A surface aeration pond is used to treat an industrial wastewater that contains a high loading of biodegradable organics. The pond is open to the atmosphere, and the partial pressure of oxygen in air is 0.21 atm. The dimensionless Henry's law constant of O2 at 20°C is H' = 32. (a) Calculate the equilibrium mass concentration of dissolved oxygen in the lake at 20 °C. (b) Using mass balance principle, derive the equation for oxygen concentration in the pond water as the result of oxygen transfer from water surface to water body. The oxygen concentration is assumed uniform through the depth D of the pond (complete mixing). The flux of oxygen to water is proportional to the driving force (Cs - C), where C, and C are the saturation oxygen concentration and actual oxygen concentration in water, respectively. (c) Calculate the time needed for the water in the tank to reach a DO level of 8.0 mg/L. The coefficient of oxygen transfer from gaseous phase to liquid phase is K₁= 1.5×103cm/s. The average depth of the pond is 1.5 m. The initial DO of the water in the pond is 2.0 mg/L.
A surface aeration pond is used to treat an industrial wastewater that contains a high loading of biodegradable organics. The pond is open to the atmosphere, and the partial pressure of oxygen in air is 0.21 atm. The dimensionless Henry's law constant of O2 at 20°C is H' = 32. (a) Calculate the equilibrium mass concentration of dissolved oxygen in the lake at 20 °C. (b) Using mass balance principle, derive the equation for oxygen concentration in the pond water as the result of oxygen transfer from water surface to water body. The oxygen concentration is assumed uniform through the depth D of the pond (complete mixing). The flux of oxygen to water is proportional to the driving force (Cs - C), where C, and C are the saturation oxygen concentration and actual oxygen concentration in water, respectively. (c) Calculate the time needed for the water in the tank to reach a DO level of 8.0 mg/L. The coefficient of oxygen transfer from gaseous phase to liquid phase is K₁= 1.5×103cm/s. The average depth of the pond is 1.5 m. The initial DO of the water in the pond is 2.0 mg/L.
Introduction to Chemical Engineering Thermodynamics
8th Edition
ISBN:9781259696527
Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Chapter1: Introduction
Section: Chapter Questions
Problem 1.1P
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Transcribed Image Text:A surface aeration pond is used to treat an industrial wastewater that contains a high loading of
biodegradable organics. The pond is open to the atmosphere, and the partial pressure of oxygen in
air is 0.21 atm. The dimensionless Henry's law constant of O2 at 20°C is H' = 32.
(a) Calculate the equilibrium mass concentration of dissolved oxygen in the lake at 20 °C.
(b) Using mass balance principle, derive the equation for oxygen concentration in the pond water as
the result of oxygen transfer from water surface to water body. The oxygen concentration is
assumed uniform through the depth D of the pond (complete mixing). The flux of oxygen to
water is proportional to the driving force (C: - C), where C; and C are the saturation oxygen
concentration and actual oxygen concentration in water, respectively.
(c) Calculate the time needed for the water in the tank to reach a D0 level of 8.0 mg/L. The
coefficient of oxygen transfer from gaseous phase to liquid phase is K= 1.5x10³cm/s. The
average depth of the pond is 1.5 m. The initial DO of the water in the pond is 2.0 mg/L.
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