A continuous process is set up for treatment of wastewater. Each day, 10³ kg cellulose and 105 kg bacteria enter in the feed stream, while 10² kg cellulose and 1.5 x 10² kg bacteria leave in the effluent. The rate of cellulose digestion by the bacteria is 8 x 10² kg d^-1. The rate of bacterial growth is 4x 10² kg d^-l; the rate of cell death by lysis is 6 x 10² kg d^-1. Write balances for cellulose and bacteria in the system.

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#Question id: 15647

#Section 4: Fundamentals of Biological Engineering

A liquid stream is cooled from 80°C to 30°C in a double pipe heat exchanger as illustrated below: 

Fluid flowing counter currently with this stream is heated from 15°C to 30°C. Calculate the log mean temperature difference. 

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#Question id: 15648

#Section 4: Fundamentals of Biological Engineering

The main function of baffles in a bioreactor are

P. to prevent a vortex

Q. to increase aeration

R. to reduce interfacial area of oxygen transfer

S. to reduce aeration rate

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#Question id: 15649

#Section 4: Fundamentals of Biological Engineering

A bacterial culture having a specific oxygen uptake rate of 5 mmol O2 (g DCW)⁻¹ h⁻¹ is being grown aerobically in a fed-batch reactor. The maximum value of the volumetric oxygen transfer coefficient is 0.18 s⁻¹ for the stirred tank bioreactor and the critical dissolved oxygen concentration is 20% of the saturation concentration (8 mg L⁻¹). The maximum density to which the cells can be grown in the fed-batch process, without the growth being limited by oxygen transfer, is approximately

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#Question id: 15650

#Section 4: Fundamentals of Biological Engineering

For scaling up of a bioreactor, the following parameter is assumed to be constant

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#Question id: 15651

#Section 4: Fundamentals of Biological Engineering

Power number, also called Newton’s number, is defined as a dimensionless parameter relating to:

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#Question id: 15671

#Section 6: Plant, Animal and Microbial Biotechnology

The lag phase of the bacterial growth curve is marked by