CT values are main design parameters of the ozone disinfection system, wherein C represents the ozone concentration in mg / L meter; T representative of contact time, the count in min; CT values of both plot showing the effectiveness of the sterilization process. For example, ozone concentration 0.4mg / L, contact time CT value equal to 1.6 when 4min. The higher the temperature, the shorter the response time, the lower the required CT value.
EPA and OSHA according to the results, published in the drinking water of ozone disinfection system is 1.6 CT. But pool water have its own features, (1) Pool is closed cycle that and at least 4 times per day, but drinking water is flowing. (2) With the increase of the number of swimmers, the water will also increase the amount of oxidant required. (3) Swimming pool water temperature is generally 25 ℃ ~ 40 ℃, and the drinking water temperature is generally 0.5 ℃ ~ 25 ℃. (4) Chlorinated swimming pool water but also as an auxiliary disinfectant.(5) The pool water need to filtered first then do ozone disinfection. So CT values be 1.6 is safe. Some area with low CT values 0.8, ozone concentration of 0.2mg / L ~ 0.25mg / L, contact time 3.5min ~ 4min, in this case the amount of chlorine as an auxiliary disinfection can reduce 65%.When chlorine as a primary disinfectant and ozone as a disinfectant polishing, CT value may be less than 0.8, the ozone concentration is less than 0.5mg / L, the contact time is less than 1min.
The follow method can help to chose ozone machine output,
Ozone output (g/hr )= Circulating water flow (m3/hr) * Ozone level (g/m3), like, 380m3 swimming pool ,ozone level be 0.4mg/L(g/m3),water cycle time 6hr, cycle water flow is 63m3/hr, so ozone machine should be 63* 0.4=25.2g/hr .
And ozone contact tank size: ozone tank (m3)= Circulating water flow (m3/hr) * Side-stream flow percent(%) * Ozone contact time( h ), like, 380 m3 swimming pool , circulating water flow is 63 m3/hr, side-stream flow percent is 25% ,contact time is 4 min, so ozone contact should be 63*0.25*0.067=1.05 m3.