Semiconductor Oxides Mediated Photocatalytic Removal of Chemical and Bacterial Pollutants from Wastewater

School of Environmental Studies, Cochin University of Science and Technology

Relative survival of Escherichia coli and Salmonella typhimurium in a tropical estuary

Microcosm studies have been carried out to find out the relative survival of Escherichia coli and Salmonella typhimurium in a tropical estuary. Survival has been assessed in relation to the important self-purifying parameters such as biotic factors contained in the estuarine water, toxicity due to the dissolved organic and antibiotic substances in the water and the sunlight. The results revealed that sunlight is the most important inactivating factor on the survival of E. coli and S. typhimurium in the estuarine water. While the biological factors contained in the estuarine water such as protozoans and bacteriophages also exerted considerable inactivation of these organisms, the composition of the water with all its dissolved organic and inorganic substances was not damaging to the test organisms. Results also indicated better survival capacity of E. coli cells under all test conditions when compared to S. typhimurium

Comparative effectiveness of solar disinfection using small-scale batch reactors with reflective, absorptive and transmissive rear surfaces

This study investigated the enhancement of solar disinfection using custom-made batch reactors with reflective (foil-backed) or absorptive (black-backed) rear surfaces, under a range of weather conditions in India. Plate counts of Escherichia coli ATCC11775 were made under aerobic conditions and under conditions where reactive oxygen species (ROS) were neutralised, i.e. in growth medium supplemented with 0.05% w/v sodium pyruvate plus incubation under anaerobic conditions. While the addition of either an absorptive or a reflective backing enhanced reactor performance under strong sunlight, the reflective reactor was the only system to show consistent enhancement under low sunlight, where the process was slowest. Counts performed under ROS-neutralised conditions were slightly higher than those in air, indicating that a fraction of the cells become sub-lethally injured during exposure to sunlight to the extent that they were unable to grow aerobically. However, the influence of this phenomenon on the dynamics of inactivation was relatively small

Thermal stability of myofibrillar protein from Indian major carps

The characteristics and stability of natural actomyosin (NAM) from rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) were investigated. The total extractable actomyosin (AM) was higher (7.60mgml−1) in the case of rohu compared with that from catla and mrigal (5mgml−1). Although the specific AM ATPase activity was similar (0.43–0.5 μmolPmin−1 mgP−1) among the three species, the total ATPase activity was lower in mrigal (25 μmol g−1 meat) compared with the other species (37 μmol g−1 meat). The inactivation rate constants (kd) of AM Ca ATPase activity showed differences in the stabilities of actomyosin among these fish, the actomyosin from catla being least stable. The NAM from these species was stable up to 20 ◦C at pH 7.0. Catla AM became unstable at 30 ◦C, while rohu and mrigal AM could withstand up to 45 ◦C. The thermal denaturation with respect to solubility, turbidity, ATPase activity, sulphhydryl group and surface hydrophobicity showed noticeable changes at around these temperatures