Kinetic Modeling for Water Disinfection Using H2O2

FLORES, M. J.; BRANDI, R. J.; CASSANO, A. E.; LABAS, M. D.

San Diego, California

Congreso; 17th International Conference on Advanced Oxidation Technologies for Treatment of Water, Air and Soil (AOTs-17); 2011

Microbiological contamination of water is problem under constant review because of its importance for life and for the development of civilization. An ideal disinfection system should ensure maximum efficiency for the removal of pathogens without producing toxic and undesirable byproducts. The correct solution to the problem of contamination is the use of clean technologies that none of its steps affect the environment. Hydrogen peroxide is disinfectant with recognized antimicrobial properties that can be used because is effective, safe and easy to manipulate. For water disinfection purposes, the non-persistent characteristic of hydrogen peroxide becomes a disadvantage to maintain the water quality in the distribution system. However, its use is widely spread because it is relatively inexpensive, is easily removed when desired and is unlikely to be health hazardous if used properly. In addition, it does not give rise to disinfection byproducts as it is the case of other strong oxidants. The antimicrobial and/or antiseptic properties of hydrogen peroxide have been known for many years because it is effective against a wide spectrum of bacteria, yeast, molds, viruses and spore forming organism. The chemical mechanisms that promote the hydrogen peroxide decomposition can be inferred but infrequently established, however it is know that is due to its ability to generate strongly oxidant chemical species like hydroxyl radical (OHÿ). This radical species reacts with almost all biological molecules. The attack by the OHÿ radical, in the presence of oxygen, initiates a complex cascade of oxidative reactions leading to decomposition of the all the enzymes and organic compounds that result from the rupture of the cell membrane . This work is an attempt to model the disinfection process based on a chemical interpretation of the possible mechanism of cell damage. The key point is to search for the most accepted assumptions concerning the possible place where the action of reactive hydroxyl radical can take place. According to literature, in the case of bacteria three sites of the cell could be the targets for OHÿ invasion: (1) The peptidoglycan layer, (2) the lipopolysaccharide layer (found only in Gram-negative bacteria) and (3) the phospholypid bilayer. In this study Escherichia coli was the chose bacteria and consequently the three layers will be present. After attack to the membrane, the oxidation of the products resulting from the lysis of the bacteria, was modeled as a series of chemical events, which leads to its dead or to an irreversible damage. The path way of the kinetic model includes: undamaged (Bu), damaged (Bd) and lysed (Bl) population of bacteria, as well as and several additional chemical products of the lysis with the generic denomination of P1, P2 …Pn. The kinetic model developed in this work was successfully validated with experimental data.