Sedimentation: Hydraulic improvement of drinking water biofiltration

Abstract

The performance of drinking water biofiltration systems is commonly measured by the effluent water quality and filter runtime (FRT). At constant flow rates, lower FRTs increase backwashing frequencies and thus lower water recovery and increase the water production cost. This study was conducted on a pilot scale in two parallel trains; one included sedimentation and one did not. Both trains have three matched filter columns. Sedimentation improved FRT by up to 30% and reduced head loss and head loss accumulation rate up to 29% and 35%, respectively. Natural organic matter removal remained unchanged. Adenosine triphosphate levels did not differ, while extracellular polymeric substance was reduced by 36%. In conclusion, sedimentation increased long‐term stability and reliability while reducing the backwash frequency, offering a robust approach for optimizing biofiltration performance. Potential operating cost savings have to be weighed versus the capital costs of retrofitting sedimentation in future studies.