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 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 include effective disinfection, oxidizing organic compounds (185nm and 254nm) to <5ppb TOC.
Disadvantages include lowering of resistivity of the water, and no removal of 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
The advantage is that it can effectively remove harmful ions dissolved in water, such as heavy metal ions, and the resistivity of the ultrapure water produced is close to 18 megohms. The disadvantage is that it can not remove insoluble minerals, and the cost of producing pure water is high. Therefore, more with reverse osmosis used in conjunction.