Current Technology
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Our current water filtration systems use a combination of mechanical and chemical filtration methods to get rid of harmful particles. Specifically, many water plants follow a five-step filtration process: coagulation, flocculation, sedimentation, filtration, and disinfection.
Image from Karki et al.
1. Coagulation
Mixing chemicals with a positive charge into the water, the (+) charge will neutralize the (-) charge in the dirt and particles within the water, allowing these particles to bind to each other to form slightly larger particles.
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2. Flocculation
The water is mixed with more chemicals (called flocculants) to form even larger particles named flocs.
3. Sedimentation
Once the particles have gained sufficient weight, the water plants allow the flocs to settle to the bottom, letting the system filter the remaining water above.
4. Filtration
The water is sent through multiple filters with different pore sizes and materials. This gets rid of most dissolved particles and germs. Within the filtration processes, there are many different methods used.
For example, ultrafiltration and reverse osmosis are popular options.
Ultrafiltration involves using filters with very small pores that only allow water and other tiny molecules, typically salts and small charged particles, to pass.
Reverse osmosis and nanofiltration are processes that force water at high pressure through semi-permeable membranes so that molecules with a certain molecular weight will be unable to make it through
5. Disinfection
Finally, the water is disinfected using a variety of chemical disinfectants to kill any germs or parasites in the water. The levels of chemical disinfectant in the water are monitored as they leave the actual treatment plant. Some water plants may also use UV light or ozone to sanitize and clean water.
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Potable Water!
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