Coliform-Specific Solar Disinfection of Treated Wastewater

Our research investigated the potential use of solar radiation in water disinfection. Contaminated water was exposed to solar radiation under controlled conditions to deactivate and destroy pathogenic microorganisms. The experiment was directed toward examining the effective radiation time required for total coliform inactivation in the wastewater. The experiments were carried out between March and July 2009 with temperature ranges between 30-25oC and solar radiation intensity of 2073.9-2775.2 Jul/cm 2 . The impact of three parameters under direct exposure to the sun was studied: depth (10, 20, 30 cm), turbidity (135, 160, 200 NTU), and container color (white and black). Comparison between solar disinfection and chlorination also was conducted. The maximum removal of total coliform was found to be 92.95% at 10 cm depth for sunny conditions, at 110 NTU, and white container. It was found that the optimum contact time in the chlorination experiment was 240 min, which gives a disinfection efficiency of 99.6%. No significant difference in the disinfection efficiency is shown with extra exposure time. These findings of photo-biological inactivation of coliform could be applied in reducing the hazards of water-borne pathogens in an environmentally sound and low-cost system.