Water Treatment Systems for Dialysis Flashcards

What is the maximum allowable endotoxin level in hemodialysis product water per AAMI standards?

Answer: 0.25 EU/mL

AAMI standards require endotoxin levels below 0.25 EU/mL in product water for standard hemodialysis. Ultrapure dialysate (used for on-line hemodiafiltration) requires <0.03 EU/mL. Action level is 0.125 EU/mL.

Which test is performed daily to confirm that the carbon tanks are effectively removing chloramine?

Answer: Total chlorine colorimetric test using DPD reagent (or equivalent) on water sampled between and after the carbon tanks

DPD (N,N-diethyl-p-phenylenediamine) colorimetric testing is the standard method for daily chloramine monitoring. Samples are taken from between the two carbon beds and after the last carbon bed to confirm complete removal.

A technician notices the RO machine's product water conductivity has suddenly increased from 5 µS/cm to 45 µS/cm. What is the most likely cause?

Answer: RO membrane failure or bypass, allowing unfiltered water to pass through

A sudden spike in product water conductivity indicates that dissolved solids are passing through the RO system. This most commonly points to membrane failure, a bypass valve left open, or a broken O-ring seal. Treatment must not proceed until resolved.

What is the purpose of a 5-micron sediment filter placed upstream of the carbon tanks?

Answer: To remove particulate matter that would clog or foul the carbon beds and RO membrane

The 5-micron (or 10-micron) sediment pre-filter is the first stage of water treatment. It removes sand, rust, and particulates that would foul the carbon beds and damage the RO membrane, extending system life and efficiency.

How should a water treatment technician document findings from daily water quality checks?

Answer: In a dated log that records test results, operator initials, and any corrective actions taken

All water quality test results must be recorded in a dedicated logbook with date, time, results, operator initials, and corrective actions. This documentation is reviewed during regulatory inspections (CMS, state agencies).

What happens to the water softener resin during regeneration, and what chemical is used?

Answer: Saturated sodium chloride (brine) solution flushes the resin, replacing accumulated calcium and magnesium with sodium ions

Water softener regeneration uses concentrated brine (NaCl solution). The high sodium concentration displaces calcium and magnesium ions from the resin exchange sites via mass action, restoring the resin's softening capacity.