Water Treatment Systems for Dialysis Flashcards

What is the primary purpose of a reverse osmosis (RO) unit in a dialysis water treatment system?

Answer: To remove dissolved solids, minerals, and most contaminants from feed water to produce purified product water

The RO unit is the core purification stage. It forces water through a semipermeable membrane under pressure, rejecting 95–99% of dissolved ions, organic molecules, bacteria, and endotoxins.

Why is chloramine particularly dangerous for hemodialysis patients compared to the general population?

Answer: Chloramine cannot be removed by dialyzer membranes and enters the bloodstream, causing hemolytic anemia

Dialysis patients are exposed to 120–150 liters of water per treatment. Chloramine passes through the dialyzer membrane and binds to hemoglobin, causing methemoglobin formation and hemolytic anemia. It must be removed by activated carbon.

Which component in the water treatment system is specifically designed to remove chlorine and chloramines from municipal water?

Answer: Activated carbon adsorption tanks

Activated carbon tanks adsorb chlorine and chloramine through chemical bonding. Two carbon tanks in series are required, with testing between them to verify complete removal before water reaches the RO membrane.

According to AAMI/ANSI standards, what is the maximum allowable bacterial count (CFU/mL) in hemodialysis product water?

Answer: 100 CFU/mL

AAMI standards (ANSI/AAMI RD52) specify a maximum of 100 CFU/mL for product water. The action level is 50 CFU/mL. Exceeding these levels requires immediate investigation and corrective action.

What is the function of a water softener in the pre-treatment stage of a dialysis water system?

Answer: To remove calcium and magnesium ions that would foul and damage the RO membrane

Hard water minerals (calcium and magnesium) cause scaling on the RO membrane, reducing efficiency and lifespan. The water softener exchanges these divalent ions for sodium through cation exchange resin.

How often should a dialysis facility test product water for chloramine residuals?

Answer: Before each patient treatment shift (daily)

Chloramine testing must be performed before each patient treatment shift (at minimum daily). The carbon tank can exhaust without warning, and delayed detection could expose multiple patients to hemolytic risk.