Water Treatment Flashcards
Discuss the Medicare Conditions of Participation requirements regarding carbon tanks.
The purpose of the carbon tank is to remove chlorines from dialysis water with activated charcoal through absorption. The Medicare Conditions of Participation require two carbon tanks in a series. The first tank is the worker tank and the second is a polisher tank. The water must be exposed to the carbon bed for 5 minutes each tank, a total of 10 minutes. This is the empty bed contact time. If chlorine is found in water leaving the first tank then the carbon should be replaced. If chlorine is found leaving the second tank dialysis in the facility must be stopped until both tanks can be changed and the chlorine level rechecked.
Describe the methods of treating water for dialysis.
Filtration- removes particles that are roughly 5mm in size in feed water.
The Silt Density (SDI) measures the volume of suspended particles in feed water. The more particles the slower the filtration of the solution by the filtration process. Most reverse osmosis systems require that the feed water have an SDI less than 5.
The carbon tanks remove chlorine and chloramines by the process of adsorption. There are two tanks The second tank removes any chlorine particles not adsorbed by the first tank.
A water softener removes calcium and magnesium from the water by exchanging these ions for sodium.
The reverse osmosis (RO) system is the most effective system for water treatment in dialysis. Thr RO process moves water under pressure across a membrane, removing sodium and even endotoxins. The RO system has a rejection rate of at least 80%.
Explain why plain tap water cannot be used for dialysis.
Tap water contains many impurities, dissolved minerals, pesticides, herbicides and discarded medicines. Dialysis directly exposes the blood to any impurities that are present in the water in concentrations that are 20-25 times the amount consumed by drinking. Trace levels accumulate over time. Patients who dialyze three times per week would sustain a significant amount of exposure to these toxic substances.
In addition the pH of tap water may be either alkaline or acidic due to the presence of various substances that vary by region. Bicarbonate delivery systems will only work properly within a pH range of 6.5-7.8.
