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Stephanie Reiner

Joined: 28 Oct 2010
Posts: 1
Location: Virginia

 Posted: Fri Oct 29, 2010 1:08 pm    Post subject: Claculating feeding rate using flow rate I'm trying to calculate the feeding rate of larvae on algae cells in a tank that has water flowing into and out of it at a continuous rate but am not sure if this is right. Inflow water: 1.4 L/min Inflow algae: 0.055 L/min Total inflow: 1.4 + 0.055 = 1.455 L/min (algae inflow connected to water inflow, so they enter tank through same pipe) Outflow: 1.455 L/min (water flows out at rate it is coming in) *Inflow conc. algae: 70,000 cells/mL *Outflow conc. algae: 25,000 cells/mL *I'm assuming the algae inflow/outflow conc. are constant for the entire day Please let me know if this calculation is correct: 70,000 cells/mL * 1.455 L/min * 1 mL/0.001L = 101,850,000 cells/min coming in 25,000 cells/mL * 1.455 L/min * 1 mL/0.001L = 36,375,000 cells/min going out 101,850,000-36,375,000 = 65,475,000 cells/min retained in tank to be fed on 65,475,000 cells/min * 60 min/hr * 24 hr/day = 9.4 x 10^10 cells/day This seems like way too many, and I feel like I'm missing a step. Any help is appreciated! Thanks!
hepcj

Joined: 23 Jun 2007
Posts: 125

 Posted: Sat Oct 30, 2010 4:36 pm    Post subject: I think the problem is in this part: 70,000 cells/mL * 1.455 L/min * 1 mL/0.001L = 101,850,000 cells/min coming in 25,000 cells/mL * 1.455 L/min * 1 mL/0.001L = 36,375,000 cells/min going out Water is incompressible and so the rate of flow in will equal the rate of flow out. The question gives the inflow is 0.055 L/min = 55mL/min and the number of cells entering and exiting. 55 mL/min x 70,000 cells/mL = 3,850,000 cells/min 55 mL/min x 25,000 cells/mL = 1,370,000 cells/min difference = 3,850,000 cells/min - 1,370,000 cells/min = 2,480,000 cells/min left in tank. Thanks for your question.
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