Treatment of simulated industrial wastewater by photo-Fenton process: Part II. The development of mechanistic model (original) (raw)
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A mixture of five commercial pesticides (Vydate ® , Metomur ® , Couraze ® , Ditimur-40 ® and Scala ®) commonly used in intensive agriculture has been selected as an example of highly toxic, non-biodegradable wastewater to be treated by solar Photo-Fenton. The effect of the total concentration of organics as dissolved organic carbon (100-500 mg/L), operating temperature (25-50 • C), dissolved iron concentration and their relationship to different process efficiency parameters (mineralization rate, hydrogen peroxide consumption and treatment time) were evaluated. Experiments were carried out under sunlight in a pilot plant. It consists of four compound parabolic collectors (CPCs) and a total volume of 75 L. From the results of the study it can be concluded that solar plants should be designed for operating at temperatures below 45 • C to avoid significant loss of iron. H 2 O 2 should be carefully dosed during the photo-Fenton treatment to avoid its continued excess and inefficient use.
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The industries are bearing with the high concentration of COD in the industrial wastewater, which is to be reduced within the acceptable limits given by the state pollution control board (SPCB). The Fenton process is a conventional process to reduce the COD of the effluent, but has a disadvantage of large production of ferric hydroxide during the Fenton Reaction. But to overcome the disadvantage of sludge formation of hydroxide, employment of the additional process of solar and photo Fenton. By employing the process COD reduction of the effluent is increased. This research presents a comparative study of the reduction of COD of the effluent taken from the industry, which was treated by Solar-Fenton process, Photo-Fenton process and Solar-Photo Fenton process. The experimental results revealed that compared with conventional Fenton process, reduction in Chemical Oxygen Demand (COD) increased by applying the Solar-Fenton as well as Photo-Fenton Process and both. The important conclusion from the research is that every Advance Oxidation Processes (including Fenton) dependent on many process parameters. Temperature effect, initial pH effect, H2O2 dose, Fe +2 concentrations, and most important reaction time were checked and analyzed for reducing the COD. The key point of this research is Reduction of COD using conventional Fenton process followed by UV/solar process. However, using solar energy (renewable source) in place of UV also give same results. It's a greener approach.
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Advanced Oxidation Processes (AOPs) have emerged as a promising technology for the treatment of wastewaters containing toxic, recalcitrant organic compounds such as dyes, pesticides etc. This review paper focuses on the Fenton and photo- Fenton technique which is one of the most efficient AOPs developed to decolorize and/or degrade organic pollutants. This oxidation method can produce biodegradable intermediates and mineralize complex organic pollutants effectively and efficiently. In this paper Fenton and photo-Fenton methods are categorised into two broad groups as homogeneous and heterogeneous Fenton and photo-Fenton processes. Applications of fundamental and advanced combined Fenton and photo-Fenton processes are also discussed.
Chemosphere, 1994
Results of the photochemical mineralization of 4-¢hlorophenol (4-CP) and of a wastewater ~om dyehouse industry by the methods UV/O3, UV/I-I202, UV/TiO2 and UV/I-~O~-~ 2÷ (photo-Fenton reaction) are reported and compared. Under illumination with a 150 W high pressure merettry lamp, TOC-degra~fion efficiency for 4-CP had the following order:. UV/I-I20~/Fe2÷ > UV/O3 > UV/I~O 2 = UV/TiO 2. Complete deeolotuq.z~on of the dye waste ooctnred within 20 minutes with ozone. A mineralization grade of approximately 75% was reached after 90 minutes with the photo-Fenton reaction and after 150 minutes with UV/ozone. The combinations UV/TiO 2 and UV/I-I~O 2 were found to be less efficient for bleaching and degradation of the dye waste. Furthermore, a novel combination for wastewater treatment, UV/Fe2÷/O3, was investigated. Addition of Fe 2÷ to the UV/ozone process increased the mineralization rate of 4-CP while no significant effect on dye waste degradation could be observed.
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The elimination of aromatic compounds present in surface water by photo-Fenton with sunlight as the source of radiation was studied. The concentrations of Fe 3+ and H 2 O 2 are key factors for this process. A solar simulator and a prototype parabolic collector were used as laboratory-scale reactors to find the parameters of those key factors to be used in the CPC (compound parabolic collector) pilot plant reactor. The initial mineralization rate constant (k obs ) was determined and evaluated at different Fe 3+ and H 2 O 2 concentrations to find the best values for maximum efficiency. In all the experiments the mineralization of an aqueous phenol solution was described by assuming a pseudo-first-order reaction. The intrinsic kinetic constants not dependent on the lighting conditions were also estimated for scale-up.
Solar photo-Fenton treatment—Process parameters and process control
Applied Catalysis B-environmental, 2006
Photo-Fenton experiments were performed using alachlor as a model compound (initial concentration 100 mg/L) in a compound parabolic collector solar pilot-plant. Three process parameters were varied following a central composite design without star points (temperature 20-50 8C, iron concentration 2-20 mg/L, illuminated volume 11.9-59.5% of total). Under all experimental conditions, complete alachlor degradation, mineralisation of chloride and 85-95% mineralisation of dissolved organic carbon (DOC) was achieved. An increase in temperature, iron concentration and illuminated volume from minimum to maximum value reduced the time required for 80% degradation of initial DOC by approximate factors of 5, 6 and 2, respectively. When process parameter changes were made simultaneously, these factors multiplied each other, resulting in degradation times between 20 and 1250 min.
Clean-soil Air Water, 2009
In the present study, the effects of initial COD (chemical oxygen demand), initial pH, Fe 2+ /H 2 O 2 molar ratio and UV contact time on COD removal from medium density fiberboard (MDF) wastewater using photo-assisted Fenton oxidation treatment were investigated. In order to optimize the removal efficiency, batch operations were carried out. The influence of the aforementioned parameters on COD removal efficiency was studied using response surface methodology (RSM). The optimal conditions for maximum COD removal efficiency from MDF wastewater under experimental conditions were obtained at initial COD of 4000 mg/L, Fe 2+ /H 2 O 2 molar ratio of 0.11, initial solution pH of 6.5 and UV contact time of 70 min. The obtained results for maximum COD removal efficiency of 96% revealed that photo-assisted Fenton oxidation is very effective for treating MDF wastewater.
Modelling and experimental verification of a solar reactor for photo-Fenton treatment
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In the present work, a novel design of a solar reactor is presented. This pilot plant scale reactor uses the UV-Visible and Near-Infrared solar radiation to promote the photo-Fenton treatment. A theoretical study and experimental verification were performed using formic acid as a model pollutant. The radiative transfer, thermal energy and mass balances equations were solved to compute the formic acid (F) and hydrogen peroxide (P) concentrations as a function of time. The spectral and broadband solar radiation incident on the reactor window was calculated from a computational code: the SMARTS2 program. Statistical estimators have been used to measure the departure of theoretical model from experimental data. A good agreement for formic acid and hydrogen peroxide concentrations, temperature and total and UV broadband solar radiation was obtained. The normalized root mean square errors (NRMSE) of the model for predicted variables were lower than 11%.
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International Journal of Photoenergy, 2013
We evaluated the use of Fenton reactions induced by solar radiation in the treatment of effluent from a factory of paints for buildings, after prior removal of the suspended solids. The increase of H 2 O 2 concentration from 100 to 2500 mg L −1 for a [Fe 2+ ] = 105 mg L −1 contributed to the reduction of DOC, COD, and toxicity. Our best results were achieved using 1600 mg L −1 H 2 O 2 , with 90% of DOC and COD removal and a complete removal of the toxicity with respect to Artemia salina. Additionally, through increasing Fe 2+ concentration from 15 to 45 mg L −1 , the DOC removal rate increased 11 times, remaining almost constant in the range above 45 until 105 mg L −1. Under our best experimental conditions, 80% of DOC removal was achieved after an accumulated dose of 130 kJ m −2 of UVA radiation (82 ± 17 min of solar irradiation under an average UVA irradiance of 34.1 ± 7.3 W m −2), while 40% of DOC removal was reached after 150 min under only thermal Fenton reactions. The results suggest the effectiveness of implementation of solar photo-Fenton process in the decontamination and detoxification of effluents from factories of paints for buildings.