RapStech® service for comparison of service life of GAC filters


United Utilities


Aug. 2006 to 2008

RapStech® service provides a rapid method to test the capacity of GAC using Rapid Small Scale Column Tests (RSSCTs) and determine the optimum time for regeneration or replacement.

The design of the project was developed in close conjunction with United Utilities, actual site water was used spiked with a pesticide Diuron to allow for inclusion of background Natural Organic Matter (NOM). The GACs were selected to ensure that samples from within a typical regeneration time-line were used and this provided GACs with different service life history.

The data obtained could be calculated into adsorption capacity for Diuron. As service life increases, adsorption capacity for Diuron decreases, however some capacity for Diuron remains even after 2 years in service.

The use of RSSCTs together with the analysis of the physical and chemical characteristics of the GAC can assist with service life evaluation. This strategy can provide water utilities with a greater understanding of this critical asset and thus the capability to make more informed operational decisions regarding regeneration frequency.