✅ MCQs: Reverse Osmosis (RO) System in Hemodialysis Water Treatment
1. What is the primary function of the reverse osmosis system in hemodialysis?
A. To warm the dialysate
B. To sterilize the dialyzer
C. To remove chemical and microbial contaminants from water
D. To balance electrolytes
➡️ Answer: C. To remove chemical and microbial contaminants from water
2. Which of the following contaminants is most effectively removed by the RO membrane?
A. Chlorine
B. Bacteria
C. Endotoxins
D. Dissolved salts and heavy metals
➡️ Answer: D. Dissolved salts and heavy metals
3. What is the typical rejection rate of solutes by a functioning RO membrane in dialysis water treatment?
A. 30–40%
B. 50–60%
C. 85–95%
D. 99.9%
➡️ Answer: C. 85–95%
4. What component is typically placed before the RO unit to remove chlorine/chloramine?
A. Micron filter
B. UV sterilizer
C. Carbon filter
D. Water softener
➡️ Answer: C. Carbon filter
5. Why is chlorine/chloramine removal important before the RO membrane?
A. They improve membrane performance
B. They reduce endotoxin levels
C. They can damage the RO membrane
D. They help sterilize the water
➡️ Answer: C. They can damage the RO membrane
6. Which water quality standard is followed for hemodialysis water treatment?
A. FDA
B. WHO
C. AAMI (Association for the Advancement of Medical Instrumentation)
D. CDC
➡️ Answer: C. AAMI
7. What is the recommended frequency for testing product water conductivity from the RO system?
A. Annually
B. Monthly
C. Weekly
D. Continuously during operation
➡️ Answer: D. Continuously during operation
8. What does a rise in RO product water conductivity indicate?
A. Better water quality
B. RO membrane damage or failure
C. Chlorine presence
D. UV system failure
➡️ Answer: B. RO membrane damage or failure
9. In a double-pass RO system, water passes through:
A. Two separate dialysis machines
B. The same RO membrane twice
C. Two RO membranes in sequence
D. The carbon filter twice
➡️ Answer: C. Two RO membranes in sequence
10. What is the primary purpose of the deionizer (DI) tanks, sometimes used after RO?
A. Kill bacteria
B. Adjust pH
C. Remove organic particles
D. Remove remaining ions and improve purity
➡️ Answer: D. Remove remaining ions and improve purity
11. The recommended maximum allowable level of total chlorine (free + combined) in water used for dialysis is:
A. 0.1 mg/L
B. 0.5 mg/L
C. 1.0 mg/L
D. 4.0 mg/L
➡️ Answer: A. 0.1 mg/L
(AAMI standard – above this may cause hemolysis in patients.)
12. The RO membrane should be disinfected:
A. Only when patient infection occurs
B. Once a year
C. As per manufacturer guidelines and at regular intervals
D. When endotoxin levels rise
➡️ Answer: C. As per manufacturer guidelines and at regular intervals
13. Which component is used after the RO unit to ensure microbiological purity of water?
A. Softener
B. UV light
C. Carbon filter
D. Dechlorinator
➡️ Answer: B. UV light
(Helps in microbial and endotoxin reduction post-RO.)
14. The correct order of water treatment components is typically:
A. RO → UV → Carbon → Softener
B. Carbon → Softener → RO → UV
C. Softener → UV → RO → Carbon
D. RO → Carbon → UV → Softener
➡️ Answer: B. Carbon → Softener → RO → UV
15. Which of the following is a limitation of RO systems in dialysis water treatment?
A. Cannot remove dissolved solids
B. Cannot remove bacteria
C. Cannot remove volatile gases like chlorine
D. Cannot filter particles
➡️ Answer: C. Cannot remove volatile gases like chlorine
(Carbon filters are needed to remove chlorine/chloramines before RO.)
16. When pressure across the RO membrane increases significantly, it usually indicates:
A. Normal operation
B. Membrane fouling or clogging
C. Good flow rate
D. Bacteria growth
➡️ Answer: B. Membrane fouling or clogging
17. According to AAMI standards, how often should endotoxin levels in RO product water be monitored?
A. Daily
B. Weekly
C. Monthly
D. Quarterly
➡️ Answer: C. Monthly
(Or more frequently if system issues occur.)
18. The term "product water" in RO systems refers to:
A. Water before carbon filtration
B. Water used to regenerate the softener
C. Water that exits the RO membrane for dialysis
D. Rejected water going to drain
➡️ Answer: C. Water that exits the RO membrane for dialysis
19. The main role of micron prefilters (e.g., 5-micron, 1-micron) is to:
A. Remove chlorine
B. Adjust pH
C. Trap sediments and particulates before reaching the RO membrane
D. Produce dialysate
➡️ Answer: C. Trap sediments and particulates before reaching the RO membrane
20. Water that fails RO rejection limits should be:
A. Used for rinsing the dialyzer
B. Used for cleaning dialysis machines only
C. Recycled into the product water tank
D. Rejected and sent to drain
➡️ Answer: D. Rejected and sent to drain
