Inactivation of pathogenic microorganisms in freshwater using HSO5−/UV-A LED and HSO5−/Mn+/UV-A LED oxidation processes

Freshwater disinfection using photolytic and catalytic activation of peroxymonosulphate (PMS) through PMS/UV-A LED and PMS/Mn+/UV-A LED [Mn+ = Fe2+ or Co2+] processes was evaluated through the inactivation of three different bacteria: Escherichia coli (Gram-negative), Bacillus mycoides (sporulated Gram-positive), Staphylococcus aureus (non-sporulated Gram-positive), and the fungus Candida albicans. Photolytic and catalytic activation of PMS were effective in the total inactivation of the bacteria using 0.1 mM of PMS and Mn+ at neutral pH (6.5), with E. coli reaching the highest and the fastest inactivation yield, followed by S. aureus and B. mycoides. With B. mycoides, the oxidative stress generated through the complexity of PMS/Mn+/UV-A LED combined treatments triggered the formation of endospores. The treatment processes were also effective in the total inactivation of C. albicans, although, due to the ultrastructure, biochemistry and physiology of this yeast, higher dosages of reagents (5 mM of PMS and 2.5 mM of Mn+) were required. The rate of microbial inactivation markedly increased through catalytic activation of PMS particularly during the first 60 s of treatment. Co2+ was more effective than Fe2+ to catalyse PMS decomposition to sulphate radicals for the inactivation of S. aureus and C. albicans. The inactivation of the four microorganisms was well represented by the Hom model. The Biphasic and the Double Weibull models, which are based on the existence of two microbial sub-populations exhibiting different resistance to the treatments, also fitted the experimental results of photolytic activation of PMS

Treatment of winery wastewater by sulphate radicals: HSO5−/transition metal/UV-A LEDs

© 2016 Elsevier B.V.In this study, the effectiveness of the HSO5-/M n+/UV process on the treatment of winery wastewater (WW) was investigated. The optimal operating conditions were determined: [HSO5-]=2.5mM; [M2(SO4) n ]=1.0mM; pH=6.5 and reaction temperature=323K. Under the given conditions, 51%, 42% and 35% of COD removal was achieved using respectively Fe(II), Co(II) and Cu(II) as catalysts. Different UV sources were tested with the previously selected optimal conditions in order to increase the treatment efficiency. The highest COD removal (82%) was achieved using a UV-A LEDs system (70W/m2). These conditions were also promising for the treatment of WW with COD concentrations of 5000mg O2/L, reaching 79% and 64% of COD and TOC removal, respectively, after 180min of treatment. At 323K, the most effective treatment was obtained when Co(II) was used as catalyst (79% and 64% of COD and TOC removal), while at ambient temperature (293K) the highest COD (65%) and TOC (52%) removals were obtained with Fe(II) catalyst. Moreover, it was demonstrated that the use of HSO5-/M n+ in several consecutive doses was more efficient than adding the reagents as a single dose at the beginning of the reaction. A comparison between the performance of the HSO5-/Fe(II)/UV-A LED process and the conventional photo-Fenton demonstrated important advantages associated with the HSO5-/Fe(II)/UV-A LED process, including the absence of the costly pH adjustment and of the hydroxide ferric sludge which characterise the photo-Fenton treatment process. The HSO5-/M n+/UV-A LED process demonstrates a high COD and TOC removal efficiency, and it can be considered a promising technology for application in real scale agro-food wastewater treatment plants

Removal of emerging contaminants by Fenton and UV-Driven Advanced Oxidation Processes

The removal efficiencies of four different parabens (methylparaben (MP), ethylparaben (EP), propylparaben (PP), and butylparaben (BP)) using Fenton reagent, UV irradiation, UV/H2O2, and UV/ H2O2/Fe2+ were evaluated to assess the level of paraben degradation achieved using different advanced oxidation processes (AOPs). UV irradiation by itself provided paraben conversions between 27 and 38 % after a reaction time of 180 min. The UV/ H2O2 system increased the paraben conversion to values between 62 and 92 %, and the Fenton process was revealed as inefficient in paraben degradation within the experimental conditions used. Photo- Fenton presented similar removal rates to the UV/ H2O2 process. Among the four parabens studied, butylparaben was the most easily removed, and it was possible to attain degradations higher than 90 %. In the UV/H2O2 and photo-Fenton processes, the overall kinetic constant could be split into two main components: direct oxidation by UV radiation (photolysis) and oxidation by free radicals (mainly HO•) generated from the photodecomposition of H2O2. This work reveals that UV-driven oxidation processes can be widely used to remove parabens from contaminated aqueous solution

Removal of COD from olive mill wastewater by Fenton's reagent: kinetic study

Removal of COD from olive mill wastewater by Fenton's reagent: kinetic stud

Degradation of Reactive Black 5 by Fenton/UV-C and ferrioxalate/H2O2/solar light processes

The feasibility of employing different photoxidation systems, like Fenton/UV-C and ferrioxalate/H2O2/solar light in the decolorization and mineralization of an azo dye, has been investigated. Batch experiments were carried out to evaluate, on the first stage, the influence of different processes on Reactive Black 5 (RB5) decolorization. During the second stage were investigated the optimal operational conditions of Fenton/UVC and ferrioxalate/H2O2/solar light processes, like pH, H2O2 dosage, iron dosage, RB5 concentration and source of light. The experiments indicate that RB5 can be effectively decolorized using Fenton/UV-C and ferrioxalate/H2O2/solar light processes with a small difference between the two processes, 98.1% and 93.2%, respectively, after 30 min. Although there is lesser difference in dye decolorization, significant increment in TOC removal was found with Fenton/UV-C process (46.4% TOC removal) relative to ferrioxalate/H2O2/solar light process (29.6% TOC removal). This fact reveals that UV-C low-pressure mercury lamp although with its small effect on dye decolorization is particularly important in dye mineralization, when compared to solar light. However, ferrioxalate/H2O2/solar light system shows large potential on photochemical treatment of textile wastewater with particular interest from the economical point of view

Treatment of olive mill wastewater by a combined process: Fenton’s reagent and chemical coagulation

Treatment of olive mill wastewater by a combined process: Fenton’s reagent and chemical coagulatio

Decolorization of the azo dye Reactive Black 5 by Fenton and photo-Fenton oxidation

The oxidative decolorization of Reactive Black 5 (RB5) in aqueous solution has been studied using Fenton (H2O2/Fe2+) and photo-Fenton (H2O2/Fe2+/UV) processes. This investigation reveals that both methods can remove the color of RB5. Batch experiments were carried out to investigate the process's optimal operational conditions: pH, H2O2 dosage, Fe2+ dosage, RB5 concentration and optimal [Fe2+]0/[H2O2]0/[RB5]0 ratio, to obtain the bests results at low cost, render AOP competitive with other processes. The optimal conditions found were a ratio [H2O2]0/[RB5]0 of 4.9:1, a ratio [H2O2]0/[Fe2+]0 of 9.6:1 and pH = 3.0. The decolorization experiments indicate that RB5 can be effectively decolorized using Fenton and photo-Fenton processes with a little difference between the two processes, 97.5% and 98.1%, respectively, for optimal conditions. This small difference in dye decolorization is not similar to TOC removal: with photo-Fenton process there is a significant increment (46.4% TOC removal) relatively to Fenton process (only 21.6% TOC removal). This fact indicates that although UV low-pressure mercury lamp has little effect on dye decolorization it is particularly important in dye mineralization

Aerobic biological treatment of chestnut processing wastewater

Aerobic biological treatment of chestnut processing wastewate

Combination of long term aerated storage and chemical coagulation/flocculation to winery wastewater treatment

Combination of long term aerated storage and chemical coagulation/flocculation to winery wastewater treatmen

Treatment of concentrated fruit juice wastewater by the combination of biological and chemical processes

Treatment of concentrated fruit juice wastewater by the combination of biological and chemical processe