An industry is planning to use a 250 m3 bioreactor to treat 400 m3/day of wastewater containing 80 mg/L of benzene (CsHe). Benzene is expected to degrade by microbial action in a completely-mixed reactor (CSTR) with a first-order degradation rate coefficient of 5.0/ day a. Write a balanced reaction for the complete oxidation of benzene to carbon dioxide and water. b. Draw a diagram and write a mass balance equation for benzene in the tank reactor. c. Assuming steady-state conditions, determine the concentration of benzene in the outflow d Determine the mass of benzene that comes into the reactor each day, the mass of benzene that goes out of the reactor each day, and the mass of benzene that is degraded each day. e. Calculate the percent removal. If air is com bubbled oxygen transfer efficiency is equal to 15%. posed of 21 percent oxygen, estimate the volume of air that would have to be through the reactor each day. Assume the air temperature is 25°C and that the Ans: c) 19.4 mg/L d) mass rate in -32.0 kg/day, mass rate out 7.8 kg/day, mass rate loss by reactions 24.2 kg/day, e) 75.8% f) 1,809 m3 air/day
An industry is planning to use a 250 m3 bioreactor to treat 400 m3/day of wastewater containing 80 mg/L of benzene (CsHe). Benzene is expected to degrade by microbial action in a completely-mixed reactor (CSTR) with a first-order degradation rate coefficient of 5.0/ day a. Write a balanced reaction for the complete oxidation of benzene to carbon dioxide and water. b. Draw a diagram and write a mass balance equation for benzene in the tank reactor. c. Assuming steady-state conditions, determine the concentration of benzene in the outflow d Determine the mass of benzene that comes into the reactor each day, the mass of benzene that goes out of the reactor each day, and the mass of benzene that is degraded each day. e. Calculate the percent removal. If air is com bubbled oxygen transfer efficiency is equal to 15%. posed of 21 percent oxygen, estimate the volume of air that would have to be through the reactor each day. Assume the air temperature is 25°C and that the Ans: c) 19.4 mg/L d) mass rate in -32.0 kg/day, mass rate out 7.8 kg/day, mass rate loss by reactions 24.2 kg/day, e) 75.8% f) 1,809 m3 air/day
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