A mechanistic model of the inactivation of Escherichia coli by solar water disinfection (SODIS) technique ispresented. Bacterial inactivation by SODIS is commonly attributed to the oxidative stress generated bysynergy among solar radiation (UV photons) and mild temperature. Photons may increase the naturallyoccurring amount of internal Reactive Oxygen Species (ROS), such as hydroxyl radical (HO�) and superoxideradical (O2 ��). ROS attacks to different targets inside the cells are one of the main sources of oxidativedamage over cells. Besides, photons may damage the two essential enzymes of the defense systemagainst intracellular oxidative stress, catalase (CAT) and superoxide dismutase (SOD). Therefore, theproposed model is a simplified approach of the complex processes occurring inside cells during SODIS,which is based on the photo-induced formation of intracellular ROS and the photo-inactivation of CATand SOD. The model considers two individual volume units in which the processes are occurringsimultaneously: (i) a single cell (mass balances for intracellular ROS and enzymes) and (ii) the reactor(mass balance for bacteria).Kinetic constant from literature were used, meanwhile CAT photo-inactivation kinetic constant wasdetermined experimentally, (1.50 ± 0.04)�107 cm3 Einstein�1. Model regression was done usingexperimental data of E. coli inactivation by solar disinfection at different controlled conditions of solarirradiance and initial bacterial concentration. The good fit of the simulated and experimental resultssuggested that the mechanistic process proposed is a realistic approach of the disinfection process.Moreover, simulations of the time profile of intracellular ROS and enzymes involved during bacterialinactivation by SODIS are also presented.
- E. coli
- Mechanistic model