Treatment Efficiencies of Slow Sand Filtration for Landscape Water

The performance of the slow sand filter was examined using the landscape water with the experimental period of 46 days. The filter installed was similar to the traditional slow sand filter; expect that the top 5-cm sand was changed to the quartz sand. In this study, the variations of the turbidity, COD, BOD and TN were measured based on the filtration rate of 0.2m/h. Results showed that the average removal efficiencies of turbidity, BOD5 and COD achieved 86%, 67% and 34%, respectively, with the effluent turbidity ranged from 0.47 NTU to 2.58 NTU, BOD5 ranged from 0.4 mg/l to 1.1 mg/l and COD ranged from 13 mg/l to 18 mg/l, respectively. TN had a relatively high removal efficiency of 59% (average), with an effluent TN concentration lower than 1 mg/l. Also, the TN removal rate increased with the operational time after the steady operation was obtained. In addition, it was calculated that the efficient operation period for the slow sand filter was approximately 60 days, after which the head loss would increase to the maximum available of the SSF and the filter would be clogged significantly.