Synonym: retention time
Chemicals that may be removed include:
(1) chemicals contaminating ground water
(2) chemicals like chloramines added to a municipal water supply to control bacteria
Factors impacting the EBCT:
(1) uniformity of water flow through the medium
(2) absorption of water by the filtration medium
(3) absorption capacity of the filtration medium, which declines over time
(4) temperature
Parameters:
(1) volume of filtration medium in cubic feet
(2) flow rate over the medium in gallons per minute
EBCT in minutes =
= (volume of medium in cubic feet) * 7.48 / (flow rate in gallons per minute)
where:
• 7.48 is the number of gallons per cubic foot
Each chemical that needs to be removed is associated with a minimum value for the EBCT. An EBCT less than this target will be ineffective in removing the compound.
If the target EBCT is known:
volume of filtration medium required in cubic feet =
= (target EBCT in minutes) * (flow rate in gallons per minute) / 7.48
