Depth and performance evaluation of a laboratory scale sand filtration system for wastewater treatment


Abstract: Intermittent sand filtration (ISF) was adopted in the treatment of synthetic wastewater having septic tank effluent's properties in the laboratory. Over a period of 84 days synthetic wastewater was intermittently dosed onto two sand filters of 50 cm and 100 cm depths at an interval of 4 h. The filter material has an effective size d$_{10}$ of 0.42 mm, d$_{60}$ of 0.92 mm, coefficient of uniformity, Cu, of 2.2, and hydraulic conductivity of 4.632 $\times $ 10$^{-3\, }$ms$^{-1}$ with an effective pore diameter of 0.094 mm. The hydraulic loading was 0.144 m/day and the BOD$_{5}$ of the wastewater was 172.3 mg/L. The removal of suspended solids, ammonium-nitrogen (NH$_{4}$-N), and BOD$_{5}$ in 100- and 50-cm columns was 91.4% and 88.6%, 98.7% and 99.8%, and 92% and 90%, respectively, while PO$_{4}$-P removal was about 45% in both columns. Unlike other parameters, NO$_{3}$-N was increasing, which signifies that denitrification did not take place in the filter columns. Based on the results, the filter column of 50 cm is economically preferable due to the insignificant difference when compared with the 100-cm filter column. The bacteria removal was slightly higher in 100 cm depth (99.88%) than in 50 cm depth (99.68%).

Keywords: Intermittent filtration, synthetic wastewater, depth variation

Full Text: PDF