TEST YOUR KNOWLEDGE
Expert Biofouling Control Training Level: Expert
To test your proficiency on the topics covered in this seminar, 20 questions are provided. The questions cover the major concepts participants learn in this seminar.
1. Which is more biofouling to an RO unit (biofouling bacteria present)?
a. 200 mg/L Total Dissolved Solids (TDS) feed water b. 2,000 mg/L TDS feed water c. 35,000 mg/L TDS feed water d. Can’t tell
2. Which is more biofouling to an RO unit (biofouling bacteria present)?
a. 10 cfu/mL feed water, measured by Heterotrophic Plate Count (HPC) b. 50 cfu/mL feed water (from HPC) c. 100 cfu/mL feed water (from HPC) d. Can’t tell
3. Which is more biofouling to an RO unit (biofouling bacteria present)?
a. 1 mg/L TOC feed water b. 5 mg/L TOC feed water c. 10 mg/L TOC feed water d. Can’t tell
4. Which is more biofouling to an RO unit (biofouling bacteria present)?
a. 1 mg/L VOC feed water b. 5 mg/L VOC feed water c. 10 mg/L VOC feed water d. Can’t tell
5. Which is more biofouling to an RO unit (biofouling bacteria present)?
a. 1 mg/L AOC feed water b. 5 mg/L AOC feed water c. 10 mg/L AOC feed water d. Can’t tell
6. Surface water contacts the atmosphere, which contains 21% oxygen. Viable (living, reproducing) bacteria in the water near the surface will be:
a. Aerobic b. Anaerobic c. Facultative anaerobic d. a. and b. are correct e. b. and c. are correct f. a. and c. are correct g. None of the above h. All of the above
7. If the feed water in #6 is chlorinated, pretreated, and then dechlorinated with bisulfite to the point of removing all oxygen from the feed water, the RO is less likely to foul.
a. True b. False
8. From a potential RO unit biofouling standpoint, which of the following feed waters would likely produce more biofouling?
a. Water Sample 1 b. Water Sample 2 c. Neither would likely cause biofouling d. Both would cause equal biofouling
Water Sample 1: Mississippi Lake Water
Total Dissolved Solids, mg/L
96-131
Conductivity, μS/cm
96-225
pH
6.5-7.9
Temperature, oF
50-95
TOC, mg/L
10-16
Water Sample 2: Mississippi River Water
300
683
7.4-8.8
34-87
5
9. From a potential RO unit biofouling standpoint, which of the following feed waters would likely produce more biofouling?
Water Sample 1: Persian Gulf Seawater
38,000
59,000
6.3
84
NA
Water Sample 2: Atlantic Ocean Seawater (Morocco)
22.109
8
63-68
10. From a potential RO unit biofouling standpoint, which of the following feed waters would likely produce more biofouling?
Water Sample 1: Surface Water
450
7.5
90
8.2
AOC, mg/L
1.7
Water Sample 2: Surface Water
500
750
7.4
5.5
3.1
11. Where can biofouling occur in an RO membrane element (with typical natural water and good membrane performance)?
a. Surface of the membrane b. Feed spacer c. Permeate spacer (water carrier) d. Both a. and b. are correct e. Both b. and c. are correct f. Both a. and c. are correct g. None of the above h. All of the above
12. Which element in an RO unit typically has the highest fouling potential because it has the highest water flux?
a. 1st Element, 1st Stage b. Last Element, 1st Stage c. 1st Element, Last Stage d. Last Element, Last Stage e. None of the above
13. A higher crossflow rate:
a. Decreases scaling potential b. Decreases fouling potential c. Increases scaling potential d. Increases fouling potential e. Both a. and b. are correct f. Both c. and d. are correct g. None of the above
14. Operating an RO unit such that all elements have a water flux rate less than the sustainable flux rate will result in:
a. Less permeate production b. Less pressure drop c. Lower permeate conductivity d. No fouling e. Both a. and b. are correct f. Both c. and d. are correct g. None of the above
15. Stable colloids are:
a. Repelled by each other b. Attracted to each other c. Repelled by RO membranes d. Attracted to RO membranes e. Both a. and c. are correct f. Both b. and d. are correct g. None of the above
16. What is the current understanding of the steps in membrane biofouling? (Put in correct order)
l. Transport of Microbial Cells m. Steady State Due to Shear Force n. Adsorption of Organics o. Growth & Biofilm Development p. Attachment of Microbial Cells a. p, l, m, n, o b. p, o, n, m, l c. p, l, n, o, m d. n, m, o, p, l e. n, l, p, m, o f. n, l, p, o, m
l. Transport of Microbial Cells m. Steady State Due to Shear Force n. Adsorption of Organics o. Growth & Biofilm Development p. Attachment of Microbial Cells
a. p, l, m, n, o b. p, o, n, m, l c. p, l, n, o, m d. n, m, o, p, l e. n, l, p, m, o f. n, l, p, o, m
17. Which of the following are pretreatment issues that can promote biofouling?
a. Chlorination followed by dechlorination b. Upstream coagulant injection c. Dechlorinated water in surge tanks d. Low AOC concentration e. Only 2 of the above (a. – d.) are correct f. Only 3 of the above (a. – d.) are correct g. All of the above (a. – d.) are correct h. None of the above is correct
18-20. Here is the sample RO unit at startup. Compare this startup data to Today’s data in 18-20.
18. Based on Today’s data, this unit is likely biofouled, because:
a. The pressure drop across the first stage is higher b. The pressure drop across the second stage is higher c. The pressure drop across the whole RO unit is higher d. The feed pressure is higher e. a., c., & d. f. b., c., & d. g. All of the above h. None of the above
19. Based on Today’s data, this unit is likely biofouled, because:
20. Based on Today’s data, this unit could be biofouled, because: