Residence time distribution analysis of an intermittently operating truck fill facility to determine effective contact time. (1st August 2006)

• Record Type: Journal Article
• Authors: Svrcek, Clark; Guest, R K; Smith, Daniel W
• Is Part Of: Journal of environmental engineering and science. Volume 5(2006)Supplement 1
• Page Start: S53
• Page End: S67
• Publication Date: 2006-08-01
• Subjects: truck fill; -- public health; -- residence time distribution; -- Ct concept, tracer study; -- water treatment facility design; Environmental engineering -- Periodicals; Sanitary engineering -- Periodicals; Environmental engineering -- Canada -- Periodicals; Environnement, Technique de l' -- Périodiques; Technique sanitaire -- Périodiques; Environnement, Technique de l' -- Canada -- Périodiques; Environmental engineering; Sanitary engineering; Canada; Electronic journals; Computer network resources; Periodicals; 628.05
• DOI: 10.1139/s06-005
• Languages: English
• ISSNs: 1496-2551

Abstract

Abstract : Two tracer studies were performed on a First Nations water treatment plant (WTP) reservoir in order to determine the reactor mixing pattern as well as the effective contact time, or t 10, value. A unique characteristic of the reservoir in question was that the major outlet from the tank was a truck fill station that operated intermittently throughout the day as water haul trucks filled up for delivery. Almost three times the flowrate was removed as was added, and coupled with the undersized reservoir resulted in major short-circuiting in the unbaffled contact chamber. The reservoir showed an almost ideal completely mixed flow regime, and the lowest t 10 value determined from 2 days of testing was 14 min, much lower than what was required for chlorine Ct compliance. The residence time distribution curves also showed a unique step shape that resulted from the intermittent operation of the truck fill. With the introduction of a lagged time factor a generalized approach for analysis of existing truck fills and the design of new facilities was developed using easily quantifiable variables. An alternative approach for the design of new truck fill facilities was also provided and is somewhat more conservative than the lagged time factor method but allows for a more flexible water delivery schedule. Given the prevalence of truck fill stations in northern communities and the upcoming need for infrastructure upgrades to comply with new standards and guidelines this approach will help ensure the continued protection of public health through the potable water system.