Effect of Ozone Dissolution Systems on Ozone Exposure and Bromate Formation. Issue 7 (1st July 2017)

• Record Type: Journal Article
• Authors: Wert, Eric C.; Lew, Julia; Rakness, Kerwin L.
• Is Part Of: Journal ‐ American Water Works Association. Volume 109:Issue 7(2017)
• Page Start: E302
• Page End: E312
• Publication Date: 2017-07-01
• Subjects: bromate -- dissolution -- fine bubble diffusion -- ozone -- sidestream addition; Ozone -- Bromate -- Diffusion -- CT Values -- Contactors; Water-supply -- United States -- Periodicals; Water-supply engineering -- United States -- Periodicals; 363.61097305
• DOI: 10.5942/jawwa.2017.109.0048
• Languages: English
• ISSNs: 0003-150X

Abstract

Abstract : Pilot‐scale data were generated to improve operational guidance for fine bubble diffusion (FBD) and sidestream addition (SSA) systems with respect to unaccounted‐for ozone exposure—i.e., concentration times time ( C × T ), and bromate formation during ozone dissolution. In FBD systems, results showed significant ozone dissolution C × T (0.31–2.85 mg‐min/L) and bromate formation (0.8–9.1 µg/L) occurring in the bubble column, which is not included in regulatory compliance C × T calculations. Utilities may consider taking contactors out of service to minimize contact time and corresponding bromate formation in the dissolution zone. In SSA systems, ozone dosages (7.2–18.6 mg/L) were transferred to approximately 20% of the overall plant flow for ~5 s, which produced bromate (2.6–5.7 µg/L). As the contact time exceeded the design guidance in the sidestream flow (>30 s), bromate formation became far more significant (40–140 µg/L). When the sidestream flow is operated with short contact times (~5 s), bromate formation can be minimized.