CHBT Water Treatment Systems for Dialysis 2 — Questions and Answers
Question 1: What does total dissolved solids (TDS) measurement indicate in a water treatment system?
- The overall ionic load in the water; high TDS after the RO suggests membrane failure (Correct answer)
- The bacterial contamination level of the product water
- The concentration of endotoxins in the distribution loop
- The hardness of the water before softener treatment
Correct 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.
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.
Question 2: What is the purpose of the distribution loop in a dialysis facility water system?
- To continuously circulate purified water to all dialysis stations, preventing bacterial stagnation (Correct answer)
- To store reserve dialysate concentrate for emergency use
- To mix product water with dialysate concentrate before delivery to the machine
- To return used dialysate to the pre-treatment tank for re-purification
Correct 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.
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.
Question 3: Why must a dialysis water treatment system use two activated carbon beds in series?
- To provide a redundant safety barrier; the first bed removes most chloramines and the second confirms complete removal (Correct answer)
- To double the filtration capacity for high-volume facilities
- Because a single carbon bed cannot remove sediment particles
- To allow one bed to regenerate while the other operates
Correct 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.
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.
Question 4: What chemical is commonly used to disinfect a hemodialysis water distribution loop?
- Peracetic acid or sodium hypochlorite (bleach) (Correct answer)
- Formaldehyde only (no substitutes)
- Hydrogen peroxide is prohibited in water systems
- Ethanol at 70% concentration
Correct 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.
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.
Question 5: Which contaminant in dialysis water is associated with aluminum bone disease and encephalopathy in dialysis patients?
- Aluminum (Correct answer)
- Fluoride
- Nitrates
- Copper
Correct 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).
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).
Question 6: What is the 'reject water' from a reverse osmosis system?
- The concentrated waste stream containing all filtered contaminants that is drained away (Correct answer)
- Product water that failed conductivity testing and is discarded
- The pre-filtered water returned to the softener for reprocessing
- Dialysate that has passed through the dialyzer and is discarded
Correct 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.
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.
CHBT Water Treatment Systems for Dialysis 2
What does total dissolved solids (TDS) measurement indicate in a water treatment system?