# Characterization of disinfection by-product precursors from natural organic matter through a novel membrane fractionation

Karlien Dejaeger, Gabriel Billon, Cécile Vignal, Marjolein Vanoppen, Emile Cornelissen, Justine Criquet

► To cite this version:

Karlien Dejaeger, Gabriel Billon, Cécile Vignal, Marjolein Vanoppen, Emile Cornelissen, et al.. Characterization of disinfection by-product precursors from natural organic matter through a novel membrane fractionation. 4th IWA Specialized International Conference on Disinfection and DBPs, IWA, Oct 2024, Almeria, Spain. hal-05288631

HAL Id: hal-05288631

https://lilloa.hal.science/hal-05288631v1

Submitted on 29 Sep 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# Characterization of disinfection by-product precursors from natural organic matter through a novel membrane fractionation

K. Dejaeger<sup>a,b,c,†</sup>, G. Billon<sup>b</sup>, C. Vignal<sup>c</sup>, M. Vanoppen<sup>a</sup>, E.R. Cornelissen<sup>a,d</sup> and J. Criquet<sup>b</sup>

**Abstract:** Although drinking water disinfection has been a great discovery to prevent the mortality of waterborne diseases, the formation of potentially harmful disinfection by-products from the reaction of organic matter with chlor(am)ine remains an important drawback. Therefore, this work assessed which type of organic matter is responsible for the formation of different (un)regulated disinfection by-products after chlor(am)ination. For this, a novel membrane fractionation protocol was developed to facilitate the identification of the precursors from the complex pool of natural organic matter. An intensive sampling campaign has been executed for one year at a water treatment plant in Belgium to monitor the reactivity of the different fractions on a seasonal basis. Overall, each membrane fraction had a particularly high reactivity potential towards one specific disinfection by-product family and the reactivity was very dependent on the type of disinfectant used.

**Keywords:** haloacetamides; haloacetic acids; haloacetonitriles; nitrosamines; sampling campaign; trihalomethanes

## Introduction

Although drinking water disinfection efficiently inactivate waterborne pathogens, the disinfectant will also react with natural organic matter (NOM) present in drinking water resources and produce disinfection by-products (DBPs) which are associated with negative health issues. A large variety of by-products have been detected, but only 4 trihalomethanes and 5 haloacetic acids are currently widely regulated [2, 3]. Many other DBPs such as haloacetonitriles and haloacetamides are not regulated since they are found in lower concentrations [2].

To identify the precursors of these DBPs, the characterization of the NOM which is known to be a very heterogeneous mixture of aliphatic and aromatic compounds, is paramount [4, 5]. Therefore, NOM is fractionated into fractions having similar physical or chemical characteristics with membranes or resins [6].

Subsequently, these fractions are oxidised to identify which DBPs are formed from each fraction. Our meta-analysis showed that dead-end, stirred cell ultrafiltration membrane fractionation currently used in research seems to not produce sharply separated fractions. Therefore, no clear correlation could be found between different membrane fractions and DBP formation [6].

This work will therefore fractionate NOM using a novel membrane fractionation method into more sharply separated fractions to identify the precursors of 5 different disinfection by-product families after chlorination and chloramination.

## Methodology

Surface water from the reservoir of the Blankaart drinking water treatment plant was collected 6 times over the course of 2023. The water was characterized with high

<footnote><sup>a</sup>PaInT, Particle and Interfacial Technology group, Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium, (Email: karlien.dejaeger@ugent.be, marjolein.vanoppen@ugent.be, emile.cornelissen@ugent.be)</footnote>

<footnote><sup>b</sup> Univ. Lille, CNRS, UMR 8516 - LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement F-59000 Lille, France, (Email: karlien.dejaeger@univ-lille.fr, justine.criquet@univ-lille.fr, gabriel.billon@univ-lille.fr)</footnote>

<footnote><sup>c</sup> Univ. Lille, Inserm, CHU Lille, U1286 - INFINITE - Institute for Translational Research in Inflammation, F-59000 Lille, France, (Email: cecile.vignal2@univ-lille.fr)</footnote>

<footnote><sup>d</sup> KWR Water Research Institute, Groningenhaven 7, 3433 PE Nieuwegein, Netherlands (Email: emile.cornelissen@kwrwater.nl)</footnote>
performance size exclusion chromatography coupled to a total organic carbon detector (HPSEC-TOC) to quantify the amount of three fractions: biopolymers (> 20 kDa), humic substances (0.3 – 20 kDa) and low molecular weight compounds (< 0.3 kDa). Next, these three fractions were separated physically using a novel membrane fractionation method. Briefly, the fractionation consists of a consecutive ultra- and nanofiltration crossflow filtration combined with a diafiltration step.

Before chlorinating the fractions, several Cl₂/DOC ratios were tested for both chlorine and chloramine on the reservoir water to obtain a chlorine residual of 1 mgCl₂/L after 24h in the dark (pH 7, 25°C). Next, the obtained fractions were chlor(am)inated with the same Cl₂/DOC ratio as the reservoir water, and also the Br/DOC and I/DOC-ratios were put at the same level in all fractions. This makes the comparison of the reactivity of the different fractions more evident. Experiments were conducted in triplicate and blanks were included. The samples were quenched using ascorbic acid. Samples before and after chlor(am)ination were analysed for (un)regulated trihalomethanes (THM, 8) and haloacetic acids (HAA, 9) and several nitrogenous DBPs such as haloacetonitriles (HAN, 6), haloacetamides (HAM, 5) and nitrosamines (7).

# Results and Discussion

## The fractionation

The average composition of the raw water and the resulting fractions after the membrane fractionation from the 6 different sampling rounds as quantified by HPSEC-TOC is found in *Average composition of the raw water, the biopolymer fraction, the humic substances fraction and the low molecular weight fraction from 6 sampling rounds*. Table 1. The biopolymer fraction (BP) shows a clear enrichment of biopolymers (going from 3.67% in the raw water to 31.0% on average). There are still 68.7% humic substances present in this BP fraction on average, however, this accounts for only 5.00 ± 3.10% of the initial amount of humic substances present in the raw water, meaning that almost all humic substances are removed from the BP fraction in absolute numbers. Furthermore, the BP fraction are free from low molecular weight compounds. Next, the humic substances fraction (HS) contained no biopolymers anymore and only 17.3% low molecular weight compounds on average. The low molecular weight fraction (LMW) was the hardest to quantify, since only 314 ± 151 µgC/L was present in this fraction, presumably only consisting of low molecular weight compounds, although this could not be confirmed by the HPSEC-TOC chromatograms due to the low concentrations.

## Disinfection by-product formation

The specific DBP formation potential (= ratio of by-products formed per concentration of organic carbon in the sample) of the three different fractions is found in Figure 1. No nitrosamines could be detected in the three fractions for all the sampling rounds.

The relative reactivity of each fraction was very dependent on the type of disinfectant used, e.g. the HS fraction had clearly the highest formation potential for unregulated I-THMs and regulated HAA5 during chloramination, while the LMW and the BP fractions became very reactive for these compounds respectively during chlorination (Figure 1A and B). On the contrary, for the nitrogenous unregulated DBPs (HAN and HAM, Figure 1C), the HS fraction had the highest formation potential during chlorination, while the LMW fraction was very reactive during chloramine treatment.
<figure><img src="image_2.png" /><figcaption>**Figure 1.** Disinfection by-product formation potential (µg/mgC) of regulated trihalomethanes (THM4, Top A) and haloacetic acids (HAA5, Bottom A), unregulated iodinated trihalomethanes (I-THM, Top B) and haloacetic acids (HAA, Bottom B), nitrogenous haloacetonitriles (HAN, Top C) and nitrogenous haloacetamides (HAM, Bottom C) in the biopolymer fraction (BP), humic substances fraction (HS) and low molecular weight fraction (LMW). p ≤ 0.05 (*), p ≤ 0.01 (**), p ≤ 0.001 (***), p ≤ 0.0001 (****).</figcaption></figure>

Overall, it is clear from our results that during chlorination, the (hydrophilic) biopolymer and (hydrophobic) humic substances fraction have similar formation potentials for the majority of disinfection by-product families investigated. This is not in line with previous observations were hydrophobic moieties form more THMs and HAAs and where hydrophilic moieties form more unregulated by-products such as HANs and HAMs [6].

The high reactivity potential found for the BP and LMW fraction can have implications on the efficiency of a drinking water treatment plant to reduce DBP precursors. For example, coagulation, a very common drinking water treatment step, targets hydrophobic, negatively charged compounds (i.e. humic substances) and insufficiently removes LMW and part of BP in a typical drinking water treatment plant and can therefore still be present as an important source of disinfection by-product precursors [7, 8].
<table><caption>**Table 1.** Average composition of the raw water, the biopolymer fraction, the humic substances fraction and the low molecular weight fraction from 6 sampling rounds.</caption><thead><tr><th></th><th>Biopolymers</th><th>Humic substances</th><th>Low molecular weight compounds</th></tr></thead><tbody><tr><td>Raw water</td><td>3.67 ± 1.17%</td><td>80.9 ± 3.73%</td><td>15.4 ± 3.34%</td></tr><tr><td>Biopolymer fraction</td><td>31.0 ± 14.3%</td><td>68.7 ± 14.0%</td><td>0%</td></tr><tr><td>Humic substances fraction</td><td>0%</td><td>82.7 ± 3.61%</td><td>17.3 ± 3.61%</td></tr><tr><td>Low molecular weight fraction</td><td>0%</td><td>0%</td><td>100%</td></tr></tbody></table>

**Conclusion and future work**

This work achieved a clear separation between biopolymers, humic substances and low molecular weight compounds using a novel membrane fractionation approach. Using these fractions, this work showed for the first time clear differences in reactivity potential between the different fractions towards DBP formation. Extra characterization techniques such as fluorescence and orbitrap mass spectrometry will be executed in future work to further investigate the specific molecular characteristics of the DBP precursors.

**References**

1. Aiken, G.R., et al., *Comparison of XAD Macroporous Resins for the Concentration of Fulvic Acid from Aqueous Solution*. Analytical Chemistry, 1979. **51**(11): p. 1799-1803.

2. Richardson, S.D., et al., *Occurrence, genotoxicity, and carcinogenicity of regulated and emerging disinfection by-products in drinking water: A review and roadmap for research*. Mutation Research-Reviews in Mutation Research, 2007. **636**(1-3): p. 178-242.

3. Diana, M., et al., *Disinfection byproducts potentially responsible for the association between chlorinated drinking water and bladder cancer: A review*. Water Research, 2019. **162**: p. 492-504.

4. Filella, M., *Freshwaters: which NOM matters?* Environmental Chemistry Letters, 2009. **7**(1): p. 21-35.

5. Leenheer, J.A. and J.P. Croue, *Peer Reviewed: Characterizing Aquatic Dissolved Organic Matter*. Environmental Science & Technology, 2003. **37**(1): p. 18A-26A.

6. Dejaeger, K., et al., *Identification of disinfection by-product precursors by natural organic matter fractionation: a review*. Environmental Chemistry Letters, 2022.

7. Matilainen, A., et al., *Natural organic matter removal by coagulation during drinking water treatment: A review*. Advances in Colloid and Interface Science, 2010. **159**(2): p. 189-197.

8. Kimura, K. and N. Ando, *Maximizing biopolymer removal by coagulation for mitigation of fouling in the following membrane process*. Separation and Purification Technology, 2016. **163**: p. 8-14.