Define Electrodialysis (ED), draw a schematic diagram of the process, and determine the main characteristics of ion exchange membranes to be used. What are the process limitations in ED systems? then differentiate between dialysis and osmosis phenomena.

What is sludge volume index used for? Describe the term “bulky sludge” and identify the reason behind its formation.

List examples of major unit operations in preliminary, primary, secondary and tertiary treatment stages. What is the main objective of each treatment stage?

What are the main advantages and disadvantages of MBRs? Compare submerged (internal) versus external types of MBRs. and what are the important parameters to be considered in the design of ASP or MBRs?

The walls of an industrial freezer are constructed from a composite of three materials, an inner layer of plastic, a layer of insulation material, and an outer layer of stainless steel. Heat transfer occurs into the interior of the freezer from the external atmosphere.

a) Provide a sketch to illustrate the variation in temperature from the interior of the freezer compartment to the outer ambient air. In your sketch clearly identify the individual thermal resistances and identify the mode of heat transfer for each resistance. You may assume there are no contact resistances at the interfaces

b) Determine the rate of heat transfer (per unit area) through the walls of the freezer. State any assumptions that you make.

c) What thickness of insulation material is required such that the rate of heat transfer per unit area is reduced to 18 W/m2 ?

Data :
Temperature of freezer compartment, 253 K Ambient temperature, 27 °C
Internal heat transfer coefficient, 13 W/(m2 K) External heat transfer coefficient, 6 W/(m2 K)

Plastic material: Thickness, 5 mm Thermal conductivity,

Insulation material: Thickness, 100 mm Thermal conductivity,

Stainless steel: Thickness, 1.5 mm Thermal conductivity,

1 W/(m K)

0.07 W/(m K)

16.5 W/(m K)

What are the main advantages of incorporating membrane technology in biological treatment such as ASP? Draw a schematic diagram of activated sludge process (ASP) and membrane bioreactors (MBRs). Label all streams and provide a brief description for mixed liquor suspended solids (MLSS), return activated sludge, wastage sludge, hydraulic retention time, solid retention time, and F/M ratio.

A liquid is stored in a vessel at 102 bar (absolute) from where it is transferred (at 1.5 kg/s) into another vessel via a 5 cm steel pipe (friction factor = 0.025). The pressure above the liquid surface in the second vessel is maintained at 2000 Pa (gauge). The pipe length between the two vessels is 200 m. Total minor head losses due to fittings, valves as well as entry and exit losses amount to 4,000 equivalent length in pipe diameters. The liquid level in the first vessel is 25 m higher than the liquid level in the second vessel. The specific gravity of the liquid is 0.9 while its viscosity is 0.76 mPa s. In order to recover excess energy, a turbine is integrated into the pipeline. (i) Calculate the Reynolds number for this liquid flow. (ii) Describe the characteristics of this flow in the context of its flow regime (laminar or turbulent). (iii) Estimate the power that can be recovered using the turbine (assuming it is 80% efficient).

Q1.

Describe the operation of a biofusion bioreactor.

Q2.

Why KL_a of a bubble column reactor is more than that of airlift bioreactor.

Q3.

For mycellial pellet growth, how is adequate interrupted O₂ supply maintained in case of large pellets?

Q4.

Why is dynamic method for KL_a determination in O₂ concentration not allowed to drop below its critical level?

Q5.

Describe hollow fibre reactor for the monoclonal antibodies by animal cell culture.

Electrostatic precipitator question,

I'm designing an electrostatic precipitator (ESP) to capture the particulate matter(fly ash) from flue gas at 130C that exits from a coal-fired power plant.

My question is: how can i increase the efficiency of the electrostatic precepitator without conditioning the flue gas (ie. injecting so3 or ammonia or water)? what are the alternative ways to increase the efficiency of the ESP? please show references with solution. Thanks

Question 8.

When a polyethylene wax is chlorinated, chlorine replaces hydrogen at random. Invariably, small amounts of chlorine (10 - 50 mass % CI) cause a lowering of the softening point. However, large amounts (ca. > 70 %) raise the softening point. Rationalise this on the basis of expected morphologies and intermolecular forces.

Air at 25 C and 750mmHg has a dew point of 16C. If you want to remove 50% of the initial moisture in the air (at a constant pressure of 750 mmHg), to what temperature should you cool the air?

Equilibrium How is O2 transported form the lungs to the body’s tissues? By bonding to the iron atoms of Haemoglobin in red blood cells, changing their colour from blue to red. Haemoglobin is a tetrameric molecule that can sequentially bind four oxygen molecules, but the equilibrium may expressed in simplified form for the first added molecule by this reaction:1 Hb(aq) + O2(g) ? HbO2(aq) = 0.84 kPa-1 What happens to the ratio of oxygenated HbO2(aq) to deoxygenated Hb(aq), i.e. when there is a high pressure of oxygen, PO2(g), in the lungs? The magnitude of K is critical for O2 to be pass first from lungs into red blood cells and then subsequently into the tissues. (a) If K was very small, would the equilibrium favour reactants or products in the above reaction? How would that affect the proportion of oxygenated HbO2(aq) to deoxygenated Hb(aq) in blood leaving the lungs? (b) Now consider the situation in the tissues of the body that rely on diffusion of oxygen from the bloodstream. If K was very large, how would that affect the amount of oxygen passing from blood into the tissues? (hint: Consider whether the forward or reverse reaction is required now)

Centrifuge Parts (match the part in Column A with the one correct function in Column B)

Column A

1. Rheostat ______

2. Bucket _______

3. Trunnion ring _____

4. Brake _______

Column B

A. sets spinning time

B. speed control

C. tube holder

D. holds bucket

E. allow for faster slow down time ?

Types of Centrifuges (match the Centrifuge name in Column A with the one correct function in Column B)

Column A

5. Cytospine

6. Horizontal head

7. Microheamatocrit

Column B

A. greater speed than angle head

B. retains good cellular detail

C. spins capillary tubes in hematology

D. better separation of layers

8. An advantage of a horizontal head centrifuge is (may be more than 1 answer)

a) gives best separation of layers

b) spins faster than angle head due to less wind resistance

c) holds more tubes

9. 8 tubes of whole blood were placed in a centrifuge. The speed was set for 2000 rpm for 10 minutes. The imbalance light came on as soon as the instrument started spinning. Choose from the list below all possible causes

a) rubber cushion missing from 1 or more buckets

b) tubes not placed opposite each other in buckets

c) blood volumes for opposite tubes not equal

d) tube sizes not all the same

10. If a method required spinning at an exact gravitational force, you must know the Relative Centrifugal Force for that centrifuge for a specific speed. The 2 things that will influence the RCF are: a) speed of rotation (RPM) b) size of the centrifuge (distance of tubes from motor shaft) c) nature of the samples to be spun RCF = 1.12R(RPM/1000)2, R= radius

11.State the steps to be followed if a tube of serum breaks in a centrifuge.