The objective of this study was to quantify the effects of ozone level used as a water disinfectant on corrosion of cement-mortar lined ductile iron pipe. This research is focused on the interaction of two factors, ozone level and flow rate, on cement-mortar lined ductile iron pipe corrosion. Ozone addition was set for three levels 0.0, 0.5 and 1.0 ppm. Flow rates were set at 0, 20, and 40 gallons per minute (0, 0.076 and 0.15 m~3/minute). To obtain results in a controlled laboratory system, hardness and fluoride concentration were fixed at 60 to 120 ppm and 1ppm respectively. Ambient values of pH (5.0 to 8.0 s.u.), and chlorine, (free and total) in the range of 0.0 to 1.0 ppm, were set and monitored. In addition, temperature was controlled in the range of 20 +/-5°C (degrees centigrade) using a submersible heater.A closed recycle system was used to observe changes over time and to simulate actual field conditions. The circulating pump was run to simulate normal water usage in a distribution system with flow on 12 hours and off 12 hours during a 24 hour period. Ozone addition was on only when the water flow was on. The on/off cycles were controlled by a timer. Each test point was run for two weeks and then replicated for a second two weeks. Iron level was observed to increase over time with the addition of ozone while flow had little or no effect at the rates studied. Based on these findings, corrosion, measured as iron in solution, increased with larger doses of ozone and its associated ammonia. Flow had little or no affect on corrosion.
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