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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 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.

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

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.

Aqueous solutions of aniline and p-chloroaniline were treated with ozone in order to study the reaction and oxidation by-products. Aniline solutions were ozonated at low and high pH, so as to compare both molecular and hydroxyl free radical mechanisms, respectively. The main identified aromatic by-products were nitrobenzene and azobenzene when the experiment was carried out at acid pH. Formation of nitrobenzene, azobenzene, azoxybenzene and 2-pyridine-carboxylic was observed when the ozonation was carried out at basic pH. p-Chloroaniline was treated with ozone only at high pH and the identified by-products were in accordance with those obtained in the ozonation of aniline: p-chloronitrobenzene, 4,4'-dichloroazobenzene and 4-chloro-2-pyridine-carboxylic acid. All the aromatic by-products found were less toxic than the raw materials. The pseudo-first-order constants in aniline concentration were calculated, whilst kinetic in p-chloroaniline concentration could not be adjusted to a first-order reaction.