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Chloramine chemistry - web based application
Citation:
Wahman, D. Chloramine chemistry - web based application. Presented at 2015 American Water Works Association Water Quality & Technology Conference, Salt Lake City, UT, November 15 - 19, 2015.
Impact/Purpose:
Provide knowledge about drinking water chloramine chemistry
Description:
Chlorine disinfection remains quite popular in the United States, but because of the Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules, many United States utilities now use combinations of chlorine and chloramines to avoid excessive regulated trihalomethane and haloacetic acid formation. Surveys report that 30% of the respondents currently chloraminate to maintain distribution system residual, and other surveys suggest that between 8 and 12% of drinking water utilities are contemplating a future switch to chloramination. Upon implementation of the Stage 2 Disinfectants and Disinfection Byproducts Rule (i.e., ~2015), chloramination for secondary disinfection in the United States is predicted to increase to 57% of all surface and 7% of all ground water treatment systems. Therefore, an understanding of chloramine chemistry is of practical importance.Fortunately, for almost 30 years, a reaction scheme typically termed the Unified Model has existed that describes inorganic chloramine formation and decay over a range of conditions applicable to drinking water. Even though a reasonable reaction scheme has existed, a widely and freely accessible implementation of the Unified Model has not, largely because of the requirement to program and solve the reaction scheme, preventing model implementation in a user-friendly environment where proprietary software or user modeling experience was not required.To address the limited access and accelerate the learning curve associated with simulating inorganic chloramine chemistry formation and stability, two web-based applications (WBAs) relevant to drinking water practice were developed to (1) simulate inorganic chloramine formation and subsequent stability, including a simple inorganic chloramine demand reaction for organic matter and (2) generate chlorine breakpoint curves. The intent is for the two WBAs to serve as learning tools for drinking water operators, engineers, researchers, and students. The WBAs provide the user a free, interactive environment to explore and understand fundamental inorganic chloramine chemistry where the only requirement is a web browser and Internet connection to access the WBAs’ web pages. Although not intended to simulate specific “real-life” situations, the WBAs may be used to evaluate and understand the implications of possible operational changes (e.g., chlorine to nitrogen mass ratios, target inorganic chloramine residual, booster chlorination, and pH) and their possible impacts to inorganic chloramine formation and subsequent stability. Recent developments in freely available software allowed a web based interface to be developed, overlaying a robust statistical software package; thereby, allowing a simple outward facing Unified Model implementation to be accessible over the Internet. The WBAs’ implementation along with example uses will be presented.
URLs/Downloads:
http://www.awwa.org/Portals/0/files/education/conferences/wqtc/wqtc15/pdfs/2015WQTCTechnicalProgramWEB.pdf