Disinfection By-product Formation Potential Research Articles

Effects of temperature and microorganism densities on disinfection by-product formation

This study investigated the role of microorganisms on the correlation between temperature changes and disinfection by-product formation in natural waters. Climate changes have resulted in an increase in the global surface temperature. Studies have revealed that increases in temperature may change the composition of dissolved organic matter (DOM), which may contain major disinfection by-product (DBP) precursors. This change in the DOM composition may affect DBP formation after conventional water treatment processes. Understanding the role of microorganisms in DOM composition as well as DBP formation and speciation is critical for controlling DBP formation. In this study, laboratory stimulatory experiments were conducted on water samples from various sources, at various temperatures, and with various microbial concentrations. The results revealed a decreasing trend of dissolved organic carbon (DOC), trihalomethane formation potential (THMFP), and haloacetic acid formation potential (HAAFP) at high temperature incubations irrespective of microbial concentrates. This result may be attributed to the fact that microorganism activities or concentrations in water increase at higher temperatures, which may result in higher DOC consumption and lower DBP formation. Water samples spiked with bacteria concentrates exhibited higher THMFP or HAAFP reduction than did samples without bacteria concentrates. A higher biomass in water may contribute to a higher consumption of DOC and consequently lower DBP formation potentials, especially at high incubation temperatures.

Characterization of enoxacin (ENO) during ClO2 disinfection in water distribution system: Kinetics, byproducts, toxicity evaluation and halogenated disinfection byproducts (DBPs) formation potential

Enoxacin (ENO) is widespread in water because it is commonly used as a human and veterinary antibiotic. However, little effort has been dedicated to revealing the transformation mechanisms of ENO destruction using ClO2, especially within a water distribution system (WDS). To address this knowledge gap, the kinetics, byproducts, toxicity, and formation potential of halogenated disinfection byproducts (DBPs) associated with ENO destruction using ClO2 in a pilot-scale PE pipe was explored for the first time. Statistical analyses showed that the destruction efficiency of ENO in the pilot-scale PE pipe was lower than that in deionized water (DI water), and the reactions in DI water followed the second-order kinetic model. Furthermore, pH has a significant effect on the destruction of ENO, and the removal ratio increased at a higher pH. Additionally, increasing the flow rate elevated the ENO removal efficiency; however, the influence of flow velocity was limited to ENO destruction. The ENO removal rates within the diverse pipes exhibited the following order: stainless steel pipe < PE pipe < ductile iron pipe. Nine possible intermediates were identified, and those that were formed by piperazine group cleavage represented the major primary byproducts of the entire destruction process. Additionally, the ENO destruction in a pilot-scale PE pipe had minimal influence on halogenated DBPs and chlorite formation. Finally, the toxicity evaluation illustrated that the presence of ENO increased the potential risk of water quality safety when treated with ClO2.

Tracking spatio-temporal dynamics of fluorescence characteristics of Huangpu River, China by parallel factor analysis: Correlation with disinfection by-product precursor and pesticide level variations

The components and characteristics of dissolved organic matter (DOM), the main precursor of toxic disinfection by-products (DBPs), have attracted increasing attention in water sources. In this study, fluorescence excitation-emission matrix (EEM) coupled with parallel factor (PARAFAC) analysis was used to investigate the DOM fluorescence characteristics of river water along the Huangpu River, China. Four fluorescence components were identified, including two protein-like components (C1 and C2) and two humic-like components (C3 and C4). The fluorescence characteristics showed spatial and temporal variations with the highest total fluorescence intensities observed in autumn, and the increased relative abundance of humic-like substance in the metropolitan area of Shanghai. Fluorescence index and biological index indicated that the DOM of Huangpu River water had both terrestrial and microbial origins and mainly autochthonous characteristic. Moreover, the formation potentials (FPs) of DBP for Huangpu River water were determined, and trihalomethanes were the predominant species formed in all samples. The correlation analysis further showed that PARAFAC C4 (microbial humic-like fluorescence) significantly correlated with the FP of N-DBPs, providing an insight for drinking water treatment to control specific DBPs precursor. In addition, the humic-like components also correlated with the concentrations of triazole and organophosphate pesticides detected in the Huangpu River. These results indicated that fluorescence-PARAFAC analysis is a promising tool to assess the DBPFPs and pesticide occurrence in surface waters.

Control of disinfection byproducts in drinking water treatment plants: Insight into activated carbon filter

The removal efficiencies of disinfection byproducts formation potentials (DBPFPs) and generated DBPs under pre-chlorination condition (pre-generated DBPs) during different drinking water treatment trains in eight full-scale drinking water treatment plants (WTPs) were investigated through field and laboratory studies. Haloacetic acids (HAAs) and haloacetonitriles (HANs) were identified to be two representative DBPs based on cytotoxicity and genotoxicity assessments. The performances of advanced treatment train for HAAs and HANs were better than that of conventional treatment train. However, the efficacy of ozone - biological activated carbon (O3-BAC) was affected by its service time and position in the water treatment process. In addition, the consumption of free chlorine by activated carbon in old granular activated carbon (GAC) filter was higher than that in new one under pre-chlorination condition, resulting in the increase of HAAs and HANs in the GAC filter effluent. This demonstrated that the organic matter adsorbed on older activated carbon generated more HAAs and HANs during pre-chlorination, which inhibited the adsorption of pre-generated DBPs. The ability of GAC/O3-BAC to remove HAAs and HANs was consistent with that of protein-like and low molecular weight organic substances, which could predict the performance of GAC and O3-BAC in treating DBPs.

Dynamic exchange between particulate and dissolved matter following sequential resuspension of particles from an urban watershed under photo-irradiation

Particulate matter (PM) has long-term effects on water quality compared to dissolved matter (DM) during downstream transfer after inflows into an aquatic environment. In the present study, the characteristics, behavior, and effects of PM from an urban watershed under photo-irradiation were investigated through sequential resuspensions before being compared. Changes in the organic matter content, heavy metals (Mn, Fe, Zn, Pb), spectroscopic indices (SUVA254, slope ratio (SR), humidification index (HIX), fluorescence index (FI), and biological index (BIX)), excitation-emission matrix combined with parallel factor analysis components (EEM-PARAFAC), and disinfection by-product formation potential (DBPFP) were analyzed. According to our results, light enhanced the release of organic matter from PM but reduced dissolved heavy metals. The PMU affected by urban-derived pollutants (i.e., rainfall particles, road-deposited sediment, sewer-pipeline-deposited sediment) exhibited higher quantities of terrestrial humic-like organic matter than PMR, which contains base particles from riverines (i.e., soil, sediments). For the PMU, the humic-like fluorescent components (C1 and C2) enhanced under light conditions with every resuspension, whereas the components decreased in the PMR. Consistent with the PARAFAC results, the trihalomethane formation potential (THMFP) of the PMU was enhanced by approximately 2.8 times more than that of the PMR, and exhibited a high correlation with the fluorescent components (C1, r = 0.81, p < 0.001). The principal component analysis results also confirmed that the characteristics of dynamic exchanges between PM and DM were distinguished by PM sources and light, and the photo-released DM and their spectral characteristics displayed opposite behaviors depending on the PM sources during the sequential resuspensions.

UV254 irradiation of N-chloro-α-amino acids: Kinetics, mechanisms, and N-DBP formation potentials

This study explores the degradation kinetics and mechanisms of N-chloro-α-amino acids and the changes in the formation potential of nitrogenous disinfection byproducts (N-DBPs) upon UV254 irradiation. UV254 irradiation significantly accelerated the degradation of all the tested N-chloro-α-amino acids compared to those in the dark. Both direct photolysis-induced cleavage of the N-Cl bonds and radical oxidation (e.g., Cl• and Cl2•−) involved reactions that contributed to their enhanced degradation. The fluence-based photolysis rate constants of the N-chloro-α-amino acids varied in the range of (1.06—5.47) × 10−3 cm2 mJ−1 at pH 6.0 and (0.74—2.79) × 10−3 cm2 mJ−1 at pH 8.0. The apparent quantum yields (Φapp) of the majority of the N-chloro-α-amino acids were in the range of 0.41−0.95 at pH 6.0 and 0.22−0.79 at pH 8.0, except N-chloroaspartic acid, N-chlorohistidine, and N-chloroalanine. UV254 irradiation significantly enhanced the formation of trichloronitromethane (TCNM) from the tested N-chloro-α-amino acids after post-chlorination, but exhibited various effects on the formation of dichloroacetonitrile (DCAN). A longer UV254 irradiation time generated more TCNM, and a lower pH produced more DCAN from the N-chloro-α-amino acids. The degradation pathways of N-chlorotyrosine, as a representative N-chloro-α-amino acid, are proposed, and the β-scission and 1,2-H shift pathways led to the formation of different precursors of TCNM and DCAN. The results of this study improve our understanding of the fate of N-chloro-α-amino acids under UV254 irradiation and post-chlorination.

Long-term fouling evolution of polyvinyl chloride ultrafiltration membranes in a hybrid short-length sedimentation/ ultrafiltration process for drinking water production

Despite the rapid increase of ultrafiltration (UF) membranes in water treatment, the UF performance in large-scale drinking water treatment plants (DWTPs) in long-term operation has not been well understood. This study was carried out to investigate the fouling evolution of two types of polyvinyl chloride (PVC) hollow fiber UF membranes in a hybrid coagulation/short-length sedimentation/UF process. Water quality analysis showed that safe drinking water could be produced in the life time (i.e., 5 years) of the UF membranes. The fractions with large molecular weight (e.g., biopolymers), microbial by-product and aromatic protein II in raw water were easily removed, and the formation potentials of most disinfection by-products except trihalomethanes were found to decrease in the DWTP. Constant filtration fluxes were maintained for both types of UF membranes, while PVC composite membranes exhibited higher anti-fouling properties than PVC alloy membranes. The key fouling factors varied with operation time, and the top three factors were hydraulically cleaning efficiency, temperature and chemical oxygen demand using statistical analyses. Finally, the evolution model of membrane fouling in the first 5-year with potential fouling factors was established using artificial neural network, and membrane fouling of another year was predicted after UF membranes were replaced with new ones.

Impact of UV irradiation on disinfection by-product formation and speciation from post-chlorination of dissolved organic matter

Abstract The objective of this study was to investigate the effects of combined low-pressure ultraviolet (UV)irradiation and chlorination on the formation of disinfection by-products (DBPs) from different dissolved organic matter (DOM) as DBP precursors. Commercially available humic acid (HA), extracellular organic matter (EOM) from green algae, cyanobacteria, and diatom, namely Scenedesmus quadricauda (SQ), Merismopedia sp. (Msp), and Phaedactylum tricornutum (PT), were used as the sources of DOM. The DBP formation increased with increasing total residual chlorine; EOM from PT presented the highest formation potential followed by HA, Msp, and SQ. The low dosage of 40 mJ/cm2 UV irradiation is insignificant to change the DBP formation from HA and SQ; however, it decreased the DBP formation from bromide-containing EOM of PT and promoted the DBP formation from EOM of Msp at various total residual chlorines. The DBP formation of each DOM correlated well with total residual chlorine. The maximum DBP formation potential (DBPFP) reduction of 42.25 and 13.75% for haloacetic acid formation potential (HAAFP) and trihalomethane formation potential (THMFP) was obtained at the UV irradiation dosage of 300 mJ/cm2 for EOM of PT. However, for the EOM derived from Msp, a maximum increase of 58.1 and 51.1% for HAAFP and THMFP was observed after UV-chlorination.

Formation and control of disinfection by-products from iodinated contrast media attenuation through sequential treatment processes of ozone-low pressure ultraviolet light followed by chlorination

Different groups of disinfection by-products (DBPs) were studied through the degradation of iopamidol by the sequential oxidation process of ozone-low pressure ultraviolet light (O3-LPUV) followed by chlorination. This paper investigates the attenuation of iopamidol under this sequential treatment and the effect of chlorine contact time (30 min versus 3 days) to control the formation potential of DBPs: trihalomethanes (THMs), haloacetonitriles (HANs) and haloacetamides (HAMs). Thirty target DBPs among the 9 iodinated-DBPs (I-DBPs), were monitored throughout the sequential treatment. Results showed that O3-LPUV removed up to 99% of iopamidol, while ozone and LPUV alone removed only 90% and 76% respectively. After chlorine addition, O3-LPUV yielded 56% lower I-DBPs than LPUV. Increasing chlorine contact time resulted in higher concentrations of all DBP groups (THMs, HANs, and HAMs), with the exception of I-DBPs. One new iodinated-haloacetamide, namely chloroiodoacetamide (CIACM) and one iodoacetonitrile (IACN) were detected. These results suggest the iodine incorporated in iopamidol may be a precursor for iodinated-nitrogenous-DBPs, which are currently not well studied.

EEM–PARAFAC characterization of dissolved organic matter and its relationship with disinfection by-products formation potential in drinking water sources of northeastern China

Dissolved organic matter (DOM) is the precursor of disinfection by-products (DBPs) which is widely found in the aquatic environment. The analysis of DOM in raw water is helpful to evaluate the formation potentials of DBPs. However, there is relatively little research on the DOM identification of raw water in northern China. In this study, the variation in DOM in M reservoir water in one year by fluorescence excitation–emission matrix-parallel factor analysis (EEM–PARAFAC) was investigated to evaluate the DBP formation potential (DBPFP). The results suggested that five components, namely, two humic-like substances (C2, C3), two fulvic-like substances (C1, C4) and one protein-like substance (C5), were identified in the DOM of M reservoir water. The content of DOM in autumn and winter was higher than that in spring and summer. The source of DOM in the water body of M reservoir was mainly from terrestrial source, but less from aquatic source. The source, types and humification degree of DOM affect the formation of DBPs. The formation potential of DBPs had the following order: trihalomethanes (THMs) > dichloroacetic acid (TCAA) > trichloroacetic acid (DCAA) > chloral hydrate (CH). The formation potentials of THM and TCAA were strongly correlated with C2 (rTHM = 0.805, rTCAA = 0.857). The formation potential of CH has a good correlation with C1 (r = 0.722). The formation of DCAA has a good correlation with C4 (r = 0.787). DOM and DBPFP were negatively correlated with the biological index (BIX) and fluorescence index (FI) of the raw water, and positively correlated with the humification index (HIX).

Derivates variation of phenylalanine as a model disinfection by-product precursor during long term chlorination and chloramination

Dissolved nitrogenous organic matter in water can contain precursors of disinfection by-products (DBPs), especially nitrogenous DBPs (N-DBPs). Amino acids are ubiquitous as dissolved nitrogenous organic matter in source water and can pass through drinking water treatment processes to react with disinfectants in finished water and in the distribution system. Phenylalanine (Phe) was selected as a model amino acid precursor to investigate its derived DBPs and their variations during a chlorination regime that simulated water distribution with residue chlorine. The 7-day DBPs formation potential (DBPsFP) test with chlorine revealed chlorination by-products of phenylalanine including trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), and halonitromethanes (HNMs), but not trichloronitromethane (TCNM) which was a significant N-DBP detected during the first 48 h of chlorine contact. The formation of most carbonaceous DBPs (C-DBPs) increased with chlorination time; however N-DBPs and non-chlorinated byproducts of phenylacetonitrile and phenylacetaldehyde reached their highest concentration after 2 h of reaction, and then gradually decreased until below detection after 7 days. The chlorination influencing factors indicated that light enhanced the peak yield of DBPs; the pH value showed different influences associated with corresponding DBPs; and the presence of bromide ions (Br−) generated a variety of bromine-containing DBPs. The DBPsFP test with chloramine reduced C-DBPs generation to about 1/3 of the level observed for chlorine disinfection and caused an increase in dichloroacetonitrile. Surveillance of DBPs during drinking water distribution to consumers should consider the varying contact times with disinfectants to accurately profile the types and concentrations of C-DBPs and N-DBPs present in drinking water.

Size and resin fractionations of dissolved organic matter and characteristics of disinfection by-product precursors in a pilot-scale constructed wetland

Abstract Controlling the formation of disinfection by-products (DBPs) is a major issue in the drinking water industry, and understanding the characteristics of DBP precursors in treatment processes for micro-polluted raw water is key to improving water quality. In this study, a sampling program was undertaken to investigate the fate of dissolved organic matter (DOM) and the characteristics of DBP precursors in a pilot constructed wetland imitating the Yanlong Lake ecological project. Using XAD resin adsorption and ultrafiltration techniques, the dissolved organic carbon, UV254, and DBP formation potential (DBPFP) were measured in different DOM fractions in raw water and wetland effluents. After the constructed wetland treatment, the low molecular weight fraction (&amp;lt;3 kDa) of DOM and DBPFP generally showed a decreasing trend along the water path, while the high molecular weight fraction (&amp;gt;3 kDa) of DOM increased. The specific DBPFP (SDBPFP) was much higher in the &amp;lt;1 kDa fraction than in the other fractions. Although the hydrophobic fraction of DOM was the most abundant in all stages of the wetland treatment, the SDBPFP of the hydrophilic fraction was higher than that of the hydrophobic fraction. Furthermore, compared with raw water, the DOC, UV254 and DBPFP in the treated wetland effluents increased; however, all of the chemical DOM fractions exhibited decreased SDBPFP in accordance with a decrease in the specific ultraviolet absorbance during wetland treatment. These conclusions indicate that the DOM produced by the wetland system may generate DBPs less readily compared with the DOM of raw water.

Characterization of algal organic matter as precursors for carbonaceous and nitrogenous disinfection byproducts formation: Comparison with natural organic matter

Algal organic matter (AOM) and natural organic matter (NOM) from a typical eutrophic lake were comprehensively investigated in terms of their physico-chemical property, components and disinfection byproduct formation potentials (DBPFPs). The relationships between specific chemical properties of AOM and NOM with their corresponding DBPFPs were further evaluated during chlorination. Results indicated that AOM had lower specific UV absorbance (SUVA) but richer organic nitrogen contents than NOM. Fluorescence excitation emission matrix spectroscopy further demonstrated that AOM were chiefly composed of aromatic protein-like and soluble microbial byproduct-like matters, while NOM were mainly contributed from humic acid-like and soluble microbial byproduct-like substances. Although the molecular weight (MW) distribution of AOM and NOM showed no significant difference, size-exclusion chromatography with organic carbon as well as organic nitrogen detection (LC-OCD-OND) revealed that AOM were concentrated with the fraction of building blocks and NOM had higher concentrations of biopolymers and humics (HS). Moreover, AOM displayed higher DBPFPs than NOM, especially for nitrogenous DBPFP (N-DBPFP). MW < 1 kDa fractions both in AOM and NOM contributed the largest proportion to the formation of carbonaceous disinfection byproducts (C-DBPs). In addition, Pearson correlation analysis showed that bulk parameter SUVA was significantly relevant to the formation potentials of trihalomethane both in AOM and NOM, but was ineffective for carbonaceous DBPFP (C-DBPFP) prediction. Dissolved organic nitrogen contents in biopolymer and HS characterized by LC-OCD-OND had strong correlations with N-DBPFPs from AOM and NOM, indicating that LC-OCD-OND quantitative analysis could improve the prediction accuracy of the DBP formation than bulk parameters during NOM and AOM chlorination.

Influence of atmospheric deposition on surface water quality and DBP formation potential as well as control technology of rainwater DBPs: a review

This manuscript mainly conducted a literature review of the contribution of atmospheric dry and wet deposition to surface water quality and DBP formation potential.

Impact of simulated wildfire on disinfection byproduct formation potential

AbstractWildfires are complex phenomena that have served a vital role in ecosystem function for millennia. However, thermal alterations to dissolved organic matter's (DOM) solubility and chemical features can change disinfection byproduct (DBP) formation dynamics. Physicochemical changes to DOM are influenced by several factors, the most prominent being heating temperature. In this study, mineral soil samples were collected from fire‐prone areas, artificially heated in a muffle furnace to simulate wildfire heating, and leached. As heating temperature increased, chloroform and dichloroacetic acid yields decreased and increased, respectively. Of particular interest was the stimulation of dichloroacetonitrile, a highly toxic and unregulated DBP, at moderate heating temperatures. To demonstrate further insight into the chemical attributes of wildfire‐impacted DOM, optical properties were used as proxy measurements. This work provides water utilities with information on how wildfires can alter DBP formation potential, and a means to investigate correlations between intrinsic optical measurements and DBP yields.

Source identification and characteristics of dissolved organic matter and disinfection by-product formation potential using EEM-PARAFAC in the Manas River, China.

Dissolved organic matter (DOM) is ubiquitous in natural water and reacts with disinfectants to form disinfection by-products (DBPs). The analysis of DOM in raw water is helpful in evaluating the formation potential of DBPs. However, there is relatively little research on the DOM identification of raw water in northern China. In this study, the sources and characteristics of DOM were investigated in the samples collected from the Manas River. Dissolved organic carbon (DOC), UV254, specific ultraviolet absorbance, and fluorescence indices (fluorescence index, humification index, and biological index) were measured to characterize the DOM, and trihalomethanes (THMs) were quantified following formation potential tests with free chlorine. The maximum amount of total trihalomethane formation potential (THMsFP) was 225.57 μg L−1. The DOM of the Manas River consisted of microorganisms and soil resources. The excitation–emission matrix combined with parallel factor analysis (EEM-PARAFAC) identified microbial humus (C1, 54%) and tryptophan-like protein (C2, 46%). PARAFAC components were evaluated as the precursor surrogate parameters of THMsFP. Additionally, the linear THMsFP correlation was stronger with C1 + C2 (r = 0.529, p < 0.01) than with C1 (r = 0.485, p < 0.01). Thus, C1 + C2 is an accurate THMsFP precursor surrogate parameter for the Manas River, and the use of fluorescence spectroscopy may be a robust alternative for predicting DOC removal.

Emerging investigator series: emerging disinfection by-product quantification method for wastewater reuse: trace level assessment using tandem mass spectrometry

A sensitive analytical method was developed that simultaneously characterizes 25 unregulated DBPs in wastewater effluents. DBP formation potential with HOCl and NH2Cl was evaluated across a full-scale wastewater reuse facility for the first time.

Modifying the initial rates of disinfection by-product formation potentials

Modifying the initial rates of disinfection by-product formation potentials

Disinfection by-product formation potential of algogenic organic matter from Microcystis aeruginosa: Effects of growth phases and powdered activated carbon adsorption

Algae can exhibit different disinfection by-product formation potential (DBPFP) depending on the characteristics of the algogenic organic matter (AOM) released during growth. In this study, the amount of AOM released by Microcystis aeruginosa and its DBPFP were compared between the exponential growth phase and the death phase. Moreover, the efficiency of DBPFP removal through powdered activated carbon (PAC) adsorption was evaluated. The correlations between DBPFPs and dissolved organic carbon concentration or ultraviolet absorbance at 254 nm (UV254) were also investigated to predict DBPFPs. Among DBPFPs, which were higher at the death phase, the formation potential (FP) of haloacetic acid was the highest. In addition, the high relative haloacetonitrile FP at the death phase indicated that a relevant portion of the intracellular organic matter derived from cell autolysis was converted into a large amount of haloacetonitriles. Furthermore, PAC addition reduced all DBPFPs at both growth phases. PAC was found to selectively adsorb dichloroacetic acid precursors at the death phase and dichloroacetonitrile precursors at both growth phases. Finally, UV254 showed greater correlations with the three DBPFPs at all growth phases. These results highlight the possible use of UV254 as an alternative analytical tool for fast determination of M. aeruginosa DBPFPs.

Effects of ozonation on disinfection by-product formation potentials and biostability in a pilot-scale drinking water treatment plant with micro-polluted water

ABSTRACT The accelerated urbanization in China has caused intensified micro-pollution problems for drinking water sources, severely challenging drinking water treatment efficiencies and its biostability. This study mainly investigated the effects of ozonation on disinfection by-product formation potentials (DBPFPs) and biological dissolved organic carbon (BDOC) in a pilot-scale ozonation-biological activated carbon advanced drinking water treatment plant with micro-polluted raw water. The results indicated that the micro-polluted water would be effectively treated in the advanced treatment processes with DBPFPs significantly eliminated. The total removal rates of trihalomethane formation potentials (THMFPs) and haloacetic acid formation potentials (HAAFPs) increased with the elevated ozone dosage to finally a relatively stable stage, and the maximum removal rates of 77.3% and 57.0%, respectively, were achieved at the ozone dosage of 2 mg/L. The bromine incorporation in total THMFPs (TTHMFPs) was dramatically suppressed after integrated advanced treatment processes, while that in total HAAFPs (THAAFPs) was promoted with the corresponding increment of up to 25.3% for bromine incorporation factor, which caused relatively high brominated HAAFP proportions in the treated water than in the raw water. In addition, the BDOC generation rate and THAAFP removal rate during the post-ozonation treatment displayed apparent positive correlation, and a similar relationship was observed for the BDOC degradation rate and TTHMFP removal rate during the BAC treatment in the studied ozone dosage (1 ∼ 5 mg/L). The findings strongly implied a promising alternative to measure DBPFP removal rate instead of BDOC level for more sensitive and convenient monitoring of the biostability in the reclaimed water.