MICRO-TRACERS INC — Environmental Protection Agency SBIR Phase I: "Effective electrolytic sanitizing of contaminated waters using chloride requires a relati

Description

"Effective electrolytic sanitizing of contaminated waters using chloride requires a relatively high concentration of the elemental chlorine and hypochlorides. This requires a high concentration of chloride salt (higher the 0.15%). At such a concentration, chloride ions cause corrosion of various bimetal connections found in water plumbing systems, such as water distributors, cooling towers, etc. Replacement of chloride anions with anions of phosphates, nitrates, sulfates, benzoates or carbonates that do not cause corrosion would be advantageous in reducing the cost of equipment. In addition, other problems, associated with using chlorine in wastewater treatment, include: unfavorable odor, ineffectiveness when used alone against resistant microorganisms such as Cyptorsporodium parvum and occasional failure to meet regulatory standards. This project relates to advanced oxidation disinfecting processes, and more particularly to the combined use of singlet oxygen and electrochemical sterilization utilizing non-chloride electrolytes to kill non-pathogenic and pathogenic bacteria in contaminated water. The photochemical reaction of triplet oxygen with excited molecule of insoluble for of fluorescent dyes will generate singlet oxygen. We plan to provide experimental proof that singlet oxygen generated during irradiation of the water-insoluble form of photosensitizer (Al-salts of fluorescent dyes, deposited on the silica gel and dispersed in polymer coating) has a significant sanitizing effect on water contaminated with non-pathogenic bacteria such as E. coli B, and pathogenic bacteria, such as S. typhimurium. The sanitizing effect against non-pathogenic and pathogenic bacteria provided by AC electrolytic processes that product oxidants in chloride-free water solutions will be investigated in such media as phosphate buffer, ammonium sulfate, sodium carbonate, sodium nitrate, sodium sulphate, sodium dihydrogen phosphate, trisodium phosphate and calcium benzoate at low current (from 0.15 to 1.2 A), relatively low current densities (from 45 ma/cm2) and initial voltage demand of 20-80 volts. We plan to demonstrate that the combination of two sterilization method, namely, the singlet oxygen generation and chlorine-free electrolytic process, provides a more effect sanitizing effect against non-pathogenic and pathogenic bacteria than either of the two individual methods. The mechanism of the sanitizing effects of the singlet oxygen generation, as well as the chlorine-free electrolytic methods will be investigated and the nature of intermediate products (free radicals, peroxides, etc.) will be identified. Potential commercial application of new method includes a sterilization of poultry rinse water contaminated with non-pathogenic and pathogenic bacteria. "