Removal Efficiency Of Diclofenac Research Articles

Application of electro-membrane bioreactor in the treatment of pharmaceutical wastewater

In the present study, the integrated process of an electro-membrane bioreactor (EMBR) with conventional membrane bioreactor (MBR) was used for wastewater treatment. The removal rates of chemical oxygen demand (COD), phosphate (PO43-), turbidity, diclofenac (DCF), and UV254 were investigated in both reactors, which operated with a sludge retention time (SRT) of 60 d and a hydraulic retention time (HRT) of 24 h. The assessment of the current density effect on DCF removal in an electrocoagulation reactor indicated that 0.5 mA/cm² was an appropriate current for the operation of the EMBR. The results of conventional pollutant removal showed that applying an electric current to the MBR approximately increased COD removal by 1.1 times, PO43- removal by 1.56 times, UV254 removal by 1.26 times, and turbidity removal by 1.11 times compared to the conventional MBR. The DCF removal efficiency increased from 43.90 % in the MBR process to 76.46 % in the EMBR. Membrane fouling was investigated through transmembrane pressure (TMP) monitoring, and the findings showed an increase in membrane usage time in EMBR compared to conventional MBR. Finally, the results explained that the application of current to MBR improves the removal of contaminants, mitigates membrane fouling, and reduces the residual DCF concentration.

Enhanced diclofenac adsorption and degradation using iron‐loaded modified spent bleaching earth carbon in the presence of clofibric acid: mechanistic insights and toxicity assessment

AbstractBACKGROUNDThe presence of pharmaceutical active substances such as diclofenac (DCF) and clofibric acid (CA) in aquatic environments poses significant ecological threats. Existing treatments have not fully explored the impact of CA on DCF removal efficiency. This research introduces nZVI/CTAB‐SBE@C, a novel adsorbent developed from industrial spent bleaching earth (SBE), modified with cetyltrimethylammonium bromide (CTAB) and nano zero‐valent iron (nZVI), enhancing both adsorption and degradation of DCF and CA.RESULTSThis study investigated the impact of CA on the removal capabilities of nZVI/CTAB‐SBE@C for DCF in a coexisting system. Systematic examinations were conducted on the effects of various parameters, including reaction time, dosage, temperature, actual wastewater, humic acid content and coexisting ions. Results indicated that the presence of CA significantly enhanced the DCF removal efficiency, achieving an optimal rate of 87.3% under conditions of reaction time 2 h, adsorbent dosage 5 g L−1 and temperature 25 °C. Moreover, interactions between Al3+ ions and the adsorbent matrix notably improved removal efficiencies for both DCF and CA. Analysis revealed that CA facilitated new degradation pathways for DCF, including hydroxylation and decarboxylation reactions. Additionally, the presence of CA reduced the toxicity of degradation intermediates, enhancing environmental safety compared to systems containing only DCF.CONCLUSIONThis study effectively transforms industrial waste into the efficient nZVI/CTAB‐SBE@C adsorbent. The presence of CA not only boosts DCF removal efficiency but also promotes its safer degradation, thereby reducing the ecological impact of contaminants. © 2024 Society of Chemical Industry (SCI).

Solar powered membrane bioreactor (MBR) treating wastewater for reuse at a hospital in Kampala, Uganda – Results of pilot-scale trials

A robust and cost-effective pilot solar-powered membrane bioreactor (MBR) with downstream granular activated carbon (GAC) filter hospital wastewater treatment was developed for the Lubaga hospital in Kampala, Uganda. The MBR-GAC pilot included a 25 m2 ultrafiltration (UF) module, a 100 kg GAC filter, 20 photovoltaic panels totaling 7 kWp and a 3.55 kWh supercapacitor energy storage unit to produce non-potable and reusable water for toilet flushing, cleaning and irrigation. The pilot operated with 43% clean energy autonomy with grid and diesel generator backup for power outages of more than 1 hour. The MBR pilot produced an average flux of 10–15 L m–2 h–1 with 50% total organic carbon (TOC) removal. The nitrification, denitrification and filtration tanks were separated to achieve a nitrification of 80% and denitrification of 20%. The removal of typical hospital pharmaceutical residues that could not be reduced by the MBR increased to approximately 90% after the downstream GAC filter was upgraded. The removal efficiency of the GAC decreased to approximately 25% at 4,290 bed volume (BV). The significant increase of 75% in the removal efficiency of diclofenac in the MBR was attributed to the acclimation of the activated sludge. The quality of the treated wastewater from the pilot plant was sufficient for reuse by irrigation of the hospital garden, toilet flushing and cleaning. Finally, the study discussed ways to optimize the design and operation of the plant. The pilot is scalable to be replicated elsewhere and adapted in an efficient and cost-effective manner in sub-Saharan countries in Africa.

Diclofenac Degradation in Aqueous Solution Using Electron Beam Irradiation and Combined with Nanobubbling

Diclofenac (DCF) degradation in aqueous solution under electron beam (EB) irradiation after nanobubbling treatment was studied and compared with treatments using nanobubbling or EB irradiation alone. It was found that the removal efficiency of DCF increased by increasing the adsorbed dose, and it depended on the initial concentration of DCF in solution, being higher for the lower concentrations. Furthermore, when using the nanobubbling treatment alone, about 16% of the DCF was removed from the aqueous solution due to the OH radicals generated during the process. On the other hand, using EB treatment at 0.5 kGy, the degradation of DCF increased from 36% to 51% when adding a nanobubbling pretreatment before the EB radiation. At higher doses (5 kGy), the degradation of DCF was 96% using EB radiation and 99% using nanobubbling before EB radiation, indicating that the nanobubbling effect was not synergistic. With an increase in the adsorbed doses, EB radiation seemed to play a more important role on the degradation of DCF, probably due to the reactive species generated. Moreover, the solutions treated with nanobubbling and EB radiation presented higher COD values and radiolytic by-products with aromatic rings with chlorine. This work can support the development of innovative strategies to treat municipal wastewaters using ionizing radiation technologies.

Synthesis of recyclable and light-weight graphene oxide/chitosan/genipin sponges for the adsorption of diclofenac, triclosan, and microplastics

Emerging micropollutants, such as pharmaceuticals and microplastics (MPs), have become a pressing water environmental concern. The aim of this study is to synthesize chitosan sponges using graphene oxide (GO) and genipin (GP) for the removal of pharmaceuticals (diclofenac (DCF) and triclosan (TCS)) and MPs, verify their adsorption mechanisms, evaluate the effects of temperature, pH, and salinity on their adsorption capacities, and determine their reusability. The GO5/CS/GP sponge exhibited a macroporous nature (porosity = 95%, density = 32.6 mg/cm3). GO and cross-linker GP enhanced the adsorption of DCF, TCS, and polystyrene (PS) MPs onto the CS sponges. The adsorption of DCF, TCS, and PS MPs involved multiple steps: surface diffusion and pore diffusion of the sponge. The adsorption isotherms demonstrated that Langmuir model was the most fitted well model to explain adsorption of TCS (qm = 7.08 mg/g) and PS MPs (qm = 7.42 mg/g) on GO5/CS/GP sponge, while Freundlich model suited for DCF adsorption (qm = 48.58 mg/g). DCF adsorption was thermodynamically spontaneous and endothermic; however, the adsorption of TCS and PS MPs was exothermic (283–313 K). The optimal pH was 5.5–7 due to the surface charge of the GO5/CS/GP sponge (pHzpc = 5.76) and ionization of DCF, TCS, and PS MPs. As the salinity increased, DCF removal efficiency drastically decreased due to the weakening of electrostatic interactions; however, TCS removal efficiency remained stable because TCS adsorption was mainly caused by hydrophobic and π–π interactions rather than electrostatic interaction. The removal of PS MPs was enhanced by the electrostatic screening effects of high Na+ ions. PS nanoplastics (average size = 26 nm) were removed by the GO5/CS/GP sponge at a rate of 73.0%, which was better than that of PS MPs (41.5%). In addition, the GO5/CS/GP sponge could be recycled over five adsorption–desorption cycles.

The electro-Fenton/sulfite process with Fe-Mn bimetallic catalyst for diclofenac degradation at neutral pH

The application of bimetallic catalysts in heterogeneous electro-Fenton (Hetero-EF) is limited due to its poor performance over a wide pH range. In this work, the Hetero-EF/sulfite process was constructed with FeMn@C as the catalyst to improve the degradation of pollutants under neutral pH. The removal efficiency of diclofenac (DCF) (97.8%) was significantly higher than that of Hetero-EF (15.0%) at pH 7, in which the degradation rate constant k was increased by 19.75 times. The existence and transformation process of various active species (•OH, SO4•-, O2•-, and 1O2) in the process were verified by capture experiments and electron paramagnetic resonance (EPR) test. The possible DCF degradation pathway was also proposed. The introduction of sulfite could reduce Fe3+ and Mn3+, promote the Fe(II)/Fe(III) and Mn(II)/Mn(III) cycles, strengthen the generation of active species, and thus promote the degradation of pollutants. The removal efficiency was still maintained 76.6% after five cycles. The Hetero-EF/sulfite process is a simple, feasible, and efficient method to degrade pollutants, which has a broad application prospect.

Removal of Diclofenac in Wastewater by Activated Sludge in Batch and Moving-bed Biofilm Reactor Experiments

This study aimed to determine the diclofenac removal in wastewater by sludge taken from an operating wastewater treatment facility. Laboratory experiments were conducted in two parts: batch and moving-bed biofilm reactor (MBBR) experiments. Results from batch experiments showed that 0.1–2 mg L-1 of diclofenac could be removed more than 80% within 72 h, and the removal efficiency reduced to less than 60% for higher concentrations. The increase in the removal rate from 0.00058 to 0.16527 mg L-1 h-1 was observed when the initial diclofenac concentration increased from 0.1 to 10 mg L-1, respectively. The average first-order rate constants of 24-h and 72-h degradation were calculated as 4.71 × 10-2 and 1.99 × 10-2 h-1, respectively. The removal of diclofenac by sludge was mainly from biodegradation by microorganisms in sludge, followed by the adsorption onto the sludge biomass. The addition of various metal ions in the studied range did not significantly increase the diclofenac removal; however, the addition of Ca2+, Co2+, Fe3+, Mn2+, and Zn2+ tended to increase both diclofenac removal rate and efficiency. This positive effect was reduced when the metal ion concentrations were increased up to 0.75 ppm. Lastly, results from an initial phase of continuous MBBR showed that sludge addition during the start-up also extended the diclofenac removal efficiency to one week compared with 3 days in the experiment without sludge addition. In conclusion, the findings show the capability of using activated sludge in diclofenac wastewater treatment by the traditional or alternative systems.

Coupled adsorption-photocatalysis process for the removal of diclofenac using magnetite/reduced graphene oxide nanocomposite

Diclofenac (DCF) is frequently detected in water bodies (ng/L to g/L) as it is not completely removed by conventional wastewater treatment plants. Adsorption and photocatalysis have been studied as promising methods for treating DCF; however, both processes have limitations. Thus, in this study, the removal efficiency of DCF is evaluated using a magnetite/reduced graphene oxide (Fe3O4/RGO) nanocomposite via a coupled adsorption-catalysis process. The Fe3O4/RGO nanocomposite was successfully synthesized using a microwave-assisted solvothermal method and exhibited a bandgap of 2.60 eV. The kinetic data best fitted the Elovich model (R2 = 0.994, χ2 = 0.29), indicating rapid adsorption. The maximum DCF adsorption capacity calculated using the Langmuir model was 80.33 mg/g. An ultraviolet C (UVC) light source and 0.1 g/L of Fe3O4/RGO nanocomposite were the optimum conditions for the removal of DCF (C0 = 30 mM) by a coupled adsorption-photocatalysis process (first-order rate constant (k) = 0.088/min), which was greater than the single adsorption (k = 0.029/min) and pre-adsorption and post-photocatalysis (k = 0.053/min) processes. This indicates that the adsorbed DCF did not hamper the photocatalytic reaction of the Fe3O4/RGO nanocomposite, but rather enhanced the coupled adsorption-photocatalytic reaction. DCF removal efficiency was higher at acidic conditions (pH 4.3–5.0), because high H+ promotes the generation of certain reactive oxygen species (ROS) and increases of electrostatic interaction. The presence of NaCl and CaCl2 (10 mM) did not notably affect the total DCF removal efficiency; however, Ca2+ affected the initial DCF adsorption affinity. Scavenger experiments demonstrated O2∙− and h+ play a key ROS than ·OH to degrade DCF. The acute toxicity of DCF towards Aliivibrio fischeri gradually decreased with increasing treatment time.

Polyaniline-coated magnetic nanoparticles to enhance removal of diclofenac from aqueous media

This study presents a straightforward and cost-effective synthesis method for producing magnetic nanoparticles coated with polyaniline. These nanoparticles are utilized for the efficient removal of diclofenac from aqueous solutions. The synthesized material underwent thorough characterization through various techniques. Additionally, the adsorbent's properties were investigated, and adsorption experiments were conducted to explore the effects of pH, contact time, and diclofenac concentration. The most favorable outcomes were achieved at pH 4, using 25 mg of adsorbent, and with a stirring time of 10 min. Under these optimized conditions, the material exhibited a diclofenac removal efficiency of approximately 90 %. The adsorption process was comprehensively studied employing the pseudo-second-order kinetic model and the isothermal Langmuir-Freundlich dual-site model. Furthermore, the adsorbent displayed exceptional regenerative capabilities, allowing for multiple reuse cycles without a noticeable decline in efficiency. Theoretical investigations suggested that the interaction between diclofenac and the polyaniline surface predominantly involves the nucleophilic groups of diclofenac (-CO, -OH, and -NH) as well as the electrophilic group of polyaniline (-NH-). Overall, these findings underscore the high potential of this adsorbent material for effectively extracting diclofenac from water sources.

Harnessing water fleas for water reclamation: A nature-based tertiary wastewater treatment technology

Urbanisation, population growth, and climate change have put unprecedented pressure on water resources, leading to a global water crisis and the need for water reuse. However, water reuse is unsafe unless persistent chemical pollutants are removed from reclaimed water. State-of-the-art technologies for the reduction of persistent chemical pollutants in wastewater typically impose high operational and energy costs and potentially generate toxic by-products (e.g., bromate from ozonation). Nature-base solutions are preferred to these technologies for their lower environmental impact. However, so far, bio-based tertiary wastewater treatments have been inefficient for industrial-scale applications. Moreover, they often demand significant financial investment and large infrastructure, undermining sustainability objectives. Here, we present a scalable, low-cost, low-carbon, and retrofittable nature-inspired solution to remove persistent chemical pollutants (pharmaceutical, pesticides and industrial chemicals). We showed Daphnia's removal efficiency of individual chemicals and chemicals from wastewater at laboratory scale ranging between 50 % for PFOS and 90 % for diclofenac. We validated the removal efficiency of diclofenac at prototype scale, showing sustained performance over four weeks in outdoor seminatural conditions. A techno-commercial analysis on the Daphnia-based technology suggested several technical, commercial and sustainability advantages over established and emerging treatments at comparable removal efficiency, benchmarked on available data on individual chemicals. Further testing of the technology is underway in open flow environments holding real wastewater. The technology has the potential to improve the quality of wastewater effluent, meeting requirements to produce water appropriate for reuse in irrigation, industrial application, and household use. By preventing persistent chemicals from entering waterways, this technology has the potential to maximise the shift to clean growth, enabling water reuse, reducing resource depletion and preventing environmental pollution.

Response surface methodology mediated optimization of diclofenac and norfloxacin biodegradation using laccase immobilized on metal–organic frameworks

In this work, laccase immobilized on a zeolitic imidazolate framework (Lac-ZIF) is used as a biocatalytic composite to decontaminate pharmaceutically active compounds (PhACs): diclofenac (DFC), and norfloxacin (NOR). A central composite face (CCF) design was used, and operational parameters were optimized using a quadratic response surface methodology (RSM) regression model, resulting in pH 6.4, 10 mg Lac-ZIF dosage, 10.4 mg L−1 initial concentration, and 8 h contact time. The model proved viable and effective for application in this study, giving predictions of 93.9 and 95.1% removal efficiencies of DFC and NOR, which were confirmed by actual experimental results with high accuracy. The Lac-ZIF revealed enhanced thermal stability with subsequently higher deactivation energies (Ed) than the free form of laccase. Additionally, the application of the biocatalyst in the treatment of real water samples, outperformed the free laccase by approximately 1.5 folds. Furthermore, the Lac-ZIF preserved 79 and 83% residual removal efficiencies after 6 cycles of reuse, with enhanced storage stabilities of 87.2 and 91.1% efficacies at 25 days for storage for DFC and NOR elimination, respectively. This study, therefore, demonstrates the potential of laccase immobilized on ZIFs for efficient biodegradation of DFC and NOR, which can be exploited for the remediation of wastewater containing PhACs.

Highly adsorptive removal of molecular diclofenac and bacteria using polycation modified ZnO/SiO2 nanocomposites

The present study investigated the adsorptive removal of non-steroidal medication diclofenac (DCF) using polycation, PVBTAC modified zinc oxide/silica nanocomposite (ZnO/SiO2). The ZnO/SiO2 which was fabricated based on nanosilica rice, was examined by XRD, FT-IR, TEM, EDX, and zeta potential measurements. Surface of ZnO/SiO2 was modified by PVBTAC adsorption at pH 9 and 100 mM KCl to reverse the high charge of material. The optimum parameters for DCF removal using PVBTAC-modified ZnO/SiO2 were contact time 90 min, pH 8 and adsorbent dosage 10 mg/mL. The maximum adsorption capacity and the removal efficiency of DCF were found to be 66 mg/g and 91.8%, respectively, while the bacteria Escherichiacoli(E.coli) removal reached greater than 88 %. Adsorption of DCF on PVBTAC-modified ZnO/SiO2 was mainly controlled by electrostatic attraction between anionic DCF molecules and positively charged PVBTAC-modified ZnO/SiO2 surface whereas the E.coli removal was controlled by both electrostatic and non-electrostatic interactions. Adsorption isotherms of DCF on PVBTAC-modified ZnO/SiO2 at different ionic strengths were reasonably represented by a two-step model while adsorption kinetics fitted well with the pseudo-second-order model. After four regenerations of PVBTAC modified ZnO/SiO2, the DCF removal still exceeded 84%. Our materialis agreat performance adsorbent to remove pharmaceutical and bacteria.

Simultaneous and selective removal of diclofenac and ibuprofen from aqueous matrices by a hybrid TiO2-dual-template molecularly imprinted polymer

ABSTRACT Dual-template molecularly imprinted polymer based on TiO2 nanoparticles (NPS) (TiO2-MIP) was synthesised by surface molecularly imprinted method to achieve the simultaneous and selective removal of diclofenac and ibuprofen in aqueous media. The characterisation results of Fourier Transformed Infrared spectroscopy (FTIR), X-ray Diffractometry (XRD), Brunauer, Emmett and Teller (BET) and Field Emission Scanning Electron Microscopy (FE-SEM) revealed the successful imprinting process on the surface of titania. The effects of operating parameters including pH, initial concentration of target pollutants and dosage of nanocomposite were first investigated. Then, TiO2-MIP nanocomposites were prepared at different TiO2 NPS to imprinted polymer mass ratios, and the optimal value was determined. The best treatment performance was obtained at pH = 4, 10 mg/L of target pollutants, 1 g/L of the nanocomposite, and 1:4 mass ratio, in which the simultaneous and selective removal efficiency of diclofenac and ibuprofen was 86.6% and 75.0%, respectively. The adsorption capacity of synthesised TiO2-MIP nanocomposites for DCF and IBP was 5.22 and 4.38 mg/g, respectively. The pseudo-second-order model (R2 ≥ 0.99) and Langmuir isotherm model (R2 = 0.99) demonstrated the best fitting with experimental data. The adsorption capacity, photodegradation activity, selectivity and reusability of polymeric nanocomposite were also studied. The results revealed that the synthesised TiO2-MIP nanocomposite had higher adsorption capacity, enhanced photodegradation performance and better selectivity for target pollutants than non-imprinted TiO2 nanocomposite. The results further showed that the selection factor of TiO2-MIP for diclofenac and ibuprofen was 5.4 and 3.8 times of the competitive pollutant, respectively, indicating stronger and more specific interactions for the target molecules. The brilliant adsorption and photodegradation performance, simultaneous removal of contaminants, good stability and selectivity towards target pollutants in the presence of competitive compounds are the advantages of the as-prepared TiO2-MIP nanocomposite. Thus, a hybrid TiO2-molecularly imprinted polymer can play an influential role in the treatment of persistent environmental insults in complex aquatic environments.

Organic polymer doped graphene-based composite for the effective elimination of diclofenac: A detailed study with phytotoxic assessments

In recent years, diclofenac (DCF), a non-steroidal anti-inflammatory drug (NSAID), has become globally ubiquitous in various environments, most frequently detected in freshwater bodies posing potential toxic effects on aquatic and terrestrial life as well as human health. Considering the currently available processes to eliminate DCF, adsorption is one of the effective means for this purpose. In the current study, polypyrrole-doped reduced graphene oxide (GAP) was evaluated for the efficient removal of DCF from industrial wastewater. The incorporation of polypyrrole proved to augment the removal efficiency compared to the raw graphene oxide. In the optimisation of the process parameters, the removal efficiency of diclofenac using GAP was obtained to be 95.3 %. The adsorption process was found to be a good fit for the Freundlich isotherm and the pseud-second-order kinetics. The treated DCF aqueous solution using GAP has been evaluated for plant growth to determine the efficacy of the remediation process. The regenerative study indicated promising removal efficiency, demonstrating the excellent performance of GAP as an alternative to current adsorbents used for diclofenac removal from industrial wastewater.

Combination of advanced nano-Fenton process and sonication for destruction of diclofenac and variables optimization using response surface method

Diclofenac (DCF) as a non-steroidal pharmaceutical has been detected in aquatic samples more than other compounds due to its high consumption and limited biodegradability. In this study, ultrasound waves were applied along with an advanced nano-Fenton process (US/ANF) to remove DCF, and subsequently, the synergistic effect was determined. Before that, the efficiency of the US and ANF processes was separately studied. The central composite design was used as one of the most applicable responses surface method techniques to determine the main and interactive effect of the factors influencing DCF removal efficiency in US/ANF. The mean DCF removal efficiency under different operational conditions and at the time of 1–10 min was obtained to be about 4%, 83%, and 95% for the US, ANF, and US/ANF, respectively. Quadratic regression equations for two frequencies of US were developed using multiple regression analysis involving main, quadratic, and interaction effects. The optimum condition for DCF removal was obtained at time of 8.17 min, H/F of 10.5 and DCF concentration of 10.12 at 130 kHz US frequency. The synergy index values showed a slight synergistic effect for US/ANF (1.1). Although the synergistic effect of US/ANF is not very remarkable, it can be considered as a quick and efficient process for the removal of DCF from wastewater with a significant amount of mineralization.

Removal of Diclofenac Sodium from Wastewater in Microbial Fuel Cell by Anode Modified with MnCo2O4

Microbial fuel cell (MFC) with a modified anode is one of the new methods to increase MFC efficiency. This study synthesized an anode modified with cobalt manganese oxide (MnCo2O4@CF) on carbon felt (CF) by easy hydrothermal method and binder-free. Chemical oxygen demand (COD) was measured with and without diclofenac (DCF). According to SEM results, MnCo2O4 was uniformly dispersed on the anode electrode surface. Moreover, the maximum power density in COD (1000 mg/L), 48 h. condition without DCF (726 mA/m2) was 165 ± 0.012 mW/m2 and with DCF concentration of 20 mg/L, it was 308 ± 0.013 mW/m2 (992 mA/m2). In addition, in the presence of 10 mg/L DCF concentration, the maximum COD removal efficiency was 82% ± 1.93 at 48 h. COD removal efficiency without DCF was 94.67% ± 0.02 at 72 h. After 72 h, the maximum removal efficiency of COD and DCF in the carbon anode was 41% ± 1.15 and 9.5% ± 0.23, respectively. Moreover, the maximum DCF removal efficiency using a MnCo2O4 anode was 56% ± 0.55, at 48 h; the initial COD concentration was 500 mg/L, and the DCF concentration was 20 mg/L. This research showed that coating the anode with MnCo2O4 could lead to the increased growth of microorganisms on the surface of the anode, decreased load transfer resistance, increased power density, and more removal of COD and DCF. As a result, the performance of fuel cells with modified anode and removal of DCF increased compared to anode with CF-MFC. Thus, the performance of fuel cells with modified anode and removal of DCF increased compared to anode with CF-MFC.

Stability improvement of laccase for micropollutant removal of pharmaceutical origins from municipal wastewater

Micropollutants are persistent and hazardous materials in low concentrations (ng L−1–μg L−1), including substances such as pharmaceuticals, personal care products and industrial chemicals. The advancement of analytical chemistry has allowed for the detection of micropollutants; however, an efficient and economical treatment solution is yet to be installed. Fungal laccase has been a successful biocatalyst of these compounds. However, large-scale application of free enzyme is currently not feasible for removing water-borne micropollutants, partly due to relatively rapid loss in enzyme stability. In this paper, three types of cyclodextrin, α, β and γCD, were chosen to immobilise the laccase under various conditions with the aim to improve the stability of the enzyme. Laccase activity was chosen as a response parameter, and laccase-cyclodextrin binding was evaluated by Fourier-transform infrared spectroscopy (FTIR). Results showed an optimum using α-cyclodextrin immobilisation. At that level, α-cyclodextrin increased the half-life of laccase and slightly improved its activity in all tested pH by physically bonding to laccase. By protecting the enzyme structure, activity was maintained under a range of circumstances (acidic conditions, from 10 to 50 °C). Under room temperature and at pH 5, α-cyclodextrin-laccase nanocomposite had a better removal efficiency of diclofenac compared to free laccase of the same concentration.Graphical abstract

Synergistic adsorption and degradation of diclofenac by zero-valent iron modified spent bleaching earth carbon: Mechanism and toxicity assessment

Diclofenac (DCF) is a drug compound that exists widely in water bodies, which may pose a threat to the ecological environment. In this study, spent bleaching earth (SBE) was pyrolyzed, modified with cetyltrimethylammonium bromide (CTAB) and loaded with zero-valent iron (nZVI) to obtain CTAB-SBE@C-nZVI. The effects of CTAB concentration, Fe0 loading, CTAB-SBE@C-nZVI dosage, and initial pH value on the removal efficiency of DCF were studied. The results showed that the DCF removal efficiency could reach a maximum of 87.0% with 2.0 g/L dosage of the optimal material, which was prepared under the conditions of 30 mmol/L CTAB concentration, 25% Fe0 loading, and initial pH 5. It indicated that the strong adsorption of the material and the reduction effect of nZVI can achieve high-efficiency removal of DCF. Based on the detected reaction intermediate products, four possible degradation paths were inferred. The toxicity assessment of DCF and its intermediates manifested that the degradation of DCF by CTAB-SBE@C-nZVI was a process of gradual dechlorination and toxicity reduction. CTAB-SBE@C-nZVI displayed excellent DCF removal efficiency, good stability and environmental friendliness, achieving wastes treat wastes and exhibiting good prospects.

Enhanced removal of nutrients and diclofenac by birnessite sand vertical flow constructed wetlands

The application of constructed wetlands (CWs) in organic micropollutants elimination is receiving increasing attention worldwide. However, acclimatization periods of CWs were long due to uncontrollable biotic factors and external conditions. In this study, manganese oxide was applied to enhance the simultaneous removal of nutrients and diclofenac (DFC) in CWs. To evaluate the treatment performance, two vertical up-flow CWs (VFCWs), with/without (experimental/ control) birnessite-coated sand VFCW, were set up to treat synthetic secondary effluent of the wastewater treatment plant. The removal performance of ammonia was significantly higher in experimental VFCW than that of control during the first 80 d, indicating that experimental VFCW could maintain a stable NH4+-N treatment performance (over 60%) when wastewater contained DFC. After 200 d of operation, the removal efficiency of DFC was achieved 98.5% in experimental VFCWs. The application of birnessite sand increased 12.8% of nitrogen load in the substrate, while phosphorus removal performance was enhanced by 10.0% on account of plant uptake. Though the final nutrients treatment performance was equivalent in experimental and control VFCWs, micro-environments at the middle layer were diverse for microbial communities. This work presents birnessite sand as the potential substrate of VFCWs for treating DFC as well as nitrogen and phosphorus pollutants.

Evaluating the effect of diclofenac on hydrogen production by anaerobic fermentation of waste activated sludge

Hydrogen production from waste-activated sludge (WAS) anaerobic fermentation is considered to be an effective method of resource recovery. However, the presence of a large number of complex organic compounds in sludge will affect the biological hydrogen production process. As an extensively applied prevalent anti-inflammatory drug, diclofenac (DCF) is inevitably released into the environment. However, the effect of diclofenac on hydrogen production from WAS anaerobic fermentation has not been fully investigated. This work therefore aims to comprehensively investigate the removal efficiency of DCF in mesophilic anaerobic fermentation of WAS and its effect on hydrogen yield. Experiment results showed that 32.5%–38.3% of DCF was degraded in the fermentation process when DCF concentration was ranged from 6 to 100 mg/kg TSS (total suspended solids). DCF at environmental level inhibited hydrogen production, the maximal hydrogen yield decreased from 24.2 to 15.3 mL/g VSS (volatile suspended solids) with an increase of DCF addition from 6 to 100 mg/kg TSS. This is because the presence of DCF caused inhibitions to acetogenesis and acidogenesis, the processes responsible for hydrogen production, probably due to that the polar groups of DCF (i.e., carboxyl group) could readily bind to active sites of [FeFe]- Hydrogenase. Besides, the microbial analysis revealed that DCF increased the microbial diversity but had few influences on the microbial structure.