[Introduction to Dialysis]
Module 6: Water Treatment
questions with complete
verified solutions (graded A+)
Water Treatment - answer In dialysis, we use water to mix concentrates
and germicides, flush out and reprocess dialyzers, and rinse out jugs.
When we are healthy, we can handle some contaminants in our drinking
water. Our digestive tracts and kidneys can help protect us. Hemodialysis
patients do not have those protections. Their blood comes in contact with
large volumes of water in dialysate through the dialyzer membrane at
each treatment. Using purified water for HD is vital. Contaminated water
can cause illness and death.
To keep patients safe, all water for HD is passed through a water
treatment system. This system is made up of a several components; each
removes some contaminants until the water is safe to use.
Water Supply - answer Dialysis water starts out as tap water that has
been treated to be safe for drinking. Tap water comes from one of two
sources which can also interact with each other:
- Ground water comes from wells and springs. It is often higher in ions
(e.g., iron, calcium, magnesium), but lower in microbes (e.g., bacteria,
viruses, endotoxins) than surface water.
- Surface water comes from lakes, ponds, rivers, and reservoirs. Surface
water may be higher than ground water in pesticides, industrial waste,
sewage, and microbes.
Drinking Water Contaminants - answer We call water the universal
solvent. It dissolves more substances than any other liquid. As rainwater
falls through the air toward earth, it picks up contaminants like carbon
dioxide and sulfur dioxide gases. These dissolve in the water to make
weak carbonic and sulfuric acids: acid rain. When acid rain flows over
limestone and other minerals, the acid dissolves them. This process forms
,calcium carbonate and calcium sulfate, common impurities in tap water.
Other substances also dissolve in water, such as:
- Sodium chloride (salt).
- Fluoride.
- Nitrate salts.
- Pesticides.
All tap water has some contaminants. Which ones occur in your water will
depend on what is nearby, the season, and the types of industry in the
area. Fertilizers and pesticides can show up in water in farm regions, for
example. When you are responsible for dialysis water treatment, you will
need to be aware of the challenges that affect your local water in the
short or long term. For example:
- Severe storms or floods can overwhelm water treatment systems and let
raw sewage wash into water.
- Pharmaceutical drugs can be present at low levels in even treated
drinking water, because so many medicines are flushed down or excreted
into toilets.
- Hydraulic fracking pumps a cocktail of chemicals (such as benzene and
formaldehyde) into the ground to obtain natural gas from shale. These
chemicals can seep into local water.
- Chemical spills can contaminate water supplies.
Drinking Water Standards - answer U.S. drinking water is regulated by the
Environmental Protection Agency (EPA) to protect us all from harm. All
public water supplies must at least meet the minimal standards set by the
Safe Drinking Water Act, which passed in 1974 to make water safe for the
public to drink. States monitor and enforce the law, and your state may
also have set more stringent rules than the EPA. A system is "public" if it:
- Has at least 15 service connections.
- Serves at least 25 people per day for 60 days of the year.
Certain other water systems do not have to meet EPA Safe Drinking Water
standards:
- "Small" water systems that serve fewer than 3,000 people (small
systems may still need to meet stringent state standards, however).
,- Water systems in disadvantaged areas that serve fewer than 500 people.
- Private wells that serve fewer than 25 people.
- Towns that receive variances for the presence of certain chemicals in the
water supply.
Many contaminants can make their way into drinking water. We must
remove these before the water can be used for HD.
Tap Water Treatment - answer To help keep us all safe, tap water is tested
and treated with several steps that include:
1. Coagulation and flocculation. Dirt and many dissolved particles have a
negative charge. So, chemicals like alum (an aluminum compound) with a
positive charge are added to the water as a first treatment step. These
neutralize the charge, then bind (coagulate) with particles to form larger
clump, or "floc." Alum is called a flocculant for this reason.
2. Sedimentation. The heavy clumps settle to the bottom of the water.
3. Filtration. Clear water on top of the sediment is passed through a series
of filters, like gravel, sand, and charcoal to remove dissolved particles of
varying sizes.
4. Disinfection. Chlorine or chloramine is added by public systems to kill
microbes and parasites. Chloramines are made by mixing chlorine and
ammonia. They are used by cities when a long-acting chlorine is needed,
for example, when a water distribution system is large. These compounds
can also form in nature, when chlorine combines with organic material. In
most cases, public systems use monochloramine. Some towns switch back
and forth between chlorine and chloramines. Some use other products like
chlorine dioxide.
5. Fluoride is added by public water treatment systems to prevent tooth
decay. Levels of fluoride in drinking water may vary from day to day.
, 6. Some cities change the water pH (acid/ base level) to reduce the
amount of metals that might leach (dissolve) out of the water system's
pipes and into drinking water.
Dialysis Water - answer People with healthy kidneys drink about 10-14
liters of water or other beverages each week. People who do standard in-
center HD have their blood exposed to 270-576 liters of water per week in
the dialysate and through a dialyzer membrane. High-flux HD membranes,
which have large pores, allow chemicals or endotoxins (toxic bacterial wall
fragments) to pass into the blood. Longer and/or more frequent HD can
expose patients to even more water. Thus, HD water must be far cleaner
than drinking water, and must meet at least the minimum standards for:
- Bacteria.
- Endotoxins.
- Metals.
- Trace elements.
- Salts.
- Other substances.
AAMI Standards for Dialysis Water - answer The Association for the
Advancement of Medical Instrumentation (AAMI) writes the guidelines for
dialysis water. These become standards when the American National
Standards Institute (ANSI) approves them. Some products that make
water safe to drink can harm patients and machines. So, we must test and
treat tap water to meet ANSI/AAMI standards for HD. If HD water
treatment fails, we can use tap water only if the levels of all contaminants
still meet the standards.
In the Conditions for Coverage, the Centers for Medicare and Medicaid
Services (CMS) adopted ANSI/AAMI RD52:2004 and RD62:2001 for water
treatment.
Home Dialysis and Water Treatment - answer Water used for home HD
must be tested, too, and some patients may have private wells. If well
water quality does not meet the standards for HD, the clinic may need to
offer a machine that uses bags of dialysate and does not require water
treatment.
Module 6: Water Treatment
questions with complete
verified solutions (graded A+)
Water Treatment - answer In dialysis, we use water to mix concentrates
and germicides, flush out and reprocess dialyzers, and rinse out jugs.
When we are healthy, we can handle some contaminants in our drinking
water. Our digestive tracts and kidneys can help protect us. Hemodialysis
patients do not have those protections. Their blood comes in contact with
large volumes of water in dialysate through the dialyzer membrane at
each treatment. Using purified water for HD is vital. Contaminated water
can cause illness and death.
To keep patients safe, all water for HD is passed through a water
treatment system. This system is made up of a several components; each
removes some contaminants until the water is safe to use.
Water Supply - answer Dialysis water starts out as tap water that has
been treated to be safe for drinking. Tap water comes from one of two
sources which can also interact with each other:
- Ground water comes from wells and springs. It is often higher in ions
(e.g., iron, calcium, magnesium), but lower in microbes (e.g., bacteria,
viruses, endotoxins) than surface water.
- Surface water comes from lakes, ponds, rivers, and reservoirs. Surface
water may be higher than ground water in pesticides, industrial waste,
sewage, and microbes.
Drinking Water Contaminants - answer We call water the universal
solvent. It dissolves more substances than any other liquid. As rainwater
falls through the air toward earth, it picks up contaminants like carbon
dioxide and sulfur dioxide gases. These dissolve in the water to make
weak carbonic and sulfuric acids: acid rain. When acid rain flows over
limestone and other minerals, the acid dissolves them. This process forms
,calcium carbonate and calcium sulfate, common impurities in tap water.
Other substances also dissolve in water, such as:
- Sodium chloride (salt).
- Fluoride.
- Nitrate salts.
- Pesticides.
All tap water has some contaminants. Which ones occur in your water will
depend on what is nearby, the season, and the types of industry in the
area. Fertilizers and pesticides can show up in water in farm regions, for
example. When you are responsible for dialysis water treatment, you will
need to be aware of the challenges that affect your local water in the
short or long term. For example:
- Severe storms or floods can overwhelm water treatment systems and let
raw sewage wash into water.
- Pharmaceutical drugs can be present at low levels in even treated
drinking water, because so many medicines are flushed down or excreted
into toilets.
- Hydraulic fracking pumps a cocktail of chemicals (such as benzene and
formaldehyde) into the ground to obtain natural gas from shale. These
chemicals can seep into local water.
- Chemical spills can contaminate water supplies.
Drinking Water Standards - answer U.S. drinking water is regulated by the
Environmental Protection Agency (EPA) to protect us all from harm. All
public water supplies must at least meet the minimal standards set by the
Safe Drinking Water Act, which passed in 1974 to make water safe for the
public to drink. States monitor and enforce the law, and your state may
also have set more stringent rules than the EPA. A system is "public" if it:
- Has at least 15 service connections.
- Serves at least 25 people per day for 60 days of the year.
Certain other water systems do not have to meet EPA Safe Drinking Water
standards:
- "Small" water systems that serve fewer than 3,000 people (small
systems may still need to meet stringent state standards, however).
,- Water systems in disadvantaged areas that serve fewer than 500 people.
- Private wells that serve fewer than 25 people.
- Towns that receive variances for the presence of certain chemicals in the
water supply.
Many contaminants can make their way into drinking water. We must
remove these before the water can be used for HD.
Tap Water Treatment - answer To help keep us all safe, tap water is tested
and treated with several steps that include:
1. Coagulation and flocculation. Dirt and many dissolved particles have a
negative charge. So, chemicals like alum (an aluminum compound) with a
positive charge are added to the water as a first treatment step. These
neutralize the charge, then bind (coagulate) with particles to form larger
clump, or "floc." Alum is called a flocculant for this reason.
2. Sedimentation. The heavy clumps settle to the bottom of the water.
3. Filtration. Clear water on top of the sediment is passed through a series
of filters, like gravel, sand, and charcoal to remove dissolved particles of
varying sizes.
4. Disinfection. Chlorine or chloramine is added by public systems to kill
microbes and parasites. Chloramines are made by mixing chlorine and
ammonia. They are used by cities when a long-acting chlorine is needed,
for example, when a water distribution system is large. These compounds
can also form in nature, when chlorine combines with organic material. In
most cases, public systems use monochloramine. Some towns switch back
and forth between chlorine and chloramines. Some use other products like
chlorine dioxide.
5. Fluoride is added by public water treatment systems to prevent tooth
decay. Levels of fluoride in drinking water may vary from day to day.
, 6. Some cities change the water pH (acid/ base level) to reduce the
amount of metals that might leach (dissolve) out of the water system's
pipes and into drinking water.
Dialysis Water - answer People with healthy kidneys drink about 10-14
liters of water or other beverages each week. People who do standard in-
center HD have their blood exposed to 270-576 liters of water per week in
the dialysate and through a dialyzer membrane. High-flux HD membranes,
which have large pores, allow chemicals or endotoxins (toxic bacterial wall
fragments) to pass into the blood. Longer and/or more frequent HD can
expose patients to even more water. Thus, HD water must be far cleaner
than drinking water, and must meet at least the minimum standards for:
- Bacteria.
- Endotoxins.
- Metals.
- Trace elements.
- Salts.
- Other substances.
AAMI Standards for Dialysis Water - answer The Association for the
Advancement of Medical Instrumentation (AAMI) writes the guidelines for
dialysis water. These become standards when the American National
Standards Institute (ANSI) approves them. Some products that make
water safe to drink can harm patients and machines. So, we must test and
treat tap water to meet ANSI/AAMI standards for HD. If HD water
treatment fails, we can use tap water only if the levels of all contaminants
still meet the standards.
In the Conditions for Coverage, the Centers for Medicare and Medicaid
Services (CMS) adopted ANSI/AAMI RD52:2004 and RD62:2001 for water
treatment.
Home Dialysis and Water Treatment - answer Water used for home HD
must be tested, too, and some patients may have private wells. If well
water quality does not meet the standards for HD, the clinic may need to
offer a machine that uses bags of dialysate and does not require water
treatment.
