Problem
During blood purification, the dialysis machines in a haemodialysis unit need water that is free of bacteria, pH-adjusted and of low conductivity. It was not possible to feed this water to machines connected to patients without removing the chlorine, hardness and dissolved salts in the mains water.
Solution
- Pretreatment with chlorine dosing, a sand filter and an activated carbon filter
- Membrane protection with duplex softening and antiscalant dosing
- RO1750 reverse osmosis and pH-controlled dosing in the first pass
- RO1250 reverse osmosis in the second pass via an intermediate transfer tank
- Treated water tank with demineralisation and redox-controlled dosing
- Constant-pressure supply to the dialysis line with a treated water booster set
- UV disinfection and 0.22 micron endotoxin filtration after the treated water tank
Result
The dialysis machines are supplied with pure water from two separate reverse osmosis passes; while the pretreatment, softening and dosing stages protect the membranes, demineralisation and redox control keep the conductivity and microbiological safety of the water constant. After the treated water tank, the UV system inactivates bacteria and germs that may enter from the air; because the dead bacteria inactivated by UV remain in the water, they are removed with a 0.22 micron endotoxin filter.
Technical specifications
Double-pass reverse osmosis line
| System type | Double-pass reverse osmosis |
|---|---|
| 1st pass | RO1750 reverse osmosis unit, 42,000 L/day |
| 2nd pass | RO1250 reverse osmosis unit, 30,000 L/day |
| Pretreatment | Sand filter, activated carbon filter, duplex softening |
| Dosing | Chlorine, antiscalant, pH-controlled and redox-controlled |
| Final stage | Demineralisation |
| Storage | Raw water, intermediate transfer and treated water tanks |
| Pressurisation | Raw water and treated water booster sets |
| Disinfection | UV system after the treated water tank |
| Endotoxin filter | 0.22 micron, removal of dead bacteria |
