Advanced oxidation technologies for the degradation of pesticides in ground water and surface water

Abstract

An overview of the Advanced Oxidation Processes (AOP) studied for the degradation of pesticides combined with the formation of by-products is presented. It was found that the degree of conversion of pesticides is about the same with the Fenton process and UV/H2O2 within the margin of practical application, but slightly different with ozone/H2O2. Bentazone is readily degraded by the latter process, but more persistent during water treatment with the Fenton process and UV/H2O2, whilst atrazine is difficult to convert with all of these processes. Although bromate formation cannot be avoided completely with ozone/H2O2, it can be realized with the Fenton process and UV/H2O2. Upon degradation of pesticides with UV/H2O2 nitrite is produced, the amount depending on the water quality with respect to the nitrate concentration. Based on the a-selective nature of the hydroxyl radical AOC is formed out of DOC, which indicates that ozone/H2O2, the Fenton process as well as UV/H2O2 should be applicable for the development of biological GAC filtration.

Humic acid degradation in aqueous solution by the photo-Fenton process

“…Therefore, the optimum pH was found to be 3.5 and the photo-Fenton reaction is strongly affected by pH of the solution. The pH is in agreement with the expected range [24,25]. The optimal pH of the photo-Fenton reaction was reported to be around 3 [26] because the main species at pH 2-3, Fe(OH) 2+ , is the one with the largest light absorption coefficient and quantum yield for OH • radical production, along with Fe(II) regeneration, in the range 280-370 nm [27].…”

Removal of natural organic matter from groundwater using fenton’s process

“…With the addition of excessive H 2 O 2 , most ferrous ions were quickly oxidized to ferric ions that had a strong hydrolyzing potential and were believed to have a high capacity for adsorbing organics and the significant removal of TOC was achieved due to adsorption by ferric hydroxides. At ambient pH Fe 2+ is hydrolyzed instantaneously and this approach is based on a single production of hydroxyl radicals (Ijpelaar et al, 2002b) resulting in lower process efficiency at higher pH values. It is believed that at higher pH TOC is removed mainly by adsorption.…”

“…The key parameters, which determine the removal efficiency, are pH and the Fe 2+ dose (Murray and Parsons, 2004a). Process performance is also dependent on reaction time, peroxide dose and organic strength (Murray and Parsons, 2004a, Ijpelaar et al, 2002b, Stasinakis, 2008. Besides NOM removal from water, Fenton's process can be successfully used for elimination of many different contaminants from natural water and wastewater.…”

“…Good removal of DBPs like THMs (Tang and Tassos, 1997) was achieved, as well as removal of precursor species which can be problematic with respect to THM formation potential (THMFP) Parsons, 2004b, Kleiser andFrimmel, 2000). Fenton's process is a promising method for pesticide control in groundwater and surface water (Ijpelaar et al, 2002a, Ijpelaar et al, 2002b. Phenols can be completely removed by the Fenton's process (Kavitha and Palanivelu, 2004).…”

Photo-Assisted Oxidation of Indigocarmine in an Acid Medium

“…Research carried out in recent years has been based on the combined action of UV-radiation and a photocatalyst such as H 2 O 2 (Sprehe et al, 2000), O 3 (Beltrán et al, 1997), or TiO 2 (Stafford et al, 1996;Hsien et al, 2001). These photocatalytic techniques have been applied to treat a great number of organic pollutants (Herrmann, 1999), such as phenols and chlorinated derivatives (De et al, 1999;Ormad et al, 2001), PCBs (Huang et al, 2000), PHAs (Tuhkanen et al, 2000), and numerous pesticides (Burrows et al, 2002;Ijpelaar et al, 2002).…”