Supporting Information for

Tradeoffs Between Pathogen Inactivation and Disinfection Byproduct Formation During Sequential Chlorine and Chloramine Disinfection for Wastewater Reuse

Kirin E. Furst1, Brian Pecson2, Brie Webber2, and William A. Mitch1, *

1 Department of Civil and Environmental Engineering, Stanford University, 473 Via Ortega, Stanford, California 94305, United States2Trussell Technologies, Inc., 1939 Harrison St., Suite 600, Oakland, CA 94612, United States

*Contact Information: email: wamitch@stanford.edu, Phone: 650-725-9298, Fax: 650-723-7058

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Contents

Table S1 – DBP acronyms S3

Table S2 – LC50 or LECR50 values for halogenated DBPs S4

Table S3 – LECR50 values for nitrosamines S6

Table S4 – Basic water quality parameters S7

Table S5 – Disinfectant residuals, CTs and cumulative exposures S8

Table S6 – DBPs on the first sampling day S9

Table S7 – DBPs on the second sampling day S13

Figure S1 – Regulated DBPs during Event 2 S17

Figure S2 – Total DBPs on a mass basis during Event 2 S18

Figure S3 – Toxicity-weighted DBPs during Event 1 S19

Figure S4 – Toxicity-weighted DBPs during Event 2 S20

References S21

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Table S1 - Classes of DBPs and individual species and their acronyms

DBP Class DBP AcronymTrihalomethanes (THMs)

Chloroform TCM

Bromodichloromethane BDCMDibromochloromethane DBCMBromoform TBM

Haloacetic acids (HAAs)

Chloroacetic acid CAA

Bromoacetic acid BAADichloroacetic acid DCAATrichloroacetic acid TCAABromochloroacetic acid BCAADibromoacetic acid DBAABromodichloroacetic acid BDCAADibromochloroacetic acid DBCAATribromoacetic acid TBAAIodoacetic acid IAA

Iodinated THMs (I-THMS)

Dichloroiodomethane DCIM

Bromochloroiodomethane BCIMDibromoiodomethane DBIMChlorodiiodomethane CDIMBromodiiodomethane BDIMIodoform TIM

Halonitromethanes Chloropicrin TCNMHaloketones 1,1-dichloropropanone 1,1-DCP

1,1,1-trichloropropanone 1,1,1-TCPHaloacetaldehydes (HALs)

Trichloroacetaldehyde TCAL

Bromodichloroacetaldehyde BDCALDibromochloroacetaldehyde DBCALTribromoacetaldehyde TBAL

Haloacetonitriles (HANs)

Dichloroacetonitrile DCAN

Bromochloroacetonitrile BCANDibromoacetonitrile DBANTrichloroacetonitrile TCAN

Haloacetamides (HAMs)

Dichloroacetamide DCAM

Bromochloroacetamide BCAMDibromoacetamide DBAMTrichloroacetamide TCAM

Nitrosamines (NAs) N-nitrosodimethylamine NDMAN-nitrosomorpholine NMOR

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Table S2 - LC50 or LECR50 of the halogenated DBPs (lower of the two selected to be conservative)

LC50 or LECR50 (M) ReferenceTHMsTCM 9.17×10−3 LC50 (Plewa and Wagner 2009)BDCM 1.69×10-3 LECR50 (US EPA, 2017b)DBCM 1.00×10-3 LECR50 (US EPA, 2017b)TBM 3.96×10−3 LC50 (Plewa and Wagner 2009)HAAsCAA 8.48×10−4 LC50 (Plewa et al. 2010)BAA 9.60×10−6 LC50 (Plewa et al. 2010)DCAA 2.75×10-3 LECR50 (US EPA, 2017b)TCAA 1.53×10-3 LECR50 (US EPA, 2017b)BCAA 7.78×10−4 LC50 (Plewa et al. 2010)DBAA 5.21×10−4 LC50 (Plewa et al. 2010)BDCAA 6.85×10−4 LC50 (Plewa et al. 2010)DBCAA 2.00×10−4 LC50 (Plewa et al. 2010)TBAA 8.50×10−5 LC50 (Plewa et al. 2010)IAA 3.20×10−6 LC50 (Plewa et al. 2010)I-THMsDCIM 4.13×10−3 LC50 (Richardson et al. 2008)BCIM 2.42×10−3 LC50 (Richardson et al. 2008)DBIM 1.91×10−3 LC50 (Richardson et al. 2008)CDIM 2.41×10−3 LC50 (Richardson et al. 2008)BDIM NA NATIM 6.60×10−5 LC50 (Richardson et al. 2008)HNMsTCNM 5.36×10−4 LC50 (Plewa et al. 2004)HKs1,1-DCP NA1 NA1,1,1-TCP NA NAHALsTCAL 1.16×10−3 LC50 (Jeong et al. 2015)BDCAL 2.04×10−5 LC50 (Jeong et al. 2015)DBCAL 5.15×10−6 LC50 (Jeong et al. 2015)TBAL 3.56×10−6 LC50 (Jeong et al. 2015)HANsDCAN 5.73×10−5 LC50 (Muellner et al. 2007)BCAN 8.46×10−6 LC50 (Muellner et al. 2007)

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DBAN 2.85×10−6 LC50 (Muellner et al. 2007)TCAN 1.60×10−4 LC50 (Muellner et al. 2007)HAMsDCAM 1.92×10−3 LC50 (Plewa et al. 2008)BCAM 1.71×10−5 LC50 (Plewa et al. 2008)DBAM 1.22×10−5 LC50 (Plewa et al. 2008)TCAM 2.05×10−3 LC50 (Plewa et al. 2008)

1 NA = not available

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Table S3 - LECR50 of the nitrosamines (lowest available selected to be conservative)

Calculated LECR50 (M)

10-6 lifetime excess cancer risk (ng/L)

Federal Register 2014-24582

California 27 CCR §25705

N-Nitrosamines (ng/L)NDMA 4.04×10−6 a 0.6 3NMEA 1.70×10−5 a 3 1.5NDEA 1.96×10−6 a 0.4 1NDPA 2.69×10−5 a 7 5NPYR 9.99×10−6 a 2 15NPIP 1.53×10−5 b --- 3.5

NDBA 9.49×10−5 a 30 3NMOR 2.15×10−5 b --- 5

a Calculations using the age-adjusted 10-6 lifetime excess cancer risk values in Federal Register 2014-24582 (U.S. Environmental Protection Agency 2014).b Calculations using the 10-6 lifetime excess cancer risk values derived from California 27 CCR §25705 (CADPH 2013).

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Table S4 – Basic water quality parameters

T a Turbidity a DOC UV254 SUVA NH3 a NO3- Br- I-

°C NTU mg/L cm-1 L/(m×mg) mg/L N mg/L N mg/L mg/L1 No NH3 spike 25 7.1 0.7 8.6 0.15 1.7 0.1 5.1

5/1/2017 NH3 spike 26 7.3 0.7 8.6 0.16 1.9 0.1/1.2 b 8.52 No NH3 spike 24 7.4 0.5 9.0 0.15 1.6 0.1 8.1 160

5/22/2017 NH3 spike 27 7.4 0.6 8.9 0.15 1.7 0.1/0.9 b 8.0 170

a Measurements taken by online metersb NH3 measured before/after spiking with ammonium sulfatec Measured by the utility

Event pH a

280 c 27

22

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Table S5 – Disinfectant residuals, CTs and cumulative exposures

Modal ContactTime Residual CT Exposure1

(min) (mg/L as Cl2) (mg×min/L) (mg×min/L)Event 1, no NH 3 spike

2.8 3.9 10.9 10.98.3 1.6 13.3 19.7

22.1 0.6 13.3 28.035.5 0.3 10.7 32.0

Event 1, NH 3 spike2.8 3.8 10.6 10.68.3 1.5 12.5 18.9

22.1 0.7 15.5 28.635.5 0.7 24.9 37.9

Event 2, no NH 3 spike2.8 3.5 9.8 9.88.3 1.5 12.5 18.1

22.1 0.4 8.8 23.635.5 0.8 28.4 34.3

Event 2, NH 3 spike2.8 3.7 10.4 10.48.3 1.1 9.1 16.4

22.1 0.8 17.7 27.535.5 0.8 28.4 38.2

1 Exposure was calculated by summing the CT values determined between each modal contact time

Free Chlorine

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Table S6 - DBPs measured during the first sampling day. Halogenated DBPs in mg/L. Nitrosamines in ng/L. MRL = minimum reporting level. Quenched = DBPs measured directly after the free chlorine exposure.

EVENT 1THMs

THMs TCM BDCM DBCMcontact time (min)Nitrification (quenched)

0 1.6 0.2 <MRL2.8 14 12 8.18.3 19 22 1222.1 25 27 1435.5 26 27 15

Nitrification (24 hour chloramine)2.8 25 20 9.68.3 29 28 1522.1 26 33 1835.5 26 34 18

Ammonia challenge0 1.4 0.2 <MRL2.8 34 18 9.48.3 34 26 1422.1 35 27 14

EVENT 1THMs

THMs TCM BDCM DBCMcontact time (min)Nitrification (quenched)

0 1.6 0.2 <MRL2.8 14 12 8.18.3 19 22 1222.1 25 27 1435.5 26 27 15

Nitrification (24 hour chloramine)2.8 25 20 9.68.3 29 28 1522.1 26 33 1835.5 26 34 18

Ammonia challenge0 1.4 0.2 <MRL2.8 34 18 9.48.3 34 26 1422.1 35 27 14

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EVENT 1THMs

THMs TCM BDCM DBCMcontact time (min)Nitrification (quenched)

0 1.6 0.2 <MRL2.8 14 12 8.18.3 19 22 1222.1 25 27 1435.5 26 27 15

Nitrification (24 hour chloramine)2.8 25 20 9.68.3 29 28 1522.1 26 33 1835.5 26 34 18

Ammonia challenge0 1.4 0.2 <MRL2.8 34 18 9.48.3 34 26 1422.1 35 27 14

HAMs

HAMs TCAM DCAM BCAM DBAMcontact time (min)Nitrification (quenched)

0 <MRL <MRL <MRL <MRL2.8 <MRL 0.52 0.90 <MRL8.3 <MRL 0.87 1.9 0.5422.1 0.25 0.94 1.8 0.5935.5 <MRL 0.67 1.6 0.58

Nitrification (24 hour chloramine)2.8 0.83 2.3 3.3 0.778.3 0.78 2.3 3.0 0.8322.1 0.74 1.9 2.8 0.6735.5 0.82 1.9 3.2 0.90

Ammonia challenge0 <MRL <MRL <MRL <MRL2.8 0.55 0.61 0.71 0.268.3 0.64 0.81 1.3 0.4922.1 1.0 1.8 3.3 1.4

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HAMs TCAM DCAM BCAM DBAM I-THMscontact time (min) contact time (min)Nitrification (quenched) Nitrification (quenched)

0 <MRL <MRL <MRL <MRL 02.8 <MRL 0.52 0.90 <MRL 2.88.3 <MRL 0.87 1.9 0.54 8.322.1 0.25 0.94 1.8 0.59 22.135.5 <MRL 0.67 1.6 0.58 35.5

Nitrification (24 hour chloramine) Nitrification (24 hour chloramine)2.8 0.83 2.3 3.3 0.77 2.88.3 0.78 2.3 3.0 0.83 8.322.1 0.74 1.9 2.8 0.67 22.135.5 0.82 1.9 3.2 0.90 35.5

Ammonia challenge Ammonia challenge0 <MRL <MRL <MRL <MRL 02.8 0.55 0.61 0.71 0.26 2.88.3 0.64 0.81 1.3 0.49 8.322.1 1.0 1.8 3.3 1.4 22.135.5 0.91 1.9 3.5 1.4 35.5MRL 0.24 0.14 0.17 0.22 MRL

HAMs TCAM DCAM BCAMcontact time (min)Nitrification (quenched)

0 <MRL <MRL <MRL2.8 <MRL 0.52 0.908.3 <MRL 0.87 1.922.1 0.25 0.94 1.835.5 <MRL 0.67 1.6

Nitrification (24 hour chloramine)2.8 0.83 2.3 3.38.3 0.78 2.3 3.022.1 0.74 1.9 2.835.5 0.82 1.9 3.2

Ammonia challenge0 <MRL <MRL <MRL2.8 0.55 0.61 0.718.3 0.64 0.81 1.322.1 1.0 1.8 3.335.5 0.91 1.9 3.5MRL 0.24 0.14 0.17

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EVENT 1

HAAs CAA DCAA TCAA BAA DBAA TBAA BCAA BDCAA CDBAAcontact time (min)Nitrification (quenched)

0 <MRL 0.25 1.7 <MRL <MRL <MRL <MRL <MRL <MRL2.8 1.1 5.4 13 1.0 1.6 0.33 2.9 8.8 2.88.3 1.1 8.0 13 1.3 3.1 0.83 4.9 12 7.422.1 1.0 10 16 1.2 3.9 1.1 6.5 17 1035.5 1.5 8.1 20 1.7 3.8 0.76 6.0 20 7.4

Nitrification (24 hour chloramine)2.8 2.0 10 7.8 1.3 2.3 <MRL 4.7 4.3 1.28.3 3.2 10 9.9 2.0 2.5 <MRL 4.9 7.1 2.322.1 3.2 10 12 2.1 2.7 <MRL 5.2 8.7 2.535.5 4.2 11 15 2.6 3.7 0.25 6.7 9.9 2.9

Ammonia challenge0 <MRL 0.44 2.3 <MRL <MRL <MRL <MRL <MRL <MRL2.8 2.9 13 12 1.4 2.3 <MRL 5.0 4.9 1.28.3 3.7 13 14 2.0 3.2 <MRL 5.6 7.0 2.222.1 3.6 11 14 1.8 3.0 <MRL 5.1 6.2 1.9

EVENT 1

NAs NDMA NMEA NDEA NDPA NMOR NPYR NPIPcontact time (min)Nitrification (quenched)

0 10 <MRL <MRL <MRL 8.1 <MRL <MRL2.8 7.7 <MRL <MRL <MRL 5.9 <MRL <MRL8.3 9.2 <MRL <MRL <MRL 7.0 <MRL <MRL22.1 8.7 <MRL <MRL <MRL 7.2 <MRL <MRL35.5 8.1 <MRL <MRL <MRL 7.1 <MRL <MRL

Nitrification (24 hour chloramine)2.8 36 <MRL <MRL <MRL 9.0 <MRL <MRL8.3 19 <MRL <MRL <MRL 7.1 <MRL <MRL22.1 14 <MRL <MRL <MRL 7.7 <MRL <MRL35.5 13 <MRL <MRL <MRL 11 <MRL <MRL

Ammonia challenge0 8.8 <MRL <MRL <MRL 6.4 <MRL <MRL2.8 17 <MRL <MRL <MRL 6.6 <MRL <MRL8.3 11 <MRL <MRL <MRL 5.8 <MRL <MRL22.1 14 <MRL <MRL <MRL 5.7 <MRL <MRL

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Table S7 - DBPs measured during the second sampling day. Halogenated DBPs in mg/L. Nitrosamines in ng/L. MRL = minimum reporting level. Quenched = DBPs measured directly after the free chlorine exposure.

EVENT 2THMs

THMs TCM BDCM DBCMcontact time (min)Nitrification

0 1.9 0.2 <MRL2.8 18 16 108.3 25 25 1222.1 29 30 1535.5 28 29 15

Ammonia challenge0 1.9 <MRL <MRL2.8 20 15 108.3 26 22 20

EVENT 2THMs

THMs TCM BDCM DBCMcontact time (min)Nitrification

0 1.9 0.2 <MRL2.8 18 16 108.3 25 25 1222.1 29 30 1535.5 28 29 15

Ammonia challenge0 1.9 <MRL <MRL2.8 20 15 108.3 26 22 20

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EVENT 2THMs

THMs TCM BDCM DBCMcontact time (min)Nitrification

0 1.9 0.2 <MRL2.8 18 16 108.3 25 25 1222.1 29 30 1535.5 28 29 15

Ammonia challenge0 1.9 <MRL <MRL2.8 20 15 108.3 26 22 20

HALs

DCAN BCAN DBAN HALscontact time (min)Nitrification

<MRL <MRL <MRL 03.9 0.7 <MRL 2.85.2 1.1 <MRL 8.36.1 1.5 <MRL 22.15.8 1.8 0.31 35.5

Ammonia challenge<MRL <MRL <MRL 04.9 1.2 <MRL 2.86.1 1.8 0.53 8.3

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HAMs

TCAL BDCAL DBCAL TBAL HAMs TCAMcontact time (min) contact time (min)Nitrification Nitrification

<MRL <MRL <MRL <MRL 0 <MRL0.63 1.1 0.36 <MRL 2.8 <MRL1.8 2.3 0.64 <MRL 8.3 <MRL3.2 3.4 1.0 <MRL 22.1 <MRL2.7 3.0 1.1 <MRL 35.5 <MRL

Ammonia challenge Ammonia challenge<MRL <MRL <MRL <MRL 0 <MRL1.1 2.3 0.85 0.43 2.8 0.272.9 4.3 1.9 <MRL 8.3 0.36

I-THMs

BCAM DBAM I-THMscontact time (min)Nitrification

<MRL <MRL 02.2 0.58 2.82.0 0.77 8.32.8 1.1 22.12.0 0.77 35.5

Ammonia challenge<MRL <MRL 01.9 1.0 2.83.3 3.1 8.3

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EVENT 2

HAAs CAA DCAA TCAA BAA DBAA TBAA BCAA BDCAA CDBAAcontact time (min)Nitrification (24 hour chloramine)

0 1.1 0.3 1.2 <MRL <MRL <MRL <MRL <MRL <MRL2.8 4.0 13 6.2 1.8 1.8 <MRL 6.3 2.1 0.848.3 3.9 13 7.5 2.5 2.8 <MRL 8.4 4.8 2.222.1 4.6 13 6.8 3.1 2.3 <MRL 6.9 3.3 1.535.5 4.9 13 9.6 3.3 2.8 <MRL 8.6 5.3 2.4

Ammonia challenge0 1.6 0.33 0.49 <MRL <MRL <MRL <MRL <MRL <MRL2.8 2.5 12 8.5 1.4 3.1 <MRL 7.4 3.7 1.28.3 5.3 12 10 2.5 5.6 0.57 10 4.8 4.4

EVENT 2

NAs NDMA NMEA NDEA NDPA NMOR NPYR NPIPcontact time (min)Nitrification (24 hour chloramine)

0 12 <MRL <MRL <MRL 9.1 <MRL <MRL2.8 29 <MRL <MRL <MRL 7.9 <MRL <MRL8.3 15 <MRL <MRL <MRL 7.6 <MRL <MRL22.1 9.8 <MRL <MRL <MRL 5.4 <MRL <MRL35.5 11 <MRL <MRL <MRL 9.0 <MRL <MRL

Ammonia challenge0 9.1 <MRL <MRL <MRL 6.6 <MRL <MRL2.8 19 <MRL <MRL <MRL 5.3 <MRL <MRL8.3 10 <MRL <MRL <MRL 7.0 <MRL <MRL

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Fig. S1 - Regulated DBPs measured during Event 2. Concentrations of regulated THM4 and HAA5 in µg/L and NDMA in ng/L following 24 hour chloramination as a function of various free chlorine exposures with A) 0.1 mg/L as N influent ammonia and B) 0.9 mg/L as N influent ammonia.

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Fig. S2 - Total concentration of DBPs measured during Event 2 on a mass basis (µg/L) as a function of free chlorine (FC) exposure. Concentrations of THM4, HAA9, iodo-THMs (I-THMs), haloacetonitriles (HANs), haloacetaldehydes (HALs), haloacetamides (HAMs), haloketones (HKs), nitrosamines (NAs) after free chlorine exposure and 24 hour chloramination A) with 0.1 mg/L as N influent ammonia, and B) with 0.9 mg/L as N influent ammonia. Error bars represent the standard deviation of experimental replicates for halogenated DBPs or the range of nitrosamine duplicates.

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Fig. S3 - Toxicity-weighted concentrations of all DBPs measured during Event 1 as a function of free chlorine (FC) exposure calculated by dividing the mass concentration of each DBP by the lowest LC50 or LECR50 value available (Tables S4 and S5). DBP classes include THM4, HAA9, iodo-THMs (I-THMs), haloacetonitriles (HANs), haloacetaldehydes (HALs), haloacetamides (HAMs), haloketones (HKs), and nitrosamines (NAs). Toxicity-weighted concentrations calculated after A) the free chlorine exposure with 0.1 mg/L as N influent ammonia, and B) after the free chlorine exposure and 24 hour chloramination with 1.2 mg/L as N influent ammonia.

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Fig. S4 - Toxicity-weighted concentrations of all DBPs measured during Event 2 as a function of free chlorine (FC) exposure calculated by dividing the mass concentration of each DBP by the lowest LC50 or LECR50 value available (Tables S4 and S5). DBP classes include THM4, HAA9, iodo-THMs (I-THMs), haloacetonitriles (HANs), haloacetaldehydes (HALs), haloacetamides (HAMs), haloketones (HKs), and nitrosamines (NAs). Toxicity-weighted concentrations calculated after the free chlorine exposure and 24 hour chloramination A) with 0.1 mg/L as N influent ammonia, and B) with 0.9 mg/L as N influent ammonia.

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References

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Muellner, Mark G., Elizabeth D. Wagner, Kristin Mccalla, Susan D. Richardson, Yin T. Woo, and Michael J. Plewa. 2007. “Haloacetonitriles vs. Regulated Haloacetic Acids: Are Nitrogen-Containing DBFs More Toxic?” Environ. Sci. Technol. 41 (2): 645–51.

Plewa, Michael J., Mark G. Muellner, Susan D. Richardson, Francesca Fasano, Katherine M. Buettner, Yin Tak Woo, A. Bruce Mckague, and Elizabeth D. Wagner. 2008. “Occurrence, Synthesis, and Mammalian Cell Cytotoxicity and Genotoxicity of Haloacetamides: An Emerging Class of Nitrogenous Drinking Water Disinfection Byproducts.” Environ. Sci. Technol. 42 (3): 955–61.

Plewa, Michael J., and E.D. Wagner. “Quantitative Comparative Mammalian Cell Cytotoxicity and Genotoxicity of Selected Classes of Drinking Water Disinfection By-products [Project #3089].” 2009. Water Research Foundation, Denver, CO.

Plewa, Michael J., Elizabeth D. Wagner, Paulina Jazwierska, Susan D. Richardson, Paul H. Chen, and A. Bruce McKague. 2004. “Halonitromethane Drinking Water Disinfection Byproducts: Chemical Characterization and Mammalian Cell Cytotoxicity and Genotoxicity.” Environ. Sci. Technol. 38 (1): 62–68.

Plewa, Michael J, Jane E Simmons, Susan D Richardson, and Elizabeth D Wagner. 2010. “Mammalian Cell Cytotoxicity and Genotoxicity of the Haloacetic Acids, A Major Class of Drinking Water Disinfection By-Products.” Environmental and Molecular Mutagenesis 51: 871–78.

Richardson, Susan D, Francesca Fasano, Gene F Crumley, Katherine M Buettner, John J Evans, Benjamin C Blount, Lalith K Silva, Tim J. Waite, George W. Luther, A. Bruce McKague, Richard J. Miltner, Elizabeth D. Wagner and Michael J. Plewa, 2008. “Occurrence and Mammalian Cell Toxicity of Iodinated Disinfection Byproducts in Drinking Water.” Environ. Sci. Technol. 42 (22): 8330–38.

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