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

Intermittent sand ltration (ISF) was adopted in the treatment of synthetic wastewater having septic tank euent s properties in the laboratory. Over a period of 84 days synthetic wastewater was intermittently dosed onto two sand lters of 50 cm and 100 cm depths at an interval of 4 h. The lter material has an e ective size d10 of 0.42 mm, d60 of 0.92 mm, coefficient of uniformity, Cu, of 2.2, and hydraulic conductivity of 4.632 X10^-3 ms^-1 with an e ective pore diameter of 0.094 mm. The hydraulic loading was 0.144 m/day and the BOD5 of the wastewater was 172.3 mg/L. The removal of suspended solids, ammonium-nitrogen (NH4 -N), and BOD5 in 100- and 50-cm columns was 91.4% and 88.6%, 98.7% and 99.8%, and 92% and 90%, respectively, while PO4 -P removal was about 45% in both columns. Unlike other parameters, NO3 -N was increasing, which signi es that denitri cation did not take place in the lter columns. Based on the results, the lter column of 50 cm is economically preferable due to the insigni cant di erence when compared with the 100-cm lter column. The bacteria removal was slightly higher in 100 cm depth (99.88%) than in 50 cm depth (99.68%).