An integrated MBR-TiO2 photocatalysis process for the removal of Carbamazepine from simulated pharmaceutical industrial effluent

Effect of zeolites on the reduction of the ecotoxicity of carbamazepine in the environment

In this study, the impact of calcination of zeolites on the ecotoxicity of carbamazepine solutions in two matrices, water and synthetic sewage, was assessed. Two types of zeolites were tested: natural zeolite, in the form of a zeolite rock consisting mainly of clinoptilolite, and a synthetic zeolite type 5 A. Additionally, zeolites were calcined at a temperature of 200 °C. The kinetics of carbamazepine adsorption in aqueous solutions and in synthetic sewage matrix was determined. Higher adsorption capacity was obtained for carbamazepine aqueous solutions as well as zeolites after the calcination process. Considering type of zeolite, the highest and fastest uptake of carbamazepine was observed for natural zeolite after calcination. In the case of ecotoxicity, carbamazepine solutions before adsorption was the most toxic towards Raphidocelis subcapitata, next Aliivibrio fischeri and Daphnia magna, regardless to the matrix type. The differentiation in toxicity regarding the type of matrix was observed, in the case of algae and bacteria, higher toxicity was demonstrated by carbamazepine solutions in the water matrix, while in the case of crustaceans-the sewage matrix. After the adsorption process, the toxicity of carbamazepine solutions on zeolites decreased by 34.5-60.9 % for R. subcapitata, 33-39 % for A. fischeri and 55-60 % for D. magna, thus confirming the effectiveness of the proposed method of carbamazepine immobilization.

Bone-mimicking scaffold based on silk fibroin incorporated with hydroxyapatite and titanium oxide as enhanced osteo-conductive material for bone tissue formation: fabrication, characterization, properties, andin vitrotesting

Bone-mimicking scaffolds based on silk fibroin (SF) mixed with hydroxyapatite nanoparticles (HA NPs) and titanium oxide (TiO2) nanoparticles were created as materials for bone formation. Six scaffold groups were fabricated: S1 (SF), S2 (Silk + (HA: TiO2; 100: 0)), S3 (Silk, (HA: TiO2; 70: 30)), S4 (Silk + (HA NPs: TiO2; 50: 50)), S5 (Silk + (HA: TiO2; 30: 70)), and S6 (Silk + (HA NPs: TiO2; 0:100)). Scaffolds were characterized for molecular formation, structure, and morphology by Fourier transform infrared spectroscopy, element analysis, and X-ray diffraction. They were tested for physical swelling and compressive modulus. Scaffolds were cultured with MC3T3 and testedin vitroto evaluate their biological performance. The results showed that scaffolds with HA and TiO2demonstrated molecular interaction via amide I and phosphate groups. These scaffolds had smaller pore sizes than those without HA and TiO2. They showed more swelling and higher compressive modulus than the scaffolds without HA and TiO2. They exhibited better biological performance: cell adhesion, viability, proliferation, alkaline phosphatase activity, and calcium content than the scaffolds without HA and TiO2. Their porous walls acted as templates for cell aggregation and supported synthesis of calcium secreted from cells. S3 were the most suitable scaffolds. With their enhanced osteo-conductive function, they are promising for bone augmentation for oral and maxillofacial surgery.

Alkyl chain length of quaternized SBA-15 and solution conditions determine hydrophobic and electrostatic interactions for carbamazepine adsorption

Santa Barbara Amorphous-15 (SBA) is a stable and mesoporous silica material. Quaternized SBA-15 with alkyl chains (Q_SBA) exhibits electrostatic attraction for anionic molecules via the N⁺ moiety of the ammonium group, whereas its alkyl chain length determines its hydrophobic interactions. In this study, Q_SBA with different alkyl chain lengths were synthesized using the trimethyl, dimethyloctyl, and dimethyoctadecyl groups (C1Q_SBA, C8Q_SBA, and C18Q_SBA, respectively). Carbamazepine (CBZ) is a widely prescribed pharmaceutical compound, but is difficult to remove using conventional water treatments. The CBZ adsorption characteristics of Q_SBA were examined to determine its adsorption mechanism by changing the alkyl chain length and solution conditions (pH and ionic strength). A longer alkyl chain resulted in slower adsorption (up to 120 min), while the amount of CBZ adsorbed was higher for longer alkyl chains per unit mass of Q_SBA at equilibrium. The maximum adsorption capacities of C1Q_SBA, C8Q_SBA, and C18Q_SBA, were 3.14, 6.56, and 24.5 mg/g, respectively, as obtained using the Langmuir model. For the tested initial CBZ concentrations (2-100 mg/L), the adsorption capacity increased with increasing alkyl chain length. Because CBZ does not dissociate readily (pK_a = 13.9), stable hydrophobic adsorption was observed despite the changes in pH (0.41-0.92, 1.70-2.24, and 7.56-9.10 mg/g for C1Q_SBA, C8Q_SBA, and C18Q_SBA, respectively); the exception was pH 2. Increasing the ionic strength from 0.1 to 100 mM enhanced the adsorption capacity of C18Q_SBA from 9.27 ± 0.42 to 14.94 ± 0.17 mg/g because the hydrophobic interactions were increased while the electrostatic attraction of the N⁺ was reduced. Thus, the ionic strength was a stronger control factor determining hydrophobic adsorption of CBZ than the solution pH. Based on the changes in hydrophobicity, which depends on the alkyl chain length, it was possible to enhance CBZ adsorption and investigate the adsorption mechanism in detail. Thus, this study aids the development of adsorbents suitable for pharmaceuticals with controlling molecular structure of QSBA and solution conditions.

Continuous degradation of micropollutants in real world treated wastewaters by photooxidation in dynamic conditions

Wastewater is a major issue for the ecosystem because of its considerable quantities, the treatment methods adopted in the large majority of WWTPs, and its level of contamination by various types of pollutants, especially emerging ones. One of the solutions considered to reduce this pressure on water is the reuse of wastewater after treatment for watering green areas, road cleaning, industry, groundwater recharge but also for crop irrigation. This paper proposes to study the capabilities of a photoreactor for the removal of micropollutants contained in wastewater from wastewater treatment plants. The experiments are carried out under dynamic artificial irradiation conditions which can be controlled in order to apply irradiation representative of the sunshine conditions. The experiments aim at treating a real effluent from urban wastewater. On the basis of these data, the photo-oxidation mass capacities expressed per unit of irradiated surface and per day were evaluated. Our results show that the oxidation process acts in a selective and differentiated manner according to the categories of substances and within each category. Some molecules are not or only partially oxidized. Note that the photo-reactor fed continuously with wastewater from wastewater treatment plants containing about 80 substances, is subjected to a typical irradiation setpoint of a sunny day in April. This allows to define the instantaneous and daily capacities of the system with respect to the target molecules.

Insight into integration of photocatalytic and microbial wastewater treatment technologies for recalcitrant organic pollutants: From sequential to simultaneous reactions

The more and more stringent environmental standards for recalcitrant organic pollutants pushed forward the development of integration of photocatalytic and microbial wastewater treatment technologies. The past studies proposed mainly two typical integration ways: a) Independent sequence of photocatalysis and biodegradation (ISPB) conducting the sequential reactions; b) Intimate coupling of photocatalysis and biodegradation (ICPB) conducting the simultaneous reactions. Although ICPB has received more attraction recently due to its novelty, ISPB gives an edge in certain cases. The article reviews the state-of-the-art ISPB and ICPB studies to comprehensively compare the two systems. The strengths and weaknesses of ISPB and ICPB regarding the treatment efficiency, cost, toxicity endurance and flexibility are contradistinguished. The reactor set-ups, photocatalysts, microbial characteristics of ISPB and ICPB are summarized. The applications for different kinds of recalcitrant compounds are elaborated to give a holistic view of the removal efficiencies and transformation pathways by the two technologies. Currently, in-depth understandings about the interference among mixed pollutants, co-existing components and key parameters in realistic wastewater are urgently needed. The long-term and large-scale application cases of the integration technologies are still rare. Overall, we conclude that both ISPB and ICPB technologies are reaching maturity while challenges still exist for two systems especially regarding the reliability, economy and generalization for realistic wastewater treatment plants. Future research should not only manage to reduce the cost and energy consumption by upgrading reactors and developing novel catalysts, but also attach importance to the cocktail effects of wastewater during the sequential or simultaneous photocatalysis and biodegradation.

Strategies to enhance micropollutant removal from wastewater by membrane bioreactors: Recent advances and future perspectives

Membrane bioreactor (MBR) has been widely implemented to advance wastewater treatment and reuse. Nevertheless, conventional MBRs with porous microfiltration or ultrafiltration membranes are not designed for the removal of micropollutants, which ubiquitously occur in wastewater at trace concentrations, but potentially exert detrimental impacts to the ecosystem. Several effective strategies have been applied to improve MBR performance for micropollutant removal, particularly the hydrophilic and recalcitrant compounds. These strategies mainly include the optimization of operational conditions, employment of high-retention membranes to replace porous ones, addition of functional materials into bioreactor, and integration of effluent purification processes. In particular, effluent purification by advanced oxidation processes (AOPs) and high-retention membranes can complement MBR to secure almost complete removal of micropollutants. Nevertheless, further research is still necessary to evaluate the technical and economic feasibility of these strategies, especially for long-term treatment performance, to screen the suitable techniques for industrial MBR applications.

A Review on the Removal of Carbamazepine from Aqueous Solution by Using Activated Carbon and Biochar

Carbamazepine (CBZ), one of the most used pharmaceuticals worldwide and a Contaminant of Emerging Concern, represents a potential risk for the environment and human health. Wastewater treatment plants (WWTPs) are a significant source of CBZ to the environment, polluting the whole water cycle. In this review, the CBZ presence and fate in the urban water cycle are addressed, with a focus on adsorption as a possible solution for its removal. Specifically, the scientific literature on CBZ removal by activated carbon and its possible substitute Biochar, is comprehensively scanned and summed up, in view of increasing the circularity in water treatments. CBZ adsorption onto activated carbon and biochar is analyzed considering several aspects, such as physicochemical characteristics of the adsorbents, operational conditions of the adsorption processes and adsorption kinetics and isotherms models. WWTPs usually show almost no removal of CBZ (even negative), whereas removal is witnessed in drinking water treatment plants through advanced treatments (even >90%). Among these, adsorption is considered one of the preferable methods, being economical and easier to operate. Adsorption capacity of CBZ is influenced by the characteristics of the adsorbent precursors, pyrolysis temperature and modification or activation processes. Among operational conditions, pH shows low influence on the process, as CBZ has no charge in most pH ranges. Differently, increasing temperature and rotational speed favor the adsorption of CBZ. The presence of other micro-contaminants and organic matter decreases the CBZ adsorption due to competition effects. These results, however, concern mainly laboratory-scale studies, hence, full-scale investigations are recommended to take into account the complexity of the real conditions.

WITHDRAWN: Progress in the removal of organic microcontaminants from wastewater using high retention membrane bioreactors: A critical review

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Understanding the mechanisms of trace organic contaminant removal by high retention membrane bioreactors: a critical review

High retention membrane bioreactors (HR-MBR) combine a high retention membrane separation process such as membrane distillation, forward osmosis, or nanofiltration with a conventional activated sludge (CAS) process. Depending on the physicochemical properties of the trace organic contaminants (TrOCs) as well as the selected high retention membrane process, HR-MBR can achieve effective removal (80-99%) of a broad spectrum of TrOCs. An in-depth assessment of the available literature on HR-MBR performance suggests that compared to CAS and conventional MBRs (using micro- or ultra-filtration membrane), aqueous phase removal of TrOCs in HR-MBR is significantly better. Conceptually, longer retention time may significantly improve TrOC biodegradation, but there are insufficient data in the literature to evaluate the extent of TrOC biodegradation improvement by HR-MBR. The accumulation of hardly biodegradable TrOCs within the bioreactor of an HR-MBR system may complicate further treatment and beneficial reuse of sludge. In addition to TrOCs, accumulation of salts gradually increases the salinity in bioreactor and can adversely affect microbial activities. Strategies to mitigate these limitations are discussed. A qualitative framework is proposed to predict the contribution of the different key mechanisms of TrOC removal (i.e., membrane retention, biodegradation, and sorption) in HR-MBR.

Advanced membrane bioreactors systems: New materials and hybrid process design

Membrane bioreactor (MBR) is deemed as one of the most powerful technologies for efficient municipal and industrial wastewater treatment around the world. However, low microbial activity of activated sludge and serious membrane fouling still remain big challenges in worldwide application of MBR technology. Nowadays, more and more progresses on the research and development of advanced MBR with new materials and hybrid process are just on the way. In this paper, an overview on the perspective of high efficient strains applied into MBR for biological activity enhancement and fouling reduction is provided first. Secondly, as emerging fouling control strategy, design and fabrication of novel anti-fouling composited membranes are comprehensively highlighted. Meanwhile, hybrid MBR systems integrated with some novel dynamic membrane modules and/or with other technologies like advanced oxidation processes (AOPs) are introduced and compared. Finally, the challenges and opportunities of advanced MBRs combined with bioenergy production in wastewater treatment are discussed.

Fate of pharmaceuticals during membrane bioreactor treatment: Status and perspectives

Pharmaceuticals in surface waters and wastewater treatment plants (WWTPs) as emerging pollutants have become a major concern. In comparison with other wastewater treatments, removal of pharmaceuticals in MBR has received much attention. This review presents the source and occurrence of pharmaceuticals in WWTPs influents. Experimental studies related to the removal of pharmaceuticals during MBR treatment, key affecting factors (including the different stages of MBR process configuration and the process parameters), and the underlying mechanisms proposed to explain the biodegradation and adsorption behaviors, have been comprehensively discussed. Several transformation products of pharmaceuticals are also reviewed in this paper. Furthermore, further research is needed to gain more information about the multiple influence factors of the pharmaceuticals elimination, appropriate methods for promoting pharmaceuticals elimination, more essential removal pathways, effect of pharmaceuticals on membrane fouling, and the detection and analysis of transformation products.

Comparison of different advanced degradation processes for the removal of the pharmaceutical compounds diclofenac and carbamazepine from liquid solutions

Carbamazepine and diclofenac are two examples of drugs with widespread geographical and environmental media proliferation that are poorly removed by traditional wastewater treatment processes. Advanced oxidation processes (AOPs) have been proposed as alternative methods to remove these compounds in solution. AOPs are based on a wide class of powerful technologies, including UV radiation, ozone, hydrogen peroxide, Fenton process, catalytic wet peroxide oxidation, heterogeneous photocatalysis, electrochemical oxidation and their combinations, sonolysis, and microwaves applicable to both water and wastewater. Moreover, processes rely on the production of oxidizing radicals (•OH and others) in a solution to decompose present pollutants. Water radiolysis-based processes, which are an alternative to the former, involve the use of concentrated energy (beams of accelerated electrons or γ-rays) to split water molecules, generating strong oxidants and reductants (radicals) at the same time. In this paper, the degradation of carbamazepine and diclofenac by means of all these processes is discussed and compared. Energy and byproduct generation issues are also addressed.

Simultaneous photocatalytic and microbial degradation of dye-containing wastewater by a novel g-C3N4-P25/photosynthetic bacteria composite

Azo dyes are very resistant to light-induced fading and biodegradation. Existing advanced oxidative pre-treatment methods based on the generation of non-selective radicals cannot efficiently remove these dyes from wastewater streams, and post-treatment oxidative dye removal is problematic because it may leave many byproducts with unknown toxicity profiles in the outgoing water, or cause expensive complete mineralization. These problems could potentially be overcome by combining photocatalysis and biodegradation. A novel visible-light-responsive hybrid dye removal agent featuring both photocatalysts (g-C₃N₄-P₂₅) and photosynthetic bacteria encapsulated in calcium alginate beads was prepared by self-assembly. This system achieved a removal efficiency of 94% for the dye reactive brilliant red X-3b and also reduced the COD of synthetic wastewater samples by 84.7%, successfully decolorized synthetic dye-contaminated wastewater and reduced its COD, demonstrating the advantages of combining photocatalysis and biocatalysis for wastewater purification. The composite apparently degrades X-3b by initially converting the dye into aniline and phenol derivatives whose aryl moieties are then attacked by free radicals to form alkyl derivatives, preventing the accumulation of aromatic hydrocarbons that might suppress microbial activity. These alkyl intermediates are finally degraded by the photosynthetic bacteria.

Carbamazepine degradation by gamma irradiation coupled to biological treatment

Carbamazepine is an emerging contaminant and resistant to biodegradation, which cannot be effectively removed by the conventional biological wastewater treatment processes. In this study, the combined gamma irradiation and biodegradation was employed to remove carbamazepine from wastewater. The effect of dose on the removal of carbamazepine was studied at different doses (300, 600 and 800Gy). The results showed that the removal efficiency of carbamazepine increased with dose increasing during the irradiation process. The maximum removal efficiency was 99.8% at 800Gy, while the removal efficiency of total organic carbon (TOC) was only 26.5%. The removal efficiency of TOC increased to 79.3% after the sequent biological treatment. In addition, several intermediates and organic acids were detected. The possible degradation pathway of carbamazepine during the integrated irradiation and biodegradation was proposed. Based on the overall analysis, the combined gamma irradiation and biological treatment process can be an alternative for removing the recalcitrant organic pollutants such as carbamazepine from wastewater.

Combined photocatalysis and membrane bioreactor for the treatment of feedwater containing thin film transistor-liquid crystal display discharge

The nitrogen content of waste water generated by the thin film transistor-liquid crystal display (TFT-LCD) industry is not satisfactorily removed through the conventional aerobic-activated sludge process. In this study, the performance of three reactors – suspended type TiO2 membrane photoreactor (MPR), anoxic/oxic membrane bioreactor (AOMBR), and their combination (MPR-AOMBR) – was evaluated using feedwater containing TFT-LCD discharge. The parameters that maximized monoethanolamine (MEA) removal in the MPR were continuous ultraviolet (UV) irradiation and pH 11. Among the tested loadings, 0.1 g/l of TiO2 promoted MEA removal but degradation rate may further increase with photocatalyst concentration. The nitrified sludge recycle ratio R of the AOMBR was adjusted to 1.5 to minimize the amount of nitrate in the effluent. The AOMBR greatly decreased chemical oxygen demand and MEA, but removed only 32.7% of tetramethyl ammonium hydroxide (TMAH). The MPR was configured as the pre-treatment unit for AOMBR, and the combined MPR-AOMBR has improved TMAH removal by 80.1%. The MPR bolstered performance by decomposing slowly biodegradable compounds, and had no negative effects on denitrification and carbon removal.

Sequential chemical-biological processes for the treatment of industrial wastewaters: review of recent progresses and critical assessment

When direct wastewater biological treatment is unfeasible, a cost- and resource-efficient alternative to direct chemical treatment consists of combining biological treatment with a chemical pre-treatment aiming to convert the hazardous pollutants into more biodegradable compounds. Whereas the principles and advantages of sequential treatment have been demonstrated for a broad range of pollutants and process configurations, recent progresses (2011-present) in the field provide the basis for refining assessment of feasibility, costs, and environmental impacts. This paper thus reviews recent real wastewater demonstrations at pilot and full scale as well as new process configurations. It also discusses new insights on the potential impacts of microbial community dynamics on process feasibility, design and operation. Finally, it sheds light on a critical issue that has not yet been properly addressed in the field: integration requires complex and tailored optimization and, of paramount importance to full-scale application, is sensitive to uncertainty and variability in the inputs used for process design and operation. Future research is therefore critically needed to improve process control and better assess the real potential of sequential chemical-biological processes for industrial wastewater treatment.

Analysis and advanced oxidation treatment of a persistent pharmaceutical compound in wastewater and wastewater sludge-carbamazepine

Pharmaceutically active compounds (PhACs) are considered as emerging environmental problem due to their continuous input and persistence to the aquatic ecosystem even at low concentrations. Among them, carbamazepine (CBZ) has been detected at the highest frequency, which ends up in aquatic systems via wastewater treatment plants (WWTPs) among other sources. The identification and quantification of CBZ in wastewater (WW) and wastewater sludge (WWS) is of major interest to assess the toxicity of treated effluent discharged into the environment. Furthermore, WWS has been subjected for re-use either in agricultural application or for the production of value-added products through the route of bioconversion. However, this field application is disputable due to the presence of these organic compounds and in order to protect the ecosystem or end users, data concerning the concentration, fate, behavior as well as the perspective of simultaneous degradation of these compounds is urgently necessary. Many treatment technologies, including advanced oxidation processes (AOPs) have been developed in order to degrade CBZ in WW and WWS. AOPs are technologies based on the intermediacy of hydroxyl and other radicals to oxidize recalcitrant, toxic and non-biodegradable compounds to various by-products and eventually to inert end products. The purpose of this review is to provide information on persistent pharmaceutical compound, carbamazepine, its ecological effects and removal during various AOPs of WW and WWS. This review also reports the different analytical methods available for quantification of CBZ in different contaminated media including WW and WWS.

Involvement of process parameters and various modes of application of TiO2 nanoparticles in heterogeneous photocatalysis of pharmaceutical wastes – a short review

In recent years, the occurrence of persistent organic compounds in industrial as well as municipal effluents is becoming a serious threat to the environment. The detrimental effects can be minimized with the help of photocatalysis.

Photoelectrocatalytic degradation of carbamazepine using Ti/TiO2 nanostructured electrodes deposited by means of a pulsed laser deposition process

The objective of the present work is to evaluate the potential of photoelectrocatalytic oxidation (PECO) process using Ti/TiO2 for the degradation of carbamazepine (CBZ). Ti/TiO2 prepared by pulsed laser deposition (PLD) has been used as a photo-catalyst in a photoelectrocatalytic cell. The PLD TiO2 coatings were found to be of anatase structure consisting of nanocrystallites of approximately 15nm in diameter. Factorial and central and extreme composite design methodologies were successively employed to define the optimal operating conditions for CBZ degradation. Several factors such as current intensity, treatment time, pollutant concentration and cathode material were investigated. Using a 2(4) factorial matrix, the best performance for CBZ degradation (53.5%) was obtained at a current intensity of 0.1 A during 120min of treatment time and when the vitreous carbon (VC) was used at the cathode in the presence of 10mgL(-1) of CBZ. Treatment time and pollutant concentration were found to be very meaningful for CBZ removal. The PECO process applied under optimal conditions (at current intensity of 0.3A during 120min in the presence of 10mgL(-1) of CBZ with VC at the cathode) is able to oxidize around 73.5% ±2.8% of CBZ and to ensure 21.2%±7.7% of mineralization. During PECO process, CBZ was mainly transformed to acridine and anthranilic acid. Microtox biotests (Vibrio fisheri) showed that the treated - effluent was not toxic. The pseudo-second order kinetic model (k2=6×10(-4)Lmg(-1)min(-1)) described very well the oxidation of CBZ.

Biomass characterization by dielectric monitoring of viability and oxygen uptake rate measurements in a novel membrane bioreactor

The application of permittivity and oxygen uptake rate (OUR) as biological process control parameters in a wastewater treatment system was evaluated. Experiments were carried out in a novel airlift oxidation ditch membrane bioreactor under different organic loading rates (OLR). Permittivity as representative of activated sludge viability was measured by a capacitive on-line sensor. OUR was also measured as a representative for respirometric activity. Results showed that the biomass concentration increases with OLR and all biomass related measurements and simulators such as MLSS, permittivity, OUR, ASM1 and ASM3 almost follow the same increasing trends. The viability of biomass decreased when the OLR was reduced from 5 to 4 kg COD m(-3)d(-1). During decreasing of OLR, biomass related parameters generally decreased but not in a similar manner. Also, protein concentration in the system during OLR decreasing changed inversely with the activated sludge viability.

Economic evaluation of a combined photo-Fenton/MBR process using pesticides as model pollutant. Factors affecting costs

The aim of this paper is to carry out an economic assessment on a solar photo-Fenton/MBR combined process to treat industrial ecotoxic wastewater. This study focuses on the impact of the contamination present in wastewater, the photochemical oxidation, the use of an MBR as biological process and the plant size on operating and amortization costs. As example of ecotoxic pollutant, a mixture of five commercial pesticides commonly used in the Mediterranean area has been used, ranging from 500 mg/L to 50mg/L, expressed as dissolved organic carbon concentration. The economic evaluation shows that (i) the increase in pollution load does not always involve an increase in photo-Fenton costs because they also depend on organic matter mineralization; (ii) the use of an MBR process permits lower photochemical oxidation requirements than other biological treatments, resulting in approximately 20% photo-Fenton cost reduction for highly polluted wastewater; (iii) when pollution load decreases, the contribution of reactant consumption to the photo-Fenton process costs increase with regard to amortization costs; (iv) 30% total cost reduction can be gained treating higher daily volumes, obtaining competitive costs that vary from 1.1-1.9 €/m(3), depending on the pollution load.

Photocatalytic treatment of high concentration carbamazepine in synthetic hospital wastewater

Effective and sustainable treatment of hospital wastewater containing high concentration of pharmaceutical compounds presents a pivotal challenge to wastewater and environmental engineers worldwide. In this study, a titanium dioxide (TiO(2)) nanofiber based wastewater treatment process was assessed as a pre-treatment system to treat and enhance the biodegradability of a representative pharmaceutical compound, 5000 μg/L of carbamazepine (CBZ), in synthetic hospital wastewater. Results showed that the stand-alone TiO(2) pre-treatment system was capable of removing 78% of CBZ, 40% of COD and 23% of PO(4) concentrations from the influent wastewater within a 4h reaction time. High performance size exclusion chromatography demonstrated that a simultaneous biodegradability enhancement of hospital wastewater was observed, whereby an apparent shift in molecular weight from higher fraction (>10-1000 kDa) to a lower fraction (<10 kDa) was induced after 0.5h of photocatalytic treatment. Eventually, it was found that the photodegradation profile for high concentration CBZ in synthetic hospital wastewater was perfectly fitted to the Langmuir-Hinshelwood kinetics model. It is anticipated that this TiO(2) pre-treatment process can be further integrated with a biological wastewater treatment process to deliver treated hospital effluent of better quality that can minimise the associated human health and environmental risks.

Evaluation of a biologically-based filtration water reclamation plant for removing emerging contaminants: a pilot plant study

The effect of hydraulic retention time (HRT), solar radiation and seasonality on the removal efficiency of 18 emerging contaminants has been studied in a biological filtration pilot plant based on Daphnia sp. The pilot plant consisted of a homogenization tank and two lines, A and B, each with four 1 m(3) tanks. One of these lines was directly exposed to sunlight whereas the other line was covered. Our results suggest that biodegradation and photodegradation are the most important removal pathways, whereas sorption makes a minor contribution. The removal efficiency ranged from no detectable removal to more than 90%. The kinetics of the degradation process was fit to a first order kinetic, with half-lives from 0.6 to 42 days, depending on the particular compound. However, a scaling effect comes into play as the pilot plant was found to be more efficient than a similar full-scale polishing pond.

Removal of carbamazepine and sulfamethoxazole by MBR under anoxic and aerobic conditions

This study reveals for the first time that near-anoxic conditions (dissolved oxygen, DO=0.5 mg/L) can be a favorable operating regime for the removal of the persistent micropollutant carbamazepine by MBR treatment. The removal efficiencies of carbamazepine and sulfamethoxazole by an MBR were systematically examined and compared under near-anoxic (DO=0.5 mg/L) and aerobic (DO>2 mg/L) conditions. Preliminary batch tests confirmed that sulfamethoxazole is amenable to both aerobic and anoxic biotransformation. However, carbamazepine-a known persistent compound-showed degradation only under an anoxic environment. In good agreement with the batch tests, during near-anoxic operation, under a high loading of 750 μg/Ld, an exceptionally high removal (68±10%) of carbamazepine was achieved. In contrast, low removal efficiency (12±11%) of carbamazepine was observed during operation under aerobic conditions. On the other hand, an average removal efficiency of 65% of sulfamethoxazole was achieved irrespective of the DO concentrations.