Optimum soil depth for removal of coliphage viruses from treated wastewater, Kuwait

A study was carried out to determine the optimum soil depth for the removal of coliphage viruses from treated wastewater. Treated wastewater containing viruses was passed through soil columns filled with soil collected from Sulaibiya area, Kuwait. The soil column experiments were under operation for eight months during the period from August 2004 to March 2005. Three soil depths were used in these experiments. These are 0.1, 0.2, 0.4, and 0.8 m of natural Sulaibiya soil. For each experimental condition, two identical columns were set up, so that the changes of the results can be evaluated, producing total of eight columns. For all columns, the coliphage tests were studied only under alternating 1 d flooding and 1 d drying conditions. Influent and effluent coliphage samples were collected and analyzed following cycles of flooding periods. The coliphage virus count in the treated wastewater ranged between 0 and 62,800 pfu/100 ml. The laboratory results revealed that coliphage removal for Sulaibiya soil ranged between 58 and 100% for soil depth of 10 cm, and the viruses were completely removed after passing 20 cm thickness of soil. Also, the results indicated that no virus breakthrough occurred at soil depths of 40 and 80 cm.