Combining UV Technology with an Existing Unfiltered Water Ozone System

摘要

During the predesign of the Coquitlam UV Disinfection Project, bench- and full-scale studies were conducted at the Coquitlam Facility evaluating the impact of ozone dose on water quality, namely UV transmittance (UVT) and disinfection byproducts (DBP) formation potential. An ozone dose of 2 mg/L was deemed necessary to limit haloacetic acid (HAA5) formation to 60 μg/L. Trihalomethanes (THM) were easily kept under 80 μg/L using an ozone dose of approximately 1 mg/L. Based on historical water quality and bench- and full-scale studies, a life-cycle cost comparison was conducted for both medium pressure (MP) and low-pressure high-output (LPHO) UV lamp technologies. Two design UVTs were used during the preliminary evaluation, 87 and 91 percent. Life-cycle costs varied between $17.9 million for MP and $26.5 million for LPHO at 87 percent UVT. At a UVT of 91 percent the overall costs were reduced significantly, and ranged between $16.2 million and $21.5 million for MP and LPHO, respectively. A pilot-scale test is currently being conducted on-site, at the Coquitlam Facility, evaluating the fouling potential of the ozonated water on MP and LPHO UV quartz sleeves.