Bactericides of coliform microorganisms from wastewater using silver-clinoptilolite rich tuffs

Wastewater-like and municipal wastewater disinfection using Mexiacan zeolites from Oaxaca and Sonora and exchanged with silver ions was investigated. The natural zeolites previously conditioned with silver ions were characterized by X-ray diffraction and electron microscopy. The elementary compositions of the silver zeolites were determined by microanalyses (Electron Dispersive Spectroscopy, EDS). E. coli and total coliform microorganisms were chosen as indicators of microbiological contamination of water following the disinfection process with silver zeolite from Oaxaca and Sonora(Ag-OZ or Ag-SZ). According to the experimental data, the coefficient of specific lethality and the decay rate were determined using the Chick-Watson and Chick models, respectively. The amount of silver in both the wastewater-like and municipal wastewater was analyzed after treatment with the silver zeolites. The disinfection kinetics seemed to be carried out in one and two steps, depending of the nature of the water in contact with silver zeolites used as bactericide. The coefficients of specific lethality show that the Ag-OZ is more efficient as a bactericide on E. coli from wastewater-like than Ag-SZ. The kinetic constants show that the decay rate of the total coliforms using Ag-OZ is higher than Ag-SZ. The amount of silver found in water after treatment varied from 0.01 to 0.50 mg/L depending on the characteristics of the natural zeolites, the nature of the water to be disinfected and the disinfection time. (C) 2007 Elsevier B.V. All rights reserved.