1 III. Water Treatment Technologies Topic III. 6. Water Disinfection: Reagents, Processes and Equipment Reagents §Chlorine and Cl-compounds l Very effective in respect of bacteria l Long-time effect l Relatively cheap l Needs precise dozing and control l Cancerogenic chloramines formation l Dependence of pH and temperature §Ozone l Very effective (20 times more than Cl) l Affects both bacteria and viruses l Short-term effect l Improves water taste l Eliminates phenols, Mn -, Fe +2, etc. l Very expensive generation l Very active corrosion agent

2 Reagents §Ultraviolet rays l Don’t affect water chemical content l Effective only on the spot l Not fully effective at water containing SS l Relatively expensive §Gamma-rays l Don’t affect water chemical content l Effective only on the spot l Relatively expensive §Silver ions l Very effective l Very expensive §Ultrafiltration l Don’t affect water chemical content l Effective only on the spot l Very expensive

3 Disinfection with Chlorine and Chlorine Compounds Processes: §Doze (5) mg/l §Residual Cl concentration - 0,3 - 0,5 mg/l §Contact time - 30 min

4 Disinfection with Chlorine Chlorine Utilisation Capacity of Water 1 - water free of ammonia; 2 - dissolved ammonia in water I - monochloramines and dichloramines; II - free chlorine Б - break point

5 Disinfection with Chlorine: Equipment Scheme of Chlorine Disinfection Equipment 1 - panel; 2 - mixing chamber; 3 - automatic emergency stop device; 4 - filter; 5 - pressure reduction valve; 6 - flow regulation valve; 7 - chlorine gas flow meter; 8, 9 - manometers; 10 - gas moisture filter; 11 - liquid chlorine container; 12 - receiving container (settler)

6 Disinfection with Ultraviolet Rays Scheme of Bactericide Device with Non-submerged UV-lamps 1 - UV-lamp; 2 - reflector; 3 - channel h - minimal water depth, cm;  0 - coefficient for bactericide efficiency,  0 = 0,9;  - coefficient for UV-rays absorption,  = 0,1 - 0,3 cm -1 ; e - Neper’s Number, e = 2,71

7 Disinfection with Ultraviolet Rays Scheme of Bactericide Device with Submerged UV-lamps 1 - mercury-quartz lamps; 2 - quartz cylindrical cases; 3 - mixing baffles; 4 - equipment case; 5 - transitional parts; 6 - water pipes