Antibiotics in nutrient recovery from pig manure via electrodialysis reversal: Sorption and migration associated with membrane fouling

Unravelling the fouling behavior of cation exchange membrane (CEM) by waste salt containing decyltrimethylammonium chloride during membrane electrolysis

With the implementation of the zero liquid discharge (ZLD) process for industrial wastewater treatment, the generation of large quantities of industrial waste salts has become a growing concern. The presence of organic contaminants, however, limits the reuse of NaCl waste salts for ion exchange membrane electrolysis, and the fouling behavior during the electrolysis process needs to be investigated. In this study, decyltrimethylammonium chloride (DTAC)-containing salt was employed as a model industrial waste salt to evaluate the fouling of cation exchange membrane (CEM) during ion exchange membrane electrolysis involving waste salt reuse. Additionally, this study examined the effect of membrane cleaning on the properties of fouled CEMs. Results indicated that higher DTAC concentrations in the feed solution significantly exacerbated CEM fouling, forming a dense DTAC fouling layer on the membrane surface. This layer led to a marked increase in cell voltage and resistance. Electrochemical impedance spectroscopy (EIS) analysis further revealed that the DTAC fouling layer could hinder or completely obstruct the transmembrane migration of ions, particularly at elevated DTAC concentrations. Moreover, membrane cleaning proved effective in mitigating contamination during the electrolysis process. Notably, NaOH cleaning demonstrated superior performance compared to water cleaning, effectively removing most DTAC from fouled CEMs. This study provides valuable insights into organic fouling mechanisms and membrane cleaning strategies for the reuse of NaCl waste salts in ion exchange membrane electrolysis.

The fate of antibiotics during phosphate recovery processes - A critical review

The principles of circular economy encourage the recovery of phosphorus from nutrient-rich waste streams such as animal manure, domestic wastewater, and urine to supplement existing sources of raw phosphorus. However, these waste streams also contain a wide variety of contaminants of emerging concern including antibiotics, and the recovery of phosphorus from these waste streams results in the co-occurrence of antibiotics with the recovered phosphorus products. This paper provides a comprehensive overview of the fate of environmentally relevant antibiotics in three major existing and upcoming phosphorus recovery processes: precipitation-, membrane-, and adsorption-based treatment. In general, the co-occurrence of antibiotics in recovered phosphorus increases with the presence of dissolved organic matter (DOM) and cations due to π-π interaction and cationic bridge formation, respectively. Additionally, antibiotics display pH-based speciation resulting in electrostatic interactions with recovered phosphorus at pH > 7.0. Furthermore, this critical review establishes a new metric, the relative antibiotic-to‑phosphorus (RAP), defined as the ratio of the concentration of antibiotics to phosphorus in recovered phosphorus to that of the phosphorus-rich waste. Precipitation-based methods, particularly struvite, demonstrated the lowest RAP, while the RAP in carbon-based adsorbents was 1.8 × 108 times higher than in membrane-based processes. In reviewing literature on the fate of antibiotics in phosphorus recovery processes, several research needs are also highlighted: the fate of non-tetracycline antibiotics, simultaneous investigation of phosphorus and antibiotic fate in membrane- and adsorption-based methods, treatment methods to mitigate the co-occurrence of antibiotics in recovered phosphorus product, and the release of antibiotics from recovered phosphate products.

Selective electrodialysis for nutrient recovery and pharmaceutical removal from liquid digestate: Pilot-scale investigation and potential fertilizer production

The present research employs a pilot-scale selective electrodialysis system to treat liquid digestate, fractionating nutrient ions and exploring fertilizer creation via ammonia stripping and phosphorus precipitation, while studying pharmaceutical transport behavior and examining membrane fouling. The influence of diverse potentials was studied in simulated and real digestate, with 30 V application proven more efficient overall. Applying consecutive runs resulted in products that were 7.9, 7.4, 1.7, 5.3, and 6 times more concentrated compared to the feed solution for NH4+, K+, PO43-, Ca2+, and Mg2+, respectively. Pharmaceuticals analysis showed that ciprofloxacin was completely retained in the liquid digestate, while ibuprofen was detected in the anionic product. Diclofenac was initially present in the digestate but was undetectable in the final products, suggesting it adhered to the membrane. Membranes showed inorganic and organic fouling. The monovalent cation exchange membrane had severe salt scaling, showing calcium and magnesium deposits, and fewer functional groups.

Strain selection and adaptation of a fungal-yeast-microalgae consortium for sustainable bioethanol production and wastewater treatment from livestock wastewater

This study explores the potential of strain selection and adaptation for developing a fungi-yeast-microalgae consortium capable of integrated bioethanol production and livestock wastewater treatment. We employed a multi-stage approach involving isolation and strain selection/adaptation of these consortiums. The study started with screening some isolated fungi to grow on the cellulosic biomass of the livestock wastewater (saccharification) followed by a fermentation process using yeast for bioethanol production. The results revealed that Penicillium chrysogenum (Cla) and Saccharomyces cerevisiae (Sc) produced a remarkable 99.32 ppm of bioethanol and a concentration of glucose measuring 0.56 mg ml- 1. Following the impact of fungi and yeast, we diluted the livestock wastewater using distilled water and subsequently inoculated Nile River microalgae into the wastewater. The findings demonstrated that Chlorella vulgaris emerged as the dominant species in the microalgal community. Particularly, the growth rate reached its peak at a 5% organic load (0.105385), indicating that this concentration provided the most favorable conditions for the flourishing of microalgae. The results demonstrated the effectiveness of the microalgal treatment in removing the remaining nutrients and organic load, achieving a 92.5% reduction in ammonia, a 94.1% reduction in nitrate, and complete removal of phosphate (100%). The algal treatment also showed remarkable reductions in COD (96.5%) and BOD (96.1%). These findings underscore the potential of fungi, yeast, and Nile River microalgae in the growth and impact on livestock wastewater, with the additional benefit of bioethanol production.

Fate of micropollutants in struvite production from swine wastewater with sacrificial magnesium anode

Struvite recovery shows significant potential for simultaneously recovering nitrogen (N) and phosphorus (P) from swine wastewater but is challenged by the occurrence and transformation of antibiotic residuals. Electrochemically mediated struvite precipitation with sacrificial magnesium anode (EMSP-Mg) is promising due to its automation and chemical-free merits. However, the fate of antibiotics remains underexplored. We investigated the behavior of sulfadiazine (SD), an antibiotic frequently detected but less studied than others within the EMSP-Mg system. Significantly less SD (≤ 5%) was co-precipitated with recovered struvite in EMSP-Mg than conventional chemical struvite precipitation (CSP) processes (15.0 to 50.0%). The reduced SD accumulation in struvite recovered via EMSP was associated with increased pH and electric potential differences, which likely enhanced the electrostatic repulsion between SD and struvite. In contrast, the typical strategies used in enhancing P removal in the EMSP-Mg system, including increasing the Mg/P ratio or the Mg-release rates, have shown negligible effects on SD adsorption. Furthermore, typical coexisting ions (Ca2+, Cl-, and HCO3-) inhibited SD adsorption onto recovered products. These results provide new insights into the interactions between antibiotics and struvite within the EMSP-Mg system, enhancing our understanding of antibiotic migration pathways and aiding the development of novel EMSP processes for cleaner struvite recovery.

Reusable adsorbent of magnetite in mesoporous carbon for antibiotic removal

This study aims to evaluate the feasibility of an innovative reusable adsorbent through adsorption-degradation sequence for antibiotic removal from water. The magnetite/mesoporous carbon adsorbent was prepared using a two-step method of (i) in situ impregnation of magnetite precursor during resorcinol formaldehyde polymerization and (ii) pyrolysis at elevated temperature (800 °C). XRD spectra confirmed that magnetite (Fe3O4) was the only iron oxide species present in the adsorbent, and thermogravimetric analysis revealed that its content was 10 wt%. Nitrogen sorption analysis showed that Fe3O4/carbon features a high fraction of mesopores (> 80 vol.%) and a remarkable specific surface area value (246 m2 g-1), outstanding properties for water treatment. The performance of the adsorbent was examined in the uptake of three relevant antibiotics. The maximum adsorption uptakes were ca. 76 mg g-1, ca. 70 mg g-1, and ca. 44 mg g-1 for metronidazole, sulfamethoxazole, and ciprofloxacin, respectively. All adsorption curves were successfully fitted with Langmuir equilibrium model. The regeneration of adsorbent was carried out using Fenton oxidation under ambient conditions. After three consecutive runs of adsorption-regeneration, Fe3O4/carbon maintained its performance almost unchanged (up to 95% of its adsorption capacity), which highlights the high reusability of the adsorbent.

Treatment of anaerobically digested pig manure by applying membrane processes for nutrient recovery and antibiotics removal

A combination of membrane processes was applied to treat the digestate produced after the anaerobic treatment of pig manure in a biogas plant, aiming towards the recovery of nutrients and effective water treatment for potential reuse. Initially, coarse filtration (sieving and microfiltration) was used to remove particles larger than 1 µm, followed by ultrafiltration, to reduce the suspended solids concentrations below 1 g/L. Subsequently, selective electrodialysis is employed to recover the main nutrient ions, primarily ammonium and potassium. The ion-depleted digestate is then fed to a reverse osmosis unit, where clean water was recovered, yielding a by-product (concentrate) stream enriched in phosphates and organics content. The presence of antibiotics and the concentrations of heavy metals were monitored during all treatment stages to assess their behavior/removal in the various membrane processes. The results indicate that almost 51% of the digestate could be recovered as water free from ions and antibiotics, suitable for reuse in the biogas plant for process needs and irrigation purposes. The selective electrodialysis process can recover 51% of initial NH4+ content (corresponding to 96% of the electrodialysis feed), while the remainder largely ended up in the ultrafiltration concentrate. A similar behavior was observed for the case of K+, while approximately 68% of the phosphates content was retained by the coarse filtration process, with another 24% remaining in the ultrafiltration concentrate and the remaining 8% in the reverse osmosis concentrate. Most of the antibiotics and heavy metals were retained by the coarse and ultrafiltration steps, with smaller amounts detected in the reverse osmosis concentrate.

Visible-Light-Driven Z-Type Pg-C3N4/Nitrogen Doped Biochar/BiVO4 Photo-Catalysts for the Degradation of Norfloxacin

Antibiotics cannot be effectively removed by traditional wastewater treatment processes, and have become widespread pollutants in various environments. In this study, a Z-type heterojunction photo-catalyst Pg-C3N4 (PCN)/Nitrogen doped biochar (N-Biochar)/BiVO4 (NCBN) for the degradation of norfloxacin (NOR) was prepared by the hydrothermal method. The specific surface area of the NCBN (42.88 m2/g) was further improved compared to BiVO4 (4.528 m2/g). The photo-catalytic performance of the catalyst was investigated, and the N-Biochar acted as a charge transfer channel to promote carrier separation and form Z-type heterojunctions. Moreover, the NCBN exhibited excellent performance (92.5%) in removing NOR, which maintained 70% degradation after four cycles. The main active substance of the NCBN was •O2-, and the possible degradation pathways are provided. This work will provide a theoretical basis for the construction of heterojunction photo-catalysts.

17β-estradiol (E2) removal in anode-electrodialysis (anode-ED) during nutrient recovery from pig manure digestate

Nutrient recovery from anaerobic digestate through electrodialysis technology (ED) has been investigated and shown high promise, but the removal of 17β-estradiol (E2), which is a natural estrogen and widely found in manure digestate, is not clear. This study examined the mechanism of membrane adsorption and anodic oxidation of E2 during recovering nutrient from manure digestate, and further investigated the performance of Anode-ED in E2 removal. The results showed that the removal of E2 in conventional ED was primarily attributed to membrane adsorption, resulting in no detectable E2 in the product solution. The adsorption capacity of the anion exchange membrane for E2 was significantly higher compared to that of the cation exchange membrane. During Anode-ED operation, E2 was efficiently removed by electrochemical oxidation, in which the chlorination played a primary role. Moreover, the oxidation intermediates of E2 were further removed after 40 min. Even though the carbonate, volatile fatty acid (VFA), and humic acid in the real wastewater have a negative impact on E2 oxidation, the E2 was completely removed from digestate during nutrient recovery in the anode-ED. This study indicates that anode-ED is a promising technology for the removal of E2 during nutrient recovery from digestate.

Synergistic interface engineering in n-p-n type heterojunction Co3O4/MIL/Mn-STO with dual S-scheme multi-charge migration to enhance visible-light photocatalytic degradation of antibiotics

Constructing an effective multi-heterojunction photocatalyst with maximum charge carrier separation remains challenging. Herein, a high-efficient Co3O4/MIL-88A/Mn-SrTiO3 (Co3O4/MIL/Mn-STO) n-p-n heterojunction photocatalyst was successfully prepared by a simple hydrothermal method for the photodegradation of sulfamethoxazole (SMX). The combination of MIL and Co3O4/Mn-STO established an internal electric field and heterojunction, accelerating the separation of carriers, and thus improved photocatalytic performance. In the Co3O4/MIL/Mn-STO photocatalytic system, 95.5 % of SMX was degraded in 90 min. The photocatalytic kinetic removal rate of Co3O4/MIL/Mn-STO reached 0.0337 min-1, 8 times of Co3O4 (0.0041 min-1), 5.2 times of Mn-STO (0.0062 min-1), 4.6 times of MIL (0.0078 min-1), and 3.6 times of MIL/Mn-STO (0.0095 min-1). Remarkably, superoxide radicals (•O2-) and holes (h+) have been recognized as the main active species in the degradation process through reactive species elimination experiments and electron spin resonance (ESR) tests. The experimental and theoretical proved the in-built interfacial contact and synergistic effect between the photocatalyst accomplished with low bandgaps, high specific surface area, more reaction sites, high electron-hole pair separation, and maximum solar-light utilization. The molecular structure and possible degradation routes with intermediate products in the photocatalytic system were investigated using a liquid chromatography-mass spectrometer (LC-MS) and DFT calculations. This work provided new insight into the guidelines of rational design/growth of new multicomponent photocatalysts to remove antibiotics and other emerging contaminants in wastewater.

Mechanism and security of UV driven sodium percarbonate for sulfamethoxazole degradation using DFT and metabolomic analysis

Recently, sodium percarbonate (SPC) as a solid substitute for H₂O₂ has aroused extensive attention in advanced oxidation processes. In current work, the degradation kinetics and mechanisms of antibiotic sulfamethoxazole (SMX) by ultraviolet (UV) driven SPC system were explored. The removal efficiency of SMX was enhanced as the increasing dosage of SPC. Moreover, hydroxyl radical (•OH), carbonate radical (CO₃^•-) and superoxide radical (O₂^•-) were verified to be presented by scavenger experiments and •OH, CO₃^•- exhibited a significant role in SMX degradation. Reactions mediated by these radicals were affected by anions and natural organic matters, implying that an incomplete mineralization of SMX would be ubiquitous. The screening four intermediates and transformation patterns of SMX were verified by DFT analysis. Metabolomic analysis demonstrated that a decreasing negative effect in E. coli after 24 h exposure was induced by intermediates products. In detail, SMX interfered in some key functional metabolic pathways including carbohydrate metabolism, pentose and glucuronate metabolism, nucleotide metabolism, arginine and proline metabolism, sphingolipid metabolism, which were mitigated after UV/SPC oxidation treatment, suggesting a declining environmental risk of SMX. This work provided new insights into biological impacts of SMX and its transformation products and vital guidance for SMX pollution control using UV/SPC technology.

Current-Voltage and Transport Characteristics of Heterogeneous Ion-Exchange Membranes in Electrodialysis of Solutions Containing a Heterocyclic Amino Acid and a Strong Electrolyte

The alterations in current-voltage and transport characteristics of highly basic and strongly acidic ion-exchange membranes, during the electrodialysis of solutions containing a heterocyclic amino acid and a strong electrolyte, were studied. An increase in the catalytic activity of the water splitting process at the surface of heterogeneous MK-40 and MA-41 membranes upon prolonged contact with proline and tryptophan solutions was found. A significant effect of electroconvection on the components mass transfer through the cation-exchange membrane in the intensive current mode of electrodialysis was revealed for the solution containing a heterocyclic amino acid along with mineral salt (NaCl). This led to a reduction in the length of the "plateau" of the membrane's current-voltage characteristics, in comparison with the characteristics for an individual sodium chloride solution with the same concentration. The changes in the characteristics of the studied ion-exchange membranes caused by contact with solutions containing heterocyclic amino acids during electrodialysis were reversible when applying electrochemical regeneration (cleaning in place) using the overlimiting current mode, corresponding to the region of facilitated transport for these ampholytes.

Electrodialysis Tartrate Stabilization of Wine Materials: Fouling and a New Approach to the Cleaning of Aliphatic Anion-Exchange Membranes

Electrodialysis (ED) is an attractive method of tartrate stabilization of wine due to its rapidity and reagentlessness. At the same time, fouling of ion-exchange membranes by the components of wine materials is still an unsolved problem. The effect of ethanol, polyphenols (mainly anthocyanins and proanthocyanidins) and saccharides (fructose) on the fouling of aliphatic ion-exchange membranes CJMA-6 and CJMC-5 (manufactured by Hefei Chemjoy Polymer Materials Co. Ltd., Hefei, China) was analyzed using model solutions. It was shown that the mechanism and consequences of fouling are different in the absence of an electric field and during electrodialysis. In particular, a layer of colloidal particles is deposited on the surface of the CJMA-6 anion-exchange membrane in underlimiting current modes. Its thickness increases with increasing current density, apparently due to the implementation of a trap mechanism involving tartaric acid anions, as well as protons, which are products of water splitting and "acid dissociation". A successful attempt was made to clean CJMA-6 in operando by pumping a water-alcohol solution of KCl through the desalination compartment and changing electric field direction. It has been established that such a cleaning process suppresses the subsequent biofouling of ion-exchange membranes. In addition, selective recovery of polyphenols with high antioxidant activity is possible.

The potential of animal manure management pathways toward a circular economy: a bibliometric analysis

Improper disposal of animal waste is responsible for several environmental problems, causing eutrophication of lakes and rivers, nutrient overload in the soil, and the spread of pathogenic organisms. Despite the potential to cause adverse ecological damage, animal waste can be a valuable source of resources if incorporated into a circular concept. In this sense, new approaches focused on recovery and reuse as substitutes for traditional processes based on removing contaminants in animal manure have gained attention from the scientific community. Based on this, the present work reviewed the literature on the subject, performing a bibliometric and scientometric analysis of articles published in peer-reviewed journals between 1991 and 2021. Of the articles analyzed, the main issues addressed were nitrogen and phosphorus recovery, energy generation, high-value-added products, and water reuse. The energy use of livestock waste stands out since it is characterized as a consolidated solution, unlike other routes still being developed, presenting the economic barrier as the main limiting factor. Analyzing the trend of technological development through the S curve, it was possible to verify that the circular economy in the management of animal waste will enter the maturation phase as of 2036 and decline in 2056, which demonstrates opportunities for the sector's development, where animal waste can be an economic agent, promoting a cleaner and more viable product for a sustainable future.

Accelerate sulfamethoxazole degradation and detoxification by persulfate mediated with Fe2+&dithionite: Experiments and DFT calculation

Advanced oxidation process (AOPs) is one of the most effective technologies for organic pollutants removal. In this study, diverse reactive species generation and enhanced sulfamethoxazole (SMX) degradation were investigated based on persulfate (PDS) activated by Fe²⁺&dithionite (DTN). When involving Fe²⁺&dithionite in PDS, SMX degradation efficiency reached 84 % within 30 min following a pseudo-first-order kinetic, which was higher than those in Fe²⁺/PDS (50.4 %) and Fe²⁺/O₂/DTN (41.3 %). SO₄^•- and ^•OH were identified as dominant reactive species with a crucial role of FeSO₃⁺ based on quenching experiment and electron spin resonance (ESR). The contributions of SO₄^·-, ^·OH, and other species to SMX degradation were 60.1 %, 33.9 %, and 6 %, respectively. In Fe²⁺/DTN/PDS system, SMX was effectively degraded under nearly neutral pH (5.0-9.0), with activation energy of 96.04 kJ·mol^-1. The experiments and density functional theory (DFT) calculation demonstrated that three functional groups (benzenesulfonamido, benzene ring, and oxazole ring) were attacked for SMX degradation. Moreover, acute toxicity to Vibrio fischeri has enhanced in the earlier degradation process due to the intermediates and weaken with the continuous reaction. This work not only provides a high-activity SO₄^·--AOP for refractory pollutant treatment with possible dual radical generation resources, but elucidated diverse reactive species formation with Fe²⁺&dithionite.

Fate of antibiotic resistant genes in wastewater environments and treatment strategies - A review

Antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) have emerged in aquatic environments through the discharge of large amounts of antibiotics into wastewater. Well-designed wastewater treatment plants (WWTPs) with effective treatment processes are essential to prevent the release of ARGs directly into the environment. Although some systematic sequential treatment methods are used to remove ARGs, considerable gaps in removal mechanisms will be discussed. Therefore, deep analysis and discussion of various treatment methods are required to understand the ARGs removal mechanisms. In this manuscript, the role of antibiotics and the resistance mechanism of ARB are discussed in depth. In addition, the fate of ARGs in an aquatic environment and detection methods are compared comprehensively and discussed. In particular, the advantages and disadvantages of various methods are summarized and reviewed critically. Finally, combined technologies, such as advanced oxidation process (AOP) with biochemical systems, membrane separation with electrochemical AOP, ultrafiltration (UF) membrane coupled with photocatalytic treatment, and UF membrane separation coupled with sonication, are introduced. Overall, low-energy anaerobic treatment reactors with any of the above combined treatments might reduce the discharge of large quantities of ARGs into the environment. Finally, this review provides valuable insights for better ARG removal technologies by introducing combined effective treatment strategies used in real WWTPs.

A Review on Ion-Exchange Membrane Fouling during the Electrodialysis Process in the Food Industry, Part 1: Types, Effects, Characterization Methods, Fouling Mechanisms and Interactions

Electrodialysis (ED) was first established for water desalination and is still highly recommended in this field for its high water recovery, long lifetime and acceptable electricity consumption. Today, thanks to technological progress in ED processes and the emergence of new ion-exchange membranes (IEMs), ED has been extended to many other applications in the food industry. This expansion of uses has also generated several problems such as IEMs' lifetime limitation due to different ageing phenomena (because of organic and/or mineral compounds). The current commercial IEMs show excellent performance in ED processes; however, organic foulants such as proteins, surfactants, polyphenols or other natural organic matters can adhere on their surface (especially when using anion-exchange membranes: AEMs) forming a colloid layer or can infiltrate the membrane matrix, which leads to the increase in electrical resistance, resulting in higher energy consumption, lower water recovery, loss of membrane permselectivity and current efficiency as well as lifetime limitation. If these aspects are not sufficiently controlled and mastered, the use and the efficiency of ED processes will be limited since, it will no longer be competitive or profitable compared to other separation methods. In this work we reviewed a significant amount of recent scientific publications, research and reviews studying the phenomena of IEM fouling during the ED process in food industry with a special focus on the last decade. We first classified the different types of fouling according to the most commonly used classifications. Then, the fouling effects, the characterization methods and techniques as well as the different fouling mechanisms and interactions as well as their influence on IEM matrix and fixed groups were presented, analyzed, discussed and illustrated.

Degradation of sulfamethoxazole by ozonation combined with ionizing radiation

In this study, the degradation and mineralization of sulfamethoxazole (SMX) by ozonation and ionizing radiation were investigated respectively, and the performance of the combined process of ozonation and ionizing radiation was evaluated. Results showed that complete degradation of SMX could be obtained by ozonation in 12 min or by ionizing radiation with the absorbed dose of 1.5 kGy. However, the mineralization of SMX was very limited in ozonation and ionizing radiation system, TOC removal efficiency was less than 15% and 27% in single-ozonation and single-radiation process, respectively. The combination of ozonation and radiation process obviously enhanced the mineralization of SMX, TOC removal efficiency increased to 65.7%. Moreover, the ozonation-radiation process also exhibited good performance in the mineralization of sulfamethazine (SMT) and sulfanilamide (SM), suggesting a good application prospect of the combined process in treating wastewater contaminated with antibiotics. In addition, some different intermediate products were identified during SMX degradation in ozonation process and ionizing radiation process by a high-performance liquid chromatography-mass spectrometry (LC-MS), and possible pathways of SMX degradation by ozonation and radiation were proposed.

Degradation and mineralization of ofloxacin by ozonation and peroxone (O3/H2O2) process

The degradation and mineralization of ofloxacin (OFX) by ozonation and peroxone process (O₃/H₂O₂) was investigated. The influence of operational conditions and inorganic anions on the mineralization of OFX were also studied. Results showed that OFX could be rapidly oxidized by both O₃ alone and O₃/H₂O₂ process. The mineralization of OFX was significantly enhanced (55%) in peroxone process, compared with that in ozonation alone (30%). The direct oxidation of OFX by ozone molecules might account for the degradation of OFX in both ozonation and peroxone process, whereas, in the presence of H₂O₂, the improvement of the ozone decomposition and the formation of OH radicals were responsible for enhancing OFX mineralization. The applied dosage of H₂O₂ and O₃ was important for the performance of peroxone process in OFX mineralization. The addition of HCO₃^- and PO₄^3- enhanced OFX mineralization, while the presence of Cl^- and NO₃^- had negative effect on OFX mineralization in both ozonation and peroxone processes. Ozonation process might be a promising technology for the degradation of OFX, while the combination process of O₃/H₂O₂ could be an effective method for the improvement of the mineralization of refractory organic pollutants.

Fenton/Fenton-like processes with in-situ production of hydrogen peroxide/hydroxyl radical for degradation of emerging contaminants: Advances and prospects

Fenton processes based on the reaction between Fe²⁺ and H₂O₂ to produce hydroxyl radicals, have been widely studied and applied for the degradation of toxic organic contaminants in wastewater due to its high efficiency, mild condition and simple operation. However, H₂O₂ is usually added by bulk feeding, which suffers from the potential risks during the storage and transportation of H₂O₂ as well as its low utilization efficiency. Therefore, Fenton/Fenton-like processes with in-situ production of H₂O₂ have received increasing attention, in which H₂O₂ was in-situ produced through O₂ activation, then decomposed into hydroxyl radicals by Fenton catalysts. In this review, the in situ production of H₂O₂ for Fenton oxidation was introduced, the strategies for activation of O₂ to generate H₂O₂ were summarized, including chemical reduction, electro-catalysis and photo-catalysis, the influencing factors and the mechanisms of the in situ production and utilization of H₂O₂ in various Fenton/Fenton-like processes were analyzed and discussed, and the applications of these processes for the degradation of toxic organic contaminants were summarized. This review will deepen the understanding of the tacit cooperation between the in situ production and utilization of H₂O₂ in Fenton process, and provide the further insight into this promising process for degradation of emerging contaminants in industrial wastewater.

Assessment of degradation characteristic and mineralization efficiency of norfloxacin by ionizing radiation combined with Fenton-like oxidation

In this study, the degradation of norfloxacin was investigated by ionizing radiation combined with Fenton-like oxidation in order to enhance the degradation and mineralization of norfloxacin. The result showed that the removal efficiency of norfloxacin was 100%, 81.8%, 64.5%, 51.9%, and 45.6% at 0.4 kGy radiation when its concentration was 5, 10, 20, 30, and 40 mg/L. Norfloxacin could be completely degraded over pH range of 3.06-10.96 at 2 kGy radiation. The presence of inorganic anions had obvious influence on the degradation of norfloxacin, which decreased from 89.4% to 59.0%, 76.9%, 86.9%, 88.7% and 83.9% in the presence of 10 mmol/L CO₃^2-, HCO₃^-, NO₃^-, SO₄^2-, Cl^-, HPO₄^2-. The removal efficiency of norfloxacin decreased from 100% to 11.8%, 27.6% and 89.3% in the presence of peptone, glucose, and humic acid. The addition of Fenton-like catalysts, such as magnetite and goethite, could improve the mineralization ratio of norfloxacin because they could decompose hydrogen peroxide generated during the radiation process, to form hydroxyl radicals, leading to the enhancement of removal efficiency of norfloxacin. Finally, the intermediate products of norfloxacin degradation were analyzed by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF), and the degradation pathway was proposed.

Magnetic COFs as catalyst for Fenton-like degradation of sulfamethazine

A novel magnetic covalent organic frameworks (COFs) (Fe₂O₃@COFs) composite was fabricated by restricting the growth of Fe₂O₃ in the nanoscale channel of COFs, which can be used as the Fenton-like catalyst for sulfamethazine (SMT) degradation in aqueous solution. The as-prepared catalyst had good crystallinity, porosity and nano-flower-shaped morphology, and the encapsulated Fe₂O₃ particles were well-distributed and restrained in the nano-channels of COFs. Furthermore, magnetic COFs could not only adsorb SMT, but also catalyze the Fenton-like degradation of SMT in the presence of H₂O₂ (about 100% of removal efficiency). Acidic condition (pH = 3) facilitated SMT degradation in Fe₂O₃@COFs/H₂O₂. system. In consecutive 5 cycles, the catalyst showed a good stability and reusability with a high removal efficiency (>96%), a good mineralization rate (about 35%)，and a very low Fe²⁺ leaching (below 0.1 mg L^-1). Electron spin resonance (ESR) and quenching tests proved that hydroxyl radicals were the main reactive species generated in the Fe₂O₃@COFs/H₂O₂ system for the degradation of SMT. In conclusion, Fe₂O₃@COFs is a promising Fenton-like catalyst for the degradation of SMT and other toxic organic pollutants in water and wastewater.

Catalytic ozonation of norfloxacin using Co3O4/C composite derived from ZIF-67 as catalyst

In this study, Co₃O₄-carbon composite was synthesized by calcined metal organic framework (MOF) ZIF-67 and used as efficient catalysts for ozonation of norfloxacin (NOF). The MOF-derived Co₃O₄-C composite remained similar polyhedrons structure of ZIF-67, suggesting that Co₃O₄ was well-dispersed in Co₃O₄-C composite. Furthermore, a larger amount of surface carbon-oxygen functional groups were distributed on Co₃O₄-C composite, which resulted in the diversification of active sites for catalytic ozonation reaction. NOF degradation and mineralization could be effectively enhanced in Co₃O₄-C/O₃ process. Moreover, NOF mineralization by catalytic ozonation strongly depended on the solution pH, while other operational conditions, such as O₃ concentration and catalyst dosage had not obvious influence on it. Co₃O₄-C composite could significantly accelerate O₃ decomposition to produce active free radicals (such as •OH), which enhanced the mineralization of NOF. The possible catalytic mechanism of Co₃O₄-C composite was proposed. Additionally, after five consecutive use of Co₃O₄-C composite in catalytic ozonation process, there was no obvious decrease in TOC removal efficiency, indicating a stable performance of Co₃O₄-C composite, which was suitable for the catalytic ozonation for wastewater treatment.

Fouling of ion exchange membranes used in the electrodialysis reversal advanced water treatment: A review

Electrodialysis self-reversal (EDR) technology has attracted in the treatment of water for domestic and industrial uses. The self-reversal consists of a frequent reversal of the direction of current between the EDR-cell electrodes to combat fouling of ion exchange membranes (IEMs). Irrespective of the EDR self-cleaning processes, the role of natural organic matter and their complexing ability with metal ions on IEMs fouling is partially understood. The objective of this review is to identify the research gaps present in the elucidation of IEM fouling routes. The common IEMs' foulants are identified, and several fouling mechanisms are briefly discussed. The effectiveness of self-cleaning mechanisms to reduce IEMs fouling is also be discussed. Dissolved organic carbon (DOC) possesses high chelation which forms metal complexes with di and trivalent cations found in water. The role of ternary complexes, e.g. M^2+/3+-DOC and membrane surface, on membrane fouling via surface bridging, are also addressed. Finally, mitigation methods of IEMs membrane fouling are also discussed.

Sustainable livestock wastewater treatment via phytoremediation: Current status and future perspectives

Phytoremediation, the application of vegetation and microorganisms for recovery of nutrients and decontamination of the environment, has emerged as a low-cost, eco-friendly, and sustainable approach compared to traditional biological and physico-chemical processes. Livestock wastewater is one of the most severe pollution sources to the environment and water resources. When properly handled, livestock wastewater could be an important alternative water resource in water-scarce regions. This review discussed the characteristics and hazards of different types of livestock wastewater and available methods for the treatment. Meanwhile, the current status of investigations on phytoremediation of livestock wastewater via different hydrophyte systems such as microalgae, duckweed, water hyacinth, constructed wetlands, and other hydrophytes is reviewed, and the utilization of hydrophytes after management is also discussed. Furthermore, advantages and limitations on livestock wastewater management via phytotechnologies are emphasized. At last, future research needs are also proposed.

Electrodialysis Applications in Wastewater Treatment for Environmental Protection and Resources Recovery: A Systematic Review on Progress and Perspectives

This paper presents a comprehensive review of studies on electrodialysis (ED) applications in wastewater treatment, outlining the current status and the future prospect. ED is a membrane process of separation under the action of an electric field, where ions are selectively transported across ion-exchange membranes. ED of both conventional or unconventional fashion has been tested to treat several waste or spent aqueous solutions, including effluents from various industrial processes, municipal wastewater or salt water treatment plants, and animal farms. Properties such as selectivity, high separation efficiency, and chemical-free treatment make ED methods adequate for desalination and other treatments with significant environmental benefits. ED technologies can be used in operations of concentration, dilution, desalination, regeneration, and valorisation to reclaim wastewater and recover water and/or other products, e.g., heavy metal ions, salts, acids/bases, nutrients, and organics, or electrical energy. Intense research activity has been directed towards developing enhanced or novel systems, showing that zero or minimal liquid discharge approaches can be techno-economically affordable and competitive. Despite few real plants having been installed, recent developments are opening new routes for the large-scale use of ED techniques in a plethora of treatment processes for wastewater.

The Development of Electroconvection at the Surface of a Heterogeneous Cation-Exchange Membrane Modified with Perfluorosulfonic Acid Polymer Film Containing Titanium Oxide

One way to enhance mass transfer and reduce fouling in wastewater electrodialysis is stimulation of electroconvective mixing of the solution adjoining membranes by modifying their surfaces. Several samples were prepared by casting the perfluorosulfonic acid (PFSA) polymer film doped with TiO₂ nanoparticles onto the surface of the heterogeneous cation-exchange membrane MK-40. It is found that changes in surface characteristics conditioned by such modification lead to an increase in the limiting current density due to the stimulation of electroconvection, which develops according to the mechanism of electroosmosis of the first kind. The greatest increase in the current compared to the pristine membrane can be obtained by modification with the film being 20 μm thick and containing 3 wt% of TiO₂. The sample containing 6 wt% of TiO₂ provides higher mass transfer in overlimiting current modes due to the development of nonequilibrium electroconvection. A 1.5-fold increase in the thickness of the modifying film reduces the positive effect of introducing TiO₂ nanoparticles due to (1) partial shielding of the nanoparticles on the surface of the modified membrane; (2) a decrease in the tangential component of the electric force, which affects the development of electroconvection.