An evaluation of household drinking water treatment systems in Peru : the table filter and the safe water system

Abstract

(cont.) storage, and education. Tests on the SWSs in Peru demonstrated 99.6% E.coli removal and 95% total coliform removal. Only 30% of the SWSs tested contained water at or above the WHO-recommended concentration of free chlorine residual (0.2 mg/L). The author recommends that use of these HWTSs continues and that the program receives increased support. The two HWTSs would be most effective if combined: filtration plus post-chlorination. In order to further distribute these systems in the future, a sustainable funding plan must be created.

A household water treatment program was implemented in southern Peru in 2003 by CEPIS and the country's Ministry of Health. This program involves the use of two household water treatment systems (HWTSs): the Table Filter and the Safe Water System. The author and a team of researchers from MIT traveled to Peru in January 2004 to assess the program and technologies through water quality tests and personal interviews. This research continued in Peru during March 2004 by local chemical engineering graduates of San Augustine National University. The Table Filter is a combination filter, involving a geotextile cloth pre-filter, sand, and two Pozzani ceramic candles from Brazil. Table Filters tested in Peru provided an average 99% E.coli removal, 98% total coliform removal, and 67% turbidity removal. Two Table Filters were also tested at MIT, using two different grades of sand. The "Medium Sand Table Filter" demonstrated 98% thermotolerant coliform removal and 91% turbidity removal, and the "Fine Sand Table Filter" showed 98% thermotolerant coliform removal and 92% turbidity removal. Tests performed on the Pozzani ceramic candles alone (without sand) showed similar coliform removal rates and slightly decreased turbidity removal rates, although the difference was statistically insignificant. Previous research shows that this combination of filtration media helps sustain a higher flow rate through the filters (Rojas & Guevara, 2000). Thus the chief advantage of the complete Table Filters, over the Pozzani ceramics candles alone, is a sustained higher flow rate, not coliform or turbidity removal. The Safe Water System (SWS), designed by the Centers for Disease Control and Prevention, involves local small-scale chlorine generation, household