Evaluation of Horizontal Flow Roughing Filtration Performance


The HRF was studied by using pilot plant. This pilot plant was designedand applied in Al – Wehda Water Treatment Plant which treats the raw water of Tigris River in Al – Karradah in Baghdad city. Design characteristics of the pilot HRF are 5.5m length × 1m width × 1m depth , the HRF length consists of inlet ( 0.5 m ) , outlet ( 0.5 m ) and three compartments ( 2m , 1.5m and 1m ) filled with three different size of gravel ( 15mm , 10mm and 5mm ) respectively . The HRF was continuously operated (24 h in a day) during the period from 15/May / 2007 to 15/ July / 2007. Operated done in two stages. In the first stage, raw water (free from any addition) was used, with three different flow rate 1.3, 1.1 and 0.9 m3/h. While in the second stage, coagulated water (raw water + alum) was used, with flow rate 1.3 m3/h. To assess the performance of HRF, the required tests were carried out. These tests are Turbidity, S.S, Temperature, pH and Bacteriological tests. The results of tests were analyzed statistically. The mean ofremoval efficiency of turbidity for first stage with discharges 1.3 , 1.1 and 0.9 m3/h is 92% , 94% and 95% respectively , and for second stage is 97% . These results indicate the high performance of HRF in turbidity removal.