HEALTH CARE >> Water Treatment for Dialysis Unit

Introduction:

• Water has a unique property of being an excellent solvent, high heat capacity and surface tension and hence it is very susceptible to be contaminated to the point where it becomes a health hazard.
• Water is used extensively for making the dialysate required for hemodialysis treatment. A normal person drinks between 1.5-2 liters of water per day and this amounts to about not mote than 15 liters per week. Apatient on hemodialysis is exposed indirectly to about 120 liters or water per session (Dialystate flow rate 500 ml x 60 min x 4 hours) of dialysis therapy and this amounts to about 400 liters per week.
• The quality of water used is therefore critical to the preparation of a dialysis fluid. It should be free of contaminants which have harmful effects on the health of patient.
• The contaminants which may be present in water include suspended solids, dissolved organics and inorganics, heavy metals and trace minerals and microorganisms.

CONTAMINANTS IN WATER AND ASSOCIATED DIALYSIS COMPLICATIONS

Min Categories of water impurities are:

1	Suspended solids	-Sand, Silica, etc.
2	Dissolved inorganics	Culcium, sodium, magnesium, nitrates, sulphates.
3	Dissolved organics	Chloramines, pesticides, etc.
4	Heavy metals and trace elements	iron, copper, lead, aluminium, cadmium, etc.
5	Microorganisms	bacteria, pyrogens, algae, endotoxins

Contaminants and potential toxic effects

1	Aluminium	Dialysis encephalopathy, Bone disease, Microcytic anaemia
2	Calcium/Magnesium	Hypercalcaemia, Hypermagnesaemia
3	Chloramine	Hemolysis, anaemia
4	Fluoride	Osteoporosis, Osteomalacia
5	Sodium	Hypertension, pulmonary oedema, tecycardia, vomiting, headache
6	Zinc	Anaemia, nausea, Vomiting
7	Sulphate	Nausea metabolic acidosis
8	PH	Heparin inactivation, itching
9	Microorganism	Febrile reaction.

Importance of water treatment

1. To prevent premature damage to the hydraulic parts in the machine
2. To facilitate production of dialyste with accurate electrolyte content.
3. To prevent long term side effects of inadequately treated water.

Acceptable Water Content

1. Calcium and magnesium< 0.5 ppm (parts per milion).
2. Free from chlorine.
3. Free from ions
4. Bacteria count < 200 cfu/ml (AAMI Standard)
                         < 100 cfu/ml (EU Standard)
5. Endotoxin level < 2 EU/ml (AAMI Standard)
                          < 0.25 EU/ml (EU Standard)

AAMI Haemodialysis Water Quality Standard

Substance Maximum conectrations (mg/l) Aluminium 0.01 Chloramine 0. 10 Copper 0. 10 Fluoride 0.20 Nitrate 2.00 Sulphate 100.0 Zinc, barium 0.01 each Calcium 2.00 Magnesium 4.00 Sodium 70.00

Substance Maximum conectrations (mg/l) Potassium 8.00 Chlorine 0.50 Arsenic, lead, silver 0.005 each Chromium 0.014 Cadmium 0.001 Selenium 0.9 Mercury 0.002 Bacteria <200 cfu/ml Endotoxin <2 EU/ ml

Function of Multimedia Filter

Large particulates of 10 micron or greater that cause the supply water to be turbid- such as dirt, slit, colloidal matter (Suspended matter)- are removed by multimedia filter, sometimes referred to as a Depth bed filter.

Function Of Carbon Filter
Chlorine and Chloramines are added to the city water supply for disinfections purpose.
In drinking water these additives allows us to drink the water with minimal risk of becoming ill from a parasite or pathogenic bacteria.
Carbon filter remove Chlorine and Chloramines from water.

Function of Water Softener
Water containing calcium and magnesium from scale deposits on the RO membrane and eventually foul the membrane. Once mineral deposits form on the RO membrane the percent rejection (membrane performance) and product water quality decline. Mineral scale can become permanent and decrease the life expectancy of the RO membrane if not cleaned.

Water softener removes hardness from source water. High level of calcium and magnesium in the supply water causes the water to be hard.

Softener works as an ion exchange basis. The resin beads within the tank have a high affinity for the cations calcium and magnesium (both divalent) present in the source water and release two sodium ions (mono valent) for one calcium or magnesium captured.

Function Of RO Machine
The feed water passes through a replaceable 5-micron cartridge pre-filter, which removes bulk suspended solids. Filtered water then flows to the inlet control valve. This solenoid valve is wired to the on/off switch and opens when the machine is turned on, allowing water to flow to the pump inlet. When the machine is turned off, the valve close, preventing non-turbulent flow through the membrane elements, which would lead to shortened membrane element lifes.

The pump feeds water to the membrane element housing arranged in series. The direction of water flow is indicated by an arrow on each membrane element housing. Water is separated by the membrane element and leaves the membrane element housing in two streams: permeate and concentrate.