Answer:
1. Reverse Osmosis
Reverse Osmosis works by forcing feedwater through a semi-permeable membrane.
A pump is used to apply pressure to reverse the normal osmotic flow across a membrane, meaning purified water molecules (permeate) are forced through the reverse osmosis membrane and recovered in preference to contaminants in the concentrated side which are left behind (reject concentrate).
2. Oxidisation
Oxidisation in the form of chlorination has been used as a means of water purification since the beginning of the last century. Hypochlorite is the key agent, achieving a disinfection of water by oxidising bacteria to eliminate waterborne diseases. Several different methods can be used to provide oxidation, including ozonation, chloramination, UV, bromination & chlorine dioxide. During the treatment, hydroxyl radicals are generated to destroy bacteria cells.