Chlorine fate and transport in drinking water distribution systems: Results from experimental and modeling studies

Abstract

It has become generally accepted that water quality can deteriorate in a distribution system through microbiological and chemical reactions in the bulk phase and/or at the pipe wall. The most serious aspect of water quality deterioration in a network is the loss of the disinfectant residual that can weaken the barrier against microbial contamination. Studies have suggested that one factor contributing to the loss of disinfectant residuals is the reaction between bulk phase disinfectants and pipe wall material. Free chlorine loss in corroded metal and PVC pipes, subject to changes in velocity, was assessed during an experiment conducted under controlled conditions in a specially constructed pipe loop located at the US Environmental Protection Agency’s (EPA’s) Test and Evaluation (T&E) Facility in Cincinnati, Ohio (USA). These studies demonstrated that in older unlined metal pipes, the loss of chlorine residual increases with velocity but that wall demand in PVC was negligible.

Keywords

chlorine fate / transport / drinking water

References

[1] Al-Jasser A O (2007). Chlorine decay in drinking-water transmission and distribution systems: Pipe service age effect. Water Res, 41(2): 387–396

[2] Benjamin M M, Sontheimer H, Leroy P (1996). Corrosion of iron and steel. Internal Corrosion of Water Distribution Systems, American Water Works Association Research Foundation/DVGW-Technologiezentrum Wasser, 29–77

[3] Biswas P, Lu C, Clark R M (1993). A model for chlorine concentration decay in pipes. Water Res, 27(12): 1715–1724

[4] Clark R M, Coyle J A (1990). Measuring and modeling variations in distribution system water quality. J Am Water Works Assoc, 82(8): 46–53

[5] Clark R M, Grayman W M, Goodrich J A, Deininger R A, Hess A F (1991). Field testing distribution water quality models. J Am Water Works Assoc, 83(7): 67–75

[6] Clark R M, Haught R C (2005). Characterizing pipe wall demand: Implications for water quality. J Water Resour Plan Manage, 131(3): 208–217

[7] Clark R M, Haught R C, Panguluri S, Roman W (2006). Predicting the Loss of Chlorine and Chloramine Residuals in Metallic Pipes. In: Proceedings of the 8th Annual Water Distribution Systems Analysis Symposium, Cincinnati, USA, August 27th–30th

[8] Clark R M, Rossman L, Wymer L (1995). Modeling distribution system water quality: Regulatory implications. J Water Resour Plan Manage, 121(6) :423–428

[9] Clark R M, Smalley G, Goodrich J A, Tull R, Rossman L A, Vasconcelos J, Boulos P (1994). Managing water quality in distribution systems: Simulating TTHM and chlorine residual propagation. J Water Supply, 43(4): 182–191

[10] Clark R M, Yang Y J, Impellitteri C A, Haught R C, Schupp D A, Panguluri S, Krishnan E R (2010). Chlorine fate and transport in distribution systems: Experimental and modeling studies. J Am Water Works Assoc, 102 (5): 144–155

[11] Digiano F A, Zhang W (2005). Pipe section reactor to evaluate chlorine–Wall reaction. Journal AWWA, 97(1): 74–85

[12] Doshi P E, Grayman W M, Guastella D (2003). Field Testing the Chlorine Wall Demand in Distribution Mains. In: Proceedings of the 2003 Annual Conference of the American Water Works Association, American Water Works Association, Denver, USA, 1–10

[13] Grayman W M, Rossman L A, Gill M A, Li Y, Guastella D E (2002). Measuring and Modeling Disinfectant Wall Demand in Metallic Pipes. In: Proceedings of the EWRI Conference on Water Resources Planning and Management, Reston VA, ASCE

[14] Panguluri S, Yang Y J, Haught R C, Clark R M, Krishnan E R, Schupp D A (2007). Tracer Dispersion Studies for Hydraulic Characterization of Pipes. In: Proceedings of the Water Environmental and Water Resources Congress, EWRI 2007, Tampa, USA, May15th–19th

[15] Powell J C (1998). Modeling chlorine in water distribution networks. A thesis submitted to the faculty of Engineering at the University of Birmingham for the degree of Doctor of Philosophy

[16] Rossman L A, Brown R A, Singer P C, Nuckols J R (2001). DBP formation kinetics in a simulated distribution system. Water Res, 35(14): 3483–3489

[17] Rossman L A, Clark R M, Grayman W M (1994). Modeling chlorine residuals in drinking water distribution systems. J Environ Eng, 120(4): 803–820

[18] Vasconcelos J J, Rossman L A, Grayman W M, Boulos P F, Clark R M (1997). Kinetics of chlorine decay. J Am Water Works Assoc, 89 (7): 54–65

[19] Williams D B (1958). Dechlorination linked to corrosion in water distribution systems. Water and Sewage Works, 106–111

Acknowledgments

The author gratefully acknowledges the assistance of the following individuals in completing this study: Mr. Brad Smith, Ms. Michelle Latham, Dr. Y. Jeffery Yang, Dr. Chris Impellitteri, and Mr. Roy Haught of the USEPA, Mr. Tim Gray of Lakeshore Engineering Services, Ms. Jill Webster, Ms. Lenora Stephens, and Messers Kit Daniels, John Brannon Don Schupp, Sri Panguluri, and E.R. Krishnan of Shaw Environmental & Infrastructure, Inc.

Notations

a = pipe radius in cm

C0 = initial chlorine concentration in mg/L

C = bulk flow chlorine concentration in mg/L

Ct = the concentration of chlorine in mg/L at time t

Cw = chlorine concentration at the pipe wall in mg/L

Dab = molecular diffusion constant in cm2/s

dc/dt = rate of change of concentration with respect to t

e= exponential

gpm= gallons per minute

Jw = radial flux in mg·cm/(L·s)

Jb = axial flux in mg·cm/(L·s)

K = the total first-order decay rate for chlorine in s-1

k0 = the zero-order reaction coefficient in mg·cm/(L·s)

kr = the wall reaction constant (s-1)

kw = first order coefficient for the pipe-wall reaction coefficient in cm/s

kb = bulk decay coefficient in s-1

kmt = coefficient of mass transfer to the pipe wall in cm/s

ln= the natural log

t = time in second

u = advective velocity in the x direction in cm/s

x = the dimension along the pipe in cm

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