Impact of flocculated and softened particles on UV254 inactivation of indigenous spores

Judith Straathof; Zuzana Bohrerova; Natalie M. Hull

doi:10.1002/aws2.70010

journal article Open Access Nov 01, 2024

Impact of flocculated and softened particles on UV254 inactivation of indigenous spores

Judith Straathof

Zuzana Bohrerova Natalie M. Hull

AWWA Water Science Vol. 6 No. 6 · Wiley

View at Publisher Save 10.1002/aws2.70010

Abstract

AbstractUS regulatory ultraviolet (UV) disinfection credit is typically granted when turbidity is ≤1 NTU. However, studies show turbidity does not always correlate well with UV dose responses. This study examined the impact of worst‐case high turbidity scenarios at drinking water treatment plants on UV254 inactivation of indigenous spores from unfiltered source water and unsettled flocculation and softening steps. Flocculated water (turbidity = 6.49–164 NTU) had the lowest dose response with a significantly lower Geeraerd‐tail maximum inactivation rate (kmax = 0.021 cm2/mJ) and higher residual population density (Nres = 7.081 SFU/mL). Raw source water (kmax = 0.027 cm2/mJ, Nres = 1.168 SFU/mL, turbidity = 0.978–215 NTU) and softened water (kmax = 0.030 cm2/mJ, Nres = 0.216 SFU/mL, turbidity = 318–495 NTU) had similar dose responses despite significantly different water quality. Particle size and the degree of particle‐associated spores best explained the differences in dose responses. Almost all spores were associated with flocculated particles instead of free‐floating, which increased tailing and negatively impacted UV inactivation. Based on regulatory reduction equivalent dose bias factors and UV sensitivities of spiked Bacillus subtilis spores, Cryptosporidium would be 4‐log inactivated in these raw, flocculated, or softened waters if UV transmission were ≥65%, 90%, or 80%, respectively, even though turbidity was grossly >1 NTU. Depending on particle characteristics, partial inactivation credit when turbidity is >1 NTU should be considered to avoid high‐tier violations while still protecting public health.

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References

72

[1]

10.5962/bhl.title.6966

[2]

10.2166/aqua.2005.0016

[3]

10.1016/j.watres.2021.117496

[4]

10.1139/m97-140

[5]

10.1002/j.1551-8833.2004.tb10651.x

[6]

10.1016/j.vetpar.2004.09.002

[7]

10.2175/106143006x99795

[8]

Standardization of Methods for Fluence (UV Dose) Determination in Bench-Scale UV Experiments

James R. Bolton, Karl G. Linden

Journal of Environmental Engineering 10.1061/(asce)0733-9372(2003)129:3(209)

[9]

10.1021/acs.est.5b05296

[10]

10.1002/j.1551-8833.2007.tb07892.x

[11]

10.1016/j.watres.2008.02.002

[12]

10.1016/j.watres.2010.10.020

[13]

10.2166/wqrj.2010.030

[14]

10.1016/j.watres.2007.06.032

[15]

10.1016/j.jwpe.2018.01.016

[16]

10.1016/j.watres.2009.09.011

[17]

10.1002/j.1551-8833.2003.tb10344.x

[18]

City of Columbus. (2022).Drinking water consumer confidence report.https://www.columbus.gov/utilities/water-protection/CCR/

[19]

10.1002/j.1551-8833.2000.tb09008.x

[20]

10.1002/j.1551-8833.1994.tb06198.x

[21]

10.2175/wer.65.2.10

[22]

10.5942/jawwa.2012.104.0075

[23]

10.2175/106143000x137969

[24]

10.2175/106143097x122004

[25]

Eskaf S.(2015 January 28).Small water systems with financial difficulties are more likely to violate EPA regulations.Environmental Finance Blog.https://efc.web.unc.edu/2015/01/28/small-water-systems-financial-difficulties-likely-violate-epa-regulations/

[26]

10.1016/j.scitotenv.2017.12.173

[27]

10.1128/aem.69.4.1898-1903.2003

[28]

10.1016/s0168-1605(00)00362-7

[29]

10.1016/j.ijfoodmicro.2004.11.038

[30]

10.2166/wqrj.2001.036

[31]

10.1016/j.desal.2012.01.015

[32]

10.1002/aws2.1295

[33]

10.2175/106143001x139218

[34]

10.1016/j.envres.2006.05.005

[35]

10.1016/j.watres.2011.11.046

[36]

10.1007/s11269-015-1047-2

[37]

10.1016/s0021-9258(18)62213-6

[38]

10.1016/j.watres.2008.10.025

[39]

10.2166/aqua.2007.104

[40]

10.2175/106143096x127910

[41]

10.2175/106143005x94385

[42]

10.1061/(asce)0733-9372(2006)132:6(596)

[43]

10.1061/(asce)0733-9372(2006)132:6(607)

[44]

UV disinfection of indigenous aerobic spores: implications for UV reactor validation in unfiltered waters

Hadas Mamane-Gravetz, Karl G Linden

Water Research 10.1016/j.watres.2004.03.035

[45]

10.1111/j.1365-2672.2004.02455.x

[46]

10.1021/es048446t

[47]

10.1201/9781420032178

[48]

10.1128/aem.64.11.4460-4466.1998

[49]

10.1016/j.scitotenv.2019.06.339

[50]

10.2134/jeq2018.06.0229

Showing 50 of 72 references

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Details

Published: Nov 01, 2024
Vol/Issue: 6(6)
License: View

Authors

J

Judith Straathof

Department of Civil, Environmental and Geodetic Engineering The Ohio State University Columbus Ohio USA; Department of Civil Engineering and Geosciences Delft University of Technology Delft The Netherlands

Z

Zuzana Bohrerova

Ohio Water Resources Center The Ohio State University Columbus Ohio USA; The Sustainability Institute The Ohio State University Columbus Ohio USA

N

Natalie M. Hull

Department of Civil, Environmental and Geodetic Engineering The Ohio State University Columbus Ohio USA; The Sustainability Institute The Ohio State University Columbus Ohio USA

Funding

Ohio Water Resources Center, Ohio State University Award: 60069036

Cite This Article

Judith Straathof, Zuzana Bohrerova, Natalie M. Hull (2024). Impact of flocculated and softened particles on UV254 inactivation of indigenous spores. AWWA Water Science, 6(6). https://doi.org/10.1002/aws2.70010

Impact of flocculated and softened particles on UV254 inactivation of indigenous spores

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