Technical Overview: Dialysis Water Treatment Plant
1. Purpose

The dialysis water treatment plant produces ultrapure water by removing contaminants, impurities, microorganisms, and endotoxins from municipal water to ensure safe, biocompatible dialysate for hemodialysis.

2. Key Water Quality Standards

Dialysis water must meet strict standards, such as those defined by:

AAMI (Association for the Advancement of Medical Instrumentation)

ISO 23500

European Pharmacopoeia

Typical parameters:

Parameter Max Allowable Limit
Total Dissolved Solids (TDS) < 10 mg/L
Conductivity < 15 µS/cm
Endotoxin < 0.25 EU/mL
Bacterial Count < 100 CFU/mL (or ideally <1 CFU/mL)
Chlorine / Chloramine Non-detectable
Heavy Metals (Lead, Copper) < ppm levels per standards
3. Typical System Components & Process Flow
Stage Description
Raw Water Source Municipal or well water supply
Pre-treatment Removes large particles and chlorine; protects downstream equipment
- Multimedia Filters (Sand/Carbon) Remove suspended solids, turbidity, and chlorine/chloramines
- Activated Carbon Filters Remove chlorine, chloramines, organic compounds
- Water Softener (Ion Exchange) Removes hardness (Ca²⁺, Mg²⁺) to prevent scaling in RO membranes
Microfiltration / Ultrafiltration Optional step to reduce bacteria and particulates before RO
Reverse Osmosis (RO) Core purification stage removing dissolved solids, bacteria, endotoxins, and chemicals
Deionization (DI) / Electrodeionization (EDI) Optional polishing step for further ion removal
Ultraviolet (UV) Sterilization Destroys microorganisms and endotoxins post-RO
Storage Tank Made from stainless steel with continuous circulation to maintain water quality
Distribution Loop Circulates treated water to dialysis stations; maintained with periodic disinfection
Point-of-Use Filters Final ultrafilters or 0.2 µm filters on dialysis machines to ensure ultrapure water
4. Technical Specifications
Parameter Typical Values / Features
RO Recovery Rate 60–85% (depending on feed water quality)
Water Flow Rate 200 – 2000 L/h or customized to dialysis center size
Operating Pressure 200 – 400 psi (RO system)
Feed Water Temperature 15–30°C (optimal for RO efficiency)
Storage Tank Volume 500 – 2000 L (depends on center size)
Distribution Loop Material Stainless steel or FDA-approved PVC/PEX piping
Monitoring Parameters Conductivity, TDS, chlorine, pressure, flow rates, temperature
Alarm Systems Low conductivity, high conductivity, chlorine presence, flow issues
5. Control and Automation

PLC/SCADA System: Monitors water quality parameters, controls pumps, valves, alarms.

Data Logging: Records parameters for compliance and troubleshooting.

Alarms and Safety: Immediate notification for out-of-spec water quality or system failure.

Automatic Disinfection: Scheduled hot water or chemical disinfection of storage and distribution loop.

6. Maintenance & Validation

Regular Filter Replacement: Carbon, softener, RO membranes.

System Sanitization: Heat or chemical disinfection monthly or per protocol.

Microbiological Testing: Weekly or monthly water samples cultured for bacteria/endotoxin.

Membrane Cleaning: Periodic cleaning of RO membranes to prevent fouling.

Validation: Initial and routine performance qualification to ensure compliance with standards.

7. Common Challenges

Biofilm formation in storage/distribution loop.

Membrane fouling reducing RO efficiency.

Chlorine/chloramine breakthrough causing membrane damage.

Hard water scaling without proper softening.

Endotoxin contamination requiring UV or ultrafiltration.

8. Summary Diagram (Typical Flow)
Raw Water
↓
Multimedia Filter (Sand/Carbon) → Softener → Micro/Ultrafiltration → RO → (DI / EDI) → UV Sterilizer → Storage Tank → Distribution Loop → Dialysis Machines (Point-of-use Filter)