Sewage land disposal and unpaved drains: threat to groundwater quality

Lack of proper wastewater management infrastructure is an alarming threat to the ground water quality, especially in developing countries. The objective of this study was to investigate the transport of coliform bacteria and other pollutants through soil to ground water in Taxila (Pakistan), near the unpaved sewage drain. An experimental setup was installed with five circular columns of variable depths of 0.3, 0.3, 0.9, 1.2, and 1.8 m clayey soil, taken near from drain, filled and compacted thoroughly in the columns. The sewage was poured into experimental setup from top and treated effluent was collected from the bottom. Sewerage before and after treatment were examined regularly. The Biological oxygen demand (BOD)5, Chemical oxygen demand (COD), Total suspended solids (TSS) and Total dissolved Solids (TDS), and coliform bacteria were monitored in the influent and effluent. Samples from the bores near the drain were also taken and analyzed. Coliform bacteria removal efficiency was 98.25%, in 1.8 m depth column, after 15th day of start. Similarly, BOD5, COD, and TSS maximum removal efficiencies achieved at 1.8 m depth were 90, 80, and 100%, respectively. Coliform bacteria were detected from the ground water near the sewage drain. A significant concentration of coliform bacteria was detected, even at the depth of 45 m, from the bores.