Complete Removal Of Pollutants Research Articles

3D Porous Gel from the Orthogonal-junction of Nanosheet Photosensitizers with Efficient and Selective Photosensitization

Photocatalysis waste decomposition is a promising candidate for efficient cleaning of volatile organic compounds (VOCs) with enhanced safety because of the self-degradation of toxic compounds by reactive oxygen species (ROS) under light irradiation. However, the complete removal of pollutants remains challenging due to the inert characteristics of their inactivity in the presence of electrophilic ROS. Herein, a new strategy for efficient degradation of inert VOCs such as benzaldehyde has been proposed, basing on the synergism of selective adsorption and chemical activation by the construction of 3D porous gel through an orthogonal-junction of nanosheet-shaped photosensitizers. The key to the success of the combination is the use of hierarchically assembled hydrogen bonded laminates (HBLs) as gelation scaffolds. The backbone could integrate organic photosensitizers (PSs) into robust gel skeleton with enhanced ROS generation, which promotes the photocatalytic degradation. Especially, the backbone is able to directionally recognize glue clusters by hydrogen bonding to result in orthogonal 3D gel, giving remarkable selective adsorption for inert aromatic aldehydes. The synergistic integration of chemical activation and selective entrapment gives rise to unusual rapid photo-degradation for carbonyl compounds, resulting in efficient removal of inert pollutants from the environment without any adverse effect.

Mo-BiVO4 Photocatalytically Modified Ceramic Ultrafiltration Membranes for Enhanced Water Treatment Efficiency.

This study highlights the effectiveness of photocatalytically modified ceramic ultrafiltration (UF) membranes in alleviating two major drawbacks of membrane filtration technologies. These are the generation of a highly concentrated retentate effluent as a waste stream and the gradual degradation of the water flux through the membrane due to the accumulation of organic pollutants on its surface. The development of two types of novel tubular membranes, featuring photocatalytic Mo-BiVO4 inverse opal coatings, demonstrated a negligible impact on water permeance, ensuring consistent filtration and photocatalytic efficiency and suggesting the potential for maintaining membrane integrity and avoiding the formation of highly concentrated retentate effluents. Morphological analysis revealed well-defined coatings with ordered domains and interconnected macropores, confirming successful synthesis of Mo-BiVO4. Raman spectroscopy and optical studies further elucidated the composition and light absorption properties of the coatings, particularly within the visible region, which is vital for photocatalysis driven by vis-light. Evaluation of the tetracycline removal efficiency presented efficient adsorption onto membrane surfaces with enhanced photocatalytic activity observed under both UV and vis-light. Additionally, vis-light irradiation facilitated significant degradation, showcasing the versatility of the membranes. Total Organic Carbon (TOC) analysis corroborated complete solute elimination or photocatalytic degradation without the production of intermediates, highlighting the potential for complete pollutant removal. Overall, these findings emphasize the promising applications of Mo-BiVO4 photocatalytic membranes in sustainable water treatment and wastewater remediation processes, laying the groundwork for further optimization and scalability in practical water treatment systems.

Numerical simulation of hot soak in cabin based on ventilation strategy

To address the issue of excessive heat within the vehicle’s cabin, this study employs transient simulation methods to explore and analyze how various ventilation tactics and parameters influence the cabin’s temperature distribution and air quality. Findings indicate that the optimal thermal comfort and air quality conditions are achieved through the implementation of a top ventilation strategy. Specifically, with an air supply velocity of 3 m/s, a supply air temperature of 19°C, and an airflow direction of 15°, the air age at the driver’s breathing zone is measured at 18.92 seconds, while it stands at 20.35 seconds at the child passenger’s breathing zone. This ventilation setup achieves an air exchange efficiency of up to 80.1%, nearly complete pollutant removal efficiency, and places the thermal comfort at monitored human body points within a range deemed satisfactory or comfortable. Overall, this configuration yields the most favorable conditions for the comfort of the driver and passengers compared to other scenarios examined.

Insight into Fe-O-Bi electron migration channel in MIL-53(Fe)/Bi4O5I2 Z-scheme heterojunction for efficient photocatalytic decontamination

Building a heterojunction is a fascinating option to guarantee sufficient carrier separation and transfer efficiency, but the mechanism of charge migration at the heterojunction interface has not been thoroughly studied. Herein, MIL-53(Fe)/Bi4O5I2 photocatalyst with a Z-scheme heterojunction structure is constructed, which achieves efficient photocatalytic decontamination under solar light. Driven by the newly-built internal electric field (IEF), the formation of Fe-O-Bi electron migration channel allows for rapid separation and transfer of charge carriers at the heterojunction interface, confirmed by the material characterization and density functional theory (DFT) calculation. The narrower band gap and improved visible light response also contribute to the enhanced photocatalytic activity of composite materials. With levofloxacin as the target pollutant, the optimal MIL-53(Fe)/Bi4O5I2 achieves complete removal of pollutant within 150 min, the photocatalysis rate of which is ca. 4.4 and 26.0 times that of pure Bi4O5I2 and MIL-53(Fe), respectively. Simultaneously, the optimal composite material exhibits satisfactory photodegradation of seven fluoroquinolones, and the photocatalysis rates are as follows: lomefloxacin > ciprofloxacin > enrofloxacin > norfloxacin > pefloxacin > levofloxacin > marbofloxacin. DFT calculations reveal a positive relationship between degradation rate and Fukui index (ƒ0) of main carbon atoms in seven fluoroquinolones. This study sheds light on the existence of electron migration channels at Z-scheme heterojunction interface to ensure sufficient photoinduced carrier transfer, and reveals the influence of pollutant structure on photolysis rate.

Assessing the Sustainability of Photodegradation and Photocatalysis for Wastewater Reuse in an Agricultural Resilience Context

The growths in worldwide population—of up to 8.5 billion people by 2030—and agriculture have put great pressure on water resources, above all in arid and drought-prone areas. Nowadays, water scarcity, drought and pollution of wastewater are considered major issues of concern. For this reason, the authors provided an overview of two methods of wastewater purification and removing pollutants for use in crop irrigation in a sustainable manner. The novelty lies in the reuse of recovered wastewater, purified through photodegradation and photocatalysis technologies using solar energy. The knowledge of the environmental impacts associated with the use of recycled water with these photo-processes to irrigate crops under field conditions is still scarce. In the future, this issue will be important. In particular, photodegradation and photocatalysis achieve a sustainable reduction in contaminants contained in wastewater of between 35% and 100%. The use of bismuth vanadate supports the complete removal of pollutants, and the implementation of catalytic membranes makes these processes more circular. This research was performed under the “Progetto GRINS “Growing Resilient, Inclusive and Sustainable” with the aim of “Building a dataset for the circular economy of the main Italian production systems”.

Ultrasound-Assisted Synthesis of a ZnO/BiVO4 S-Scheme Heterojunction Photocatalyst for Degradation of the Reactive Red 141 Dye and Oxytetracycline Antibiotic.

The preparation of novel sunlight active photocatalysts for complete removal of pollutants from aqueous solutions is a vital research topic in environmental protection. The present work reports the synthesis of a ZnO/BiVO4 S-scheme heterojunction photocatalyst for degradation of the reactive red dye and oxytetracycline antibiotic in wastewater. ZnO and BiVO4 were first fabricated by a hydrothermal technique, and then, the ZnO/BiVO4 heterostructure was synthesized using an ultrasonic route. An increase of the surface area, compared to that of ZnO, was found in ZnO/BiVO4. The enhancement of charge separation efficiency at the interface was obtained so that a remarkable enhancement of the photocatalytic performance was detected in the prepared heterojunction photocatalyst. Complete detoxification of harmful pollutants was achieved by using the economical solar energy. The removal of the pollutants follows the first-order reaction with the highest rate constant of 0.107 min-1. The stability of the prepared photocatalyst was detected after five cycles of use. The ZnO/BiVO4 S-scheme heterostructure photocatalyst still provides high photoactivity even after five times of use. Hydroxyl radicals play an important role in the removal of the pollutant. This work demonstrates a new route to create the step-scheme heterojunction with high photoactivity for complete removal of the toxic dye and antibiotic in the environment.

Hydrothermal synthesis of sewage sludge biochar for activation of persulfate for antibiotic removal: Efficiency, stability and mechanism

The use of biochar materials as catalysts to activate persulfate (PS) for the degradation of antibiotics has attracted much attention. In this study, a carbonaceous material (Cu/Zn-SBC) was prepared from sewage sludge by hydrothermal modification. The efficiency of PS activation by Cu/Zn-SBC was investigated using tetracycline (TC) as the model antibiotic. In the Cu/Zn-SBC + PS system, the TC removal rate reached 90.13% at 10 min and exceeded 99% within 4 h. This not only met the requirement of removing large amounts of pollutants in a short time but also achieved the complete removal of pollutants in the subsequent time. Additionally, the Cu/Zn-SBC + PS system was found to be dominated by radical and nonradical pathways. Cu, hydroxyl and carboxyl groups on the surface of Cu/Zn-SBC promoted the production of free radicals and non-free radicals. Under several changes in reaction conditions and water environment factors, the TC removal rate remained above 85% within 10 min. Furthermore, the removal rate of TC was still 85.79% when Cu/Zn-SBC combined with PS was reused twice and 77.14% when reused four times. This study provides an ideal solution for the treatment of sewage sludge, and offers a stable and efficient material for removing antibiotics from wastewater.

Morphology and Photocatalytic Activity of Zinc Oxide Reinforced Polymer Composites: A Mini Review

There is an approximately 3% of fresh water available globally for utilization, while the rest of the water is not available for usage, leaving billions of people with less water. Less water availability means that the majority of water consists of pollutants either in ground water or drinking water, which in turn may have a negative impact on the environment and people. Various methods such as plasma technology, flocculation, neutralization, and disinfection have been utilized for wastewater treatment. The wastewater treatment methods have been found to be selective in terms of the removal of other pollutants, as a result, the majority of them are unable to remove pollutants such as antibiotics at a trace level. In order to ensure that there is a complete removal of pollutants from water, there is a need for the development of alternative wastewater treatment methods. The use of solar light by photocatalysis is an alternative method for the degradation of toxic pollutants. Different photocatalysts such as zinc oxide (ZnO), titanium dioxide (TiO2), and silver (Ag) have been used in the process of photocatalysis. However, the above photocatalysts were found to have drawbacks such as agglomeration at higher contents and health problems during transportation. To solve the above problem, the nanoparticles were immobilized in various matrices such as polymers and ceramics, with polymers being preferred because of low cost, chemical inertness, and high durability. The current review discusses various methods for the preparation of ZnO and its synergy with other nanoparticles incorporated in various polymer matrices. Because it is known that the preparation method(s) affects the morphology, the morphology and the photocatalytic activity of various ZnO/polymer composites and hybrid systems of ZnO/other nanoparticles/polymer composites are discussed in depth.

A General Overview of Heterogeneous Photocatalysis as a Remediation Technology for Wastewaters Containing Pharmaceutical Compounds

The presence of persistent, difficult to degrade pharmaceutical compounds in wastewaters is a significant environmental concern. While heterogeneous photocatalysis can degrade a range of pharmaceutical compounds, as a technology, it is yet to be applied. Current research on heterogeneous photocatalysis for pharmaceutical removal is focused on the development of photocatalytic materials that are both efficient photocatalysts and solar driven as well as materials that combine both adsorption and photocatalysis. The formation of toxic by-products during photocatalytic degradation can be an issue, hence, mechanistic studies to identify reaction pathways and intermediates are important and are discussed in this review. The potential application of photocatalytic systems coupled with other technologies, to achieve complete pollutant removal and avoid toxin formation are also discussed. Given the broad range of properties of these pharmaceutical compounds and their corresponding wastewater matrices, each system needs to be optimised accordingly, with the need for pilot scale studies. Other than end of pipe solutions to reduce the occurrence of pharmaceutical pollutants in the environment, a comprehensive environmental management approach involving strategies such as the reduction of pharmaceutical prescriptions and the introduction of take back schemes are also needed to achieve a reduction of pharmaceutical compounds in the environment.

Fluoride-Doped TiO2 Photocatalyst with Enhanced Activity for Stable Pollutant Degradation

Fluoride-doped TiO2 (F-TiO2) was synthesized by an efficient and simple one-step synthesis and successfully used for the UV-photo-degradation of the toxic and stable pollutants methylene blue (MB) and bisphenol A (BPA). Initially, the synthesized catalyst was characterized and compared to untreated TiO2 (P25 Degussa) by different physical–chemical analyses such as XRD, band gap calculation, SEM, EDS, FITR, ECSA, or EIS. F-TiO2 defeated commercial TiO2, and almost complete pollutant removal was achieved within 30 min. The energy consumption was reduced as a result of the suitable reactor set-up, which reduced light scattering, and by the application of a long-pulse radiation procedure, where the lamp was switched off during periods where the radical degradation continued. This enhanced the overall photocatalysis process performance. Under these conditions, 80% of MB removal was attained within 15 min radiation with an energy consumption of only 0.070 Wh min−1, demonstrating a much better efficiency when compared to previously reported data. The catalyst was reusable, and its performance can be improved by the addition of H2O2. The results were validated by BPA degradation and the treatment of real wastewaters with both pollutants. The results were so encouraging that a scale-up reactor has been proposed for future studies.

Enhanced photocatalytic performance of magnetite/TS-1 thin film for phenol degradation

Photocatalytic degradation method is an emerging technique for complete removal of pollutants. Several semiconductor photocatalysts are reported as photocatalysts for industrial wastewater treatment in environmental applications. In this study Magnetite/TS-1 composite materials was used for photocatalytic degradation of phenol. Magnetite nanoparticles (MNP) (10 wt%) were dispersed with nanocrystalline Titanium Silicate-1 zeolite (TS-1). The Magnetite/TS-1 composite materials were characterized with various techniques. The structural analysis reveals the presence of MNP and zeolite-MFI phases in Magnetite/TS-1 composite materials. The average particles size of the magnetite nanoparticles is less than 5 nm and that of the composite nanoparticles are in the range of about 90 nm with micropore volume 0.110 cm3/g and the external surface area 120 m2/g. The photocatalytic experiments were carried out in a thin film flow photoreactor under UV radiation. The results showed that Magnetite/TS-1 composite materials exhibited improved activity for the degradation of phenol compared to TS-1. Preliminary studies proves that aeration is necessary for the photocatalytic reaction. The reaction parameters such as flow rate, pH and phenol concentration are optimized as 8 ml/min, pH 7.0 and 75 mg/L respectively. To understand the active species involved in the degradation of phenol radical scavengers such as NaI, benzoquinone and isopropyl alcohol are used to trap hole (h+), superoxide anion radical and hydroxyl radical (OH), respectively. From the obtained results it is envisaged that hydroxyl radicals are predominantly involved in complete oxidation of phenol. The extent of degradation of phenol was determined by measuring the amount of CO2 formed in the reaction. The results confirms that 99.6 % carbon in phenol is converted to CO2.

Simultaneous nanocatalytic surface activation of pollutants and oxidants for highly efficient water decontamination

Removal of organic micropollutants from water through advanced oxidation processes (AOPs) is hampered by the excessive input of energy and/or chemicals as well as the large amounts of residuals resulting from incomplete mineralization. Herein, we report a new water purification paradigm, the direct oxidative transfer process (DOTP), which enables complete, highly efficient decontamination at very low dosage of oxidants. DOTP differs fundamentally from AOPs and adsorption in its pollutant removal behavior and mechanisms. In DOTP, the nanocatalyst can interact with persulfate to activate the pollutants by lowering their reductive potential energy, which triggers a non-decomposing oxidative transfer of pollutants from the bulk solution to the nanocatalyst surface. By leveraging the activation, stabilization, and accumulation functions of the heterogeneous catalyst, the DOTP can occur spontaneously on the nanocatalyst surface to enable complete removal of pollutants. The process is found to occur for diverse pollutants, oxidants, and nanocatalysts, including various low-cost catalysts. Significantly, DOTP requires no external energy input, has low oxidant consumption, produces no residual byproducts, and performs robustly in real environmental matrices. These favorable features render DOTP an extremely promising nanotechnology platform for water purification.

Holistic approach to chemical and microbiological quality of aquatic ecosystems impacted by wastewater effluent discharges

Wastewater treatment plants (WWTPs) collect wastewater from various sources and use different treatment processes to reduce the load of pollutants in the environment. Since the removal of many chemical pollutants and bacteria by WWTPs is incomplete, they constitute a potential source of contaminants. The continuous release of contaminants through WWTP effluents can compromise the health of the aquatic ecosystems, even if they occur at very low concentrations. The main objective of this work was to characterize, over a period of four months, the treatment steps starting from income to the effluent and 5 km downstream to the receiving river. In this context, the efficiency removal of chemical pollutants (e.g. hormones and pharmaceuticals, including antibiotics) and bacteria was assessed in a WWTP case study by using a holistic approach. It embraces different chemical and biological-based methods, such as pharmaceutical analysis by HPLC-MSMS, growth rate inhibition in algae, ligand binding estrogen receptor assay, microbial community study by 16S and shotgun sequencing along with relative quantification of resistance genes by quantitative polymerase chain reaction. Although both, chemical and biological-based methods showed a significant reduction of the pollutant burden in effluent and surface waters compared to the influent of the WWTP, no complete removal of pollutants, pathogens and antibiotic resistance genes was observed.

Adsorptive removal of pollutants from water using magnesium ferrite nanoadsorbent: a promising future material for water purification.

Nanoadsorbents having large specific surface area, high pore volume with tunable pore size, affordability and easy magnetic separation gained much popularity in recent time. Iron-based nanoadsorbents showed higher adsorption capacity for different pollutant removal from water among other periodic elements. Spinel ferrite nanomaterials among iron-bearing adsorbent class performed better than single iron oxide and hydroxides due to their large surface area, mesoporous pore, high pore volume and stability. This work aimed at focusing on water treatment using magnesium ferrite (MgFe2O4) nanomaterials. Synthesis routes, properties and pollutant adsorption were critically investigated to explore the performance of magnesium ferrite in water treatment. Structural and surface properties were greatly affected by the factors involved in different synthesis routes and iron and magnesium ratio. Complete removal of pollutants through adsorption was achieved using magnesium ferrite. Pollutant adsorption capacity of MgFe2O4 and its modified forms was found several folds higher than Fe2O3 and Fe3O4 nanomaterials. In addition, MgFe2O4 showed strong stability in water than other pure iron oxide and hydroxide. Modification with graphene oxide, activated carbon, biochar and silica was demonstrated to be beneficial for enhanced adsorption capacity. Complex formation was suggested as a dominant mechanism for pollutant adsorption. These nanomaterials could be a viable and competitive adsorbent for diverse pollutant removal from water.

A review on remediation technologies using functionalized Cyclodextrin.

Modern lifestyle and alleviated anthropogenic activities have increased the pollutant load, ultimately causing stress on the environment. In industrialization, many harmful compounds are released into the environment polluting air, water, and soil, triggering adverse impacts on the ecosystem and human beings. Therefore, the development of advanced remediation technologies turns out as a significant environmental priority. Less polar cyclic oligosaccharide Cyclodextrin (CD) with cavity binding organic compounds attracted attention by helping effectively as environmental application. The formation of inclusion complexes and modified Cyclodextrin by cross-linking or surface modification enhances their capacity to abate pollutant effectively from the environment. Modification results in the formation of several novel materials such as CD-based composites, nanocomposites, crosslinked polymer or hydrogels, potent cross-linkers, CD-based membranes, and CD immobilized supports. Several environmental remediation technologies based on Cyclodextrin and modified Cyclodextrin have been discussed in detail in this review. Various environmental applications of Cyclodextrin and its derivatives have been discussed, along with their formation, properties, and characterization. Effective removal of organic pollutants, inorganic pollutants, micropollutants, volatile compounds etc., has been explained using several remediation technologies. Based on CD innocuity, this is referred to as the green process. The reversible equilibrium corresponded by the inclusion phenomenon sets a significant trend in the field of CD environmental application to develop techniques by incorporating supramolecular chemistry as well as irreversible methods such as biodegradation and advanced oxidation. It helps in the complete removal of pollutants and ultimately recycling the CD.

Advanced oxidation processes and nanomaterials -a review

Water related problems are expected to further increase considerably due to climate changes and population growth. Conventional wastewater treatment can be either a physical, chemical, and/or biological processes, or in some cases a combination of these operations. Current wastewater treatment technologies are deemed ineffective in the complete removal of pollutants, particularly organic matter. In many cases, these organic compounds are resistant to conventional treatment methods, thus creating the necessity for secondary treatment. Advanced Oxidation Processes (AOPs) are chemical oxidation processes that use powerful transitory species such as hydroxyl radicals and sulphate radicals. These species can be generated from water using energy for instance solar energy, electrical energy, sound energy etc or simply by chemicals like H2O2, ozone etc with or without the use of an appropriate catalyst. In many such methods, nanomaterials have been effectively used as catalysts for the generation of the transitory species. The large-scale commercialization of AOPs can lead to reduction of cost favorable to environmental applications as AOPs are based on physicochemical processes that produce intense changes in the structure of chemical species. The majority of AOPs can be applied to the remediation and detoxification of low or medium volumes of waters. This review summarises the major Advanced Oxidation Processes reported in recent literature with emphasis on the latest advances in the use of nanomaterials employed in various processes.

Performance of Iron-Functionalized Activated Carbon Catalysts (Fe/AC-f) on CWPO Wastewater Treatment

Two commercial activated carbon were functionalized with nitric acid, sulfuric acid, and ethylenediamine to induce the modification of their surface functional groups and facilitate the stability of corresponding AC-supported iron catalysts (Fe/AC-f). Synthetized Fe/AC-f catalysts were characterized to determine bulk and surface composition (elemental analysis, emission spectroscopy, XPS), textural (N2 isotherms), and structural characteristics (XRD). All the Fe/AC-f catalysts were evaluated in the degradation of phenol in ultrapure water matrix by catalytic wet peroxide oxidation (CWPO). Complete pollutant removal at short reaction times (30–60 min) and high TOC reduction (XTOC = 80 % at ≤ 120 min) were always achieved at the conditions tested (500 mg·L−1 catalyst loading, 100 mg·L−1 phenol concentration, stoichiometric H2O2 dose, pH 3, 50 °C and 200 rpm), improving the results found with bare activated carbon supports. The lability of the interactions of iron with functionalized carbon support jeopardizes the stability of some catalysts. This fact could be associated to modifications of the induced surface chemistry after functionalization as a consequence of the iron immobilization procedure. The reusability was demonstrated by four consecutive CWPO cycles where the activity decreased from 1st to 3rd, to become recovered in the 4th run. Fe/AC-f catalysts were applied to treat two real water matrices: the effluent of a wastewater treatment plant with a membrane biological reactor (WWTP-MBR) and a landfill leachate, opening the opportunity to extend the use of these Fe/AC-f catalysts for complex wastewater matrices remediation. The degradation of phenol spiked WWTP-MBR effluent by CWPO using Fe/AC-f catalysts revealed pH of the reaction medium as a critical parameter to obtain complete elimination of the pollutant, only reached at pH 3. On the contrary, significant TOC removal, naturally found in complex landfill leachate, was obtained at natural pH 9 and half stoichiometric H2O2 dose. This highlights the importance of the water matrix in the optimization of the CWPO operating conditions.

Integrated photocatalysis-adsorption-membrane separation in rotating reactor for synergistic removal of RhB

A synergistic system of integrated photocatalysis-adsorption-membrane separation in a rotating reactor was designed. The composite membrane was prepared via filtration process under vacuum, and it was composed of graphene oxide (GO) acted as the separation membrane, activated carbon (AC) as the adsorbent and Ag@BiOBr as the photocatalyst, respectively. In this Ag@BiOBr/AC/GO membrane system, rotation of the membrane could avoid the light-shielding effect from organic color pollutants to achieve the complete removal of pollutants. More importantly, the synergistic effect among photocatalysis, adsorption and membrane separation in rotating reactor was significant for the efficient removal of rhodamine B (RhB). In the Ag@BiOBr/AC/GO composite membrane, GO membrane layer could reject the organic molecular by the assistance of AC layer with efficient adsorption capacity, and Ag@BiOBr at outer layer could photodegrade the organics under visible light irradiation. The photocatalysis process could solve the problem of membrane fouling and adsorption could assist GO membrane for stopping the permeation of pollutants. Meanwhile, GO membrane was not only beneficial for catalyst recovery, but also could concentrate the pollutants via the membrane separation to accelerate the photocatalytic degradation. At the same time, both the photocatalysis degradation and membrane separation could promote the adsorption ability of AC. This synergistic system showed the significant potential for the practical application in the future.

A study on novel coupled membrane bioreactor with electro oxidation for biofouling reduction

The present study focuses on a novel method to integrate the electro-oxidation process with membrane bioreactor to reduce biofouling and increase the biodegradability index. Here, we used electro-oxidation as pretreatment with membrane bioreactor operating at a current density of 1.5 mA/cm2 with hydraulic retention time at six h. The mixed liquor suspended solids concentration was maintained constant at 3,200 mg/L throughout the experiment for 30 days. The results obtained were promising with the percentage removal of COD, TOC, total nitrogen, and chlorides were in the range of 97%, 90%, 94%, and 15%, respectively, which was comparatively higher than the existing membrane bioreactor. The biodegradable index of treated water was higher, reaching a maximum of 0.6, which is remarkably high compared with 0.3 in a membrane bioreactor. The integrated electro-oxidation process was efficient for the complete removal of pollutants from wastewater, which was confirmed using gas chromatography. In addition, the phytotoxicity test showed a significantly higher quality of treated water compared with that of raw tannery effluent. Hence, our proposed integrated electro-oxidation process can be used to decrease biofouling with increased biodegradability index as a replacement for MBR.

Separation of COD, sulphate and chloride from pharmaceutical wastewater using membrane integrated system: Transport modeling towards scale-up

• Nanofiltration applied to reclaim water from complex pharmaceutical wastewater. • Coupled mathematical model was followed to develop the transport model. • The model successfully validated performance of flat-sheet membranes in cross-flow modules. • The model demonstrated almost complete pollutant removal with high clean water permeation. • Developed semi-pilot system through scale-up confirms clean water production at 0.89 $/m 3 . The effluent from the pharmaceutical industries is a serious threat to the environment because of the existence of high chemical oxygen demand, ionic Chloride and Sulphate concentrations. To bring down the pollutant level as per environmental safe discharge regulations, a nanofiltration based semi pilot based system is proposed to recover clean water in continuous mode from pharmaceutical effluent. The experimental results were validated by the newly developed mathematical model, used for the transportation of molecules through nanofiltration membrane. Such mathematical approach was constructed on the basis of Extended Nernst–Planck equation which was further linearized and applied for the simulation. Effects of governing parameters like operating pressure, feed flow rates across membrane surface, constituents of feed solutions, solution pH and operational time on membrane solute rejection and solvent flux were analysed. It was found that the model predicted results corroborated extremely well with the experimental results with less relative error (<0.09), high regression (R 2 >99 %) and Willmott-d-index (>98 %), generating a steady state clean water flux of 110 L/m 2 h at 12 bar operating pressure and at a cross flow rate of 750 L/h with more than 98 % rejection to active pharmaceutical ingredients, chemical oxygen demand and other toxic molecules. Economic assessment with Scale-up shows that the proposed system is promising in producing clean water at a low cost (US 0.89 $/m 3 ) by purifying pharmaceutical wastewater.