Answer
Active substance – means a substance or organism, including a virus or a fungus, that has a general or specific action on or against harmful aquatic organisms and pathogens. Common Active substances-
1.Chlorine
2.Ozone
3.Bromine and Iodine
4.Hydrogen Peroxide and peracetic acid
E.g. Electro-Clean System (South Korea) – uses electrochlorination
Methods not using Active substances
1.Ultraviolet (UV) Treatment
2.Deoxygenation
3.Magnetic Separation and Ultrasonic/Cavitation Methods
4.Heat Treatment
5.Filtration