Applied Study Of Nano-TiO₂ On The Photocatalysis Treatment Of Hospital Wastewater With Bacillus

Study of application of nano-TiO2 on environmental decontaminate is a presently hotspot. In this paper, TiOSO4 solution was prepared from the reaction of industrial metatitanic acid and H2SO4(98%), then high active nano-TiO2 powder was got from TiOSO4 solution. TiO2 granules were made of TiO2 powder with bonds. A 500 ml beaker was used as photocatalysis reactor; high voltage hydrargyrum-lamp was used as lamp-house, andE.coli was used as microbe model. On this base effects of factors on photocatalysis sterilization of two photocatalyst were studied. Applications of two photocatalysts in the treatment of simulated hospital wastewater were studied. In this paper direct microscopic count and plate count were compared in the count of bacilus during photocatalysis reaction. The results indicated that bacilus were dyed badly, and couldn't be identified. And with plate count that was done well. Photocatalysis sterilization of two types of TiO2 powder with different particle size was compared. The results indicated that photocatalysis sterilization of TiO2 powder with less particle size was better. Effect of bonds on photocatalysis sterilization was studied. The results indicated that A-bond didn't affect photocatalysis sterilization, TiO2 granules with B-bond were nearly inactiving. And photocatalysis sterilization of TiO2 granules with A-bond were remarkable, the porous adsorption was unobvious. The granules could be revived circularly. Effects factors of photocatalysis activity of TiO2 powder were investigated, such as ultrasonic treatment, pH, photocatalyst concentration, species and concentrations of bacteria, light intensity and lighting time. The results were as follow. Photocatalysis activity of TiO2 powder was remarkably promoted after long-playing ultrasonic treatment (6h). Photocatalysis sterilization was evidently affected by pH, and its action was stonger than pH on sterilization of bacteria. Ranging between 0.25-1g/l bacteria inactivation increased as TiO2 concentration, but didn't increased when higher than 1g/l. In the photocatalysis reaction, E.coli was easily sterilized, and B.subtilis with strong resistibility was difficultly sterilized. After lighted for 2h, concentration of E.coli decreased from 105CFU/ml to 103CFU/ml. Otherwise after lighted for 4h, concentration of B.subtilis reduced not enough 1log. Photocatalysis sterilization was affected obviously by initial concentration of bacteria. Photocatalysis sterilization was affected remarkably by light intensity. Lightied for 3h at 15W/m2, concentration of bacteria decreased from 3.5×107CFU/ml to 1.45×106CFU/ml; moreover, lighted for same time at 60W/m2, concentration of bacteria decreased below 103CFU/ml. The efficiency of photocatalysis sterilization related to lighting time. At 15W/m2, the mean velocity of photocatalysis sterilization during first 2h was 1.35×107CFU/(ml×h),and that during last 2h was 3.55×106CFU/(ml×h).At 60W/m2 same phenomena was found. The results indicated that the efficiency of photocatalysis sterilization during short time was better. Applications of TiO2 granules and TiO2 powder in the treatment of simulated hospital wastewater were studied on the base of above experiments. The results indicated that photocatalysis treatment with TiO2 granules fulfilled emission regulations of hospital wastewater after lighted for 9h. TiO2 granules that could be recycled and revived circularly was promising applied.