What Technologies are used for Water Purification?

The past two decades have seen a drastic change in the water industry approach for water treatment. During this time, the water industry has started to think about alternative treatment technology to traditional water purification treatment approach.

At present, there are many technologies that are being used for water purification process like, membrane filtration, ultraviolet irradiation, advanced oxidation, ion-exchange and biological filtration. Some of these technologies are new to the water industries, and many of these are there for a long time. Some of the technologies are used extensively while others are used limitedly. In this post, we will discuss some of the simple and advanced water purification technologies.

Water Purification

Membrane Filtration Technology

There are further two classifications of membrane treatment system- low-pressure membrane systems(like microfiltration and ultra-filtration) and high-pressure membrane systems (like nano-filtration and reverse osmosis(RO)). Low-pressure membrane filtration, as a surface water treatment technology, has several advantages when compared to the conventional filtration, such as a smaller waste stream, lower chemical usage, no disinfection byproduct formation and more automation. However, due to its porous structure, low- pressure membrane systems are not effective when it comes to the removal of dissolved organic matter (the taste and odor causing compounds and the color causing organic matter). So this technology is limited to the water sources where the removal of organic matter is not required.

On the other hand, High-pressure membrane, including nano-filtration and reverse osmosis- RO, is currently considered the most reliable technology by the water industry because of its existing application for water softening.

Here, the thing is that Low-pressure membranes are effective for particulate removal while high-pressure membranes are effective for dissolved matter removal whether it is organic or inorganic. Though none of the technology alone is sufficient to remove all the impurities in the water, the combination of the two membrane systems is capable of removing the majority of dissolved and suspended material present in the water.

Ultraviolet Irradiation

UV irradiation technology is primarily used in the water and wastewater treatment as a disinfection process that works on the germicidal effect of UV light. In the process, the micro-organisms are inactivated by exposing them to UV light in the water and prevent it from reproducing. But the problem is that the UV treatment systems rely on the ability of UV light to reach and inactivate the microorganisms and if there is particulate matter present in the water, it can cover the microorganism from exposing to the UV light and make the process ineffective. Despite the claims of UV manufacturers, the available UV systems generally experience failure in various components. Conclusively, the UV irradiation is a promising disinfection technology, but more research needs to be done in this area.

Water Purification

Advanced Oxidation Technology

Advanced Oxidation Process produces hydroxyl radicals for the oxidation of organic and inorganic impurities present in the water. It includes a number of processes, but ozone, ozone with hydrogen peroxide addition and UV irradiation with hydrogen peroxide addition are the three main processes. The process is used in the oxidation of synthetic organic chemicals, color, taste and odor-causing compounds, sulfide, iron, and manganese.

Ion exchange Technology

The use of Ion exchange technology has been limited to water softening. However, the new limits are being set on several inorganic chemicals,and thus IX technology is finding new applications in water treatment.This technology is basically designed as a fixed-bed process in which a synthetic resin is packed,and water passes through it. The contaminant ions present in the water are the exchanged with the ions on the resin surface and remove the contaminant ions from the water and concentrate them on the resin. The resin is commonly regenerated to eliminate the contaminant from the resin surface and refill it with the original exchange ion.There are four main types of IX resins: strong acid cationic resin, weak acid cationic resin, strong base anionic resin, and weak base anionic resin. One of the best Faucet Water Filters uses this technology for purifying water.

Biological Filtration Technology

All the technologies that we have discussed earlier are either physical or chemical process or both. The utilization of biological process in water treatment has been discouraged by the industry due to the concern about the introduction of microorganisms to the water. However, the biological filtration has been introduced as the most effective process for the production of biologically stable water. The use of bio-filtration in drinking water treatment opens the door to new innovative applications of this process. Bio-filtration is generally used for the biological reduction of several inorganic contaminants like nitrate, bromate, perchlorate, and chlorate.

No such contaminant be removed from the water. 2 or more processes can be combined to make water purification more reliable and strong. The question comes that of cost. As alternative water resources become increasingly less available, the need for inventive and cost-effective treatment technologies will increase gradually.