, surface waters, sediments, and groundwater poses chronic ecological and human health risks, including endocrine disruption and antimicrobial resistance. Trace-level detection in complex matrices remains challenging; however, recent advances in high-resolution mass spectrometry, liquid chromatography–mass spectrometry workflows, and nano-enabled extraction have significantly improved detection limits (sub-ng/L) and enabled the identification of transformation products. Yet, the lack of analytical standardization limits cross-regional comparability and regulatory harmonization. Hybrid advanced oxidation–biological–membrane systems have demonstrated synergistic PPCP degradation, achieving removal efficiencies exceeding 80–95%, while nanostructured catalysts and biomaterial-derived adsorbents enhance reactivity, fouling resistance, and regeneration potential. Emerging sustainability frameworks, including One Health and the Circular Chemical–Water Nexus (CCWN), advocate integrated approaches to detection, treatment, and resource recovery; however, operational implementation remains fragmented. This review consolidates state-of-the-art nano-enabled analytical and hybrid treatment technologies. It proposes a mechanistic CCWN framework that uniquely translates monitoring outputs into treatment-train selection and resource-recovery decisions by linking detection, degradation pathways, and valorization within an operational circular wastewater management strategy. Future research priorities and policy pathways are outlined to advance scalable, energy-efficient, and equitable strategies for mitigating PPCPs.
Water pollution by persistent organic residues represents a major environmental challenge. Photocatalysis is an advanced oxidation process based on the activation of suitable semiconductor catalysts by light, which possess specific structural and textural characteristics, enabling the generation of reactive species capable of degrading and mineralizing pollutants. It plays a substantial role in water treatment and environmental protection due to the use of clean energy and its operation under mild conditions. This review summarizes recent progress on hydroxyapatite-based metal oxide nanocomposites, with an emphasis on the mechanisms and synergistic effects that enhance the photocatalytic activity of pharmaceutical residue degradation. Structural characteristics, porosity, and charge dynamics of these photocatalysts are identified as key factors influencing photocatalytic reactions. Their catalytic efficiency was analyzed by highlighting the underlying mechanisms, the main kinetic factors, and their main advantages, including an increased active surface area, reduced electron–hole recombination, and easy recovery of the photocatalyst. Key challenges, including material stability, limited visible-light absorption, and scaling difficulties, are highlighted with the aim of improving photocatalytic efficiency and developing sustainable hybrid systems for water treatment.
The persistent rise in atmospheric CO 2 continues to intensify global climate change, prompting an urgent global push toward a sustainable carbon mitigation strategy. Among innovative approaches, microalgae-based carbon sequestration has emerged as a high-potential solution, owing to its rapid CO 2 fixation rates (up to 1.8 kg CO 2 per kg dry biomass), high biomass productivity, and applicability in industrial waste gas capture. This study offers a comprehensive global bibliometric analysis of research trends in microalgal carbon sequestration, based on 2,053 peer-reviewed publications from the Web of Science database between 1990 and 2025. Using advanced analytical tools, Biblioshiny (RStudio) and VOSviewer v1.6.20, the study investigates coauthorship networks, citation performance, keyword co-occurrence and thematic evolution, and leading articles related to the development of this domain. The findings reveal a steady increase in publication output, with China emerging as the leading contributor to research output, followed by India and the USA. Notable research hotspots include photobioreactor optimization, genetic modification of algal strains, biomass valorization, and integration with wastewater treatment systems. The analysis also underscores growing alignment with Sustainable Development Goals (SDGs), particularly SDG 6 and SDG 13. Despite progress, the sector continues to face economic and scalability barriers. High cultivation costs, energy-intensive harvesting, and limited industrial-scale deployments restrict commercial viability. This study emphasizes the need to cut costs via strain engineering, system integration, and policy support, along with cross-disciplinary efforts to move microalgae-based CO 2 capture toward real-world applications.
Algal–bacterial biofilms are being recognized as a promising bioresource technology for wastewater treatment and resource recovery, facilitating the simultaneous removal of pollutants, biomass production, and energy-efficient operation. Due to the vertically layered microbial structure of these biofilms, established by light and oxygen gradients, they can support the coexistence of aerobic, anoxic, and anaerobic microzones within a single biofilm matrix. The extracellular polymeric substances matrix in these biofilms has been recognized as a crucial component in maintaining biofilm structure, mass transfer, and functional microbial interactions under dynamic operating conditions. This review critically examines recent developments in the design and operation of algal–bacterial biofilms, focusing on nitrogen and phosphorus transformation mechanisms, microbial interactions, and the effects of key operational variables, including light intensity, biofilm thickness, and hydraulic retention time. The bioresource potential of novel reactor designs, such as inclined biofilm reactors, moving bed biofilm reactors, and membrane photobioreactors, is assessed based on energy efficiency, CO 2 capture, and biomass productivity. Finally, the role of algal–bacterial biofilms in advancing carbon-conscious wastewater treatment through waste valorization, biogenic oxygenation, and integration with CO 2 capture strategies is discussed, along with key challenges and future research needs.
Lake eutrophication and harmful algal blooms (HABs) have emerged as paramount concerns in the global aquatic environment. Microcystis aeruginosa is a kind of common harmful algae in fresh water. In this study, the surface of TiO 2 was modified by incorporating molybdenum disulfide (MoS 2 ) and zeolitic imidazolate framework-67 (ZIF-67), resulting in the formation of a novel titanium dioxide (TiO 2 ) photocatalyst (MoS 2 @ZIF-67/TiO 2 ). MoS 2 @ZIF-67/TiO 2 photocatalyst was also used to investigate the inactivation of M. aeruginosa under visible light. After doping with MoS 2 @ZIF-67, the energy bandgap of MoS 2 @ZIF-67/TiO 2 was reduced to 2.4 eV, while exhibiting an increase in the average pore diameter. The inactivation efficiency of 10% MoS 2 @ZIF-67/TiO 2 composite photocatalyst for M. aeruginosa was 86.08%. The content of photosynthetic pigment, soluble protein, and various antioxidant indexes also continued to decline during the experiment, dropping to the lowest level on the fifth day. Based on the comprehensive data analysis, it was evident that the 1030% MoS 2 @ZIF-67/TiO 2 photocatalyst exhibited remarkable potential for advancements in the realm of photocatalytic algae removal and mitigation of HABs.
Environmental and surface-associated biofilms function as persistent reservoirs and amplification hubs of antimicrobial resistance (AMR) across agricultural, industrial, and clinical ecosystems. Their ability to colonize diverse substrates including pipelines, filtration membranes, irrigation systems, medical devices, and natural aquatic interfaces confers structural and functional stability that enhances microbial survival and accelerates the dissemination of resistance. Biofilm architecture restricts antimicrobial penetration, supports metabolic heterogeneity, and promotes the formation of persister cells, while quorum-regulated efflux activity and high-frequency horizontal gene transfer further intensify resistance acquisition. As a result, biofilms act not merely as passive repositories of resistant organisms, but as active ecological drivers that sustain AMR across the One Health continuum. This review synthesizes the mechanistic basis of biofilm-mediated tolerance in relation to environment-to-human transmission pathways, emphasizing wastewater infrastructure, livestock production, food processing environments, and built surfaces as critical pathways for circulation. Emerging mitigation strategies, including bacteriophage therapy, CRISPR-based antimicrobials, quorum-sensing inhibitors, antimicrobial peptides, and matrix-degrading enzymes, are evaluated alongside translational constraints such as assay variability and regulatory challenges. By integrating molecular mechanisms with applied system-level interventions, this review outlines a coordinated research and policy framework to mitigate biofilm-driven AMR at its environmental and ecological sources.
Phytoremediation is a green technology that utilizes plants to remove pollutants from contaminated soil, water, and air. It is a promising and sustainable alternative to traditional remediation methods. This review will explore the patent landscape related to phytoremediation for water pollution. This patent landscaping examined the patent on phytoremediation from PATENTSCOPE (World Intellectual Property Organization database), Scopus Patents, Google Patents, and Lens (a public patent knowledge database). This landscaping reviewed around 190 patent records related to phytoremediation belongs to the International Patent Classification (IPC) C02F class for treatment and removal of pollutants from contaminated water. Out of 190 applications, 142 applications (75%) were granted, while 48 applications (25%) were published and await examinations. The analysis identified emerging innovations, key patent holders, and trends in IPC classifications. Innovative phytoremediation strategies for water pollution include: (1) plant species and genetic modification: engineering plants with improved pollutant uptake, especially for heavy metals or organic compounds; (2) hydroponic and aquatic systems: designing hydroponic tanks and nutrient solutions for effective aquatic plant cultivation methods of pollutant removal; (3) rhizofiltration and phytodegradation: enhancing root-based pollutant absorption and optimizing plant metabolism for pollutant breakdown; (4) combined approaches with bioaugmentation: phytoremediation enhanced by adding beneficial microorganisms; and (5) monitoring and assessment using sensors: utilizing sensors for effective phytoremediation. Additionally, phytoremediation is discussed for addressing the challenges of climate change and achieving sustainable development goals. At last, the policy recommendation is described to significantly enhance the efficiency and applicability of phytoremediation techniques.
Inspired by foam fractionation (FF) and coagulation for per- and polyfluoroalkyl substances (PFAS) removal, we explored using photosynthesized O 2 bubbles from microalgae cells to extract PFAS from water. Each cell serves as a microscale site for O 2 bubble generation. The system was introduced as coagulant-assisted algae-bubble matrix (CAABM). In the system, two types of green algae ( Chlorella sp. and Ankistrodesmus falcatus ) and supporting media (glass wool, cotton balls) with different surface charges, and three coagulants (FeCl 3 , alum, and poly (diallyldimethylammonium chloride) were investigated. Results showed that 12.7–13.9% of perfluorooctanoic acid (PFOA) and 7.5–10.3% of the perfluorobutanoic acid (PFBA) could be removed within 97 min. The coagulants are necessary as they can neutralize the negative charge of algae cells to enhance PFAS removal via cell adsorption and bubble extraction. It should be noted that, unlike conventional FF, the foams or accumulated oxygen bubbles in the CAABM are not separated but remain in the column due to the slow bubble generation via photosynthesis and strong bubble attachment to cells. An advantage of this system is the faster removal of PFAS when compared to reported cases using algae alone. Specifically, the PFAS removal rate was enhanced by 21.3 and 428.3 times for PFOA and PFBA, respectively (it is an overall comparison based on a single column test without considering other factors such as biomass loading density, O 2 generation rate). In particular, the CAABM helps promote short-chain PFBA removal as compared to reported algal or coagulation systems. Plus, the PFAS-laden biomass, enriched with lipids, is likely to reduce fuel cost in the incineration treatment. More work will be conducted later to clarify it.
The rapid development of textile, dyeing, and metallurgical industries has led to the discharge of large volumes of wastewater contaminated with dyes and heavy metal ions, posing significant environmental challenges. To address this issue, we developed a novel urea-modified magnetic PPy nanocomposites (Fe 3 O 4 @PPy-CM) via silane modification for the efficient removal of Mn(VII), methylene blue (MB), and malachite green (MG). A uniform PPy layer was successfully coated onto Fe 3 O 4 nanoparticles through in situ polymerization, which increased the material’s specific surface area and adsorption capacity. The grafted urea moiety serves as a key functional component, providing abundant nitrogen-based active sites for binding the target contaminants. Adsorption efficiency evaluations at 308.15 K demonstrated high removal rates exceeding 90% for both Mn(VII) and MB and 85% for MG. Kinetic studies confirmed a chemisorption-dominated process, with Mn(VII) uptake following pseudo-first-order kinetics and MB/MG adsorption adhering to pseudo-second-order kinetics. The equilibrium data for all contaminants were accurately described by the Langmuir isotherm model, indicating monolayer adsorption. Remarkably, the composite maintained excellent stability and adsorption performance over five consecutive adsorption-desorption cycles, underscoring its strong potential for practical wastewater treatment applications.
Microplastics, as emerging contaminants, have drawn widespread attention; however, the impact of different types of microplastics on wetland plants remains poorly understood. Radial oxygen loss (ROL) is a unique trait of wetland plants that reflects their growth status. This study investigated the effects of nondegradable (polyethylene terephthalate, PET) and biodegradable (polylactic acid, PLA) microplastics on the ROL of Canna indica, as well as on height, chlorophyll, and root traits, and additionally examined the correlations between soil microorganisms and ROL. After 60 days of incubation, microplastics migrated toward plant roots. The results exhibited that both low and medium concentrations of PET and PLA promoted ROL (103.02-170.44%, in comparison with the control group), reaching up to 74.28-96.36 mmol/(mu m & centerdot;h). However, as the microplastic concentration increased, the ROL decreased. The high concentration of 3 g/kg PLA appeared to weakly inhibit the secretion of ROL to 31.84 mmol/(mu m & centerdot;h). Additionally, microplastic addition can promote growth indicators, manifesting the improvement of physiological indicators such as plant height, chlorophyll, and porosity. Moreover, adding different concentrations of PET and PLA led to changes in the bacterial communities. Norank_f_Roseiflexaceae, the genus with the greatest variation, increased in abundance with increasing microplastic concentrations, whereas the opposite was true for Sphingomonas. The change in the PET colony was relatively small, whereas the PLA group exhibited a significant difference, suggesting that the bacterial community was more sensitive to PLA. Research indicates that microplastics can affect ROL and reshape soil microbial structure, especially in the PLA group.
Microcystis, Synechococcus, and Cyanobium are cyanotoxin-releasing microbes in harmful algal blooms. They often coexist and share similar morphology and flocculation patterns, making it difficult to differentiate in microscopic images. Multiwavelength laser microscopy was used (405-, 488-, 561-, and 640-nm lasers with black-and-white), and a deep learning model was developed to classify cyanobacteria. The accuracy was 76.56% using only black-and-white images for machine training; however, it improved to 98.44% with all five channel images, emphasizing the importance of wavelength laser microscopy. Microscopic images of individual wavelength lasers (with black-and-white images) improved classification performance, but the improvements were insufficient for strain-level classification. For optimal model performance, 45 image sets per sample, 200 epochs, and 256 & times; 256 pixel images are recommended, requiring only 11 min for machine training. In conclusion, multiwavelength laser microscopy allowed very efficient training of the deep learning model as a promising step toward reliable classification of cyanobacteria in environmental monitoring applications.
Effective remediation of contaminated brownfields requires coordinated decisions among regulators, developers, and communities; however, existing environmental engineering research lacks a framework to capture how uncertaint y in media supervision influences multistakeholder behavioral d y namics. To address this gap, this study develops a tripartite evolutionar y game model that links supervision uncertainty, incentive and penalty structures, and stakeholder behavior in brownfield pollution governance. Policy-based social network analysis identifies key actors and provides evidence for model development. Probabilistic media supervision is modeled as an external factor influencing reputational risks and regulatory responses. Numerical simulations spanning the latent, development, and recovery stages of public opinion, along with sensitivity analyses of key parameters, are used to investigate how governance conditions influence the evolution of cooperative remediation. Results indicate that limited transparency and weak institutional pressure push the s y stem toward a passive and low-efficiency equilibrium. Moderate and time-varying media supervision promotes early regulator y action, increases resident engagement, and slows the decline in cooperative behavior. Performance-linked subsidies and differentiated compensation help sustain remediation efforts, whereas penalties generate rapid but short-lived deterrence. These findings clarify how reputational mechanisms and incentive structures influence remediation performance, highlighting the importance of maintaining transparency, aligning subsidies with verifiable progress, and sustaining enforcement to prevent strategic backsliding. Although parameterized in the Chinese context, the model is adaptable to diverse regulatory settings and serves as a transferable tool for managing contaminated sites under uncertainty. By incorporating uncertain media supervision into a multistakeholder evolutionary framework, this study advances decision support for contaminated-site governance in environmental engineering practice.
Blends of coal with potential fuels, such as bagasse, may help reduce greenhouse gas (GHG) emissions. This study investigates the combined effect of Thar lignite coal and sugarcane bagasse on their suitability for gasification or combustion. Extensive experimental investigations were conducted to assess the suitability of these blends as potential fuels. The Gross Calorific Value of Thar coal blended with sugarcane bagasse was found to be similar to 8,610 Btu/lb, 8,387 Btu/lb, 7,968 Btu/lb, and 7,448 Btu/lb after being mixed in ratios of 100%, 75%, 50%, and 25% with coal, respectively. Thermogravimetric analysis revealed weight loss with increasing temperature in Thar coal; the data obtained will help in setting parameters for fluidized bed conditions. The activation energy and frequency factor were determined to be 68.11 kJ/mol and 636.60 min(-1), respectively. Gamma spectrometry was also performed on these samples, revealing the presence of four main natural radioactive elements: 127.4 +/- 45.2 Bq/kg for K-40, 2.1 +/- 0.3 Bq/kg for U-235, 71.2 +/- 12.1 Bq/kg for U-238, and 20.7 +/- 3.1 Bq/kg for K-40, U-235, U-238, and Th-232. The radiometric measurements of Thar coal show lower emissions compared with the global average values of activity concentration in coal samples. The composition of a 50% bagasse and Thar coal blend results in a notable reduction in sulfur and ash content; however, there is some compromise in the heating value (from 8,610 to 7,969 Btu/lb). The findings of the present study will significantly impact sustainable energy and environmental protection by demonstrating that blending sugarcane bagasse with Thar lignite coal can effectively reduce GHG emissions, thereby contributing to cleaner energy production. These results encourage policymakers and industry stakeholders to adopt biomass-coal blending for sustainable development and environmental benefits. Future research should focus on developing advanced gasification and combustion technologies, along with comprehensive emission control measures, to further reduce GHGs and enhance energy efficiency.
Understanding short-term variations in disinfection by-products (DBPs) is essential for effective drinking-water management. This study applied Innovative Polygon Trend Analysis (IPTA) to evaluate temporal trends in DBP concentrations in treated water from 2011 to 2022 across four source-water types: river water (RW), riverbed water (RBW), underground water, and lake water. IPTA provides a visual framework for identifying month-specific and asymmetrical trends in environmental time-series data. A dataset from 82 treatment plants was analyzed. Trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetonitriles (HANs) were evaluated, with detailed correlation analysis performed for THMs due to complete data availability. Results indicate that THM concentrations decreased during January-April but increased during warmer months, with peak values observed in the 20-30 degrees C range based on monthly average temperature data. THM concentrations were consistently lower in advanced treatment plants, with average reductions of similar to 10-25% compared with conventional systems. HAAs exhibited seasonal variability, increasing during cooler periods and decreasing during warmer months in RW and RBW. IPTA effectively identified month-specific trend reversals and asymmetries across water sources. These findings highlight the importance of seasonal optimization of treatment processes, including precursor removal and chlorination control, and demonstrate the applicability of IPTA for operational monitoring and DBP management.
Environmental engineering design is a key course for students in environmental engineering, as it aims to develop their skills in analyzing, evaluating, and solving environmental problems. However, with the rapid development of modern information technology (IT), this course needs to adapt to the changing times and leverage the benefits of modern IT. In this article, the applications, role, and influence of modern IT in environmental engineering design are discussed, the relevant practical cases demonstrating the use of modern IT applications are presented, and some suggestions to improve and enhance the course by using modern IT are proposed. Modern IT can not only improve the teaching outcomes and quality of environmental engineering design but also stimulate students’ creativity and practical abilities, as well as foster innovation and optimization in the teaching methods and content of environmental engineering design. This article has the potential to advance the field of environmental engineering education.
