Burnt Clay Bricks as an Alternative Filter Media for Pebble Matrix Filters (PMF)

A novel method called PMF has proved to be suitable under tropical monsoon conditions for pre-treating high turbidity water before water is introduced to Slow Sand Filters (SSFs). The scarcity of sources of pebbles of the required quality, government regulations on pebble dredging and higher material cost were identified as key problems during the construction of the first ever full scale PMF plant in Sri Lanka at Kataragama. In order to investigate possibilities of utilizing alternative-filter media for PMF, laboratory tests were conducted using different configurations of chips and burnt clay bricks which are available readily in Sri Lanka. Two filter media configurations were tested using a laboratory scaled model at an influent turbidity of 60 NTU. The optimum configuration was selected based on the maximum turbidity removal efficiency obtained and was tested by changing influent turbidity. Broken clay bricks with sand in a 1:1 ratio are found to have greater potential as a pre-treatment media for turbidity removal. Moreover, bricks can be utilized as a feasible alternative to natural pebbles. Test results showed that in contrast to chips ,turbidity removal efficiency increased with the increment of influent turbidity when bricks were used as the filter media.