An integrated MBR–TiO2 photocatalysis process for the removal of Carbamazepine from simulated pharmaceutical industrial effluent (original) (raw)
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Chemical Engineering Journal, 2011
Removal of pharmaceutical Carbamazepine (CBZ) compound from municipal wastewater has become an issue from the human health and environmental risks point of view, due to its latent recalcitrance and toxicity properties. This study investigated the photodegradation performance of a sequential batch annular slurry photoreactor (SB-ASP) system for the removal of CBZ compound from secondary municipal wastewater. Two different immobilised TiO 2 photocatalysts, namely anatase titanate nanofiber and mesoporous TiO 2 impregnated kaolinite catalyst were applied in the SB-ASP system. Various modes of sequential batch reactor (SBR) cycles, presence of effluent organic matter (EOM) and inorganic ions, mainly nitrate and phosphate that could affect the photodegradation performance of the SB-ASP system were evaluated during the removal of CBZ. High performance size exclusion chromatography revealed that the photocatalytic reaction will preferentially compete and attack on high molecular weight EOM prior to the photodegradation of CBZ. The presence of inorganic ions was found to affect the surface fouling of immobilised photocatalysts used to a different extent, without completely retarding their photoactivity. This study also highlighted that the operation of SB-ASP system was useful to enhance the photodegradation of CBZ compound in a semi-continuous operation without constant catalyst replacement. It is foreseeable that the integration of SB-ASP system with biological treatment systems could provide an advanced treatment option for the recycling and reuse of municipal wastewater.
Journal of Chemical Technology & Biotechnology, 2020
BACKGROUND: Occurrence of pharmaceutical compounds in wastewater has become a major concern 3 for human health and the environment. Therefore, it is challenging to improve the conventional 4 wastewater treatment to remove these compounds. Coupling a biological treatment with an advanced oxidation technology has been widely studied in the literature, but only sequential associations of the 6 two processes have been used. This study proposes an innovative concept based on a real integration of 7 the photocatalytic oxidation process in a continuous recycling loop on a membrane bioreactor. The role 8 of the oxidation is not here to completely degrade pharmaceuticals, but to oxidize them moderately to 9 increase their biodegradability so that they can be eliminated by the biological process. 10 RESULTS: Preliminary experiments on oxidation process indicated that a flux density of 5 W.m-2 was 11 sufficient to increase biodegradability and decrease toxicity of a cocktail of 3 pharmaceuticals. Then 12 performances of a 20-L continuous membrane bioreactor treating wastewater with 7 pharmaceuticals, 13 without and with pre-oxidation at 5 W.m-2 were compared. Pre-oxidation has increased the global 14 removal for some recalcitrant pharmaceuticals (from 3 to 47 % for diclofenac and for 1 to 44 % for 15 furosemide) without affecting neither the removal of carbon, nitrogen and phosphorous by activated 16 sludge neither the removal of already highly removed pharmaceuticals. 17 CONCLUSION: This work proves the feasibility and interest of the innovative concept of a continuous 18 hybrid process coupling a photocatalytic oxidation process and a membrane bioreactor for the treatment 19 of pharmaceuticals in wastewater, with a low cost and size.
Journal of the Taiwan Institute of Chemical Engineers, 2016
This study aims to demonstrate that a combined system of membrane bioreactor (MBR) with electrooxidation (EO) can be a promising technology to treat compounds such as carbamazepine (CBZ). The MBR showed high capacity to remove the chemical oxygen demand (COD) and low capacity for the degradation (20% of removal), after 120 d of operation; which presumably indicates that CBZ was not toxic for microorganisms, despite its poor degradation. On the other hand, the EO system was capable to completely degrade CBZ (99.99% of removal). In addition, the MBR achieved 83% of conversion efficiency of NH 4 + to NO 3 − or NO 2 − ; and only 20.5% of PO 4 − removal. A toxicity test using Dapnia magna and Vibrio fischeri was carried out. Results indicated that MBR is an efficient method to decrease wastewater toxicity but during electrooxidation treatment higher toxicity was obtained, probably due to the generation of more toxic compounds than the initial pollutants.
Journal of hazardous materials, 2016
Commercial α-Al2O3 photocatalytic membranes with a pore size of 200 and 800-nm were coated with N-doped TiO2 photocatalytic film using a sol-gel technique for concurrent bottom-up filtration and photocatalytic oxidation. X-ray diffraction confirmed that the deposited N-doped TiO2 films are in the form of anatase with 78-84% coverage of the membrane surface. The concentration of N found by X-ray photoelectron spectroscopy was in the range of 0.3-0.9 atomic percentage. Membrane permeability after coating decreased by 50% and 12% for the 200- and 800-nm membrane substrates, respectively. The impact of operational parameters on the photocatalytic activity (PCA) of the N-doped TiO2-coated membranes was examined in a laboratory flow cell based on degradation of the model micropollutant carbamazepine, using a solar simulator as the light source. The significant gap in degradation rate between flow through the membrane and flow on the surface of the membrane was attributed both to the hydra...
Water
Current research on the photocatalytic activity of TiO2 mainly focuses on its nano- or micro-particle forms, which are difficult to recycle and apply in real engineering applications. This study aims to apply a small pilot of TiO2 in the ceramic form to remove carbamazepine (CBZ) from an aqueous solution under simulated sunlight. A high removal efficiency up to >99% was shown in a 5 mg L−1 CBZ solution after 6 h of irradiation with a total energy of 150.92 kJ. The kinetic degradation was not affected in an alkaline solution (at pH 7, pH 10, and pH 13) but was faster under acidic conditions (pH 2) in which CBZ existed in the protonated form. The presence of NO3− (10–50 mg L−1) slightly affected the photodegradation of CBZ while humic acid significantly reduced the photocatalytic activity. In addition, the presence of major ions in water also had a negative effect at concentrations between 10 and 50 mg L−1. The MS/MS was used to identify the transformation products of CBZ, and a po...
The light-induced degradation of clofibric acid, carbamazepine, iomeprol and iopromide under simulated solar irradiation has been investigated in aqueous solutions suspended with different TiO 2 materials (P25 and Hombikat UV100). Kinetic studies showed that P25 had a better photocatalytic activity for clofibric acid and carbamazepine than Hombikat UV100. For photocatalytic degradation of iomeprol Hombikat UV100 was more suitable than P25. The results can be explained by the higher adsorption capacity of Hombikat UV100 for iomeprol. The study also focuses on the identification and quantification of possible degradation products. The degradation process was monitored by determination of sum parameters and inorganic ions. In case of clofibric acid various aromatic and aliphatic degradation products have been identified and quantified. A possible multi-step degradation scheme for clofibric acid is proposed. This study proves the high potential of the photocatalytic oxidation process to transform and mineralize environmentally relevant pharmaceuticals and contrast media in water.
Bioresource Technology, 2020
A submerged forward osmotic membrane bioreactor (FOMBR) was used to reveal the removal and degradation mechanism of carbamazepine (CBZ) from wastewater. The results showed that the removal mechanism consisted of the rejection of the forward osmotic (FO) membrane and biodegradation of the activated sludge. The removal efficiencies of COD, NH 4 +-N, and CBZ by the FOMBR were approximately 94.77%-97.45%, 93.56%-99.28%, and 88.20%-94.45%, respectively. Moreover, the COD and NH 4 +-N removal efficiencies were positively correlated with the increased CBZ concentrations. The results of the soluble microbial products (SMP) and extracellular polymeric substances (EPS) tests illustrated that the membrane fouling potential of EPS may be higher than that of SMP. According to the identified 14 degradation products, oxidation, hydroxylation, and decarboxylation were defined as the primary CBZ degradation mechanism. In addition, the RNA results showed that Delftia could be the characteristic bacteria in the CBZ degradation process.
Carbamazepine Degradation by Photolysis and Titanium Dioxide Photocatalysis
Water Environment Research, 2012
We investigated the degradation of carbamazepine by photolysis/ultraviolet (UV)-C only and titanium dioxide photocatalysis. The degradation of carbamazepine by UV-only and titanium-dioxideonly (adsorption) reactions were inefficient, however, complete degradation of carbamazepine was observed by titanium dioxide photocatalysis within 30 min. The rate of degradation increased as initial carbamazepine concentration decreased, and the removal kinetics fit well with the Langmuir-Hinshelwood model. The addition of methanol, a radical scavenger, decreased carbamazepine removal, suggesting that the hydroxide radical played an important role during carbamazepine degradation. The addition of oxygen during titanium dioxide photocatalysis accelerated hydroxide radical production, thus improving mineralization activity. The photocatalytic degradation was more efficient at a higher pH, whereas the removal of carbamazepine and acridine (a major intermediate) were more efficient under aerobic conditions. The mineralization of carbamazepine during photocatalysis produced various ionic by-products such as ammonium and nitrate by way of nitrogen dioxide. Water Environ. Res., 84, 554 (2012).