Removal of Bulk Pollutants from Wastewater through River Sand during Gravity and Suction Flow Process

摘要

This study was conducted to understand the performance of riverbed sediments; river sand was taken from the downstream Kotri barrage for the preparation of filtration bed to treat the wastewater for the removal of bulk water pollutants. The river sand group-A was applied to filter the wastewater under aerobic conditions of the experiments at lab scale. The filtration model was designed to filter water through gravity and suction flow process. The six attempts of sampling and analysis were conducted for 26 days from 7~(th) May to 31~(st) May 2018 at frequency of each attempt after one week of filter run. Filtered water flow rate was observed during both processes which were reduced gradually due to the clogging of filter bed. The reductions during gravity flow from 1.5 L/min to 0.31 L/min and by suction flow from 6.67 L/min to 3.33 L/min were observed during the six attempts of sampling and analysis. However, wastewater dosing rate was kept constant over the filter bed. The filtered water samples through both gravity and suction processes were analyzed to determine the concentrations of turbidity, total coliform, ammonia, nitrate and phosphate. The reduction in turbidity during gravity and suction filtration processes were in range from 99.6 to 95.9 % and 97.3 to 89.1 %. The total coliforms were reduced in the range from 93.3 to 96.2 % and 88.1 to 91.3 %. The ammonia concentrations were reduced in the range from 100 to 66.1 % and 97.9 to 70.8 %. The nitrate concentration reduced in the range from 100 to 70 % and 95 to 50 %. The phosphate reduction range was from 97 to 98.5 % and 66 to 89.6 % respectively.