Field treatment and disinfection of highly turbid natural water for potable use

A drinking water treatment method for field application was developed to minimize the risk of waterborne disease among people who rely on natural surface waters for potable use. The treatment method was modeled to accommodate river rafting excursions on the Colorado River in the Grand Canyon. Because of the frequent high turbidity of the Colorado River, a two step treatment method, involving clarification with aluminum sulfate (alum) for 30 min followed by chlorine disinfection for 30 min, was developed. Treatment of turbid water with alum reduced concentrations of suspended solids, reduced total coliform (TC) and fecal coliform (FC) concentrations, and lowered pH to levels favorable for disinfection. With alum treatment, TC and EC removed by flocculation remained viable in the resulting sediment. Naturally occurring turbidity and turbidity created by resuspension of sediment reduced the disinfecting efficacy of sodium hypochlorite. Resuspension of sediment into clarified supernatant may represent a potential public health hazard.hydrology collectio