Effect of Hydraulic Retention Time (HRT) on Surveillance of Coliforms in Waste Stabilization Pond (WSP) System in Central India

Abstract

The content of total coliforms and fecal coliforms were measured for the different ponds (anaerobic, facultative and maturation) in the year 2008-09 for waste stabilization pond (WSP) system in terms of Log 10 reduction value and decay rate (k d -1 ) in order to determine the efficacy of waste stabilization ponds with respect to their hydraulic retention time (HRT). Physical and chemical parameters (temperature, hydrogen ion concentration, total suspended solids and total dissolved solids) were also determined with aim of finding the factors which influence the rate of coliforms removal. The results indicate the surveillance of coliforms were most favored in anaerobic cell and lest favored in maturation cell with decay rate to an average of (k d -1 =2.92); (k d -1 =4.88); (k d -1 = 5.83) and (k d -1 =2.80) and (k d -1 =4.30); (k d -1 =5.89) for total coliforms and fecal coliforms observed for anaerobic, facultative and maturation cells respectively. The highest removal of coliforms (total and fecal coliforms) between 3.37 log 10 to 4.0 log 10 was observed for maturation cells with hydraulic retention time (HRT) of 5 days each and two maturation ponds in series.