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Wastewater treatment plants are not specially designed to remove pharmaceutically active compounds (PhACs), since these substances are toxic and bio-refractory. This paper aims to investigate and optimize the performance of the Trisep TS80 nanofiltration (NF) membrane for the removal of a mixture of two of the most detected PhACs in municipal wastewaters worldwide, sulfamethoxazole and diclofenac. Several NF tests were carried out to study the rejections of these contaminants both spiked in demineralized water, filtrated water taken from Mondego River and secondary effluent coming from a municipal wastewater treatment plant. Among the several studied operating variables, pH was the one that most affected the contaminant rejection and membrane permeability. In the case of synthetic effluent, an applied pressure of 10 bar and pH 7 were determined as the best operating conditions, which allowed almost total chemical oxygen demand retention and a global contaminant rejection of 96.3% to be achieved. The application of different water matrices (river water and secondary municipal effluent) had no relevant impact on process efficiency. Vibrio fischeri luminescence inhibition tests revealed that treatment by nanofiltration reduced acute toxicity of all studied effluents.

The electrochemical oxidation (EO) of phenolic wastewaters mimicking olive oil mill effluents was carried out in a batch stirring reactor using Ti/IrO 2 anodes, varying the nature (NaCl and Na 2 SO 4 ) and electrolyte concentration (1.8-20 g L -1 ), current density (57-119 mA cm -2 ) and initial pH (3.4-9). Phenolic content (TPh) and chemical oxygen demand (COD) removals were monitored as a function of applied charge and over time. The nature of the electrolyte greatly affected the efficiency of the system, followed by the influence of the current density. The NaCl concentration and the initial pH influenced the process in a lesser extent. The best operating conditions achieved were 10 g L -1 of NaCl, current density of 119 mA cm -2 and initial pH of 3.4. These parameters led to 100 and 84.8% of TPh and COD removal, respectively. Under these conditions, some morphological differences were observed by SEM on the surface of the anode after treatment. To study the potential toxicity of the synthetic effluent in neuronal activity, this mixture was applied to rat brain slices prior to and after EO. The results indicate that although the treated effluent causes a smaller depression of the neuronal reactive oxygen species (ROS) signal than the untreated one, it leads to a potentiation instead of recovery, upon washout. Furthermore, the purification of a real olive mill wastewater (OMW), with the organic load of the synthetic effluent, using the same optimised operating conditions, achieved total phenolic compounds abatement and 62.8% of COD removal.This study demonstrates the applicability of this EO as a pre-treatment process of a real effluent, in order to achieve the legal limit values to be discharged into natural streams regarding its organic load.

The utilization of Fenton's oxidation for the depuration of elderberry juice wastewater was studied. The aim was to select the adequate cost-effective operating conditions suitable to lead to an effluent within the legal thresholds to be discharged into the natural water courses. The treatment efficacy was assessed by chemical oxygen demand (COD), colour, phenolic content and total solids removal besides its ability to improve biodegradability (biochemical oxygen demand (BOD5)/COD). Moreover, the costs of the applied reactants were also considered. Fenton's reaction was able to abate at least 70% of COD (corresponding to a final value below 150 mg O2 L(-1)). Besides, total phenolic content degradation was always achieved. Within these conditions, the resulting effluent is able to be directly discharged into the natural hydric channels. Fenton oxidation could be successfully applied as a single treatment method with a reactant cost of 4.38 € m(-3) ([Fe(2+)] = 20 mmol L(-1), [H2O2] = 100 mmol L(-1), pH = 3 and 4 h of oxidation procedure).

With the objective of reaching suitable techniques for olive mill wastewater treatment, ozonation and ultrafiltration were studied individually and combined. A continuous reactor was run for the treatment of a phenolic mixture mimicking an actual olive mill wastewater (OMW) by ozonation. The effect of the main operating parameters was analysed (pH, liquid flow rate and ozone inlet concentration). The increase of pH and ozone dose improved ozonation efficiency. As expected, the highest residence time led to higher steady-state degradation (35 % of chemical oxygen demand (COD) abatement). Even if the rise on ozone inlet gas concentration was able to remove COD in a higher extent, it should be taken into consideration that with the lowest oxidant load (15 g O3/m(3)), the maximum steady-state biochemical oxygen demand (BOD5)/COD ratio was reached which would reduce the process costs. These operating conditions (pH 9, 1 mL/min of liquid flow rate and 15 g O3/m(3)) were applied to an actual OMW leading to 80 % of phenolic content abatement and 12 % of COD removal at the steady state. Regarding ultrafiltration, it was concluded that the best total phenolic content (TPh) and COD abatement results (55 and 15 %) are attained for pH 9 and using a transmembrane pressure drop of 1 bar. Among the integration schemes that were tested, ultrafiltration followed by ozonation was able to reach 93 and 20 % of TPh and COD depletion, respectively. Moreover, this sequence led to an effluent with a BOD5/COD ratio of about 0.55 which means that it likely can be posteriorly refined in a municipal wastewater treatment plant.

Ozonation, catalytic ozonation, Fenton's and heterogeneous Fenton-like processes were investigated as possible pretreatments of a low biodegradable and highly toxic wastewater produced by a detergent industry. The presence of a Mn-Ce-O catalyst in ozonation enhances the biodegradability and improves the degradation at low pH values. However, a high content of carbonyl compounds adsorbed on the recovered solid indicates some limitations for real-scale application. A commercial Fe2O3-MnOx catalyst shows higher activity as well as higher stability concerning carbon adsorption, but the leaching of metals is larger than for Mn-Ce-O. Regarding the heterogeneous Fenton-like route with an Fe-Ce-O catalyst, even though a high activity and stability are attained, the intermediates are less biodegradable than the original compounds, indicating that the resulting effluent cannot be conducted to an activated sludge post-treatment. The highest enhancement of effluent biodegradability is obtained with the classic homogeneous Fenton's process, with the BOD5/COD ratio increasing from 0.32 to 0.80. This process was scaled up and the treated effluent is now safely directed to a municipal wastewater treatment plant.

In this study, the heterogeneous photosensitized oxidation treatment of winery effluents was optimized using chitosan carriers immobilized with Zn(II) Phthalocyanine tetrasulfonic acid. The influence of main operating parameters such as initial pH, aeration flow rate, photocatalyst load, and concentration of the photosensitizer used in the photocatalysts' preparation was investigated. Results for chemical oxygen demand (COD) and phenolic content (TPh) removals are presented for each of the tests performed. Best reductions were obtained after 30 min of treatment in natural sunlight at an initial pH of 4.0 and an aeration flow of 2.8 L/min since it allowed reductions of 45% for COD and 73% for phenolic content (TPh). In addition, the possibility of reusing the photocatalysts during several cycles was also assessed, where an acidic initial pH allowed their reuse, being the only pH value studied where the leaching of the photosensitizer was not observed. In these conditions, the same photocatalysts were reused for six reaction cycles, and efficiency started to decrease after the third use. Thus, a greater mass and concentration of photosensitizer contributed to a superior reduction in organic matter. The results show that heterogeneous photosensitized oxidation using sunlight radiation as an energy source is an interesting approach for obtaining reusable water from winery effluents. [ABSTRACT FROM AUTHOR]

Ensuring drinking water quality is a key factor for public health and it is especially important given the increase in industrialization. Its quality is ensured by a water treatment process that includes a disinfection stage, mainly involving chlorination. However, by applying this disinfection method, unwanted disinfection byproducts (DBPs) are formed. These compounds have, in general, a negative impact on human health. Following this, the development of stricter regulations for drinking water quality standards has been conducted worldwide. Several techniques for the removal of DBPs have already been developed to prevent DBP formation or to reduce DBPs formed during disinfection. Nevertheless, controlling the water distribution systems after drinking water treatment is still important, since DBPs can reoccur along the distribution network. To achieve this, further research should be developed to efficiently monitor and allow the performance of the necessary actions to detect and control these contaminants throughout the water distribution system. Additionally, the most suitable places for sensing along the distribution system must be further assessed. [ABSTRACT FROM AUTHOR]

The increasing consumption of pharmaceutical and personal care products (PPCPs) by humankind has been causing an accumulation of contaminants (commonly referred to as contaminants of emerging concern), in effluents and water resources. Ozonation can be used to improve the removal of these contaminants during water treatment to alleviate this burden. In this work, the degradation of methyl (MP), propylparaben (PP), paracetamol (PCT), sulfamethoxazole (SMX), and carbamazepine (CBZ) by ozonation was assessed both for individual compounds and for mixtures with increasing complexity (two to five compounds). Ozonation was performed at pH3 to gain an insight on the exclusive action of molecular ozone as oxidizing agent. The degradation of contaminants was described as a function of time and transferred ozone dose, and the corresponding pseudo-first order kinetic rate constants (k') were determined. PPCPs were degraded individually within 1.5 to 10 min. CBZ was the most quickly degraded (k' = 1.25 min−1) and MP the most resistant to ozone (k' = 0.25 min−1). When in the mixture, the degradation rate of the contaminants was slower. For parabens, the increase of the number of compounds in the mixture led to an exponential decrease of the k' values. Moreover, the presence of more PPCPs within the mixture increased energy consumption associated with the treatment, thereby reflecting higher economic costs. [ABSTRACT FROM AUTHOR]

The aims of the present work were to assess the application of a chemical process to degrade a mixture of parabens and determine the influence of a natural river water matrix on toxicity. Model effluents containing either a single compound, namely methylparaben, ethylparaben, propylparaben, butylparaben, benzylparaben or p-hydroxybenzoic acid, or to mimic realistic conditions a mixture of the six compounds was used. Fenton process was applied to reduce the organic charge and toxic properties of the model effluents. The efficiency of the decontamination has been investigated using a chemical as well as a toxicological approach. The potential reduction of the effluents' toxicity after Fenton treatment was evaluated by assessing (i) Vibrio fischeri luminescence inhibition, (ii) lethal effects amongst freshwater Asian clams (Corbicula fluminea), and (iii) the impact on mammalian neuronal activity using brain slices. From the environmental point of view such a broad toxicity analysis has been performed for the first time. The results indicate that Fenton reaction is an effective method for the reduction of chemical oxygen demand of a mixture of parabens and their toxicity to V. fischeri and C. fluminea. However, no important differences were found between raw and treated samples in regard to mammalian neuronal activity. [ABSTRACT FROM AUTHOR]

The main drawback of Fenton′s process is the formation of ferric sludge. In this work, ion exchange (IE) appears as a complement to the Fenton process, allowing, on the one hand, to remove the iron excess present in the sludge, as well as reduce the COD of the real olive oil industry extraction wastewater (OOIEW) from the Fenton process. The Fenton process uses iron (II) sulfate as catalyst, therefore concentrations of iron up to 2 g L−1 could be present in the treated OOIEW. The iron and COD adsorption equilibrium behavior has been modelized by Langmuir, Freundlich and Temkin isotherms. Moreover, the resin efficiency was tested in a continuous fixed-bed column. It was concluded that the resin maintains iron adsorption capacity over at least three reuse cycles. Overall Fenton's process followed by ion exchange seems to be a promising approach for the treatment of cumbersome industrial wastewaters. [ABSTRACT FROM AUTHOR]

Abstract: A mixture of six phenolic acids, corresponding to an initial TOC of 370mgC/L, was studied by Fenton''s peroxidation aiming to improve the biodegradability of agro-industrial wastewaters. Input operating variables including the concentration of pollutants, iron and hydrogen peroxide as well as the reaction time were used to assess the mineralization degree through a factorial experimental methodology. A TOC removal in the range of 15.0–58.8% was attained within the operational conditions used. A reduced model was achieved using the statistically important independent factors and interactions to predict TOC degradation. On the hydrogen peroxide injection methodology, the results showed that the continuous introduction of small volumes is advantageous when compared with one single addition of the overall volume at the zero reaction time with a mineralization improvement of 11%. The use of FeSO4·7H2O correspondent to a Fe2+ load of 271mg; [H2O2]=488.0mM, injected in twelve aliquots each 30min during 6h of reaction reached optimal efficiencies with the parent compounds (quantified by HPLC and the Folin–Ciocalteau method) quickly totally removed and TOC, COD and BOD5 final values of 123mgC/L, 180mgO2/L and 146mgO2/L, respectively. Toxicity assessment by Vibrio fischeri light inhibition revealed that Fenton''s process reduces the effluent ecological impact related with the decomposition of the toxic phenolic acids. Indeed, EC50 changed from 32.2% dilution to no-dilution needed. The analysis of BOD5/COD ratio pointed out a high improvement of the treated wastewater biodegradability from 0.30 to 0.80 meaning that the application of Fenton''s oxidation as a pre-treatment enables a further application of an efficient post-biological technology which was also confirmed by respirometry. [Copyright &y& Elsevier]

Application of solar photocatalysis for water treatment is intensively studied. In this work, we investigated TiO2 modified with platinum (Pt/TiO2) and palladium (Pd/TiO2) using sulfamethoxazole (SMX) as the model contaminant. We considered the following parameters: (i) level of TiO2 modification with Pt/Pd, (ii) initial concentration of photocatalysts, (iii) geographic location where processes were conducted, and (iv) natural water matrix. The catalysts characterized by SEM, EDX, DRS, and XRD techniques showed successful deposition of Pd and Pt atoms on TiO2 surface that enabled light absorption in the visible (Vis) range, and therefore caused efficient SMX removal in all tested conditions. A comparison of the rate constants of SMX degradation in various conditions revealed that modification with Pd gave better results than modification with Pt, which was explained by the better optical properties of Pd/TiO2. The removal of SMX was higher with Pd/TiO2 than with Pt/TiO2, independent of the modification level. In the experiments with the same modification level, similar rate constants were achieved when four times the lower concentration of Pd/TiO2 was used as compared with Pt/TiO2. Formation of four SMX transformation products was confirmed, in which both amine groups are involved in photocatalytic oxidation. No toxic effect of post-reaction solutions towards Lepidium sativum was observed. [ABSTRACT FROM AUTHOR]

Due to the shortening on natural water resources, reclaimed wastewater will be an important water supply source. However, suitable technologies must be available to guaranty its proper detoxification with special concern for the emerging pharmaceutical and personal care products that are continuously reaching municipal wastewater treatment plants. While conventional biological systems are not suitable to remove these compounds, ozone, due to its interesting features involving molecular ozone oxidation and the possibility of generating unselective hydroxyl radicals, has a wider range of action on micropollutants removal and water disinfection. This paper aims to review the studies dealing with ozone based processes for water reuse by considering municipal wastewater reclamation as well as natural and drinking water treatment. A comparison with alternative technologies is given. The main drawback of ozonation is related with the low mineralization achieved that may lead to the production of reaction intermediates with toxic features. The use of hydrogen peroxide and light aided systems enhance ozone action over pollutants. Moreover, scientific community is focused on the development of solid catalysts able to improve the mineralization level achieved by ozone. Special interest is now being given to solar light catalytic ozonation systems with interesting results both for chemical and biological contaminants abatement. Nowadays the integration between ozonation and sand biofiltration seems to be the most interesting cost effective methodology for water treatment. However, further studies must be performed to optimize this system by understanding the biofiltration mechanisms. [ABSTRACT FROM AUTHOR]

• Refined oil extraction units produce a highly pollutant effluent difficult to threat. • AOPs alone and combined were evaluated to reduce the oil extraction effluent impact. • Fenton's process was the most efficient of AOPs used alone to threat the effluent. • Combination of Fenton's and Ozone reaction achieve the best COD removal. • Fenton and ozone (pH 9) achieve the best phenolic content and toxicity reduction. The olive mills are theoretically waste free plants, at the refined oil extraction units, a highly pollutant effluent is generated. In this work the performance of different AOPs in the same multiphase reactor was evaluated to minimize real oil extraction effluent environmental impact. In terms of COD removal, the combination of Fenton and Ozone reaction simultaneously, allows the highest reduction (58.5%) although the combination of Fenton followed by ozone at pH3 lead to a similar removal, about 54%. In what regards mineralization, Fenton peroxidation alone was the most efficient process leading to 53% of TOC removal. Fentońs process presents an interesting role in the effluent treatment. However, if one bears in mind phenolic content removal and toxicity abatement, the best results were obtained by Fenton peroxidation (pH 3) followed by ozonation (pH 9). The treatment processes selection should consider the target results as well as a suitable economic analysis. [ABSTRACT FROM AUTHOR]

In this work, Fenton's process was evaluated as an alternative treatment of swine effluent. In order to improve depuration, coagulation and biofiltration were integrated with Fenton's peroxidation. With the optimum loads of 750 mg/L of hydrogen peroxide and iron, this process was able to remove 72% of sCOD and lowering Aliivibrio fischeri luminescence inhibition to 65%. On the other hand, integration between Fenton's process and biofiltration removed 91% of sCOD. Whereas, after coagulation sCOD degradation reaches 86%. Regarding to luminescence inhibition, the treatment processes integration can decrease it to about 30%. Coagulation and biofiltration after Fenton's process proved to be able to remove dissolved iron in the treated effluent and thus overcoming Fenton's process major disadvantage. • Fenton's process is a suitable way to remove sCOD and toxicity from swine wastewater. • Biofiltration using C. fluminea used as pre-treatment improves Fenton's peroxidation. • Coagulation can lead to an effluent more amenable for Fenton's oxidation. • Biofiltration and coagulation remove iron from Fenton's treated wastewater. • The integrated technologies are cleaner processes for swine wastewater treatment. [ABSTRACT FROM AUTHOR]