Pre-treatment before Slow Sand Filtration with Pebble Matrix Filtration at Kataragama Water Treatment Works, Sri Lanka

The Kataragama water treatment plant (WTP) currently abstracts water from the river 'Menik Ganga' and seasonal high turbidity exceeding 500 NTU put the existing four slow sand filters (SSF) out of operation several times a year. The proposed use of Pebble Matrix Filtration (PMF) ahead of SSF as a pretreatment is an attractive option as the PMF itself is a simple and sustainable solution to the problem in the developing country context. The proposal to conduct first, full-scale trials at Kataragama WTP has been submitted to the World Bank's Development Marketplace competition (with partial funding from UNESCO-DaimlerChrysler Mondialogo Engineering Award 2005), and has won the DM-2006 Award out of 2500 proposals worldwide. The background and concept of PMF technology and its proposed use at Kataragama WTP to overcome high turbidity problems associated with SSF is explained in this paper.