Water Treatment Systems for Dialysis Flashcards

What does total dissolved solids (TDS) measurement indicate in a water treatment system?

Answer: The overall ionic load in the water; high TDS after the RO suggests membrane failure

TDS is a proxy measure of the RO membrane's rejection efficiency. A rising TDS in product water indicates the membrane may be failing, allowing contaminants to pass through. It is monitored continuously by the machine's conductivity sensor.

What is the purpose of the distribution loop in a dialysis facility water system?

Answer: To continuously circulate purified water to all dialysis stations, preventing bacterial stagnation

The distribution loop keeps purified water moving continuously at a velocity that prevents biofilm formation. Dead legs (stagnant sections) in the loop are a primary source of bacterial contamination.

Why must a dialysis water treatment system use two activated carbon beds in series?

Answer: To provide a redundant safety barrier; the first bed removes most chloramines and the second confirms complete removal

Two carbon beds in series provide a safety redundancy. Testing is performed between the two beds; if the first bed breaks through, the second provides backup protection. A single bed with no verification point is insufficient for patient safety.

What chemical is commonly used to disinfect a hemodialysis water distribution loop?

Answer: Peracetic acid or sodium hypochlorite (bleach)

Peracetic acid and sodium hypochlorite are the most common loop disinfectants. They must be thoroughly rinsed out and residuals verified before the system is returned to service. Formaldehyde is being phased out due to toxicity.

Which contaminant in dialysis water is associated with aluminum bone disease and encephalopathy in dialysis patients?

Answer: Aluminum

Aluminum contamination from municipal water or aluminum-containing flocculants accumulates in dialysis patients, causing aluminum bone disease (adynamic bone disorder) and dialysis encephalopathy (dementia-like syndrome).

What is the 'reject water' from a reverse osmosis system?

Answer: The concentrated waste stream containing all filtered contaminants that is drained away

RO systems produce two streams: product water (permeate, ~75% of input) and reject water (concentrate, ~25%). The reject stream carries all the removed contaminants and is sent to drain. The recovery rate affects operating cost.