Lab Water Purification technologies

Natural water is derived from rivers or underground water or reservoirs. Drinking water is produced by a series of purification steps that vary with the water source which conforms to local and national regulations and has acceptable clarity, taste, and odor.

The underground water source has a high level of salts and hardness but low organic content. River water source is intermediate in quality and has impurities from industrial, agricultural, and domestic activities. 

Seasons will also impact the quality of water. During the winter and autumn season, dead leaves and decaying plants will produce large organic contamination. The surface water organic contamination is at its peak during winter and autumn but it will be minimum on summer days. Groundwater will not get affected by seasons.

Laboratory water purification systems are usually fed with local drinking water produced by purification of natural water resources for drinking purposes. The quality and the characteristics of drinking water will determine the purification technologies and steps required to produce  lab purified water.

Impurities In Drinking Water

The unique ability of water is to dissolve substances. Natural and drinking water may contain 5 major impurities like 

  • Suspended particles
  • Chemical compounds (organic and inorganic substances)
  • Microorganisms
  • Dissolved gases

Suspended Particles

Suspended particles include hard particles (like rock, sand, or silt), soft particles (vegetal debris), and colloidal particles (organic or inorganic). Suspended particles can damage the Reverse Osmosis (RO)  membranes, block the fine holes in the purification components, as well as interfere with the operational valves and meters. The colloidal particle might raise turbidity in the water and interfere with the instrumental operation.

Inorganic impurities

Inorganic substances are the major impurities present in the water. These inorganic ions present in the water act as catalysts and affect both organic and biochemical reactions. Inorganic substances differ for different natural water sources. The major inorganic impurities are as below

  • Calcium and magnesium salts that cause temporary or permanent hardness
  • Carbon dioxide gas which dissolves in water give weakly acidic carbonic acid
  • Sodium salts
  • Ferrous and ferric ions - from minerals and rusty iron pipes
  • Chlorides from saline
  • Aluminum
  • Phosphates from detergents
  • Nitrates from fertilizers

Organic Impurities

Organic impurities in water are mainly from biological wastes. Decay vegetal matter gives rise to byproducts like humic and fulvic acids, tannins, and lignin. Organic impurities in water are increased due to industrial and domestic wastes. Dissolved organic impurities can interfere with analytical techniques and affect biological experiments such as cell culture, cause baseline instability while preparing liquid chromatography, decrease sensitivity and resolution, and also reduce column lifetime. 


There are many microorganisms like bacteria present in natural water. Harmful bacteria are removed by chlorination, but drinking water still contains live microorganisms. Bacteria are usually kept at a low level and the level of bacteria in drinking water supply for the laboratory is 10 Colony Forming Units (CFU/ml) or less. Bacteria can interfere with laboratory experiments and affect the quality of laboratory applications.

Dissolved gases

Drinking water contains dissolved gases such as nitrogen, oxygen, and carbon dioxide. The dissolved carbon dioxide in the water dissociates to form weak carbonic acid.  Dissolved oxygen and nitrogen in water can form bubbles that are detrimental to processes such as particle counting or spectrophotometer measures.

Measuring Impurities In Drinking Water

It is necessary to have information on the local drinking water which is usually fed into the laboratory water purification system. The average water quality data of your locality can be obtained from your local water supplier. Otherwise, a sample can be taken to analyze the water quality.

Methods of lab water purification system

The laboratory water purification system process starts with pretreatment purification technologies such as microporous depth filters, Activated carbon in pretreatment. This pretreatment water purification system laboratory ensures reliable operation and decreases the chance of damaging expensive components in the major lab water purification system process. Let’s discuss the various technologies and their advantages in the lab water purification system process.

Water pretreatment technologies

Microporous depth filters

Microporous depth filters

Microporous depth filters are matted fibers that provide a physical barrier to the passage of particles. Depth filters are better for pretreatment because of their large capacity. Depth filters can be enhanced by using microfilters. The depth filters are typically in the range of 1-50 μm are commonly used as an economical way to remove the bulk suspended particles. These depth filters protect the downstream purification technologies from fouling and clogging. These depth filters are replaced periodically.

Activated Carbon (AC)- in pretreatment media
Activated Carbon

Activated carbon removes chlorine and chloramine and prevents the damage of membrane filters and ion exchange resins. Granules or beads of carbon are activated to create a highly porous structure with a very high surface area. Activated carbon contains tiny pores in the range of 500-1000nm and a surface area of about 1000 square meters per gram. This pretreatment process removes the organics by adsorption and chlorine by adsorption-reduction.


Major Water Purification Technologies

Reverse Osmosis (RO)

During Reverse Osmosis (RO) the pressure is applied in the reverse direction (i,e to the input side) exceeding the osmotic pressure will force the pure water through the RO membrane. RO membranes are typically made from thin-film polyamide but that can easily be damaged by oxidizing agents such as chlorine. Pretreatment of feedwater with microporous depth filters and activated carbon is required to protect the RO membrane.


  • Effective removal of all types of contaminants like particles, colloids, bacteria, dissolved inorganics.
  • Requires minimal maintenance ( no strong acid or bases cleaning)
  • Good control to monitor operational parameters
  • Ideal protection for Ion Exchange resin


  • Not enough contaminants removed for Type II water.
  • Need of right pressure (5 bars) & right pH for proper ion rejection.
  • Require good pretreatment to avoid contaminants damaging membrane:
    • - Scaling: CaCO3 deposits on the surface
    • - Fouling: organic or colloid deposits on the surface
    • - Piercing: physical damage by particles
Ion Exchange (IX)
Ion Exchange

This Ion Exchange process of water purification systems for the laboratory removes the ionized particles from water by exchanging them for H+ and OH- ions.



  •  Removes dissolved inorganic ions,
  •  Regenerated by deionization using acid and bases or electrodeionization
  •  It is very economical


  • Limited removal of particles, colloids, organics, or microorganisms
  • Finite capacity, once all the ions are exchanged, the ions are no longer exchanged
  • Regeneration needed using strong acid and base
  • This leads to organic fouling
  • Resin breakdown occurs with multiple regenerations and the water gets contaminated

EDI is a technology used in the water purification system for the laboratory that combines ion exchange resin and ion-selective membranes to overcome some of the limitations of ion exchange resins. With the direct application of DC current, the ionized species in the water are removed. Ion-exchange added to waste channels enhance ion transfer and the removal of ions. Conductive carbon beads connected to the cathode electrode reduce the risk of scaling and the use of a softener. Cations in the ion exchange resin driven towards the negative electrode and the anions in the ion exchange resin driven towards the positive electrode. Alternating the anion and cation permeable membranes effectively separates ions from water. The feedwater treated with  Reverse Osmosis (RO) avoids plugging, fouling, and scaling.



  • Effective removal of ions and small MW charged organic (Resistivity 5 - 17 MΩ-cm)
  • Environmental friendly as no chemical is required for regeneration
  • Low maintenance
  • Resins in the cells have a minimal of organics


  • RO treated feed water is ideally required to prevent plugging and fouling of ion exchange and scaling at the cathode electrode.
  • It is difficult to remove weakly charged ions
  • Dissolve CO2 and silica
  • Moderate investment is required

Distillation is the process of a water purification system laboratory by which the contaminants in the water are removed. In this distillation process, the state of the water is changed from liquid phase to gas phase by heating the water above the boiling point and it is converted into water vapor. The water vapors rise and pass through the condenser where the water is cooled and condensed into a liquid phase again and is collected and stored. Distillation is effectively performed with pretreated water to minimize the precipitates and remove impurities.


  • A wide range of contaminants are removed by this process
  • Long shelf life


  • Slow purification process
  • Certain contaminants are transmitted at varying amounts into the condensate
  • More maintenance is required if the water is stored is for long time chances of recontamination
  • Not economical requires more electrical energy or heat energy to boil and more tap water is required for cooling

Ultrafilter membranes of the water purification system laboratory remove even small particles like protein macromolecules. Ultrafilter pores are typically in the range of 1 to 10nm. These filters are often used to give higher flow rates. This will reduce the concentration of relevant contaminants to acceptable levels.

Vent filters

Vent filters are hydrophobic microporous filters used in the water purification system for the laboratory to prevent particulates, bacteria from entering the stored water. This filter is often fitted with water storage containers. Composite Vent Filters (CVF) is the combination of absorptive media with filter media. This CVF also minimizes CO2 and organic contamination in the stored water. Regular replacement is essential to get efficient output.

Degassing  (or De-aeration) membranes

The degassing membranes remove gases (e.g. CO2, O2) from water. This membrane is a contactor device that uses a hydrophobic membrane filter in which the water steam passed from one side of the membrane and the flush gases are removed from the other side of the membrane.

UV light
UV light

UV rays are widely used to kill bacteria and to break down and photo-oxidize organic contaminants to ionize particles for subsequent removal by ion exchange polishing cartridge. The UV rays in the range between 200 and 300 nm are used to destroy the microorganisms by breaking the DNA chains. 260nm is the optimal wavelength for DNA damage of microorganisms. 254nm is close to optimum germicidal lamp output to destroy the bacteria successfully.



  • Oxidation of organic compounds
  • Destruction of bacteria and viral


  • Oxidation of organics is the converting process that decreases TOC levels by a restricted amount and the organics are not removed completely.
  • Limited effect on other contaminants
  • For optimum performance better design is required.


Measuring the contaminants present in feed water is essential to get quality purified water for laboratory purposes. We discussed the different technologies used in the lab water purification process. Depending on the contaminants present in the water, effective and economical technologies are used to remove the contaminants. Lab Q water purification provides you with the best lab water purifier that combines these technologies and delivers an ultrapure water system for the laboratory.

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