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This study assesses the influence of the presence of suspended and dissolved matter on the efficiency of TiO2 photocatalysis for the removal of cyanide from coking wastewater. Photocatalytic processes were carried out at basic pH (pH 9) with titanium dioxide (1 g/L), artificial radiation (290–800 nm) and during different time periods (20–100 min). The first assays applied in aqueous solutions achieved promising results in terms of removing cyanide. The maximum cyanide removal obtained in coking wastewater was 89% after 80 min of irradiation in the presence of suspended and dissolved matter. The presence of suspended matter composed of coal improves the efficiency of the photocatalytic process due to the synergistic effect between carbon and TiO2. The absence of dissolved matter also improves the process due to the minimization of the hydroxyl radical scavenging effect produced by carbonate and bicarbonate ions. On the other hand, the presence of certain species in the real matrix such as silicon i...

In the present study, different ozone based processes (O 3 , O 3 /OH − , O 3 /UV, O 3 /H 2 O 2 and O 3 /UV/H 2 O 2 ) and solar photo - Fenton treatment were evaluated for the pre - treatment of synthetic samples of citrus wastewater. The highest removal of organic matter in ozone based processes was achieved at high pH values, using H 2 O 2 and UV radiation at 254 nm. After the application of ozone for 150 min at 1.9 gO 3 /L, 1017 mg/L of H 2 O 2 , UV radiation and pH ∼ 7, the removal efficiency of chemical oxygen demand and dissolved organic carbon was 15.7% and 10.9%, respectively. Apparent color, real color and turbidity were reduced significantly, mainly at the initial stages of the reaction. The solar photo - Fenton treatment (pH of citrus wastewater, [H 2 O 2 ] = 15,937 mg/L, 510 mg/L of Fe 3+ and reaction time of 30 min) produced a removal of 77% of chemical oxygen demand and 53% of dissolved organic carbon. This photocatalytic process is the most appropriate technique for the pretreatment of citrus effluent. An estimation of the total production costs of the photo - Fenton process shows that when solar light is used the cost of the treatment is 13.8 €/m 3 .

The purpose of this work was to study the efficiency of TiO2 in the inactivation of Escherichia coli present in natural surface water. TiO2 is the most extensively studied semiconductor catalyst used in combination with solar irradiation due to its high photoactivity, low cost, chemical and biological stability, and harmlessness. The processes studied in this research work were: (i) UV-Vis irradiation; (ii) 0.04 mM H2O2/UV-Vis irradiation; (iii) 1 g/L TiO2/UV-Vis irradiation; and (iv) 1 g/L TiO2/0.04 mM H2O2/UV-Vis irradiation. The results showed that the process with TiO2/UV-Vis irradiation reached the highest levels of inactivation of E. coli, around 3.30 log, after 30 min of contact time. In contrast, the addition of H2O2 to the photocatalytic treatment not only did not increase the inactivation result, it actually decreased it. After 30 min of contact time, the inactivation of E. coli was 0.97 log for the process with 1 g/L TiO2/0.04 mM H2O2/UV-Vis irradiation. The fitting of experimental values to the corresponding equations through nonlinear regression techniques was carried out with Microsoft® Excel Solver and GInaFiT. The kinetic modeling of inactivation values is a powerful tool for identifying the influence of the different variables present in disinfection treatments.

This work aims to assess the effectiveness of the photo-Fenton system for the removal of fecal bacteria in treated urban wastewater effluents, using low reagent concentrations and near neutral pH. To achieve this objective, kinetic modeling was used as a tool in the study of the influence of the different factors such as the UV–vis irradiation source, kind of bacteria, presence of H 2 O 2 and particularly the influence of precipitated iron at near neutral pH on the inactivation of Escherichia coli and Enterococcus sp. Three inactivation treatments at pH 5 were carried out, based on a combination of UV–vis irradiation (artificial and solar) with oxidizing agents such as hydrogen peroxide (25 mg H 2 O 2 /L) and iron salts (5 mg Fe 3+ /L) or with each agent individually. The fitting of the experimental inactivation values to the corresponding equations through nonlinear regression techniques was carried out using the Microsoft ® Excel tool GInaFiT (Geeraerd and Van Impe Inactivation Fitting Tool; Geeraerd et al., 2005 ). Ten different mathematical models were studied (Linear, Hom, Linear with shoulder, Linear with tail, Linear with shoulder and tail, Weibull, Weibull with tail, Double Weibull, Biphasic and Biphasic with shoulder). The assessment of the inactivation rates is a useful tool to know the influence of the different variables of the treatments. Thus, this assessment shows clearly that the presence of undissolved iron at pH 5 significantly decreases the inactivation rate of Enterococcus sp. in photo-Fenton treatments compared to H 2 O 2 /UV–vis treatments, while in the case of E. coli the inactivation rates are similar in both treatments. Consequently, the amount of hydroxyl radicals and reactive oxygen species (ROS) generated because of the presence of precipitated iron at pH 5 in the photo-Fenton treatments is considered as insignificant compared to the H 2 O 2 /UV–vis irradiation treatments, worsening the inactivation of Enterococcus sp.

The aim of this research work was to evaluate the disinfection efficiency of several techniques on the inactivation of the bacteria Enterococcus sp. inoculated in synthetic treated urban wastewater. Different types and doses of reagents and times of exposure were studied. The compared treatments include chlorination, ozone-based treatments in the absence and presence of H2O2 and UVA-visible irradiation-based processes with TiO2 and H2O2. Different combinations of chlorine doses and times of contact inactivated all the bacteria (-7.5 log units). Ozone and O3/H2O2 also achieved high disinfection levels (-6 log units), showing similar inactivation curves. However, the studied phototreatments were less efficient.

The purpose of the current study is to compare the inactivation of Escherichia coli in wastewater effluents using conventional treatments (chlorination) and advanced oxidation processes (AOPs) such as UV irradiation, hydrogen peroxide (H2O2)/solar irradiation, and photo-Fenton processes. In addition, an analysis of the operational costs of each treatment is carried out taking into account the optimal dosages of chemicals used. Total inactivation of bacteria (7.5 log) was achieved by means of chlorination and UV irradiation. However, bacterial regrowth was observed 6 hours after the completion of UV treatment, obtaining a disinfection value around 3 to 4 log. On the other hand, the combination H2O2/solar irradiation achieved a maximum inactivation of E. coli of 3.30 ± 0.35 log. The photo-Fenton reaction achieved a level of inactivation of 4.87 ± 0.10 log. The order of disinfection, taking into account the reagent/cost ratio of each treatment, is as follows: chlorination > UV irradiation > photo-Fenton > H2O2/sunlight irradiation.

In this study, the photo-Fenton process was combined with a sequencing batch reactor (SBR) for the treatment of synthetic samples of citrus wastewater (CWW). An experimental design based on the surface response methodology was applied to assess the individual and combined effects of several operating parameters (CODinitial, Fe3(+) concentration and H2O2 concentration) on the photo-Fenton treatment efficiency (DOC removal) with the aim of optimizing the process. The experimental results obtained under optimal conditions for CWW with high CODinitial (10000 mgO2/L) showed a partial degradation of organic matter of around of 61% (measured as DOC). Thereafter, the photo-Fenton effluent was neutralized and clarified before being subjected to the SBR reactor. The results show degradation yields up to 93% of the initial DOC removal without producing undesired side effects, using a hydraulic retention time (HRT) of 1.59 d. The final effluent contained a concentration of organic matter (measured as COD) of 120 mg O2/L.

This research work is focused on the application and assessment of effectiveness of the Fenton-like processes induced by radiofrequency for the inactivation of faecal bacteria (Escherichia coli and Enterococcus sp.) present in treated urban wastewater effluents. Fenton processes were carried out at near neutral pH (pH 5) with different iron sources, such as iron salts (ferric chloride, 5, 50 and 100 mg/L Fe3+), magnetite (1 g/L) and clay (80 g/L), hydrogen peroxide (25 mg/L) and in absence and presence of radiofrequency. Two different electromagnetic field intensities (1.57 and 3.68 kA/m) were used in Fenton processes induced by radiofrequency. Different agents used in the Fenton processes induced by electromagnetic fields (iron source, hydrogen peroxide and RF) were analyzed individually and in combination under the same experimental conditions. First assays of ferromagnetic material/H2O2/radiofrequency processes achieved promising results in terms of bacterial inactivation. For instance, Fe3+/H2O2/Radiofrequency achieved a maximum level of E. coli inactivation of 3.55 log after 10 min of treatment. These results are higher than those obtained in absence of radiofrequency. The thermal activation of iron atoms allows the Fenton reaction to intensify, increasing the final yield of the treatment. On the other hand, different behavior was observed in the inactivation of E. coli and Enterococcus sp. due to the structural differences between Gram-negative and Gram-positive bacteria.

This study was carried out to evaluate sediment pollution related to trace elements such as Cd, Cu, Ni, Pb, Zn, Hg, As and Cr and eight polycyclic aromatic hydrocarbons (PAHs) in 127 sites located in 85 rivers in Spain. Sediment samples were classified according to similar chemical characteristics by means of statistical multivariate techniques (principal component analysis, PCA) and artificial neural networks such as self-organizing maps (SOM). Sediment sample classification provided by PCA was not as useful as the one provided by the SOM, revealing itself as a powerful tool to be incorporated in the first steps of sediment quality assessments. The use of sediment quality guidelines such as the mean-probable effects concentration quotient (m-PECQ) predicted sediment quality and gave an overall view of sediment pollution throughout Spain. Most of the samples (118 out of 127) showed m-PECQ values below 0.5 highlighting their relative low potential risk to cause adverse effects on the benthic fauna. However, some samples presented m-PECQ values higher than 0.5 suggesting a clear potential risk to these fauna. Besides, unusual high concentrations of trace elements and PAHs were related to the human activities carried out near each sampling point.

This study assesses the influence of the presence of suspended and dissolved matter on the efficiency of TiO

The purpose of this study is to compare the efficiency of ozonation and the hydrogen peroxide–ozone process for the removal of cyanide from coking wastewater. The most efficient oxidation process is combined with coagulation–flocculation–decantation and lime–soda ash softening pretreatments. The oxidation in aqueous solution and industrial wastewater (at pH 9.5–12.3) by O3 was carried out using a range of concentration of consumed O3 from 10 to 290 mg/L. A molar ratio of H2O2/O3 from 0.1 to 5.2 with different concentrations of O3 constants was used for the H2O2-O3 process. The maximum cyanide removal obtained in coking wastewater was 90% using a mass ratio of O3/CN– of 9.5. Using lower concentrations of O3, cyanide is not removed and can even be generated due to the presence of other cyanide precursor organic micropollutants in the industrial matrix. The concentration of O3 is reduced to half for the same cyanide removal efficiency if the pretreatments are applied to reduce the carbonate and bicarbonate ions. The cyanide removal efficiency in coking wastewater is not improved if the O3 is combined with the H2O2. However, the preliminary cyanide removal treatment in aqueous solution showed an increase in the cyanide removal efficiency for the H2O2-O3 process.

This research work evaluates the use of hydrogen peroxide for the removal of cyanide from coking wastewater deriving from the washing of gases in coal combustion furnace. The effect of the presence or absence of suspended solids and organic micropollutants on the efficiency of the treatment is analyzed. Various dosages of hydrogen peroxide (6.5–200 mg/L) were added to both aqueous solution (at pH 10.5) and industrial wastewater (at pH 10.3) samples. The influence of suspended solids in coking wastewater was analyzed by applying a coagulation–flocculation–decantation process before the hydrogen peroxide treatment. The preliminary cyanide removal treatment in aqueous solution showed that the maximum cyanide removal did not exceed 14 % using a mass ratio of hydrogen peroxide to cyanide of 11.6. The maximum cyanide removal obtained in coking wastewater was 47 % with a mass ratio of hydrogen peroxide to cyanide of 12.2 provided that a coagulation–flocculation–decantation pretreatment was applied to remove the suspended solids composed mainly of coal, calcium carbonate, and magnesium carbonate. On the other hand, the cyanide removal treatment in coking wastewater with hydrogen peroxide showed promising results in the removing of different organic micropollutants formed mainly by polycyclic aromatic hydrocarbons and quinolines.

This study was carried out in order to assess potential toxicity of hazardous pollutants (8 trace elements and 8 polycyclic aromatic hydrocarbons) in 20 sediment samples of the Ebro River basin (Spain) sampled in 2009. Mean-probable effect concentration quotient (m-PECQ) was found to range from 0.03 to 0.79. Two sites were classified as high priority sites in order to take future remediation actions due to their high m-PECQ value (>0.5). Worst-case scenario in equilibrium partitioning approach showed that acid volatile sulfide (AVS) content was greater than total trace element concentration in all samples. However, 4 sediments were classified as degraded due to the high AVS content measured (>50 mmol/kg). Principal component analysis classified the samples according to similar chemical characteristics and revealed that industrial activities are the main source of pollution of the basin.

The aim of this work is to apply a factorial experimental design in the disinfection of Escherichia coli present in treated urban wastewater by means of Fenton and photo-Fenton processes. As a consequence of the large number of existing variables including the matrix, irradiation (λ = 320–800 nm), and doses of H2O2 (20–50 mg L−1) and Fe3+ (2.5–5 mg L−1), an experimental design methodology has been used in order to study their influence. It is observed that the presence of irradiation is the variable with the greatest influence on the response factor (inactivation of E. coli), although other variables also have a significant influence. By applying photo-Fenton treatment to treated urban wastewater samples, an average value of disinfection of 2.43 log is achieved in the inactivation of E. coli. The influence of the matrix in the inactivation of E. coli is clear, with higher levels of disinfection being obtained in samples prepared by dilution of E. coli in distilled water (5.81 log). Furthermore, a reduced empirical model has been obtained taking into account the influence of variables of E. coli inactivation in treated urban wastewater. The model adequately describes the inactivation of E. coli.

This study was carried out to estimate the potential toxicity of 8 Polycyclic Aromatic Hydrocarbons (PAHs) and 5 organochlorine pesticides (OCPs) in sediments in the Ebro River Basin (20 sampling points) according to different methodologies. Detection limit (DL) concentrations were used for compounds reported below the DL (worst-case scenario). The majority of PAH concentrations were found to be below their method detection limit. DL concentrations for OCPs were above the threshold values set by one guideline. In such cases, no toxicity assessment was carried out. It should be noted that no sediment is expected to cause adverse effects on the benthic species living in these sediments according to the methodologies applied.

This paper presents research carried out into the disinfectant power of a series of treatments based on the individual application and possible combinations of TiO 2 (1 g/L), H 2 O 2 (0.04 mM) and irradiation (290–800 nm and 320–800 nm) on Enterococcus sp., a faecal bacterial indicator used in water analysis. The main aims are the determination of the influence of the UVB range on the inactivation of Enterococcus sp. in natural water, the mode of application of irradiation (intermittent or continuous) and the capacity of bacterial recovery after the application of the treatments in darkness conditions. The results show that when the irradiation includes the UVB range, a very high degree of inactivation is obtained in an Enterococcus sp. solution in natural water ( N 0 = 10 8 CFU 100 mL −1 ) by irradiation alone. Neither the addition of TiO 2 nor of H 2 O 2 are very relevant in these conditions. However, if the irradiation does not include the UVB range, the bactericidal action of photolysis is practically nonexistent, highlighting the positive effect of TiO 2 and H 2 O 2 on the irradiation, the photocatalysis and photocatalysis/H 2 O 2 treatments obtaining a higher degree of disinfection. Continuous and intermittent illumination give rise to similar inactivation levels in all the treatments studied, except for photolysis in which a significant increase in inactivation is observed when the irradiation is continuous. During 3 h of darkness following application of the treatments, there is no change or else a slight recovery of the bacterial population.

Due to public health concerns related to the generation of dangerous by-products from conventional systems of water disinfection, innovative technologies based on the generation of oxidant radicals are being developed. The aim of this work is to evaluate the bactericidal activity of different treatments with light ( λ : 320–800 nm), TiO 2 (1 g L −1 ) and H 2 O 2 (0.04 mM) on the viability of vegetative cells and spores of Clostridium perfringens . After spiking a natural water sample (from the Ebro River, Zaragoza (Spain)), the population of vegetative cells was of 10 8 CFU·100 mL −1 and of spores about 10 3 CFU·100 mL −1 . Treatments without radiation source (TiO 2 , H 2 O 2 , TiO 2 /H 2 O 2 ) show a poor level of inactivation ( 2 system increases the level of disinfection with a vegetative cell removal in the order of 6 log after 5 min and 0.6 log of spores after 5 min. Light/H 2 O 2 and light/TiO 2 /H 2 O 2 treatments also significantly increase the disinfection of vegetative cells of C. perfringens (>6 log). Regarding spores, light/H 2 O 2 and light/TiO 2 /H 2 O 2 treatments achieve constant inactivation of 1 log after 5 min of treatment. The application of a light/TiO 2 /H 2 O 2 treatment does not increase the level of inactivation with regard to the level reached by the light/TiO 2 and light/H 2 O 2 systems. This fact shows there is no a significant interaction between TiO 2 and H 2 O 2 under the conditions studied.

The degradation of chlorpyriphos by different advanced oxidation processes such as photo-Fenton, TiO 2 , TiO 2 /H 2 O 2 , O 3 and O 3 /H 2 O 2 was investigated. The photo-Fenton and TiO 2 processes were optimized using a solar chamber as light source. The optimum dosages of the photo-Fenton treatment were: [H 2 O 2 ]=0.01 M; [Fe 3 + ]=10 mg l −1 ; initial pH = 3.5. With these optimum conditions total degradation was observed after 15 minutes of reaction time. The application of sunlight was also efficient as total degradation was achieved after 60 minutes. The optimum dosage using only TiO 2 as catalyst was 1,000 mg l −1 , obtaining the maximum degradation at 20 minutes of reaction time. On the other hand, the addition of 0.02 M of H 2 O 2 to a lower dosage of TiO 2 (10 mg l −1 ) provides the same degradation. The ozonation treatment achieved complete degradation at 30 minutes of reaction time. On the other hand, it was observed that the degradation was faster by adding H 2 O 2 (H 2 O 2 /O 3 molar ratio = 0.5). In this case, total degradation was observed after 20 minutes.

Any nonylphenol compounds found in water have to be removed since they are endocrine disruptors. In this study, natural water from the river Ebro fortified with nonylphenol compounds (4n-nonylphenol and technical nonylphenol) is used as a sample in order to simulate a real situation in drinking water treatment plants. The aim is to compare conventional disinfection with advanced oxidation processes (O 3 , O 3 /H 2 O 2 , O 3 /TiO 2 and O 3 /H 2 O 2 /TiO 2 ) used for the removal of nonylphenol compounds present in natural water. Furthermore, a study is carried out of the by-products (THMs) generated as a consequence of the presence of natural organic matter. Preoxidation by chlorine completely oxidizes 4n-nonylphenol and technical nonylphenol. It can be seen that the best of the advanced oxidation processes is the O 3 /H 2 O 2 , achieving an average oxidation of 55%, although the differences among the processes were not very significant. Furthermore, the use of post-chlorination guarantees the total removal of nonylphenol compounds.

The aim of this research work is to study the influence of hydrogen peroxide and titanium dioxide in the ozone-based treatment to degrade 44 organic pesticides present in natural water, which are systematically detected in the Ebro River Basin (Spain). The studied pesticides are: alachlor, aldrin, ametryn, atrazine, chlorfenvinfos, chlorpyrifos, pp'-DDD, op'-DDE, op'-DDT. pp'-DDT, desethylatrazine, 3,4-dichloroaniline, 4,4'-dichlorobenzophenone, dicofol, dieldrin, dimethoate, diuron, α-endosulphan, endosulphan-sulphate, endrin, α-HCH, β-HCH, γ-HCH, δ-HCH, heptachlor, heptachlor epoxide A, heptachlor epoxide B, hexachlorobenzene, isodrin, 4-isopropylaniline, isoproturon, metholachlor, methoxychlor, molinate, parathion methyl, parathion ethyl, prometon, prometryn, propazine, simazine, terbuthylazine, terbutryn, tetradifon and trifluralin. The ozonation using 3 mg O3 L−1 produces a pesticides removal close to 23%, whereas the application of O3/H2O2 and O3/TiO2 treatments achieves average degradation yields l...

The presence of natural organic matter (NOM) in both surface and groundwater supplies produces toxic by-products, mainly trihalomethanes (THMs), during oxidation steps in drinking water production. This research work shows the efficiency of different advanced oxidation processes (AOPs) based on ozone for the degradation of precursors of trihalomethanes in aqueous solutions. Completed treatments comprised different preoxidation processes (chlorination and AOP: O(3), O(3)/H(2)O(2), O(3)/TiO(2) and O(3)/H(2)O(2)/TiO(2)), adsorption with PAC (optional operation), coagulation-flocculation and final postchlorination applied to synthetic samples which were prepared by dilution of the soluble fraction of a humic solution. A direct chlorination of synthetic humic samples which display dissolved organic carbon close to 3 mg l(-1) produced a THM concentration of around 1600 microg CCl(3)l(-1) (measured as THMFP). Comparisons between the trihalomethane formation potential of initial synthetic samples and samples treated by prechlorination and coagulation-flocculation-decantation show that the main factor responsible for THM reduction is the coagulation-flocculation process since a decrease of 90% is achieved. Considering the various completed treatments studied, the most recommendable include preoxidation by ozonation, adsorption by PAC, coagulation-flocculation using aluminium sulphate followed by decantation and final postchlorination.

The purpose of this research is to evaluate the bactericidal capacity of different Advanced Oxidation Treatments (AOTs) based on ozone: ozone, ozone/hydrogen peroxide and ozone/titanium dioxide on a wild strain of Clostridium perfringens, a fecal bacterial indicator in drinking water. The dose of ozone consumed ranges from 0.6 mg L−1 min−1 to 5.13 mg L−1 min−1 depending on the process and on the sample. In the treatments combined with O3, H2O2 dose utilized is 0.04 mM and TiO2 dose, 1 g L−1. In order to evaluate the influence of natural organic matter and suspension solids over the disinfection rate, treatments are performed with two types of water – natural water from Ebro River (Zaragoza, Spain) and NaCl solution 0.9%. To achieve 4 log units of inactivation, 3.6 mg O3 L−1 is necessary in O3 treatment, 4.25 mg O3 L−1 in O3/TiO2 system and 2.7 mg O3 L−1 in O3/H2O2 after processing the natural water. In NaCl solution, to get the same inactivation, 0.42 mg O3 L−1 is necessary in O3 treatment, 1.15 mg O3 L−1...

In this study, winery wastewaters are considered for degradation using heterogeneous photo-Fenton as a preliminary step before biotreatment. The heterogeneous photo-Fenton process assisted by solar light is able to partially degrade the organic matter present in winery wastewaters. When an initial hydrogen peroxide concentration of 0.1 M is used over 24 h of treatment, a degradation yield of organic matter (measured as TOC) of around 50% is reached. The later treatment (activated sludge process) allows the elimination of 90% of the initial TOC present in pretreated winery wastewaters without producing nondesired side-effects, such as the bulking phenomenon, which is usually detected when this treatment is used alone. The final effluent contains a concentration of organic matter (measured as COD) of 128 mg O2/L. The coupled system comprising the heterogeneous photo-Fenton process and biological treatment based on activated sludge in simple stage is a real alternative for the treatment of winery wastewater.

Winery wastewaters are difficult to treat by conventional biological processes, because they are seasonal and experience substantial flow variations. Photocatalytic advanced oxidation is a promising technology for wastewaters containing high amounts of organic matter. In this research work, solar assisted photo-Fenton processes of both heterogeneous and homogeneous phase are used in the pre-treatment of winery wastewaters. The results of these experiments have confirmed the suitability of the photo-Fenton processes, due to these treatments achieving purification levels of up to 50% (measured as total organic carbon). The intermediate effluents are treated adequately by aerobic biological treatment (activated sludge process), due to the decrease in organic matter concentration present in winery wastewaters. The possibility of a combined photo-Fenton process, based on the use of sunlight, and aerobic biological treatment (activated sludge) is suggested.

In this study the leachates derived from used tires were firstly characterized by means of the evaluation of their organic matter content. The leachate from tire powder presented a COD value of 508 mg O(2) l(-1) and a TOC of 214 mg Cl (-1). The main identified organic substances were constituents of the rubber structure: benzothiazole derivatives, phthalates, phenolic derivatives, hydrocarbons and fatty acids. The application of photo-Fenton treatment was investigated in order to obtain the maximum organic matter removal. When a solar chamber as light source was used (light intensity=500 Wm(-2)), the best operational conditions were the following: [H(2)O(2)]=3703 mg l(-1), [Fe(2+)]=92.1 mg l(-1), initial pH 2.7-3.0, reaction time=100 min. After the photo-Fenton treatment at optimum conditions, the reached COD and TOC reduction was 64% and 48%, respectively. The main initial organic substances were eliminated after the reaction and no significant by-products were identified. A complementary treatment consisted of coagulation-flocculation carried out with FeCl(3) x 6H(2)O at pH 12 produced a maximum organic matter removal of 43% as COD and 39% as TOC. A combination of photo-Fenton followed by coagulation-flocculation enhanced the organic matter removal: a reduction of 77% of COD and 64% of TOC was attained.

Winery wastewaters, being seasonal and experiencing substantial flow variations, are difficult to treat by conventional biological processes. This work proposes the photo-Fenton reaction in homogeneous phase as an alternative for their purification. Experimental design methodology has been used in order to study the main variables affecting the oxidation process as well as their most relevant interactions. Under energetic conditions the photo-Fenton treatment reached purification levels of up to 95% (measured as total organic carbon). The most influential factors behind organic matter removal are the Fe3+ and H2O2 dosage. The influence of the initial organic matter concentration and the reaction time is almost negligible for the confidence level selected (90%) in the results analysis.

The process of car body painting is one of the manufacturing processes that may involve the use of organic solvents for surface treatments. As a result of this process, wastewaters containing raw materials and auxiliary products used during the cleaning step are produced. The main objective of this study is to find an appropriate purification technique to eliminate or reduce the contamination present in this kind of wastewater. Different treatments were investigated: ozonation, ozonation combined with hydrogen peroxide, photo-Fenton treatment, and coagulation- flocculation.

Wine industry wastewaters contain a high concentration of organic biodegradable compounds as well as a great amount of suspended solids. These waters are difficult to treat by conventional biological processes because they are seasonal and a great flow variation exists. Photocatalytic advanced oxidation is a promising technology for waters containing high amounts of organic matter. In this study we firstly investigated the application of H2O2 as oxidant combined with light (artificial or natural) in order to reduce the organic matter in samples from wine industry effluents. Secondly, we studied its combination with heterogeneous catalysts: titanium dioxide and clays containing iron minerals. The addition of photocatalysts to the system reduces the required H2O2 concentration. Although the H2O2/TiO2 system produces higher efficiencies, the H2O2/clays system requires a H2O2 dosage between three and six times lower.

This study reports on Fenton and photo-assisted Fenton induced oxidation of 2,4-dichlorophenol (from here on 2,4-DCP). The pre-treatment of concentrated aqueous solutions of 2,4-DCP (453 mg l−1) up to bio-compatibility is shown to be possible using low energy 36 W black fluorescent mercury light. The degradation process of 2,4-DCP was observed to occur within minutes. Catalytic amounts of Fe3+-ion (10 mg) were only necessary to obtain acceptable degradation kinetics. Degradation of the 2,4-DCP was not observed in the dark. The total organic carbon (TOC), the adsorbable organic halogen compounds (AOX) and the amount of free chloride (Cl−) were followed in time during 2,4-DCP oxidation under light irradiation. The rate of disappearance of 2,4-DCP and that of Cl−-ion formation were not similar. This was ascribed to the formation of aliphatic and aromatic chlorinated long-lived intermediates. The latter intermediates were identified by liquid–liquid extraction, solid–liquid extraction and coupled GC/MS analysis. Based on the experimental results obtained, a mechanism for the radical intervention is suggested for the abatement of 2,4-DCP. A relatively short pre-treatment time (54 min) was necessary to reduce by 97% the toxicity (ecotoxicity) of a concentrated solution of 2,4-DCP under low energy light irradiation in the photo-reactor.

This paper presents the results obtained with heterogeneous catalytic ozonation in which model and natural waters are ozonated in the presence of supported titanium dioxide (TiC2) as a solid catalyst. The conditions in preparing the supported catalyst are experimentally optimized. The efficiencies of three catalyst supports (attapulgyte, alumina and silica gel) for organic matter oxidation have been compared. The TiC2 supported in alumina calcined at 500[ddot]C compacted to granular form with a particle diameter about 2-4 mm is demonstrated to be the best catalyst on the removal total organic carbon (TOC) by ozone.

The objective of this study was to investigate the use of advanced oxidation processes to oxidize an industrial wastewater in which chlorobenzenes were found in the range of 1 mg/L to 5 mg/L and a solution of chlorobenzenes whose concentration was 0.03 mg/L, which was prepared from stock solutions. Ozone in a neutral medium (pH=7) was compared with ozone in presence of metallic ions, such as Fe (II), Fe(III) and Mn(II) at concentration of 610-5 M.

This paper presents the results obtained with heterogeneous catalytic ozonation in which raw Ebro river (Spain) water is ozonated in the presence of titanium dioxide supported on alumina as a solid catalyst at two different O 3 :C weight basis ratios. The influence of catalytic ozonation on the trihalomethane (THM) formation during drinking-water treatment is also studied. It is shown that using this catalyst during ozonation of the natural water allowed reductions in THM formation. Characterization of the raw, ozonated and chlorinated water was made by concentrating the sample through liquid–liquid extraction, along with the gas chromatography/mass spectrometry (GC/MS). A total of 66 different organic compounds were identified, mainly carboxylic acids, aromatics, aldehydes, ketones and alcohols. The percentage of elimination or formation levels reached during ozonation and chlorination are discussed.

This paper presents the results obtained with heterogeneous catalytic ozonation in which model and natural waters are ozonated in the presence of titanium dioxide (TiO2) supported on alumina. In this work the stability of the catalyst is investigated. Four consecutive ozonations with the same catalyst revealed no reduction in the organic matter oxidation. The results obtained in natural waters with catalysts that had been previously used indicated that the applied catalysts did not appear to lose any of their efficiency after use.

The degradation of the compounds present in a previously chlorinated wastewater resulting from the production of azoic dyes has been studied in this project. Towards this end, the first step developed was the characterization of the spillage water by GC/MS and GC/FID. Secondly, a combined ozone+Ca(OH)2 treatment was carried out, determining its efficiency on this wastewater. The majority of compounds found in the wastewater are aniline derivatives and azo compounds. Also, as a result of the chlorination treatment which is carried out by the factory, some organochloride compounds were identified, being the most important those which are subjected to legislative control, namely: chloroanilines, chloronitrobenzenes and chlorophenols. After ozonation, the concentration of the compounds present is reduced to good percentages. The by-products formed after this first treatment were, mainly, nitrobenzene derivatives and organic acid compounds. The following treatment with Ca(OH)2 leads to almost total elimination of the remaining compounds in the ozone treatment. However, aniline and chloroanilines are formed after chemical coagulation due to the strong basic medium at which the sample in this process is set. C.O.D. is reduced 25% after ozonation, while it decreased 50% after the complete treatment. T.O.C. remained constant during ozonation, but a 42% reduction was obtained after chemical coagulation. Color decreased gradually during ozonation reaction, and after the final treatment the reduction was 62%. The complete process of ozonation and chemical coagulation with Ca(OH)2 is, in general, very effective to treat this kind of wastewaters.

It is shown that using Mn(II) as a catalyst during ozonation of raw Ebro river (Spain) water allows reductions in the content of organic matter. Characterization of the raw and ozonated water at two different O3:C weight basis ratios was made by concentrating the sample through liquid-liquid extraction or derivation with O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride (PF-BOA.HCl), along with the gas-chromatography/mass-spectrometry (GC/MS) and electron capture detector (GC/ECD) techniques. A total of 88 different organic compounds were identified, mainly carboxylic acids, aromatics, aldehydes, ketones and alcohols. The percentage of elimination or formation levels reached during ozonation are discussed. © 1998 Elsevier Science Ltd. All rights reserved

This paper presents the results obtained from oxidation with O3 and O3H2O2 of a residual water coming from the production of dicofol and tetradifon pesticides, where chlorobenzenes, DDTs and its metabolites and other organochloride compounds were found. The oxidation processes were carried out using ozone (O3) in basic medium (pH 9.4) at low dosage (0–1.5 g O3 g−1 initial TOC) and in the presence of hydrogen peroxide (H2O2), with a 0.5 H2O2O3 molar ratio. During the treatment, many compounds were removed (dichlorobenzophenone, tetradifon, chlorobenzene, trichlorobenzene) and their change in concentration at different ozonation contact time was monitored. Other compounds like DDE remained practically invariable. This study investigated the formation of first ozonation by-products (FOBPs) in the wastewater, specifically chlorophenols, by means of gas chromatography/mass spectrometry (GC/MS) and gas chromatography/electron capture detection (GC/ECD) analysis in terms of the amount of time the O3 has been in contact with the processed sample. o-Chlorophenol, p-chlorophenol, benzenemthanol, n-chlorohydroxibenzaldehyde, n-chlorobenzenemethanol, chlorobenzoic acid, etc., were formed during the treatment, due to the mechanism of fast and non-selective oxidation which ozone has through OH radicals, formed by the decomposition of the O3 molecule and accelerated by the presence of H2O2 in water

This study was carried out to classify 112 marine and estuarine sites of the southern Spanish coastline (about 918 km long) according to similar sediment characteristics by means of artificial neural networks (ANNs) such as Self-Organizing Maps (SOM) and sediment quality guidelines from a dataset consisted of 16 physical and chemical parameters including sediment granulometry, trace and major elements, total N and P and organic carbon content. The use of ANNs such as SOM made possible the classification of the sampling sites according to their similar chemical characteristics. Visual correlations between geochemical parameters were extracted due to the powerful visual characteristics (component planes) of the SOM revealing that ANNs are an excellent tool to be incorporated in sediment quality assessments. Besides, almost 20% of the sites were classified as medium-high or high priority sites in order to take future remediation actions due to their high mean Effects Range-Median Quotient (m-ERMQ) value. Priority sites included the estuaries of the major rivers (Tinto, Odiel, Palmones, etc.) and several locations along the eastern coastline.

Spatio-temporal variations in sediment quality (20 sample sites) of the Ebro River basin between 2001 and 2011 have been assessed. The self-organizing map classified the sediment samples according to similarities in their chemical compositions. Its powerful visualization tools helped establish the main pollution contribution on each sample. Most of the samples showed low values of the mean-probable effect concentration quotient through time. However, six samples presented several quality issues related to some trace elements or polycyclic aromatic hydrocarbons. Finally, geoaccumulation index values calculated using estimates of background trace element concentrations suggested anthropogenic influences in more than half of the samples.

The results obtained in the characterization of the micropollutants in the River Cinca by adsorption on granular activated carbon (GAC) and liquid-liquid (LL) extraction are presented. Gas chromatography-mass spectrometry was used for the identification of the various components in the water. Nineteen organochloride compounds [the complete series of chlorobenzenes, DDTs and their metabolites, dichlorobenzophenone (DCBF) and tetradifon] were quantified by gas chromatography-electron-capture detection. In the River Cinca, 229 and 74 compounds were identified by GAC and LL extraction, respectively, fifteen of which appear in the group of substances in List I of the 76/464/EEC European Council Directive as Priority Pollutants.

It is shown that using transition metals, especially Mn(II) and Ag(I), during ozonation of humic substances in water allows important reductions in the content of organic matter. Characterization of the organic compounds resulting from ozonation was made by concentrating the sample through liquid-liquid extraction or derivation with PFBOA.HCl, along with the GC/MS and GC/ECD techniques. In total, 110 different organic compounds were identified using GC/MS; mainly carboxylic acids, aromatics, hydrocarbons, aldehydes, ketones, and furan-carboxylic acids. The percentages of elimination or formation levels reached during ozonation are discussed.

The focus of this study was to investigate the use of advanced oxidation processes to oxidize a residual water in which chlorobenzenes were found in the range of 1 mg/L to 10 mg/L and whose TOC was about 1,000 mg/L, and a solution of chlorobenzenes whose concentration was 0.03 mg/L, which was prepared from stock solutions. Ozone in basic medium (pH = 9) and ozone in the presence of hydrogen peroxide (H2O2) were compared.

The purpose of the current study is to evaluate the inactivation of three different kinds of bacteria usually present in municipal wastewater treatment effluents (Enterococcus faecalis, Pseudomonas aeruginosa and Escherichia coli) using a coagulation-flocculation-decantation (CFD) process combined with photo-Fenton treatment at pH 5. Different concentrations of Fe(3+)-H2O2 (0.4/25, 5/25 and 15/25 mg L(-1)), and H2O2 (25 mg L(-1)) were evaluated for 210 minutes under artificial solar irradiation in a solar chamber ATLAS SUNTEST CPS+. The results were compared applying the CFD process before or after the disinfection treatment. The results of the bacteria inactivation show that the highest rate was observed using CFD-photo-Fenton treatment with 15 mg L(-1) of Fe(3+) and 25 mg L(-1) of H2O2, obtaining the total inactivation of Pseudomonas sp., a 5.64-log inactivation of Enterococcus sp. and a 4.61-log inactivation of E. coli. In addition, turbidity and suspended solids decreased more than 90% with the combined treatments. The treated wastewater samples could be reused in urban, agricultural, industrial, recreational and environmental uses according to current Spanish legislation (RD 1620/2007).

In this work, a first step has been made in the characterization of the organic pollutants found in the residual water from the production of dicofol and tetradifon pesticides, derived from DDT and trichlorobenzene, respectively. The behavior of the effluent also was studied using degradation techniques - treatment with ozone and ozone combined with hydrogen peroxide - and the results compared by means of the pH, conductivity, TOC, COD, TOX, ecotoxicity, GC/ECD and GC/MS analysis of the samples after the treatment.

The increase of the industrial activity and the consequent economic and social development have produced, at least until some years ago, a growth of big cities which leads and complicates the supply of one of the most important elements to the life, “water”. Nowadays, faced with the growing water demand and the hydric resources shortage, the reuse of treated water is considered as a possible solution in order to increase existing resources. However, all effluents can`t be reused since environmental minimum flows have to be guaranteed downstream of the dumping (Ormad, 2011). The water reuse is the application, before its return to the public water resources and the terrestrial maritime one to a new exclusive use of waters that, having been used by who derived them, they have been subjected to a process or processes of treatment established in the corresponding authorization of dumping and to the necessary in order to get the quality required in function of uses to which it goes to be destined. As well, reuse waters are treated wastewaters that have been subjected to an additional or complementary process which is capable to adapt its quality to the destined use. All this is carried out in reclamation plants, group of installations where treated wastewaters are subjected to additional treatments which can be needed in order to adapt the water quality to the destined use (Royal Decree 1620/2007). Waters which go to be reclaimed, it is, treated wastewaters, are waters that must obey the specifications of Directive 91/271/EEC (Directive 91/271/EEC). However, in these waters can exist some substances which can be pollutants. In general, the composition of these waters mainly depends on two factors: the industrial contribution to the urban dumping and the type of water treatment in the wastewater treatment plant (WWTP). In spite of this, in general, these waters are characterized by: The presence of a great variety of pathogenic germs The presence of organic matter, with a Biologycal Oxygen Demand 5-day (BOD5) up to 25 mg L-1 and a Chemical Oxygen Demand (COD) up to 125 mg L-1 (according to the current legislation). In this generic group, there are two types of organic matter: • Non Hazardous Organic Matter: This organic matter is mayoritary composed by compunds which haven’t degraded in the WWTP. This is because they are refractary compounds or the achieved yields aren’t of 100%; they are organic substances non toxic like carboxilic acids, esters, proteins, carbon hydrates, aminoacids, polihydroxilated alcohols, etc.

Water flowing through surface and/or subsoil acquires a chemical composition due to its dissolution effect on soluble minerals of rocks and organic compounds deriving from the degradation of organic matter. This natural composition of water is basically altered by four pollution sources: domestic wastewaters, industrial wastewaters, uncontrolled wastewaters and run-off pollution in agricultural areas. The latter can result in the presence of pesticides in natural waters, because these compounds can pass through the soil and subsoil and pollute surface and groundwaters which are supplies sources for water intended for human consumption. Pesticides are a group of artificially synthesized substances used to fight pests and improve agricultural production. However, they are generally toxic for living organisms and are very difficult to degrade, being toxic agents with persistent and bioaccumulative effects. In spite of their benefits in the agriculture, they have undesirable effects due to its toxicity, carcinogenesis and mutagenesis (Becker & Wilson, 1980; Kouras et al., 1998). In Europe, pesticides are considered Hazardous Pollutants in accordance with current legislation relating to water (Directive 2000/60/CE; Directive 2006/11/CE). In the Ebro River Basin (Spain), these substances are controlled via a Pesticides Control Network, which systematically analyzes 44 organic pesticides in surface waters. These pesticides were selected in accordance with their appearance in lists of hazardous substances and/or their high level of use in Spanish agriculture (Claver et al., 2006). Among these substances, there are a big variety of pesticides, such as triazines, urea derivates, drins, etc. Although the concentration of these substances detected in natural waters is generally very low, the maximum permissible concentration in human drinking waters in Spain is often exceeded (ROYAL DECREE 140/2003), which establishes a limit of 0.5 μg L-1 as the total amount of pesticides and 0.1 μg L-1 for any single pesticide. Consequently, the treatment used to produce drinking water must guarantee the removal of these types of substances or at least reduce their concentration below the limits established in current legislation. Systems of drinking water production consist of different stages depending on the initial water quality. Actually, a lot of drinking water plants use an adsorption stage onto activated

The evolution over time of the levels and distribution of dichlorodiphenyltrichloroethane (DDT) in water, surface sediments, and fish from the River Cinca (Spain), a tributary of the River Ebro, during the period 1999 to 2004, was investigated by means of gas chromatography coupled with mass spectrometry. The sampling site corresponded to a point downstream from Monzon, a heavily industrialized town with drainage into the river. This river has historically been a source of emissions of DDT and its metabolites. The highest levels were found in 1999 and 2000, although the concentrations of organic compounds in sediments and fish have decreased since then. The levels of DDT in water were below the quantification limit during the period of study. The average composition of DDT isomers measured in sediments and fish showed the prevalence of p,p'-DDE, the product of aerobic degradation of p,p'-DDT. Concentrations in fish were compared with sediment samples, and high quotients indicate that they are highly bioavailable.

The aim of this research work was to study the effectiveness of the treatments commonly used in drinking water plants in Spain to degrade 44 pesticides systematically detected in the Ebro River Basin. The pesticides studied are: alachlor, aldrin, ametryn, atrazine, chlorfenvinfos, chlorpyrifos, pp'-DDD, op'-DDE, op'-DDT, pp'-DDT, desethylatrazine, 3,4-dichloroaniline, 4,4'-dichlorobenzophenone, dicofol, dieldrin, dimethoate, diuron, alpha-endosulphan, endosulphan-sulphate, endrin, alpha-HCH, beta-HCH, gamma-HCH, delta-HCH, heptachlor, heptachlor epoxide A, heptachlor epoxide B, hexachlorobenzene, isodrin, 4-isopropylaniline, isoproturon, metholachlor, methoxychlor, molinate, parathion methyl, parathion ethyl, prometon, prometryn, propazine, simazine, terbuthylazine, terbutryn, tetradifon and trifluralin. The techniques applied are: preoxidation by chlorine or ozone, chemical precipitation with aluminium sulphate and activated carbon adsorption. Oxidation by chlorine removes 60% of the studied pesticides, although combining this technique with a coagulation-flocculation-decantation process is more effective. The disadvantage of this treatment is the formation of trihalomethanes. Oxidation by ozone removes 70% of the studied pesticides. Although combination with a subsequent coagulation-flocculation-decantation process does not improve the efficiency of the process, combination with an activated-carbon absorption process gives rise to 90% removal of the studied pesticides. This technique was found to be the most efficient among the techniques studied for degrading the majority of the studied pesticides.

This work studies the presence of a total number of 44 substances found in waters of the Ebro river basin (Spain), all included in the Pesticides Control Network, whose purpose is to monitor diffuse pollution of surface waters caused by pesticides contained in some of the dangerous substances lists established in existing legislation and their high degree of use in the basin. Most of the pesticide sampling points are located in the sections of river that receive run-off waters from various agricultural areas shortly before opening out onto the main river (the Ebro), in areas of special agricultural importance. Water samples are subjected to a solid-liquid extraction as a previous step to their analysis by GC/MS (gas chromatography/mass spectrometry). Pesticides most frequently found and in greater concentrations in the waters of the Ebro river basin are 3,4-dichloroaniline, molinate, desethylatrazine, dimetoate, simazine, atrazine, metolachlor and chlorpyrifos. There are certain compounds that are not detected or their concentrations are below the quantification limit, such as 4-isopropylaniline, ametryn, beta-HCH, delta-HCH, aldrin, isodrin, dieldrin, heptachlor epoxide, endosulfan and endosulfan-sulfate. Diuron appears at specific points in some of the stations.

Winery wastewaters are difficult to treat by conventional biological processes because they are seasonal and experience a substantial flow variations. Photocatalytic advanced oxidation is a promising technology for wastewaters containing high amounts of organic matter. In this work, the photo-Fenton process in heterogeneous phase is presented as an alternative methodology for the treatment of winery wastewaters. As a consequence of the great number of existing variables, an experimental design methodology has been used in order to study the influence and interaction of various variables and to obtain a reduced empirical model which describes the organic matter degradation process. Applying photo-Fenton treatment in heterogeneous phase under energetic conditions for synthetic samples simulating winery wastewaters results in purification levels of up to 50% (measured as total organic carbon). Different reduced models are obtained and their utilization depends mainly on the degree of degradation of organic matter required.