An ocean outfall diffuser that discharges treated wastewater into the pacific oc
ID: 290058 • Letter: A
Question
An ocean outfall diffuser that discharges treated wastewater into the pacific ocean is 5000 m from a public beach. The wastewater contains 10^5 coliform bacteria per milliliter. The wastewater discharge flow rate is 0.3m^3/s. the coliform first order death rate in seawater is approximately 0.3 h^-1 (tchobanoglous and schroeder, 1985). the current carries the wastewater plume toward the beach at a rate of 0.5 m/s. the ocean current may be approximated as a pipe carrying 600 m^3/s of seawater. determine the coliform concentration at the beach. assume that the ccurrent behaves as a plug reactor and that the wastewater is completely mixed in the current at the discharge point.
Explanation / Answer
Given
The waste water coliform bacteria per milliliter (Cwaste water)= 10^5
Wasre water discharge flow rate (Qw) =0.3m3 /s
pipe carrying of sea water(Qs) =600m3 /s
Cwastewater * Qw = Cseawater * Qs
105 * 0.3 =Cseawater * 600
Cseawater =0.0005*105
Cseawater = 50 caliform per milliliter
colifiorm concentration at the beach = 50 caliform per milliliter
Coliform concentration at the beach is