Water Purification Systems for Clinical Lab Prepared By Farid Khalaf

Water Quality Water is an effective “universal” solvent for polar substances. This property produces some very complex water chemistry conditions that require purification steps to produce water for laboratory use. Quality results are dependent upon reliable instrumentation and known water quality

Water Contaminants Water contaminants include particulates, organics, inorganics, microorganisms and pyrogens Presence of contaminants Particles Gases Microorganisms Purification technologies Ions Organics

Water Purification Systems An effective laboratory water purification system must efficiently remove contamination that would interfere with lab tests or procedures. A water purification system is composed of a series of purification stages Analysis of source water is used to determine the type and capacity of individual purification steps needed within the water system.

Reagent Grades of water Type IPurest – Required for sensitive tests Type IIAcceptable for most uses Type I and II are now called CLRW (Clinical Laboratory reagent Water Type III Autoclave and wash water will meet the requirements of previously classified Type III

Purification Technologies Filtration – Depth and Screen Filters Activated Carbon – Removal of organics and chlorine. Mineral scale control – Softening and Sequestering Distillation. Reverse Osmosis Electrodeionization Ultraviolet light

Depth filters Depth filters effectively remove large particles found in drinking water. A depth filter may consist of a canister of fine sand or a polymer fiber or string- wound cartridge. Particles are retained by entrapment as they move through the path of the filter matrix. Depth filters protect expensive, fragile membranes downstream in the water system from damage.

Granules or beads of carbon activated to create a highly porous structure with very high surface area. Used to remove total and free chlorine and organic substances from water. Pore sizes typically <100 to 2000 Å Removal of organics by adsorption Removal of chlorine by reduction Activated Carbon

Scale Control – Ion-exchange Softening Calcium and carbonate ions are common in tap water supplies. Scale forms when concentration exceeds solubility limits and CaCO3 precipitates as a solid. (Ca++ + CO3 = CaCO3 ). The resins used in water softening remove scale-forming cations, such as calcium and magnesium, in exchange for non-scale-forming sodium ions

Reverse Osmosis Pressure applied in the reverse direction exceeding the osmotic pressure will force pure water through the membrane. A reject line is added to rinse contaminants to drain. RO is an effective method to remove 90% to 99% of particles, ions, organics, and microorganisms from potable source water in a single step

Electrodeionization n Cations driven toward negative electrode by DC current n Anions driven toward positive electrode by DC current

Water purification system - Millipore

Millipore MILLI-Q Ultra pure water Tap water is first purified to pure (Type 3) water by reverse osmosis (RO). The pure water produced by the Reverse Osmosis is stored in a tank designed to minimize risks of contamination during water storage. From that reservoir, water can be sourced though a front valve or sent by a delivery pump to feed instruments such as a glassware washing machine, or further processed by the Milli-Q Direct to produce ultrapure (type1) water.

Water purification system Progard Pack: Depth Filtration Activated Carbon Anti-Scaling

Water Purification Unit

Distillation removes most of the common minerals such as Iron, Calcium and Magnesium but doesn’t remove volatiles such as CO2,Chlorine and Ammonia. Distillation typically produces water of Type II or III quality

Distillers - Operation principle Distiller composed of heating device and water condensing system connected to main water supply and able to produce at least 4 litres of distilled water per hour.. If the quality of the feed water is poor, a pre- filter unit should be fitted.

Double Distillation Principal Benefits Removes wide class of contaminants Bacteria / pyrogen-free Low capital cost Limitations n High maintenance n High operating cost n Low product flow n High waste water flow n Water storage

Installation requirements A well ventilated environment in which the equipment can be installed A potable water connection. Pre – treatment system according to quality of water feeding the system. An electrical connection equipped with control and safety devices.

Pretreatment system for Water Stills Pre-Filter for pre-cleaning the tap water. Dechlorite Filter Phosphate Cartridge

Maintenance Scale will accumulate in the boiler and in the heating element and must be removed on a regular basis to obtain optimal performance of the distiller. The interval between cleaning operations depends upon the quality of the water supply. Descaling is performed with concentrated hydrochloric acid. Record in the logbook. The chemical reaction should be allowed to continue until all the scale deposits have been removed

Water contaminants were measured in parts per million (PPM), Now It is common for analytical and experimental scientists to be concerned with elements and compounds in the parts per billion (ppb) and parts per trillion (ppt) range ppm : Parts per Million = mg/Liter ppb : Parts per Billion = microgram/Liter ppt : Parts per Trillion = nanogram/Liter.