The effect of sand-bed filtration on the oxygen demand characteristics of wastewaters from domestic, institutional and industrial sources

Wastewaters from three different sources, private residence (domestic), medical clinic (institutional) and polymer industry (industrial) were characterised for their pollution potentials. The results of analysis show pH of 7.6, 6.5 and 6.3 for domestic, institutional and industrial wastewater, respectively. The DO, BOD and COD was found to be 4.01, 66 and 114 mg/l for the domestic wastewater, 3.70, 88.6 and 196.8 mg/l for the institutional wastewater and 3.60, 234 and 567 mg/l for the industrial wastewater. Solids concentration were 391.8 mg/l TS, 381 mg/l TSS and 10.8 mg/l TDS for the domestic wastewater; the institutional wastewater gave 1123 mg/l TS, 893 mg/l TSS and 230 mg/l TDS; while the solids present in the industrial wastewater are 674 mg/l TS, 554 mg/l TSS and 120 mg/l TDS. The total bacteria count (TBC) per 100 ml sample was 3.5 x 103, 4.6 x 106 and 6.0 x 106 for domestic, institutional and industrial wastewater respectively. The effect of sand-bed filtration on these characteristics were also studied and it was found that while sand-bed filtration increases the values of DO, while the values of BOD and COD were reduced accordingly. It is however recommended that oxygen demand tests should be combined with other test like bacteriological to ascertain the quality and hence the portability of water abstracted for uses.