Removal Of Carbamazepine Research Articles

Catalytic effect of Fe@Fe2O3 nanowires and Fenton process on carbamazepine removal from aqueous solutions using response surface methodology

Carbamazepine is one of the hydrophilic compounds identified in aquatic environments. Due to toxicity and bio-stability of this psychotropic pharmaceutical in the environment and humans, its removal efficiency and mineralization are important. In this study, synthesized Fe@Fe2O3 nanowires were applied to improve Fenton oxidation process using FeCl3.6H2O and NaBH4. The effects of different parameters such as initial pH, H2O2, FeSO4.7H2O, carbamazepine concentrations, oxidation time, and nanowires dose were evaluated using response surface methodology. After scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffract meter analysis, Fe@Fe2O3 morphology was synthesized in the form of nanowires with diameters of about 40-80 nm. The optimum oxidation conditions for carbamazepine were established at pH= 4.3, reaction time of 45.9 min, nanowire dose of 179.4 mg/L as well as H2O2, FeSO4.7H2O and carbamazepine concentrations of 22, 52.2 and 7.7 mg/L, respectively. The oxidation efficiency (99.5%) achieved under the optimum condition, which was determined by the model, was consistent with the efficiency predicted by the model. The multi-parameter models showed good calibration and prediction abilities with R2= 0.922, R2adj= 0.907, R2pred= 0.868. According to the results, the carbamazepine degradation rate increased with the increase of Fe2+ due to the synergistic effect between Fe@Fe2O3 and Fe2+ on the catalytic decomposition of H2O2 and generation of OH•. It was concluded that the Fenton process based on the Fe@Fe2O3 nanowires can increase the carbamazepine oxidation rate in aqueous solutions. This method can also be used as an effective and pre-treatment process in the conventional treatment plants.

Evaluation of transformation products from chemical oxidation of micropollutants in wastewater by photoassisted generation of sulfate radicals

In this research, the degradation of seven different micropollutants (MPs) and the formation of their transformation products (TPs) have been assessed during the application of different advanced oxidation processes: photolytic and photocatalytic activation of peroxymonosulfate (PMS) and persulfate (PS). The results were compared with those obtained from the photolytic experiments using hydrogen peroxide (H2O2) as oxidant. A significant abatement of almost all MPs was achieved, even with very low UV-C contact time (9 and 28 s). The degradation of atenolol (ATN) and caffeine (CFN) ranged from 84 to 100% with a dose of 0.5 mM of any oxidant. The efficiencies for bisphenol-A (BPA), carbamazepine (CBZ), diclofenac (DCF), ibuprofen (IBP), and sulfamethoxazole (SMX) varied depending on the oxidation system and operating conditions (oxidant dose and UV-C contact time), leading to the photolysis of PMS to higher efficiencies than PS and H2O2. In all cases, the abatement of MPs ranged from 63 to 83%, even with the lowest PMS dosage. Moreover, the addition of Fe(II) as a catalyst enhanced the removal efficiency, reaching almost total removal, especially over CBZ, DCF, and IBP. The Dissolved Organic Carbon (DOC) removal ranged between 44 and 62%, suggesting the transformation of MPs in intermediate compounds. The identification of transformation products was carried out for each micropollutant and each oxidation treatment, being observed some transformation products specific of oxidation by sulfate radicals. For example, m/z 165.0432 only appeared after PMS/Fe(II)/UV-C on the degradation of BFA, m/z 251.082 appeared after photolytic activation of PMS and PS on CBZ removal, and m/z 128.0452 was observed after any sulfate radical oxidation treatment, but not after photolysis of H2O2.

Adsorption of pharmaceuticals from biologically treated municipal wastewater using paper mill sludge-based activated carbon.

A waste-based alternative activated carbon (AAC) was produced from paper mill sludge under optimized conditions. Aiming its application in tertiary wastewater treatment, AAC was used for the removal of carbamazepine, sulfamethoxazole, and paroxetine from biologically treated municipal wastewater. Kinetic and equilibrium adsorption experiments were run under batch operation conditions. For comparison purposes, they were also performed in ultrapure water and using a high-performance commercial AC (CAC). Adsorption kinetics was fast for the three pharmaceuticals and similar onto AAC and CAC in either wastewater or ultrapure water. However, matrix effects were observed in the equilibrium results, being more remarkable for AAC. These effects were evidenced by Langmuir maximum adsorption capacities (qm, mgg-1): for AAC, the lowest and highest qm were 194 ± 10 (SMX) and 287 ± 9 (PAR), in ultrapure water, and 47 ± 1 (SMX) and 407 ± 14 (PAR), in wastewater, while for CAC, the lowest and highest qm were 118 ± 7 (SMX) and 190 ± 16 (PAR) in ultrapure water and 123 ± 5 (SMX) and 160 ± 7 (CBZ) in wastewater. It was found that the matrix pH played a key role in these differences by controlling the surface electrostatic interactions between pharmaceutical and AC. Overall, it was evidenced the need of adsorption results in real matrices and demonstrated that AAC is a promising option to be implemented in tertiary wastewater treatments for pharmaceuticals' removal. Graphical abstract Production of an alternative activated carbon (AC) comparing favourably with a commercial AC in the removal of neutral and positive pharmaceuticals from wastewater.

Removal of micropollutants during biological phosphorus removal: Impact of redox conditions in MBBR

Further biological polishing of micropollutants in WWTP effluents is limited by the lack of available carbon for cometabolic degradation. Metabolism of polyhydroxyalkanoates (PHAs) stored intracellularly during enhanced biological phosphorus removal (EBPR) could serve as carbon source for post-denitrification and micropollutant cometabolism.The removal of nine micropollutants (i.e., pharmaceuticals and corrosion inhibitors) was investigated by using Moving Bed Biofilm Reactors (MBBRs), selecting phosphorus (PAO) or glycogen (GAO) accumulating organisms under different redox conditions. Three laboratory-scale MBBRs were operated in sequencing-batch mode under cyclical anaerobic and aerobic/anoxic conditions for phosphorus removal. Batch experiments were performed to evaluate the biodegradation potential of micropollutants along with the utilization of internally stored PHA. Experiments showed that aerobic PAO were able to efficiently remove most of the targeted micropollutants. The removal of benzotriazole, 5‑methyl‑1H‑benzotriazole, carbamazepine, ketoprofen and diclofenac occurred simultaneously to phosphorus uptake and terminated when phosphorus was no longer available. Denitrifying PAO and aerobic GAO exhibited lower removal of micropollutants than aerobic PAO. Degradation profiles of stored PHA suggested a diverse utilization of the different fractions of PHA for phosphorus and micropollutant removal, with PHV (poly 3‑hydroxyvalerate) most likely used for the cometabolism of targeted micropollutants.

Enhanced activation of peroxymonosulfate by magnetic Co3MnFeO6 nanoparticles for removal of carbamazepine: Efficiency, synergetic mechanism and stability

To achieve complete removal of persistent organic pollutant from water system, an efficient, stable, magnetic and low-energy sulfate radical-based advanced oxidation process (SR-AOPs) is in desirable to be established. In this work, magnetic trimetallic oxides Co3MnFeO6 nanoparticles were successfully synthesized and utilized as novel heterogeneous catalysts to activate peroxymonosulfate (PMS) for the degradation of carbamazepine (CBZ), a recalcitrant organic pollutant. In the degradation tests, Co3MnFeO6/PMS system showed excellent performance that 99.2% of CBZ could be removed at a relative shorter time (30 min) and in a wider pH range from 3 to 10. More in-depth investigation found that synergistic effects between Co, Mn and Fe in Co3MnFeO6 catalyst were responsible for the efficient generation of sulfate radical from PMS activation. And the roles of Co, Mn and Fe in synergistic effect were identified as: the redox cycles of Co and Mn mainly worked for the activation of PMS, and Fe mainly provided magnetism for Co3MnFeO6 catalyst as well as the adsorption site for PMS and CBZ. Moreover, it was found that Co3MnFeO6 catalyst maintained high activity and robust magnetism during repeated batch experiments. Even in real wastewater samples (municipal wastewater, tap and river water), Co3MnFeO6/PMS system was capable of high activity for CBZ removal, indicating that Co3MnFeO6/PMS system possessed promising potential in practical applications. The possible CBZ degradation pathways were also proposed based on the detected intermediates. This Co3MnFeO6/PMS system may provide some new inspirations for the construction of multiple metal-based catalysts in AOPs.

Degradation of carbamazepine by vacuum-UV oxidation process: Kinetics modeling and energy efficiency.

Vaccum-ultraviolet (VUV) is effective for elimination of organic contaminants in aqueous environment and degradation of carbamazepine (CBZ) by VUV irradiation was systematically investigated in this study. A dynamic kinetic model was developed to simulate the destruction of CBZ that is mainly initiated by hydroxyl radicals (HO). The second-order rate constant of the reaction between CBZ and HO was determined to be 1.4 × 109 M-1 s-1. Effect of initial CBZ concentration, VUV irradiation intensity and natural organic matter (NOM) were further investigated in several batch experiments. The predicted CBZ removal rates increased with the increasing VUV intensity, while decreased with the increasing initial CBZ and NOM concentrations. Based on the electrical energy per order (EE/O) calculation, the optimal VUV intensity was determined to be 7.5 × 10-8 Einstein s-1. Meanwhile, several intermediates/products were identified and their time-dependent evolution profiles were determined, and finally a plausible degradation pathway of CBZ was proposed. Ecotoxicity assessment indicated that the potential toxicity of CBZ and its oxidation products should be paid more attention in the VUV process.

Waste biomass gasification char derived activated carbon for pharmaceutical carbamazepine removal from water

Carbamazepine (CBM), a widely occurring pharmaceutical, has been removed from water by upgrading a waste biomass char from a 300 MW biomass gasification power station plant operating in Indonesia. The fuel source is the waste residue palm kernel shell (PKS) after the palm oil extraction process constituting over one million tonnes per year. The resulting waste power station biomass char (CPKS) from the power station gasification process has been converted into high quality activated carbon by carbon dioxide activation as a sequestration opportunity, at different temperatures ranging from 700 to 900°C for 1 or 1.5 hours. The highest BET surface area was 711.5 m2/g and this activated carbon was able to adsorb 1.14 mmol/g or 268.7 mg CBM/g. Equilibrium and kinetic studies have been undertaken.

Oxidative removal of carbamazepine by peroxymonosulfate (PMS) combined to ionizing radiation: Degradation, mineralization and biological toxicity

Carbamazepine is one of pharmaceutical and personal care products (PPCPs) and has been widely used to treat depression and seizures, and it cannot be effectively removed during the conventional wastewater treatment processes. In this study, three processes were used for the carbamazepine degradation, including single radiation, radiation in the presence of peroxymonosulfate (PMS) and radiation followed by PMS oxidation. The results show that radiation in the presence of PMS could enhance the degradation and mineralization of carbamazepine, decreasing the absorbed dose required for completely degrading carbamazepine from 800 Gy to 300 Gy, no matter what the molar ratio of PMS to carbamazepine was. The radiation followed by PMS oxidation significantly increased the mineralization, and the maximum mineralization achieved 46.5% at the dose of 600 Gy. Eight intermediates were tentatively identified. Compared to single radiation process, the radiation in the presence of PMS enhanced the transformation of intermediates and the release of ammonium ion. In real wastewater, the radiation in the presence of PMS could effectively remove carbamazepine and considerably decreased the biological toxicity of the wastewater containing carbamazepine.

Accelerated photocatalytic oxidation of carbamazepine by a novel 3D hierarchical protonated g-C3N4/BiOBr heterojunction: Performance and mechanism

A novel 3D hierarchical heterojunction of protonated g-C3N4/BiOBr was fabricated by a facile precipitation method with the protonation pretreatment of g-C3N4. The material was characterized by X-ray spectrometer (SEM), transmission electron microscopic (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), UV–vis reflectance spectra (UV–Vis DRS) and Brunauer-Emmett-Teller (BET). The photocatalytic activity was systematically evaluated by the degradation of carbamazepine (CBZ) under simulated solar light irradiation. The protonated g-C3N4/BiOBr with mass ratios of 5 wt% (pgB-5) achieved the optimum performance for the CBZ removal and excellent stability. The effects of some key operating parameters were further examined in detail, including photocatalyst dosage, initial solution pH, coexisting inorganic anions (HCO3−, Cl−, NO3−). The enhanced activity was ascribed to the effective charge separation occurring at the tightly contacted interface between two phases, which was revealed by electrochemical impedance spectroscopy (EIS) and photocurrent. Basing on direct evidence of the formed hydroxyl radicals (OH), superoxide radicals (O2−) and holes (h+) by electron spin resonance (ESR), the photocatalytic mechanism was proposed for the charge separation. The reaction intermediates were determined by liquid chromatography coupled with mass spectrometry (LC-MS) and a tentative degradation pathway of CBZ was proposed. This study provided a new insight for the design of novel 3D hierarchical heterojunctions and the degradation of recalcitrant organic contaminants in aquatic environment.

MP-UV/CaO2 as a pretreatment method for the removal of carbamazepine and primidone in waste activated sludge and improving the solubilization of sludge

Medium-pressure ultraviolet light (MP-UV) combined with calcium peroxide (CaO2) as a pretreatment technology for removing carbamazepine (CBZ) and primidone (PMD) in waste active sludge (WAS) and improving the solubilization of sludge were investigated. CBZ and PMD were effectively removed and the removal fitted pseudo-first kinetics under MP-UV/CaO2 treatment with R2 > 0.97. The higher CaO2 dosage and lower initial volatile suspended solids (VSS) concentration were conductive to the removal of CBZ and PMD. Of the CaO2 hydrolysates, Ca(OH)2 played a more important role than H2O2 during MP-UV/CaO2 treatment. The removal of the target compounds was attributed to direct photolysis and indirect photolysis caused by •OH, 3DOM*, and 1O2, in which •OH played a vital role with > 62.2% contribution to the overall degradation rate. A model predicting the steady concentration of •OH in WAS ([VSS] ≈ 8.6 g L−1) under MP-UV/CaO2 treatment with CaO2 dosage ranging from 0 to 0.5 g g−1-VSS was proposed and validated. Moreover, major intermediates of CBZ and PMD were detected and the probable transformation pathways during MP-UV/CaO2 treatment were proposed. In addition, MP-UV/CaO2 promoted the sludge solubilization effectively. Considering both the pharmaceutical degradation and sludge solubilization, the optimum operation condition with 0.2 g-CaO2 g−1-VSS combined with 7 h MP-UV irradiation is recommended. Under this condition, more than 92.3% of CBZ and 90.3% of PMD were removed, and soluble chemical oxygen demand (SCOD) increased by 657% and 13.6% compared with sole 10 h CaO2 (0.2 g g−1-VSS) treatment and 7 h MP-UV treatment, respectively.

Role of the radical promoter systems on the degradation of an antipeleptic drug using HO[rad] and SO4[rad]- species

The aim of this work was to determine whether the effectiveness of hydroxyl and sulfate radicals to degrade carbamazepine (CBZ) in aqueous solution is a function of the radical generator system used. For this purpose, an in-depth analysis was conducted of CBZ degradation by UV radiation, UV/H2O2, UV/S2O82−, Fe2+/H2O2, Fe2+/S2O82−, UV/Fe2+/H2O2 and UV/Fe2+/S2O82−. Results obtained show that CBZ can be degraded by direct photolysis but that the effectiveness is very low, with a quantum yield near zero. CBZ can be effectively degraded by UV/H2O2 and UV/S2O82- systems, with percentages close to 100%. CBZ degradation was 1.26- to 2.0-fold faster with SO4- radicals than with HO radicals. In contrast, CBZ degradation was 1.1- to 1.7-fold more effective with the Fe2+/H2O2versus Fe2+/S2O82- system when the Fenton process was applied. CBZ removal from water was most effective with UV/Fe2+/H2O2 and UV/Fe2+/S2O82− systems, attributable to the additional generation of HO radicals resulting from the reduction in Fe3+. A slight decrease in percentage degradation was observed with all systems when wastewater was the aqueous matrix, mainly due to the presence of organic and inorganic species that may act as radical scavengers (Cl-, NO2-, NO3- and SO42−). Finally, the highest percentage mineralization was obtained with the UV/Fe2+/H2O2 system in deionized water.

Removal of Organic Micropollutants by Grainy Bentonite-Activated Carbon Adsorbent in a Fixed Bed Column

Organic micropollutants enter effluent streams and then flow into receiving waters. The volume adversely affects aquatic biota substantially. Therefore, many efforts have been made to develop methods for their elimination. The aim of this study was the removal of organic micropollutants with different properties from WWTP (wastewater treatment plant) effluent in fixed bed columns packed with several combinations of sand, granular activated carbon (GAC), and granular clay-carbonaceous composite. Two types of bentonite-powder activated carbon-based granules (Ben-AC) were prepared within this work, with different calcination temperature. It was found that higher calcination temperature enhanced the surface porosity and adsorption potential versus studied micropollutants due to dihydroxylation resulting in higher chemical activity. Introduction of these granules in the place of GAC in a fixed bed column enhances the removal degree of micropollutants and typical water quality parameters. For example, the reduction degree of color, phosphate, and nitrate concentrations increased from 83%, 69%, and 4% to 95%, 83%, and 24% for column I and II, respectively. The concentration of carbamazepine, octylphenol, nononylphenol, and anthracene was reduced by 75%, 83%, 72%, 99% in column I, while using column II or III their removal was: 86%, 97%, 99%, 99%, respectively. Independent of the column filling, the removal of carbamazepine was the lowest (75–86%), while the highest retention was obtained for anthracene (99%). The study of column performance in the treatment of effluent in time showed that column filled with Ben-AC-400 guaranteed high removal degree in the operating time. The batch adsorption data were better described by both the Langmuir model.

Insight into enhanced carbamazepine photodegradation over biochar-based magnetic photocatalyst Fe3O4/BiOBr/BC under visible LED light irradiation

A novel, economical and magnetically separable heterojunction photocatalyst Fe3O4/BiOBr stacked on reed straw biochar (Fe3O4/BiOBr/BC) with visible light response was successfully prepared via a facile modified one-step hydrolysis method for the first time. The target pollutant carbamazepine (CBZ) was used to further investigate the photocatalytic activity of Fe3O4/BiOBr/BC. Compared with BiOBr and Fe3O4/BiOBr, novel photocatalyst Fe3O4/BiOBr/BC owing to the introduction of biochar exhibited better photocatalytic activity (95.51%) of CBZ photodegradation even under 50 W energy-saving visible LED light irradiation. Additionally, effect of pH on CBZ photodegradation using Fe3O4/BiOBr/BC was insignificant meaning wider practical application. Besides, three common anions (Cl−, NO3−, SO42−) and DOM existing in natural water exhibited beneficial or detrimental effects to some extent. Free radicals trapping experiments results illustrated high carbamazepine removal efficiency could be ascribed to superoxide radicals and hydroxyl radicals. The transformation intermediates of CBZ were determined by HRMS and the possible photodegradation pathways were proposed. Finally, good reusability and stability verified the excellent practicality and feasibility of Fe3O4/BiOBr/BC for removal of organic pollutants in aqueous.

Carbamazepine removal from water by carbon dot-modified magnetic carbon nanotubes

Carbon dot- and magnetite-modified magnetic carbon nanotubes (CMNTs) were synthesized and evaluated for carbamazepine removal from water. The adsorbent was characterized by multiple modern surface and microstructure analyzing techniques. CMNTs were composed of three components including carbon dots (CDs), carbon nanotubes (CNTs) and magnetite. CDs and CNTs introduce abundant carboxyl groups onto CMNTs and magnetite allows rapid magnetic separation of the adsorbent realizable after batch adsorption. This adsorbent has a moderately high adsorption capacity of 65 mg-carbamazepine/g-adsorbent at pH 7.0 ± 0.2, which is superior to many reported adsorbents. Carbamazepine was uptaken well in a wide pH range, regardless of the surface charging of CMNTs. Its adsorption on CMNTs was quite fast and reached 80% of removal during the initial 3 h. The mass transfer within CMNTs and the time-dependent utilization, exhaustion and depletion of the adsorption capacity were successfully described using a simplified homogeneous surface diffusion model (HSDM). The surface diffusion coefficients (Ds) rose with increasing initial carbamazepine concentrations. After six regeneration and recycle experiments, the capacity loss of CMNTs was less than 2.2% at the conditions tested. FTIR spectra showed the characteristics of the components. Raman spectra implied a π-π electron donor-acceptor (EDA) interaction during adsorption. This work proposed a method of combining π-bond-rich materials (CNTs and CDs) and magnetite to make separable composite adsorbents with high affinity interactions between carbamazepine and carbon materials. The prepared adsorbent is attractive for carbamazepine removal due to its good performance, moderate cost, ease of separation, and ability to regenerate.

Assessment of soil buffer capacity on nutrients and pharmaceuticals in nature-based solution applications.

The ability of a soil to sustain infiltration rates and to attenuate pollutants is critical for the design and operation of Managed Aquifer Recharge/Soil Aquifer Treatment and phyto-treatment schemes, also referred to as "Blue Infrastructures". We investigated the buffering capacity of a sediment sample and a peat soil sample for nutrients and selected pharmaceutical compounds and its evolution under continuous infiltration of secondary treated wastewater (TWW) in column experiments. Samples were obtained from two blue infrastructures, the Sant'Alessio Induced River Bank Filtration plant and the San Niccolò large-scale phyto-treatment plant in Italy, and were mainly different in their organic carbon contents (0.9 and 48%, respectively). In the column experiments, a constant infiltration rate of about 0.5L/d was maintained for 6months. After 4months of operation, diclofenac and carbamazepine were spiked into the TWW to evaluate their fate. Water quality was monitored by periodic water sampling from the column inflow, at sampling ports along the column length, and at the outflow. Hydraulic conductivity (K) was also monitored. The hydraulic conductivity of the Sant'Alessio sediment decreased by a factor of 10 during the first 10days of infiltration and then stabilized, while for the San Niccolò K (initially lower) remained constant for 50days until it decreased following a change of the redox condition in the column. The different redox conditions, due to the two different soils tested, influenced also the concentration and mobility of PO43-, Fe, Mn, and NPOC, and the speciation of the redox sensitive elements (nitrogen and sulfur). NOPC and phosphate were enriched during the filtration through San Niccolò peat soil (from 2 to 4 times, respectively), while they were buffered by the Sant'Alessio sediment (from 0.2 to 0.4 times, respectively). Diclofenac removal (69% and below 20% for San Niccolò and Sant'Alessio, respectively) was related to sorption and degradation processes and it was lower than the removal of carbamazepine in both soils (76 and 35%). The buffer capacity differences between the two soils were higher for diclofenac (62%) than carbamazepine (35%). Nevertheless, since no apparent degradation of carbamazepine was detected in both soils, its persistence in the soil may have a larger impact in case of desorption, posing contamination risk to groundwater. The results highlight the importance of the soils or sediments to be used as medium in such nature-based solutions for their operations. They also offer an approach to, e.g., tailor man-made soil layers in infiltration basins. We strongly suggest that soil characteristics and test duration are carefully considered in designing these infrastructures, when nature-based processes are the choice for dealing with reuse of treated wastewater management issues.

Treatment of 17α‑ethinylestradiol, 4‑nonylphenol, and carbamazepine in wastewater using an aerobic granular sludge sequencing batch reactor

This study quantifies the removal of a mixture of commonly detected emerging contaminants, 17α‑ethinylestradiol (EE2), 4‑nonylphenol (NP), and carbamazepine (CBZ) from synthetic wastewater using aerobic granular sludge in a sequential batch reactor. The emerging contaminant concentration in the influent wastewater was maintained near 500 μg/L for the duration of the experiment. Removal of EE2, NP, and CBZ is comprised of both adsorption and degradation. In general, the main removal mechanism for the emerging contaminants was initially adsorption, however it transitions to degradation as the adsorption capacity is saturated. The stabilized degradation for EE2 and NP in the SBR, was 16.09 μg/g and 20.05 μg/g, respectively. There was limited degradation of CBZ during the anaerobic phase. Both the Langmuir and Freundlich adsorption isotherms fit the data well and constants for the equations are calculated. The constants for the Langmuir Isotherm are found to be (X/m)max = 36.23, b = 0.0019 for EE2 and (X/m)max = 44.25, b = 0.0004 for CBZ. None of the tested compounds were found to be detrimental to the performance of the aerobic granules, and high macronutrient removal efficiency was maintained. The granule sludge bed and particle size were not negatively affected by EE2 and NP, however, carbamazepine appeared to interfere with the mechanism of granule formation resulting in a decrease in particle size during the experiment.

Removal Processes of Carbamazepine in Constructed Wetlands Treating Secondary Effluent: A Review

It is widely believed that constructed wetlands (CWs) own great potentiality as polishing wastewater treatment methods for removing carbamazepine (CBZ). Although the typical CBZ removal efficiencies in CWs are quite low, the CBZ removal performance could be improved to some extend by optimizing the CW design parameters. A comparison of current relevant studies indicates that horizontal sub-surface flow CWs (HSSF-CWs) and hybrid wetlands are attracting more interest for the treatment of CBZ wastewater. According to CBZ’s physicochemical properties, substrate adsorption (25.70–57.30%) and macrophyte uptake (22.30–51.00%) are the two main CBZ removal pathways in CWs. The CBZ removal efficiency of CWs employing light expanded clay aggregate (LECA) as a substrate could reach values higher than 90%, and the most favorable macrophyte species is Iris sibirica, which has shown the highest total CBZ assimilation capacity. Several methods for enhancement have been proposed to optimize CBZ removal in CWs, including development of hydraulic models for optimization of CW operation, introduction of extra new CBZ removal ways into CW through substrate modification, design of combined/integrated CW, etc.

Effective mineralization of anti-epilepsy drug carbamazepine in aqueous solution by simultaneously electro-generated H2O2/O3 process

A novel electro-generated hydroxyl radical (OH) technique was constructed to effectively degrade the anti-epilepsy carbamazepine (CBZ) representing typical recalcitrant pharmaceutical only through electrochemical method as an alterative peroxone process. The technique involves simultaneously electro-generated H2O2 using a carbon-polytetrafluoroethylene (C/PTFE) cathode to reduce the injected O2 and electro-generated O3 using H2O oxidation with a Ti mesh/PbO2 anode in membrane electrode assembly (MEA). The significant OH formation through the synergetic system of in-situ produced H2O2 and O3 electrochemically could achieved carbamazepine decomposition and total organic carbon (TOC) removal as compared to electro-generated H2O2 or O3 alone. The main influential factors including current density and aqueous pH were investigated to reveal their effect on CBZ removal efficiencies. Under optimal parameters, CBZ decomposition and TOC mineralization could be completely accomplished after 10 min and 90 min electrolysis, respectively. According to intermediates distribution (e.g. hydroxylated CBZ, phenolics, and carboxylic acids) identified by HPLC-MS/MS, the degradation pathways were proposed for CBZ removal by the synergetic system of C/PTFE-O2 and MEA. The above results indicated that this electrochemically synergetic system is a potential technique to further purify the water contaminated by recalcitrant pharmaceuticals.

In situ growth of Ag-SnO2 quantum dots on silver phosphate for photocatalytic degradation of carbamazepine: Performance, mechanism and intermediates toxicity assessment

The occurrence of carbamazepine (CBZ) in environments poses a potential risk to aquatic life and exhibits growth inhibition of human embryonic cells. In this work, for the first time a series of Ag-SnO2 quantum dots (QDs)/silver phosphate (AgSn/AgP) composites were synthesized and used as photocatalysts for CBZ degradation. The obtained AgSn/AgP composites showed superior photodegradation efficiency for CBZ removal. The degradation rate constant of 10AgSn/AgP (with 10 wt% of Ag-SnO2 QDs) was almost 8.5, 5.7, 5.7, and 1.9 times as that of Ag-SnO2 QDs, Ag3PO4, Ag/Ag3PO4, and SnO2 QDs/Ag3PO4, respectively. The improved photocatalytic activity could be primarily ascribed to the improved charge separation through a collaborative effect of Ag-SnO2 QDs and Ag3PO4, and in situ photoreduced metallic silver. Electron spin resonance (ESR) measurement and radical trapping experiments suggested that holes (h+), (superoxideradical) ·O2− and (hydroxylradical) ·OH corporately participated in the decomposition of CBZ. Moreover, a reasonable mechanism for photocatalytic degradation of CBZ over 10AgSn/AgP composites was tentatively proposed. Additionally, eight degradation intermediates were determined by liquid chromatography-mass spectrometry (LC-MS). Toxicity evaluation using the Ecological Structure Activity Relationships (ECOSAR) program revealed that the toxicity of most photodegradation intermediates were much lower than that of the parent compound CBZ. This work not only provides a new technique for preparing Ag3PO4-based photocatalysts with high activity, but also demonstrates that 10AgSn/AgP could be a promising photocatalyst for treating water and wastewaters containing CBZ.

Dynamics of emerging organic contaminant removal in conventional and intensified subsurface flow treatment wetlands

Six pilot-scale treatment wetlands treating municipal wastewater were monitored for classical wastewater parameters and selected Emerging Organic Compounds (EOCs): caffeine (CAF), ibuprofen (IBU), naproxen (NPX), benzotriazole (BTZ), diclofenac (DCL), acesulfame (ACE) and carbamazepine (CBZ) on a weekly basis over the course of one year. Treatment efficacy of the wetland systems was compared to that of a municipal wastewater treatment plant adjacent to the research site (activated sludge technology). The aerated wetlands VAp and HAp, and the two-stage vertical flow system VGp + VSp showed the highest treatment efficacy (>70% removal on a mass basis) and comparable treatment efficacy to the conventional WWTP for removal of CAF, IBU, NPX, BTZ, and DCL. Annual mass removal of ACE in the WWTP was 50% and varied in the wetlands (depending on system design) from zero to 62%. On a mean monthly basis, ACE removal in the treatment wetlands VGp + VSp, VAp, HAp, R was high (> 90%) for six months of the year. Monthly mean mass removal of CBZ was negligible for the WWTP and all treatment wetland systems except H50p, which showed up to 49% mass removal in June. Monthly mean mass removals of classical wastewater parameters and readily biodegradable EOCs (represented by CAF, IBU, NPX) were most stable in the intensified wetland designs VAp, HAp, and R. A statistical analysis confirms that system complexity, aerobic conditions, and temperature have the highest correlation to overall pollutant removal in the treatment wetland systems, including EOCs of high to moderate biodegradability. First-order removal rate coefficents and temperature correction factors for EOCs are reported for the first time in the treatment wetland literature. Limitations on the use of these values in engineering design are discussed.