Design and Evaluation of a Household Chlorination System for Treating Cistern Water in the US Virgin Islands

• Published in: Journal of environmental engineering (New York, N.Y.) N.Y.), 2022-11, Vol.148 (11)
• Main Authors: Voth-Gaeddert, Lee E., Lemley, Mandy, Brathwaite, Kela, Schranck, Andrew, Libbey, Stephen
• Format: Article
• Language: English
• Subjects: Carbon; Chlorination; Chlorine; Cisterns; Coliforms; Contact; Contamination; Dyes; Flow rates; Flow velocity; High flow; Households; Islands; Low cost; Membrane filters; Microbial contamination; Microorganisms; Pressure effects; Standard deviation; Systems stability; Technical Note; Technical Notes; Water pollution; Water purification; Water treatment; Water use
• ISSN: 0733-9372; 1943-7870
• DOI: 10.1061/(ASCE)EE.1943-7870.0002063

AbstractIn the US Virgin Islands, >90% of households have rain catchment systems that utilize large cisterns; however, these systems are at high risk of microbial contamination. Available water treatment technologies provide varying levels of protection from microbial contamination and can be expensive. Therefore, we evaluated a low-cost water treatment train that included a passive chlorinator, carbon filter, and membrane filter to provide whole-house treatment for microbial contamination in a mock, pressurized, intermittent-use water system. Two types of locally available passive pool chlorinators were modified and tested for free chlorine residual (FCR) levels across a set of different water use scenarios. Additionally, tracer dye tests were conducted to evaluate chlorine contact time in the system, a carbon filter was evaluated for chlorine removal efficiencies, and a 1-micron nominal filter was evaluated for its effect on system pressure and microbial removal efficiencies. Results suggested the modified passive chlorinators provided relatively consistent chlorine dosing (offline: standard deviation range 0.54 to 0.79 ppm FCR, 3 trials, n=43; inline: standard deviation 0.53 ppm FCR, 1 trial, n=16) and tracer dye tests identified a minimum contact time for high flow rates (18.9 LPM, 5 GPM) of >45  s. The carbon filter reduced FCR levels from as high as 18.5 ppm to