Performance of a Slurry Photocatalytic Membrane Reactor for the Treatment of Real Secondary Wastewater Effluent Polluted by Anticancer Drugs

A comprehensive review on TiO2-based heterogeneous photocatalytic technologies for emerging pollutants removal from water and wastewater: From engineering aspects to modeling approaches

The increasing presence of emerging pollutants (EPs) in water poses significant environmental and health risks, necessitating effective treatment solutions. Originating from industrial, agricultural, and domestic sources, these contaminants threaten ecological and public health, underscoring the urgent need for innovative and efficient treatment methods. TiO2-based semiconductor photocatalysts have emerged as a promising approach for the degradation of EPs, leveraging their unique band structures and heterojunction schemes. However, few studies have examined the synergistic effects of operating conditions on these contaminants, representing a key knowledge gap in the field. This review addresses this gap by exploring recent trends in TiO2-driven heterogeneous photocatalysis for water and wastewater treatment, with an emphasis on photoreactor setups and configurations. Challenges in scaling up these photoreactors are also discussed. Furthermore, Machine Learning (ML) models play a crucial role in developing predictive frameworks for complex processes, highlighting intricate temporal dynamics essential for understanding EPs behavior. This capability integrates seamlessly with Computational Fluid Dynamics (CFD) modeling, which is also addressed in this review. Together, these approaches illustrate how CFD can simulate the degradation of EPs by effectively coupling chemical kinetics, radiative transfer, and hydrodynamics in both suspended and immobilized photocatalysts. By elucidating the synergy between ML and CFD models, this study offers new insights into overcoming traditional limitations in photocatalytic process design and optimizing operating conditions. Finally, this review presents recommendations for future directions and insights on optimizing and modeling photocatalytic processes.

Methotrexate degradation in artificial wastewater using non-thermal pencil plasma jet

The rising global cancer rate is driving up the consumption of anticancer drugs. This causing a noticeable increase in the levels of these drugs in wastewater. The drugs are not metabolized effectively by the human body, leading to their presence in human waste, as well as in the effluent from hospitals and drug manufacturing industries. Methotrexate is a commonly used drug for treating various types of cancer. Its complex organic structure makes it difficult to degrade using conventional methods. The present work proposed a non-thermal pencil plasma jet treatment for methotrexate degradation. The air plasma produced in this jet setup is electrical characterized and plasma species/radicals are identified using emission spectroscopy. The degradation of drug is monitored by studying the change in solution physiochemical properties, HPLC-UV analysis, and removal of total organic carbon, etc.Results show that a 9-min plasma treatment completely degraded the drug solution that followed first-order degradation kinetics with rate constant 0.38 min^-1 and 84.54% mineralization was observed. Additionally, an increase in electrical conductivity and dissolved solids compared to virgin water-plasma interaction indicated the formation of new, smaller compounds (2,4-Diaminopteridine-6-carboxylic acid, N-(4-Aminobenzoyl)-L-glutamic acid, etc.) after drug degradation. The plasma-treated methotrexate solution also showed lower toxicity toward freshwater chlorella algae compared to the untreated solution. Finally, it can be said that non-thermal plasma jets are economically and environmentally friendly devices that have the potential to be used for the treatment of complex and resistive anticancer drug-polluted wastewaters.

Photocatalysts for a sustainable future: Innovations in large-scale environmental and energy applications

The growing environmental and energy crises have prompted researchers to seek new solutions, including large-scale photocatalytic environmental remediation and the production of solar hydrogen using photocatalytic materials. To achieve this goal, scientists have developed numerous photocatalysts with high efficiency and stability. However, the large-scale application of photocatalytic systems under real-world conditions is still limited. These limitations arise at every step, including the large-scale synthesis and deposition of photocatalyst particles on a solid support, and the development of an optimal design with high mass transfer and efficient photon absorption. The purpose of this article is to provide a detailed description of the primary challenges and potential solutions encountered in scaling up photocatalytic systems for use in large-scale water and air purification and solar hydrogen production. Additionally, based on a review of current pilot developments, we draw conclusions and make comparisons regarding the main operating parameters that affect performance, as well as propose strategies for future research.

Anticancer drugs in wastewater and natural environments: A review on their occurrence, environmental persistence, treatment, and ecological risks

The consumption of anticancer drugs (also known as chemotherapy drugs or antineoplastic drugs) has augmented over the last decades due to increased cancer incidence. Although there is an increasing concern about the presence of pharmaceutical compounds in natural environments and urban/domestic wastewater, anticancer drugs used in chemotherapy and anticancer medication have received less attention. In this review, the occurrence, environmental persistence, and known and potential ecological impacts of anticancer drugs is discussed. This review shows that these compounds are being increasingly detected in effluents of hospitals, influents and effluents of wastewater treatment plants, river surface water and sediments, groundwater, and even drinking water. Anticancer drugs can impact aquatic organisms such as algae, crustaceans, rotifers, and fish and may promote changes in soil and water microbial communities that may alter ecosystem functioning. Our knowledge of technologies for the removal of anticancer drugs is still limited, and these drugs can be dispersed in nature in a diffuse way in an uncontrolled manner. For this reason, an improved understanding of the presence, persistence, and ecological impacts of anticancer drugs in wastewater and natural environments is needed to help design management strategies, protect aquatic microorganisms, and mitigate potential ecological impacts.

Photocatalytic nanohybrid membranes for highly efficient wastewater treatment: A comprehensive review

Wastewater is inevitably generated from human activities as part of the life cycle chain that potentially damages the environment. The integration of photocatalytic reaction and membrane separation for wastewater treatment has gained great attention in recent studies. However, there are still many technical limitations for its application such as toxic metal release, catalyst deactivation, fouling/biofouling, polymer disintegration, and separation performance decline. Different types, combinations, and modifications of photocatalysts material combined with membranes such as semiconductor metal oxides, binary/ternary hybrid metal oxides, elemental doped semiconductors, and metal-organic frameworks (MOFs) for improving the performance and compatibility are presented and discussed. The strategies of incorporating photocatalysts into membrane matrix for pursuing the most stable membrane integrity, high photocatalytic efficiency, and excellent perm-selectivity performance in the very recent studies were discussed. This review also outlines the performance enhancement of photocatalytic membranes (PMs) in wastewater treatment and its potential for water reclamation. Photocatalysts enhanced membrane separation by inducing anti-fouling and self-cleaning properties as well as antibacterial activity. Based on the reviewed study, PMs are possible to achieve complete removal of emerging contaminants and ∼99% reduction of bacterial colony that leading on the zero liquid discharge (ZLD). However, the intensive exposure of photo-induced radicals potentially damages the polymeric membrane. Therefore, future studies should be focused on fabricating chemically stable host-membrane material. Moreover, the light source and the membrane module design for the practical application by considering the hydrodynamic and cost-efficiency should be a concern for technology diffusion to the industrial-scale application.

Interdependence of Kinetics and Fluid Dynamics in the Design of Photocatalytic Membrane Reactors

Photocatalytic membrane reactors (PMRs) are a promising technology for wastewater reclamation. The principles of PMRs are based on photocatalytic degradation and membrane rejection, the different processes occurring simultaneously. Coupled photocatalysis and membrane filtration has made PMRs suitable for application in the removal of emerging contaminants (ECs), such as diclofenac, carbamazepine, ibuprofen, lincomycin, diphenhydramine, rhodamine, and tamoxifen, from wastewater, while reducing the likelihood of byproducts being present in the permeate stream. The viability of PMRs depends on the hypotheses used during design and the kinetic properties of the systems. The choice of design models and the assumptions made in their application can have an impact on reactor design outcomes. A design’s resilience is due to the development of a mathematical model that links material and mass balances to various sub-models, including the fluid dynamic model, the radiation emission model, the radiation absorption model, and the kinetic model. Hence, this review addresses the discrepancies with traditional kinetic models, fluid flow dynamics, and radiation emission and absorption, all of which have an impact on upscaling and reactor design. Computational and analytical descriptions of how to develop a PMR system with high throughput, performance, and energy efficiency are provided. The potential solutions are classified according to the catalyst, fluid dynamics, thickness, geometry, and light source used. Two main PMR types are comprehensively described, and a discussion of various influential factors relating to PMRs was used as a premise for developing an ideal reactor. The aim of this work was to resolve potential divergences that occur during PMRs design as most real reactors do not conform to the idealized fluid dynamics. Lastly, the application of PMRs is evaluated, not only in relation to the removal of endocrine-disrupting compounds (EDCs) from wastewater, but also in dye, oil, heavy metals, and pesticide removal.