Module 8 Water Treatment

water storage

- must have a tight fitted lid and be vented by a hydrophobic 0.2 Micron air filter -tank have a cone or bowled shaped bottom - a centrifical pump made of inert materials needed to move product water out of tank to piping.

Central Ro systems

- produce pure water for a small medium or large number of dialysis stations. -systems are constantly being used so there is little down time for stagnant water. - designed to be easy to use and to disinfect - backwashing feature can reduce scale deposit and bacterial growth on the membrane - heat or chemical disinfection can maybe offer.

Monitoring RO device

-Check the RO operating parameters each day for flow and pressure. check pressure in: incoming water pump that pushes water through the membrane the product water measure water flow in: product flow waste flow direct systems Most often 10-12 gpm at 30-40 psi Also check TDS levels in RO water

GAC and how it works

-Granular activated charcoal -With it's large surface area GAC absorbs low-molecular-weight particles from water like a magnet attracts on

backflow prevention device

-To keep water from flowing backwards into incoming water supply, installed at start of Water treatment system. -For dialysis we must use a reduced pressure backflow assembly (RPBA) - a certified backflow assembly tester must check the device every year.

why we do not solely rely on UV light and dialysis

-UV light Fades over time which allow microbes to become resistant to it. -you must replace the light source each year or continuously monitor its strength.

Distribution system

-distribution pump will send the water to the stations or a storage tank. - unused water may go to the drain. -may have return loop that carries water back to the system this prevent stagnant spots and let the clinics use less feed water.

Portable RO system

-mainly use for HD in hospitals or at home and usually serve only one station. -units tend to have a greater chance for stagnant water than Central Ro systems -smaller units are easy to transport to point of use. -A failed system can be easily replaced with a second unit

sediment filters and media filters have either

-pores of various sizes to strain out particles solids and other substances. (cartridge filter) -layers of different size media so each there can trap smaller particles. (depth filter)

Risk of DI

-water from exhausted d i tanks may have high levels of harmful ions. -treated water may become very acidic or alkaline. -use of DI to treat water with chlorine will form cancer-causing nitrosamines -DI does not remove non charged particles like bacteria and endotoxins -A DI unit can fail catastrophicallywith no warning -at a neutral pH aluminum does not carry a charge so DI will not remove it

two kinds of RO systems

1. Central Ro systems 2. portable Ro systems

each component of a dialysis water treatment system serve one of three main functions

1. Pretreatment- preparing the water before it reaches the fragile reverse osmosis membrane 2. Purification- ensuring that the water is free of chemicals and germs 3. Distribution-bring the product water to the point of use

Protecting the RO membrane by making sure the feed water

1. has particles filtered out that could tear the membrane or cause a buildup of scale. 2. is not too hot or too cold

Key Components for Dialysis Water Systems

1. incoming water 2. blending valve- Mixes hot and cold water to reach an Ro membrane standard temperature 77°F 3. backflow prevention device- keeps treated dialysis water from backing up into the tap water system. 4. booster pump-keeps water pressure consistent so RO system has a constant flow 5. multimedia filter- layers of media ranging in size from gravel to sand trap large particles. 6. water softener- removes minerals that could form scale on Ro membrane. 7. brine tank- contains salt pellets to make brine for the water softener. 8. primary carbon tank- removes chlorine and chloramines 9. secondary carbon tank- CMS requires at least two tanks 10. cartridge filter- place before the RO to catch carbon fines resin beads to Breeze and other particles that can damage the RO. 11. reverse osmosis pump- increases water pressure across the RO membrane made of high-grade steel, inert plastics carbon graphite wetted parts 12. Ro membrane purified water to ANSI/ AAMI's standards

two types of Distribution Systems

1. indirect feed system uses a storage tank 2. direct feed system does not

limitations of TFC RO membranes

1. they must be disinfected on a regular schedule. 2. they break down when exposed to chlorine and chloramines so these must be removed before they reach the membrane. 3. use of peracetic acid for disinfection and above a 1% dilution wrist damage to the membrane 4. scale can build up and clog the membrane. Routine cleaning is needed to scrape off scale build up.

ion exchange

1. when hard water goes to the softener, the soduim ion coated polystyrene resin beads attract the strong of positive ions of calcium and magnesium. 2. Ions of calcium and magnesium are removed or traded for sodium ions which then form sodium chloride (salt). the resin gives up sodium ions of equal charge.

People with healthy kidneys drink

10-14 litres of water per week

Hemodialysis patients are exposed to

270-576 litres of water per week

RO can reject ____%-____% of charged ionic particles and nearly all organic and inorganic substances.

95-99%

in conditions for coverage, the centers for Medicare and Medicaid adopts these 2 standards for H2O treatment

ANSI/AAMI RD52:2004 standards for dialysate ANSI/AAMI RD62:2001 standards for water treatment and equipment

ANSI

American National Standards Institute

AAMI

Association for the Advancement of Medical Instrumentation. A voluntary organization that writes guidelines for medical products and procedures.

Pretreatment Components

BACKFLOW PREVENTION DEVICE- first in line to keep chemicals used for treating dialysis water from backing up into a city water supply. TEMPERATURE BLENDING VALVE- mix hot and cold water to ensure feed water that is at a safe temperature for the RO. BOOSTER PUMP-will push water through the system at a safe rate. Downstream from the backflow prevention device and temperature blending valve. PRE-FILTER- place just before the RO to remove carbon fines resin beads and other debris. PRESSURE GAUGES- should be placed before and after a filter to check for clogging. CHEMICAL INJECTION SYSTEMS- may be used to alter the feed water PH if needed. SEDIMENT FILTERS- remove particles that could damage the RO CARBON TANKS removes chlorine and chloramines that can harm patients or the RO. WATER SOFTENER- may be used to remove some minerals from the feed water.

Bacteria can form what on surfaces

Biofilm slime that anchors them in place on surfaces.

Tap Water Treatment

Coagulation and Flocculation- Alum is added which binds with dirt particles to form larger clumps or floc. Sedimentation -the heavy clumps settle in the bottom of the water Filtration- clear water at the top passes through a series of filters like gravel sand and charcoal to remove dissolved particles. Disinfection- chlorine or chloramine is added to water to kill microbes and parasites. Fluoride- added to protect teeth pH- may need to be balanced to reduce amounts of metals from leaching out through the pipes.

ANSI/AAMI's standards for Endotoxins in US dialysis water

Conventional/Critical level -2 EU/mL Action Level- 1 EU/mL Ultrapure Level- 0.03 EU/mL

ANSI/AAMI's standards for bacteria in US dialysis water

Conventional/Critical level -200 CFU/mL Action Level- 50 CFU/mL Ultrapure Level- 0.1 CFU/mL

deionization DI tank

DI can make very pure product Water by removing solutes using an electrical charge. maybe used to "polish" the water if Ro alone does not result in water that meets aami standards

types of DI system

DUAL BED- DI systems keep anion and cation resin in separate tanks or tanks in a series where the water goes to both a first and second tank. MIXED BED- tanks contain both cation and anion resin beads. mixed bed tanks make high-quality Water than dual bed systems

Hemolysis

Destruction of red blood cells

Drink water is regulated by

Environmental Protection Agency (EPA)

benefits of backwashing

For Sediment Filters rinses out trap particles and fluffs up the media layers to help reduce channeling. For Carbon tanks backwashing fluffs the carbon granules to expose new surfaces remove water channels and prolong the life of GAC.

Two types of bacteria

Gram Positive bacteria turn purple when using Gram stain Gram Negative bacteria does not retain any stain (pink)

two sources of tap water

Groundwater - comes from Wells and Springs. it's higher in ions (Fe, Mg, Ca) but lower and microbes than surface water. Surface water- comes from lakes ponds rivers and reservoirs. Higher than surface water in pesticides, industrial waste sewage and microbes.

V192

Medicare requires all system to have at least two carbon tanks in series

V187

Medicare requires each Clinic to have a schematic drawing of your system with each part labeled including which way the water flows in the pipes.

Endotoxemia

Presence of endotoxins in the blood. Can cause inflammation.

DI System operating parameters

Pure DI water has a resistivity of 18.3 megohms-cm and should not be less than 1 megohms-cm. Required to check and document resistivity on a log 2x each day of use

Purification components

RO SYSTEM- produces product Water by rejecting contaminants. DEIONIZATION (DI) - if used a carbon filter must always come before a DI system so cancer-causing nitrosamines cannot reach patients and an ultra filter or other way to remove microbes must be used after the DI tank to capture microbes. UV LIGHT- keeps microbes that might have slipped past the RO from reproducing . A UV light may be placed with pretreatment components after the carbon tanks to reduce the level of microbes going into the RO system. SUB MICRON ULTRA FILTERS- backup the UV light and remove microbes that remain. Placed before distribution piping and downstream from the DI tanks..

Acid Feed Pump

RO membrane works best with water PH range from 5 to 8.5. High pH affects RO and carbon filters. pH is lowered by injecting a small amount of hydrochloric or sulfuric acid into the feed water

How RO works

RO uses a hydraulic pressure pump to push the water with high solute levels through a membrane. Salts and other contaminants are sent to the drain.

how water collects impurities

Rain water falls through the air picking up carbon dioxide and sulfur dioxide gases. Weak carbonic and sulfuric acid is created. The acid rain dissolves the limestone and minerals forming calcium carbonate and calcium sulfate.

reverse osmosis System

Ro is the heart of a dialysis water treatment system and is the most costly and delicate. a RO system has a pressure pump and one or more semipermeable membranes.

monitoring the water softener

Test at start of the day and at the end of each day for water hardness. hardness should not exceed 1 grain per gallon gpg which equals 17 parts per million. used test strips or the EDTA method. check timer settings for correct time.

Temperature blending valve

The RO works best when feed water stays between 77 to 82°F A drop in Temp leads to a drop in product water flow and increase in solute removal. permanent damage to our own membranes may occur if the temperature is above 95°F

RD62:2001

The interpretive guidance incorporates by reference AAMI's American National standard for water treatment equipment for hemodialysis applications as the specifications for various water treatment components and has the authority regulation.

how do water softeners work

They work by ion exchange.

how does UV light work

UV changes the DNA of microbes so they die or cannot multiply

UV light structure

a low pressure mercury vapor UV lamp is a house inside a clear quartz sleeve.

when endotoxins pass into the patient's blood through an intact dialyzer membrane

a pyrogenic reaction may occur

Chemical Injection System have

a reservoir to hold the chemicals A metering pump to control the level of chemicals added to the water a mixing chamber in the feed water line

Water distribution Loop should be

as short as possible avoiding sharp angles and dead-ends where stagnant water could encourage the growth of bacteria.

when to test clinic's water for bacteria and Endotoxins

at least once a month more often if problems occur

Hemodialysis dialysis water must meet minimum standards for

bacteria endotoxins metals trace elements salts other substances

How EBCT is calculated

based on the volume of GAC and the maximum water flow rate. EBCT = (7.48× V) ÷ Q V = volume of carbon in cubic feet (cf) Q = water flow rate in gallons per minute 7.48 is the conversion factor for gallons to cf.

distribution system

carry the product water to the point of use pipes to carry the dialysis Water must be made of a material that can be disinfected and is inert so it will not release contaminants into the product water

Carbon Filters remove

chloramine free chlorine keep below 0.5 mg/L total chlorine keep below 0.1 mg/L pesticides industrial solvents some trace organic substances

Chloramine

chlorine + ammonia. A longer acting.

low level water contamination can cause

chronic inflammation ultra pure water may reduce inflammation.

you measure RO product water quality with

conductivity the level of TDS in the water in PPM

US Food and Drug Administration (FDA) 510(K) certification

devices purchased after May 30th 1997 and used to treat H2O for hemodialysis must have the US Food and Drug Administration 510k certification ESRD IG (V182.5)

Maintenance of pipes

disinfect pipes at least monthly to prevent bacterial growth

when the resin has all the calcium and magnesium it can hold and all of the sodium ions have been used up the resin bed is

exhausted

indirect feed system

feeds RO water into a storage tank. -unused product what is sent back to the storage tank by a return Loop -there is a continuous flow in the loop even when the are always not running

pyrogenic reaction symptoms

fever/chills low blood pressure nausea and vomiting muscle aches

GAC needs an iodine rating

greater than 900 to remove enough chloramines

if too high levels of calcium and magnesium reach the patients the result Maybe

hard water syndrome

Contaminants

harmful substances

How DI tanks work

have beds of electronically charged resin beads. These beads attract and hold particles with a positive (cation) and a negative (anion) charge: Anions are exchanged for hydroxyl (OH-) ions Cations are exchange for hydrogen (H+) ions The OH- and H+ ions combined to make pure product water H2O.

Booster Pump

if the flow or pressure is not high I can system not a booster pump can help.

Flocculant

is a chemical added to drinking water to remove solid particles from the water to make it clearer. Example Alum

Action level

is the point at which measures must be taken to maintain the AAMI standards.

Water Softener

is used in water treatment to reduce the level of calcium and magnesium that form scale.

when resin bed is exhausted

it must be regenerated: a salty brine solution is used to saturate the beads with sodium again

benefits of deionization

it rejects less water than an RO unit and can reach higher in organic purity.

contaminants in water are determined by

location season local industry contact time

If you can only measure post pressure for backflow prevention device

make sure there is enough pressure and flow to operate your system. watch for pressure change over time to see if the device is plugging up.

Submicron Filter

membrane filters with pore sizes of less than 1 Micron that are used to reduce levels of microbes

RO membrane filters out

metals salts chemicals bacteria endotoxins viruses

we test RO performance by

percent rejection a measure of how well the membrane removes TDS in water in parts per million.

distribution pipes may be made from

polyvinyl chloride (PVC) polyproylene (PP) Teflon tubing new plastics such as cross-linked propyl Ethylene PEX

Ultrafilter

pore sizes are even smaller range from .05 Microns down to 0.001 microns to catch the smallest microbes

Endotoxins

released when bacteria die and their cell walls break down

Micron and Ultra filter maintenance

routine bacterial and endotoxin testing will reveal issues. filters must be cleaned disinfected or replace per your clinic guidelines.

all dialysis centers must keep in close contact with the local water treatment plant by

sending a letter to the plant at least once a year remaining the plant that a dialysis clinic is present and needs update on the status of water treatment

Safe Drinking Water Act 1974

set maximum contaminant levels for pollutants that may have adverse effects on human health.

Challenges that effect your local water

severe storms or floods -overwhelm water treatment systems and let raw sewage wash in. pharmaceutical drugs- from medicines that are flushed down or excreted in toilets hydraulic fracking- pumps in cocktail of chemicals such as Benzene and formaldehyde into the ground to obtain natural gas from shale. chemical spills

direct feed system

takes RO water directly to product water loop for distribution. unused product water goes back to RO system or the drain.

why bacteria can be a major problem for water treatment systems.

the Slime Chains of biofilm called glycocalyx let's nutrients in and keep out disinfectants. bacteria can multiply quickly and can be very difficult to kill.

ultraviolet (UV) light

the UV light uses invisible UV radiation to destroy microbes that pass through the other components.

RD52:2004

the interpretive guidance incorporates by reference AAMI's American National standards for dialysate for hemodialysis 2004 and has the authority of regulations

monitoring the carbon tanks

the water system must be working for at least 15 minutes before you run your first test. Use test strips to test chlorine levels check timer settings for correct time.

Type of RO Membrane

thin film composite (TFC) made of polyamide. TFC have a thin dense membrane over a thick porous substructure for strength. they are wound in a spiral around a collecting tube

carbon tanks contain

very porous granular activated charcoal (GAC)

When replacing GAC can only use

virgin carbon

backwashing

water is forced backwards through the filter from bottom to top then flushed to the drain.

osmosis

water moves on its own through a membrane to dilute a higher solute level on the other side.

universal solvent

water. It dissolves more substances than any other liquids.

Carbon tank maintenance

we cannot disinfect or regenerate carbon but we can only backwash them and replace them.