Page 503 - Water and wastewater engineering

12-20 WATER AND WASTEWATER ENGINEERING

12-3. Estimate the area of membrane required for Bar Nunn’s new membrane filtration
plant. The manufacturer of one of the membranes they have selected for testing has
provided the following data:

Maximum TMP 103 kPa
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10
R m 3.1 10 cm
Based on their pilot tests, Bar Nunn has selected the following operating parameters:
Operating TMP 75% of maximum TMP
Temperature 20 C
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Q max 181.7 m /d
12-4. Bar Nunn has investigated an alternate manufacturer to the one identified in
Problem 12-3. The alternate manufacturer offers a vacuum operated system that
uses a maximum TMP of 55 kPa. With the exception of the TMP, the operating
conditions are the same as those given in Problem 12-3. The capital cost of mem-
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brane is $1,100/m for both membranes, but the operating costs are less for the
vacuum system because of the lower TMP. If the vacuum system operating costs
are $16,500 per year and those for the pressure system are $33,000 per year and
Bar Nunn uses 6.00% interest and a 10-year membrane life to evaluate alternatives,
which system should be chosen based on these costs alone?
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3
12-5. Yeehaw’s winter water demand is 10,400 m /d, and its summer demand is 15,600 m /d.
If the membrane filtration system is designed for the winter demand, can the system
meet the summer demand with the same area of membrane? The proposed winter and
summer design conditions are:
Maximum TMP 152 kPa
Operating TMP 75% of maximum TMP
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12
R m 2.94 10 m
Winter water temperature 4 C
Summer water temperature 20 C
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12-6. Snowshoe’s winter water demand is 7,600 m /d, and its summer demand is
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10,200 m /d. If the membrane filtration system is designed for the winter demand,
can the system meet the summer demand with the same area of membrane? The pro-
posed winter and summer design conditions are:
Maximum TMP 200 kPa
Operating TMP 75% of maximum TMP
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12
R m 3.2 10 m
Winter water temperature 1 C
Summer water temperature 15 C
12-7. A membrane manufacturer’s data sheet reports the following:
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Initial specific flux 1.24 L/h · m · kPa at 20 C
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Flux 33 L/h · m
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1
R m 2.9 10 m
What is the TMP for these conditions?