Pilot plant scale reactive dyes degradation by solar photo-Fenton and biological processes (original) (raw)
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Journal of Hazardous Materials, 2007
This paper reports on the combined solar photo-Fenton/biological treatment of an industrial effluent (initial total organic carbon, TOC, around 500 mg L −1 ) containing a non-biodegradable organic substance (␣-methylphenylglycine at 500 mg L −1 ), focusing on pilot plant tests performed for design of an industrial plant, the design itself and the plant layout. Pilot plant tests have demonstrated that biodegradability enhancement is closely related to disappearance of the parent compound, for which a certain illumination time and hydrogen peroxide consumption are required, working at pH 2.8 and adding Fe 2+ = 20 mg L −1 . Based on pilot plant results, an industrial plant with 100 m 2 of CPC collectors for a 250 L/h treatment capacity has been designed. The solar system discharges the wastewater (WW) pre-treated by photo-Fenton into a biotreatment based on an immobilized biomass reactor. First, results of the industrial plant are also presented, demonstrating that it is able to treat up to 500 L h −1 at an average solar ultraviolet radiation of 22.9 W m −2 , under the same conditions (pH, hydrogen peroxide consumption) tested in the pilot plant.
Chemical Engineering Journal, 2010
An experimental study based on the homogeneous ferrioxalate-assisted solar photo-Fenton process shows the effect of the continuous addition of hydrogen peroxide and air injection on the degradation of non-biodegradable dye Reactive Blue 4 (RB4) solutions. The reaction was carried out in a CPC (compound parabolic collector) solar pilot plant reactor. It was shown that the degree of dye solution mineralization was enhanced because the scavenger effect of H 2 O 2 was minimized. Air bubbling had a negative effect because oxygen reacted with oxalyl radical anions, diminishing the amount of generated Fe(II), and consequently the concentration of hydroxyl radicals produced under irradiation of oxalate in the presence of peroxide was lower. In addition, this system permits the use of lower concentrations of ferrous ion, reducing the costs of the later iron removal process. Under the optimal conditions selected in this system, TOC removal was increased from 61% to 82% with a shorter reaction time as compared with a peroxide dose at the beginning of the reaction. The efficiency of the mineralization of RB4 solutions was enhanced when the solar CPC reactor worked together with an artificial UV-A/C pilot plant, increasing TOC removal up to 95%. Artificial UV lamps can be used either to improve the process or as an alternative to solar CPC on cloudy days. (J.M. Monteagudo).
Photo-Fenton Treatment of Actual Agro-Industrial Wastewaters
Industrial & Engineering Chemistry Research, 2011
In this work, UV/H 2 O 2 treatment of actual pulp and paper mill wastewater (PPMW) was investigated. To determine optimal conditions, the effects of some experimental parameters (initial pH, initial H 2 O 2 concentration, temperature, and organics load) on the UV/H 2 O 2 process efficiency in terms of absorbance at 330 and 281 nm and chemical oxygen demand (COD) and total organic carbon (TOC) removals were studied. The results show that the UV/H 2 O 2 system leads successfully to the almost-complete elimination of absorbance at 330 and 281 nm, COD, and TOC from an actual PPMW containing 270 mg of C L -1 under natural pH (pH 11.25) using 2.1 g of H 2 O 2 L -1 at 28°C. Under these optimal conditions, pseudo-first-order kinetics was determined for absorbance at 330 and 281 nm and COD decay with rate constants of 0.029, 0.02, and 0.008 min -1 , respectively. Furthermore, the evolution with time of the H 2 O 2 concentration exhibits two parts: a linear decrease to 300 min and then exponential change until the end of the treatment. This shows that the kinetics of H 2 O 2 disappearance changes during the treatment from a pseudo-zeroth-order reaction in the first steps to a pseudo-first-order reaction in the final steps. On the other hand, a continuous decrease of pH and a rapid total phenols disappearance were observed during UV/H 2 O 2 treatment of PPMW. These results suggest that several steps are involved in the photochemical oxidation of organics, starting with degradation of lignin derivatives and tannins to obtain aromatic intermediates that then undergo oxidative ring opening, leading to aliphatic carboxylic acids. In the final steps, carboxylic acids are mineralized into CO 2 and H 2 O.
Solar Energy, 2004
The degradation of different commercial reactive dyes: a monoreactive dye (Procion Red H-E7B), an hetero-bireactive dye (Red Cibacron FN-R) and a Standard Trichromatic System, by using solar light assisted Fenton and photo-Fenton reaction is investigated. The reaction efficiencies have been compared with the ones obtained for the same system in the dark or under the assistance of an artificial light source. The use of solar light is clearly beneficial for the removal of color, aromatic compounds (UV 254 ), total organic carbon (TOC), and the increase of the BOD 5 /COD ratio. The possibility of a combined advanced oxidation process (AOP)/biological treatment based on the use of sunlight is suggested.
Degradation of Acid Blue 161 by Fenton and photo-Fenton processes
International Journal of Environmental Science and Technology, 2015
Degradation kinetics of azo dye, Acid Blue 161 (AB161), by Fenton and photo-Fenton processes in aqueous solution was investigated. At pH 3.5, the effects of H 2 O 2 , Fe 2? , and H 2 O 2 /Fe 2? molar ratios, on the AB161 decolorization kinetic rates, were evaluated. Experimental results confirmed that the optimal H 2 O 2 /Fe 2? molar ratio of 12 is close to the theoretical value of 11 as predicted by previously developed model. The influence of azo bond loading (L azo bond), from 0.25 to 1.0, and pH values from 2.5 to 4.0 were evaluated on AB161 decolorization kinetic rates. A correlation between the natural logarithm of the decolorization rates and L azo bond was established at the different pH values. The decolorization rate increased linearly with decreasing L azo bond , in the order of pH: 3.5 [ 3.0 [ 2.5 [ 4.0. UV radiation of Fenton processes increases degradation of AB161 more than 40 % due to the regeneration of Fe 2? through photo-catalytic reactions. This phenomenon was confirmed by measuring H 2 O 2 concentration during the photo-Fenton processes. The results suggest that Fenton processes can effectively decolorize or degrade wastewater containing azo dye, AB161. Photo-Fenton processes may further increase the degradation efficiency of AB161 by 40 %.
Photo-fenton remediation of wastewaters containing agrochemicals
Brazilian Archives of Biology and Technology, 2005
The photochemical degradation of agrochemicals in aqueous solution by means of advanced oxidation processes (AOPs) was studied. The photo-Fenton process was evaluated in terms of the time evolution of dissolved organic carbon (COD) and chemical oxygen demand (DOC), their total removals, and increase in biodegradability of treated wastewater. Under the experimental conditions studied, the process showed to be superior to other AOPs, at any Fe(II) and H2O2 concentrations. The results pointed towards the use of solar irradiation and low cost commercial application.
Solar photo-Fenton treatment of a commercial pesticide mixture
2009
The water supply situation is deteriorating globally due to economical and industrial growth. Especially in the Mediterranean basin the increase of intense agriculture caused a high consumption of fresh water and also a problematic pollution originated by pesticides and other chemical compounds. In this work the possibility of treating wastewater polluted by pesticides coming from the horticultural centre in the south of Spain, is studied. AOPs seem to be the most promising solution as a preliminary treatment of biorecalcitrant contaminants for the purpose of degrading those using an inexpensive biotreatment. AOPs are known to be the most effective way for oxidizing biorecalcitrant substances, but have the major drawback of high operation costs. The combination of a solar advanced oxidation process (AOP) and a conventional biological treatment has been reported as an attractive approach for solving this problem. This work was elaborated and carried out at the PSA (Tabernas, Spain). as a part of the FOTOBIOX project, which is focused on the optimization of a combined solar photo-Fenton/biological system for the decontamination of a pesticide mixture. Evaluating the influence of the temperature as an important factor on the photo-Fenton degradation process was the main objective of the present study. The final aim was to find the best operating conditions for the preliminary treatment of a high concentrated commercial pesticide mixture. The operational conditions should be optimized in order to minimize the costs. In this context photo-Fenton degradation experiments at four different temperatures (25, 35, 42, 50°C) were carried out and the obtained results and effects were controlled by Fenton experiments. All experiments were processed at an iron concentration of 20 mg L-1 and a pH of 2.8. Finally, selected samples from different stages of the photo-Fenton degradation process were analysed in order to determine the toxicity and biodegradability. The objective was to find the optimal point for the consequent biotreatment, and additionally prove the feasibility the proposed combined system.