Water Treatment and Quality Flashcards
6 cards from real CCHT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Water Treatment and Quality flashcards as text
What is the primary purpose of the softener in the dialysis water treatment system?
Answer: To remove calcium and magnesium ions to prevent scaling and protect the reverse osmosis membrane
The water softener exchanges calcium and magnesium ions (which cause 'hardness') for sodium ions using a cation exchange resin. This prevents scaling and mineral deposit buildup in pipes, the reverse osmosis membrane, and dialysis machines.
What is the maximum allowable bacterial count in dialysis water per AAMI standards?
Answer: 200 CFU/mL (action level 50 CFU/mL)
AAMI standards require dialysis water to have less than 200 CFU/mL of bacteria, with an action level of 50 CFU/mL. Exceeding the action level requires investigation and corrective action before results reach the maximum allowable limit.
Chloramine is particularly dangerous in dialysis water because it can cause which serious complication?
Answer: Hemolytic anemia from oxidative damage to red blood cell membranes
Chloramine (a combination of chlorine and ammonia used as a disinfectant in municipal water supplies) cannot be removed by reverse osmosis and can cross the dialyzer membrane to enter the patient's blood, causing oxidative damage to red blood cell membranes and hemolytic anemia.
What does the conductivity test of dialysate measure, and why is it important?
Answer: The total dissolved solute concentration of the dialysate, confirming correct electrolyte mixing
Dialysate conductivity measures the total ionic concentration of the dialysate, which serves as a proxy for correct electrolyte composition (sodium, potassium, calcium, magnesium, bicarbonate). It confirms that concentrate and water are being mixed at the correct proportions.
How often should activated carbon filters in the dialysis water treatment system be tested for chlorine/chloramine removal efficacy?
Answer: Before the first patient treatment of each day and after each shift
AAMI standards require testing the effluent of the activated carbon filters for total chlorine and chloramines before the first patient treatment of the day and after each shift change, because carbon capacity can be exhausted at any time, and breakthrough is not visually detectable.
What is the role of the reverse osmosis (RO) unit in the dialysis water treatment system?
Answer: To remove the majority of dissolved solutes, bacteria, and endotoxins from the pretreated water
The reverse osmosis unit is the primary purification step, removing 90–99% of dissolved solutes (including toxic metals, bacteria, viruses, and endotoxins) through membrane filtration under high pressure. It produces the ultrapure water required for dialysate preparation.