Study of the Treatment of Helminth Ova Polluted Water By an Electro-Fenton Process

Abstract

Helminths is a term designated to a wide group of organisms that includes all parasitic worms in fecal waste from animals and humans. They represent a high risk to human health because their various infectious stages (embryo, ova or larvae) are highly persistent in contaminated water, due to its large ability to survive for long periods, as they are extremely resistant to water disinfection treatments. Such resistance is given by the chemical composition of the layers of these eggs, mainly, formed by lipids and proteins. Thus, water constitutes a direct or indirect vehicle for the dissemination of helminths, even when they are found in low concentrations, giving rise to gastrointestinal diseases, especially when it is used to irrigate crops.There are some methods reported to remove Helminth ova, but the amin disadvantage is that these microorganisms are commonly inactivated but not destructed. There are other alternatives that promote disinfection through hydroxyl radical via Advanced Oxidation Processes (AOP).The objective of this study is to study the effect of an electro-Fenton treatment on water contaminated with helminth ova (HO). The inactivation of HO was studied in a continuous flow electro-Fenton reactor. Ion exchange resin was used to provide iron support, and H2O2 was produced in situ by cathodic reduction of oxygen. In order to study the electro-Fenton efficiency, three treatments were run; treatment A: without electric current and without iron promoter, treatment B: applying a potential difference of -4V but without iron promoter; and treatment C: applying the aforementioned potential difference and with iron promoter. Treatment A represents the retention capacity of the system given by sorption capacity of involved materials, while B represents the electrochemical oxidation effect, and finally C represents the electro-Fenton effect. HO determination was carried out in the influent and effluent, as well as in the internal materials of the reactor; Fe (II)-ionic exchange resin, cathode (graphite cloth), activated carbon packed reactor, anode (graphite cloth) and Na-ionic exchange resin. It was possible to retain between 96.59% and 98.33% of HO admitted to the reactor, the higher inactivation was observed in treatment C (See Figure 1). The percentage of total HO, represents the amounts of HO both viable and non-viable. The percentage of viable HO was determined by trypan blue staining and incubation to verify HO viability. A low presence of viable HO could be observed in treatments B and C, while treatment C with electro-Fenton conditions produces hydroxyl radicals that have a high oxidizing potential which affects the layers of the HO. Control treatments A and B, compared to treatment C, presented higher percentages distribution for both total and viable HO, demonstrating that inactivation of HO is possible through the electro-Fenton process. The decrease in viable HO for treatments C with conditions suitable for electro-Fenton can serve as qualitative evidence that the Fenton reaction is taking place. Figure 1