Pure water production process:
1. Reverse osmosis filtration system
Reverse osmosis is the most commonly used filtration method for laboratory water purifiers, and its filtration advantages and disadvantages, which we have already introduced many times, such as in the lecture when we have been introduced to you. The advantage is that it is effective in removing all types of contaminants (particles, colloids and dissolved inorganic matter) to a certain extent, and routine maintenance is relatively low. The disadvantages are that the flow rate is limited by the tight porosity of the RO membrane, so the amount of pure water produced is less compared to other methods, and the cost of production is higher.
2. UV Radiation for Pure Water
Advantages are effective disinfection, oxidizing organic compounds (185nm and 254nm) to <5ppb TOC.
Disadvantages are that it reduces the electrical resistivity of the water, and does not remove particles, colloids or ions.
3. Distillation for pure water
Distillation for this method is based on the transfer of water by subsequent condensation in the vapor phase. The main disadvantage of this method is the very high maintenance cost of the electricity required to convert the water to steam. In addition, along with the water molecules during steam formation, other solutes can enter the steam based on their volatility and eventually dissolve into the resulting pure water.
4. Deionization exchange
Advantage is that it can effectively remove harmful ions dissolved in water, such as heavy metal ions, and produce ultrapure water resistivity close to 18 megohms. The disadvantage is that it can not remove insoluble minerals in water, and the cost of pure water is higher. Therefore, more with reverse osmosis used in conjunction.