Publications by authors named "Tuqiao Zhang"

52 Publications

Comparison of fleroxacin oxidation by chlorine and chlorine dioxide: Kinetics, mechanism and halogenated DBPs formation.

Chemosphere 2021 Jul 16;286(Pt 1):131585. Epub 2021 Jul 16.

College of Environment, Zhejiang University of Technology, Hangzhou, 310032, China. Electronic address:

Fleroxacin (FLE) is a widely used fluoroquinolones to cure urinary tract infections and respiratory disease, which has been frequently detected in the aquatic environment. The reactivity kinetics of FLE by chlorine and chlorine dioxide (ClO) and transformation mechanism were investigated in this study. The results showed that FLE was degraded efficiently by chlorine and ClO, and both reactions followed second-order kinetics overall. The increase of disinfectant dosage and temperature would enhance the degradation of FLE. The highest removal of FLE by chlorine was achieved at a neutral condition (pH 7.4), whereas ClO reaction rates increased dramatically with the increasing pH in this study condition. The number of intermediates identified in FLE chlorination and ClO oxidation was seven and ten, respectively. The piperazine ring cleavage was the principal and initial reaction in both above reactions. Then, the removal of the piperazine group was predominantly in FLE removal by chlorine, while the decarboxylation mainly occurred in FLE removal by ClO. The intermediates increased first and then decreased with time, while three kinds of halogenated DBPs increased with time, indicating the above-identified intermediates were further transformed to the halogenated DBPs. Additionally, compared to chlorine reaction, the reaction of ClO with FLE reduced the formation of halogenated DBPs, but it also induced the formation of chlorite. The analysis of toxicity showed that compared with chlorination, the oxidation of ClO was more suitable for FLE removal.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131585DOI Listing
July 2021

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

Chemosphere 2021 Jun 18;283:131251. Epub 2021 Jun 18.

School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, China. Electronic address:

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 ClO, 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 ClO 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 ClO.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131251DOI Listing
June 2021

Removal of antibiotic-resistant genes during drinking water treatment: A review.

J Environ Sci (China) 2021 Jun 30;104:415-429. Epub 2020 Dec 30.

Zhejiang Key Laboratory of Drinking Water Safety and Distribution Technology, Zhejiang University, Hangzhou 310058, China; Ocean College, Zhejiang University, Hangzhou 310058, China. Electronic address:

Once contaminate the drinking water source, antibiotic resistance genes (ARGs) will propagate in drinking water systems and pose a serious risk to human health. Therefore, the drinking water treatment processes (DWTPs) are critical to manage the risks posed by ARGs. This study summarizes the prevalence of ARGs in raw water sources and treated drinking water worldwide. In addition, the removal efficiency of ARGs and related mechanisms by different DWTPs are reviewed. Abiotic and biotic factors that affect ARGs elimination are also discussed. The data on presence of ARGs in drinking water help come to the conclusion that ARGs pollution is prevalent and deserves a high priority. Generally, DWTPs indeed achieve ARGs removal, but some biological treatment processes such as biological activated carbon filtration may promote antibiotic resistance due to the enrichment of ARGs in the biofilm. The finding that disinfection and membrane filtration are superior to other DWTPs adds weight to the advice that DWTPs should adopt multiple disinfection barriers, as well as keep sufficient chlorine residuals to inhibit re-growth of ARGs during subsequent distribution. Mechanistically, DWTPs obtain direct and inderect ARGs reduction through DNA damage and interception of host bacterias of ARGs. Thus, escaping of intracellular ARGs to extracellular environment, induced by DWTPs, should be advoided. This review provides the theoretical support for developping efficient reduction technologies of ARGs. Future study should focus on ARGs controlling in terms of transmissibility or persistence through DWTPs due to their biological related nature and ubiquitous presence of biofilm in the treatment unit.
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http://dx.doi.org/10.1016/j.jes.2020.12.023DOI Listing
June 2021

g-CN/MoS based floating solar still for clean water production by thermal/light activation of persulfate.

Chemosphere 2021 Oct 27;280:130618. Epub 2021 Apr 27.

Zhejiang Key Laboratory of Drinking Water Safety and Distribution Technology, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058, PR China. Electronic address:

Currently, seawater desalination based on air-water interface solar heating has triggered significant research interests because it effectively makes use of the solar energy and avoids fossil fuel consumption. However, to prevent the volatile organic compounds (VOCs) from volatilizing with water vapor which later will liquefy and enter the condensed freshwater is still a challenge. In this work, a g-CN/MoS based floating solar still (CM-FSS) combined with thermal/light activation of persulfate (PS) at air-water interface was applied for clean freshwater production for the first time. The CM-FSS was composed of a g-CN/MoS top layer for solar absorption, simultaneous thermal/light activation of PS and then VOCs degradation at air-water interface, a floating layer of expandable polyethylene (EPE) foam for heat isolation, and a transport channel of air-laid paper (ALP) for seawater and PS solution delivery. The water evaporation rate of the CM-FSS was measured at 1.23 kg m h under 1 kW m, which is 4.09 times higher than that of pure water without an evaporator. With the assistance of g-CN/MoS photocatalytic degradation and thermal/light activation of PS at the air-water interface, a high removal efficiency of a selected model VOCs pollutant of nitrobenzene (NB) could reach to 98.2% in condensed freshwater. Finally, when real seawater samples were employed as source water for solar distillation, the typical water-quality indices such as salinity, turbidity, anions, cations and organics of the condensed freshwater were below the limit values of the Standards for Drinking Water Quality in WHO, US EPA and China.
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http://dx.doi.org/10.1016/j.chemosphere.2021.130618DOI Listing
October 2021

A noise adaptive approach for nodal water demand estimation in water distribution systems.

Water Res 2021 Mar 13;192:116837. Epub 2021 Jan 13.

College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, China, 310058. Electronic address:

Hydraulic models have emerged as a powerful tool for simulating the real behavior of water distribution systems (WDSs). In using the models for estimating nodal water demands, measurement uncertainty must be considered. A common approach is to use the covariance of measurement noises to quantify the measurement uncertainty. The noise covariance is typically assumed constant and estimated a priori. However, such an assumption is frequently misleading as actual measurement accuracies are affected by measuring instruments and environmental noises. In this study, we develop a variational Bayesian approach for real-time estimation of noise covariance and nodal water demands. The approach can adaptively adjust the noise covariance with the variation of the noise intensity, thereby efficiently avoiding model overfitting. The measurement residual decomposition reveals that this new approach is effective in determining model structural errors caused by topological structure parameterization.
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http://dx.doi.org/10.1016/j.watres.2021.116837DOI Listing
March 2021

Biotransformation of halophenols into earthy-musty haloanisoles: Investigation of dominant bacterial contributors in drinking water distribution systems.

J Hazard Mater 2021 02 17;403:123693. Epub 2020 Aug 17.

College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058, Zhejiang, China.

Microorganisms in drinking water distribution systems (DWDSs) can O-methylate toxic halophenols (HPs) into earthy-musty haloanisoles (HAs). However, the dominant HA-producing bacterial species and their O-methylation properties are still unknown. In this study, eight bacterial strains from DWDS were isolated and the community abundances of the related genera in bulk water and biofilms as well as their O-methylation properties were investigated. Among the genera discovered in this study, Sphingomonas and Pseudomonas are dominant and play important roles in DWDSs. All bacteria could simultaneously convert five HPs to the corresponding HAs. Two Sphingomonas ursincola strains mainly produced 2,3,6-trichloroanisole (2,3,6-TCA) (2.48 × 10-1.18 × 10 ng/CFU), 2,4,6-trichloroanisole (2,4,6-TCA) (8.12 × 10-3.11 × 10 ng/CFU) and 2,4,6-tribromoanisole (2,4,6-TBA) (2.95 × 10-3.21 × 10 ng/CFU), while two Pseudomonas moraviensis strains preferred to generate 2-monochloroanisole (2-MCA) (1.19 × 10-3.70 × 10 ng/CFU) and 2,4-dichloroanisole (2,4-DCA) (3.81 × 10-1.20 × 10 ng/CFU). Among the chloramphenicol-susceptible strains, four strains contained inducible O-methyltransferases (OMTs), while the O-methylations of the others were expressed constitutively. All bacteria could use S-adenosyl methionine as methyl donor. Potential taste and odor (T & O) risks of five HAs in DWDS followed an order of 2,4,6-TBA > 2,4,6-TCA > 2,3,6-TCA > 2,4-DCA > 2-MCA. The recommended 2,4,6-TCP criteria for T & O control is 0.003-0.07 mg/L.
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http://dx.doi.org/10.1016/j.jhazmat.2020.123693DOI Listing
February 2021

Algae-induced taste and odour problems at low temperatures and the cold stress response hypothesis.

Appl Microbiol Biotechnol 2020 Nov 23;104(21):9079-9093. Epub 2020 Sep 23.

College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058, Zhejiang, China.

The existence of taste and odour (T&O) in drinking water is one of the principal causes of consumer complaints and is commonly related to algae growth. Numerous studies have confirmed the existence of algal blooms emerging specifically in low-temperature periods, herein referred to as "cold algae"; these include chrysophytes, cryptophytes, dinoflagellates and diatoms. In addition, the adaption mechanisms of these "cold algae" involve high flexibility in their nutrient intake and to the hydrological characteristics of the waters and their high contents of intracellular polyunsaturated fatty acids (PUFAs). Like algae proliferating in higher temperature waters, cold algae can also produce offensive odours. The potential dominant T&O compounds of low-temperature algae probably include saturated/unsaturated aldehydes and even some terpenoids. Among these, the polyunsaturated aldehydes (PUAs), the derivatives of polyunsaturated fatty acids, are the dominant T&O compounds and are probably synthesized during cell rupture. It was found that, for cold algae, low temperature may have a favourable effect on the generation of algae-induced T&O compounds. Furthermore, to better understand the internal mechanisms of algal T&O production, the stress response theory is introduced, which provides ideas for T&O control in raw water and in water treatment. Finally, implications for T&O management are given based on this review. KEY POINTS: • Like algae proliferating in higher temperature waters, cold algae can produce offensive odours. • Low temperatures may have a favourable effect on the generation of algae-induced T&O compounds. • The stress response theory can help to better understand the internal mechanisms of algal T&O production.
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http://dx.doi.org/10.1007/s00253-020-10884-6DOI Listing
November 2020

Nitrous oxide emission from stormwater biofilters in alternating dry and wet weather.

Environ Res 2020 12 27;191:110137. Epub 2020 Aug 27.

The Institute of Municipal Engineering, Zhejiang University, Hangzhou, 310058, China.

The nitrous oxide (NO) flux and its possible production pathways from stormwater biofilters in response to moisture content (MC) due to a shift from dry to wet weather was investigated. In this study, we evaluated the changes in the composition of the bacterial community, the relative abundance of functional genes, and NO emission rate in laboratory-scale stormwater biofilters in response to changes of MC. The results indicated that NO flux correlated positively with soil MC (r = 0.722 p < 0.01). We observed a higher rates of NO flux when shifting from dry to wet conditions. Notably, these values decreased substantially within 8-24 h in response to the rapid decline in MC, and then gradually decreased and stabilized at 4.4-12.0 μg/m·h. The relative abundance of ammonia-oxidizing and denitrifying bacteria, as well as the relative abundance of functional groups associated with denitrification was higher under conditions of low soil MC than those in the high MC. Furthermore, the abundance of bacterial genes norB (r = 0.716 p < 0.01) and hao (r = 0.917 p < 0.01) was associated with higher NO emission in high MC soils. Studies with the stable isotope (N) revealed that N enrichment in NO was primarily via denitrification pathways and labeled ammonium ion (NH). Taken together, our results suggested that nitrifier denitrification is the main pathway generating NO emission in soils with high MC, which may be caused by the high molar ratio of NH to total nitrogen in the influent.
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http://dx.doi.org/10.1016/j.envres.2020.110137DOI Listing
December 2020

The influence mechanism of bioclogging on pollution removal efficiency of vertical flow constructed wetland.

Water Sci Technol 2020 May;81(9):1870-1881

Key Laboratory of Drinking Water Safety and Distribution Technology of Zhejiang Province, Zhejiang University, Hangzhou, China E-mail:

The effect of change of hydraulic characteristic and microbial community on pollution removal efficiency of the infiltration systems in the bioclogging development process remain poorly understood. In this study, therefore, the pollutant removal as a response to hydraulic conductivity reduction and the change of diversity and structure of microbial communities in vertical flow constructed wetlands (VFCWs) was investigated. The results indicated that the richness and diversity of the bacterial communities in the columns at different depths were decreased, and the microbial communities of the genus level were changed in the process of bioclogging. However, the variation of microbial communities has a low impact on the purification performance of VFCWs because the abundance of function groups, respiratory activity, and degradation potentiality of microorganisms remain steady or even get improved in the columns after bioclogging. On the contrary, the hydraulic efficiency of VFCWs decreased greatly by 16.9%, 9.9%, and 57.1% for VFCWs filled with zeolite (Column I), gravel (Column II), and ceramsite (Column III), respectively. The existence of short-circuiting and dead zones in the filter media cause the poor pollution removal efficiency of VFCWs due to the short contact time and decrease of oxygenation renewal, as well as low activity in the dead zone.
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http://dx.doi.org/10.2166/wst.2020.246DOI Listing
May 2020

Kinetic and mechanistic investigation into odorant haloanisoles degradation process by peracetic acid combined with UV irradiation.

J Hazard Mater 2021 01 1;401:123356. Epub 2020 Jul 1.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China. Electronic address:

This study reported the kinetics and mechanism of degradation of odorant haloanisoles by peracetic acid combined with UV irradiation (PAA/UV). The removal efficiency of haloanisoles by PAA/UV was more than 92 % after 1 h reaction at pH 5, 25 °C, [HAs] =50 μg/L and [PAA] = 10 mg/L. The degradation of haloanisoles was fitted by the first-order kinetic model, and the rate constants of various haloanisoles followed the order: 2,4,6-tribromoanisole (2,4,6-TBA, (9.25 ± 0.71)×10 s) > 2-monochloroanisole (2-MCA, (8.00 ± 0.34)×10 s) > 2,4-dichloroanisole (2,4-DCA, (6.24 ± 0.55)×10 s) > 2,4,6-trichloroanisole (2,4,6-TCA, (5.05 ± 0.04)×10 s). The contribution of PAA (mainly composed of free radicals produced from PAA activation by UV) to the degradation rate of chloroanisoles in PAA/UV process ranged from 24 % to 36 %, while 25 % to the degradation rate of bromoanisole. Direct photolysis contributed much more to the removal of bromoanisole (42 %) than chloroanisoles (9-14 %). The inhibition of tert-butanol on degradation demonstrated the existence of ·OH, and superoxide radical and carbon-centered radicals were also probably existed in PAA/UV process. Combining density functional theory (DFT) calculation and products analysis, the degradation pathway of haloanisoles in PAA/UV process were determined. The odor and toxicity evaluation indicated PAA/UV process could reduce olfactory discomfort and health risk of haloanisoles.
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http://dx.doi.org/10.1016/j.jhazmat.2020.123356DOI Listing
January 2021

Optimising the measurement of peracetic acid to assess its degradation during drinking water disinfection.

Environ Sci Pollut Res Int 2020 Sep 16;27(27):34135-34146. Epub 2020 Jun 16.

College of Civil Engineering and Architecture, Zhejiang University, Zhejiang, 310058, Hangzhou, China.

Chlorine-based compounds have been used as a disinfectant in drinking water treatment plants for decades because of their excellent sterilisation efficiency and low cost. However, the formation of disinfection by-products during chlorination is a cause for concern. Peracetic acid (PAA) is a strong oxidant with a redox potential higher than that of chlorine and does not form harmful disinfection by-products. It is thus a potential alternative for chlorine-based disinfectants. However, PAA decomposes rapidly in water at a rate that is highly affected by many factors, such as organic compounds and pH. The aim of this study is to investigate the stability of PAA during drinking water disinfection. To accomplish this, we studied methods for rapid detection of residual PAA and PAA decay in drinking water. Residual PAA was detected in water by the spectrophotometry-total chlorine reagent (SPTCR) method with a PAA concentration range of 0.090-10 mg/L (R = 0.9943). Decay tests of PAA in drinking water and other sources of water showed that the decay process conformed to the first-order kinetic model with fast and slow reactions. Among four factors, pH was the key factor in the decay process because an alkaline environment significantly promotes the decomposition of PAA. In addition, total organic carbon (TOC), conductivity, and initial PAA concentration also affected PAA decay. Experimental and statistical analyses suggested that these factors affected PAA decay in the following descending order of influence: TOC, initial PAA concentration, and conductivity. In real water matrices, the PAA decay rate increased with increasing initial PAA concentration.
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http://dx.doi.org/10.1007/s11356-020-09505-6DOI Listing
September 2020

Experimental study on volatile sulfur compound inhibition using a single-chamber membrane-free microbial electrolysis cell.

Environ Sci Pollut Res Int 2020 Aug 28;27(24):30571-30582. Epub 2020 May 28.

The Institute of Municipal Engineering, Zhejiang University, Hangzhou, 310058, China.

Odor emissions from sewer systems and wastewater treatment plants have attracted much attention due to the potential negative effects on human health. A single-chamber membrane-free microbial electrolysis cell was proposed for the removal of sulfides in a sewer system. The feasibility of the use of volatile sulfur compounds and their removal efficiency in liquid and headspace gas phases were investigated using synthetic wastewater with real sewer sediment and Ru/Ir-coated titanium electrodes. The results indicate that hydrogen sulfide and volatile organic sulfur compounds were effectively inhibited in the liquid phase upon electrochemical treatment at current densities of 1.55, 2.06, and 2.58 mA/cm, and their removal rates reached up to 86.2-100%, except for dimethyl trisulfide, the amount of which increased greatly at 1.55 mA/cm. In addition, the amount of volatile sulfur compounds in the headspace decreased greatly; however, the total theoretical odor concentration was still high, and methanethiol and ethanethiol greatly contributed to the total strength of the odor concentration due to their low odor threshold concentrations. The major pathway for sulfide removal in the single-chamber membrane-free microbial electrolysis cell is biotic oxidation, the removal rate of which was 0.4-0.5 mg/min, 4-5 times that of indirect electrochemical oxidation.
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http://dx.doi.org/10.1007/s11356-020-09325-8DOI Listing
August 2020

Interspecific competition between Microcystis aeruginosa and Pseudanadaena and their production of T&O compounds.

Chemosphere 2020 Aug 16;252:126509. Epub 2020 Mar 16.

Ocean College, Zhejiang University, Hangzhou, 310058, Zhejiang, China. Electronic address:

Microcystis aeruginosa and Pseudanabaena are two common cyanobacterial species/genus and they can occur coincidently in many eutrophic lakes globally. These two cyanobacteria could produce Taste & Odor (T&O) compounds, and their production of T&O compounds might be changed when they are present coincidently. The amounts of T&O compounds and their producers may influence the effectiveness of water treatment processes. Therefore, the mutual interactions between Microcystis aeruginosa (FACHB-905, M) and Pseudanabaena sp. (FACHB-1277, P) on T&O compounds in co-cultures were evaluated in this study. Different initial cell concentrations of M and P, with ratios of M:P = 1:1, M:P = 1:2 and M:P = 2:1 were applied in the co-cultures. The growth of M was enhanced under all of the cyanobacterial cell ratios. The growth of P was enhanced under the ratio of M:P = 1:1, while it was inhibited under the ratios of M:P = 1:2 and M: P = 2:1. In addition, the growth of the two cyanobacteria and their production of β-cyclocitral and 2-methylisoborneol (2-MIB) in the filtrate of P were higher than those in the filtrate of M, which may be attributed to their associated secondary metabolites. The cell integrity and photosynthetic capacity of the two studied cyanobacteria are greatly affected by exposure to β-cyclocitral and 2-MIB. The results showed that β-cyclocitral and 2-MIB had the allelopathic effects on the two cyanobacteria species which might influence the composition of co-existing cyanobacteria and their production of T&O compounds.
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http://dx.doi.org/10.1016/j.chemosphere.2020.126509DOI Listing
August 2020

Numerical approach for water distribution system model calibration through incorporation of multiple stochastic prior distributions.

Sci Total Environ 2020 Mar 23;708:134565. Epub 2019 Nov 23.

College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China. Electronic address:

The use of water distribution system (WDS) hydraulic models facilitates the design and operation of such systems. For offline or online model applications, nodal water demands-variables with the highest levels of uncertainty-should be carefully calibrated because these can considerably affect the accuracy of model outputs in terms of hydraulics and water quality. With the increasing utilization of automatic water metering technology, nodal water demands can be modeled with high time resolution in certain forms of probability distributions. However, the fusion of various demand probability distributions with conventional measurements to improve the accuracy of WDS hydraulic models is a difficult problem. To resolve this, a numerical approach that incorporates various probability distributions and field measurements to calibrate nodal water demands based on Bayesian theory is proposed. In particular, the linearization of the exponential family prior distribution is well elaborated in this paper. The application of this proposed approach in two cases demonstrates that the technique is more accurate than methods that merely utilize measurements or prior information. Because this technique can avoid the overfitting of measurement noise and allow the retention of calibrated nodal water demands with stochastic nature, it is robust when errors or uncertainties exist in prior demand distribution or measurements. This method is expected to improve the WDS model accuracy relative to the increasing use of automatic water metering technology.
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http://dx.doi.org/10.1016/j.scitotenv.2019.134565DOI Listing
March 2020

Ferrate(VI) pre-treatment and subsequent chlorination of blue-green algae: Quantification of disinfection byproducts.

Environ Int 2019 12 22;133(Pt B):105195. Epub 2019 Oct 22.

Department of Environmental and Occupational Health, School of Public Health, Texas A&M University, College Station, TX 77843, USA. Electronic address:

Algal organic matter (AOM) from seasonal algal blooms may be an important precursor of disinfection byproducts (DBPs) in drinking water. This paper presents the effect of ferrate(VI) treatment on two blue-green algae, Chlorella sp. and Pseudanabaena limnetica, in eutrophic water. The results demonstrated that Fe(VI) removed the algal cells by causing cell death, apoptosis, and lost integrity, and decreased AOM (in terms of total organic carbon) in water via oxidation and coagulation. Chlorination of the Fe(VI) pre-oxidized algal water samples generated halogenated DBPs (including trihalomethanes, haloacetic acids, haloketones, chloral hydrate, haloacetonitriles, and trichloronitromethane), but the concentrations of DBPs were lower than those formed in the chlorinated samples without pre-treatment by Fe(VI). Higher Fe(VI) dose, longer oxidation time, and alkaline pH were beneficial in controlling DBPs. In bromide-containing algal solutions, negligible amount of bromo-DBPs were generated in the Fe(VI) pre-oxidation, and halogenated DBPs were mainly formed in the subsequent chlorination.
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http://dx.doi.org/10.1016/j.envint.2019.105195DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7711035PMC
December 2019

Time-Series-Based Leakage Detection Using Multiple Pressure Sensors in Water Distribution Systems.

Sensors (Basel) 2019 Jul 11;19(14). Epub 2019 Jul 11.

Department of Civil Engineering, Zhejiang University, Hangzhou 310058, China.

Leak detection is nowadays an important task for water utilities as leakages in water distribution systems (WDS) increase economic costs significantly and create water resource shortages. Monitoring data such as pressure and flow rate of WDS fluctuate with time. Diagnosis based on time series monitoring data is thought to be more convincing than one-time point data. In this paper, a threshold selection method for the correlation coefficient based on time series data is proposed based on leak scenario falsification, to explore the advantages of data interpretation based on time series for leak detection. The approach utilizes temporal varying correlation between data from multiple pressure sensors, updates the threshold values over time, and scans multiple times for a scanning time window. The effect of scanning time window length on threshold selection is also tested. The performance of the proposed method is tested on a real, full-scale water distribution network using synthetic data, considering the uncertainty of demand and leak flow rates, sensor noise, and so forth. The case study shows that the scanning time window length of 3-6 achieves better performance; the potential of the method for leak detection performance improvement is confirmed, though affected by many factors such as modeling and measurement uncertainties.
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http://dx.doi.org/10.3390/s19143070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6678736PMC
July 2019

Urban flood risk assessment using storm characteristic parameters sensitive to catchment-specific drainage system.

Sci Total Environ 2019 Apr 3;659:1362-1369. Epub 2019 Jan 3.

The Institute of Municipal Engineering, Zhejiang University, Hangzhou, Zhejiang, China. Electronic address:

A recent increase in urban floods has necessitated more effective assessment of urban flood risks to quantify the failure probability of urban drainage systems. However, the random hyetographs of storm events influences the results of flood risk assessment using existing methods. In this study, an alternative and more effective method is developed. After extracting characteristic parameters from hyetographs, the correlation between storm events characteristic and urban flood is analyzed according to the hydraulic model simulation results. Based on it, the storm characteristic parameters sensitive to catchment-specific drainage system response and its threshold to urban flood can be determined. And then, the storm events probability can be described with joint probability distribution of the sensitive parameters through using the Frank Copula. Therefore, flood risks for specific urban catchment can then be assessed by calculating the frequency of occurrence of all the storm events for which sensitive parameter exceed the threshold. This methods was successfully applied for the Chengzhong drainage system in Jiaxing, China. For the catchment-specific system it was found that the most important storm event characteristics are the mean rainfall intensity (I) and the peak 30-min intensity (30-Rp). Thus, the bivariate joint probability distribution of I and 30-Rp was estimated and based on that the risks that the catchment may be flooded every year can be assessed by calculating the probabilities of occurrence of flood-causing storm events per year. The proposed method is applicable for urban areas with different catchment conditions and drainage facilities, and it can provide alternative efficient means for urban flood risk assessment.
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http://dx.doi.org/10.1016/j.scitotenv.2019.01.004DOI Listing
April 2019

Formation of odorant haloanisoles and variation of microorganisms during microbial O-methylation in annular reactors equipped with different coupon materials.

Sci Total Environ 2019 Aug 24;679:1-11. Epub 2019 Apr 24.

College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, Zhejiang, China.

Taste and odor (T & O) issues in drinking water have become serious problems which cannot be ignored by customers. Several studies have confirmed that microbes in water can biotransform halophenols (HPs) to haloanisoles (HAs) with earthy and musty flavors via microbial O-methylation. In this paper, the formation of 2-chloroanisole (2-CA), 2,4-dichloroanisole (2,4-DCA), 2,4,6-trichloroanisole (2,4,6-TCA), 2,3,6-trichloroanisole (2,3,6-TCA) and 2,4,6-tribromoanisole (2,4,6-TBA), and the microbial variation during the microbial O-methylation were investigated in annular reactors (ARs) with three coupon materials. For precursors, 42.5% of 2-CP and 68.9% of 2,4-DCP decayed during the reaction. Among the five HAs, the formation rate constant followed an order of 2,4,6-TCA > 2-CA > 2,4,6-TBA > 2,4-DCA ~ 2,3,6-TCA, while [HA] followed a totally opposite one. The simulated flow velocity had no significant effect (p > 0.05) on HA formation. Ductile iron (DI) AR could produce more HAs than stainless steel (SS) and polyvinyl chloride (PVC) ARs. The final HA molar concentration followed an order of 2,3,6-TCA > 2,4-DCA > 2,4,6-TBA ~ 2,4,6-TCA > 2-CA, which might be explained by multiple factors including HP's dissociation degree, halogen atom's steric hindrance and specificity of HP O-methyltransferases. During the reaction, the microbial biomass dramatically increased 6.8-9.0 times in bulk water but dropped significantly on coupon biofilms. The effect of HPs significantly changed the bacterial communities on coupon in terms of composition and diversity, and declined the relative abundance of HA-producing bacteria, while fungi and their HA-producing genus showed better resistance ability towards HPs. By using Pearson correlation analysis, a significant correlation (p = 0.0003) was found between [HA] and initial coupon biofilm biomass. Finally, a linear relationship was established between initial total biomass and HA formation potential.
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http://dx.doi.org/10.1016/j.scitotenv.2019.04.329DOI Listing
August 2019

Chlorination of enoxacin (ENO) in the drinking water distribution system: Degradation, byproducts, and toxicity.

Sci Total Environ 2019 Aug 19;676:31-39. Epub 2019 Apr 19.

College of Civil Engineering and Architecture, Zhejiang University, 866 Yuhangtang Rd, Hangzhou 310058, China.

Chlorine is widely used as a drinking water disinfectant to ensure water security. However, the transformation mechanisms of its degradation of emerging pollutants within the water distribution system (WDS) is insufficiently understood. Thus, the kinetics, degradation byproducts, and toxicity of the chlorination of enoxacin (ENO, a type of emerging pollutant) were explored in a pilot-scale WDS for the first time. It was found that the chlorination rate of ENO was higher in deionized water (DW) than in the pilot-scale WDS, and the degradation followed second-order kinetics in DW. The degradation efficiency was found to be sensitive to pH, and was highest at a pH of 7.4. The chlorination rate of ENO increased with increasing temperature in both DW and WDS. For different pipe materials, the relative performance of ENO chlorination efficiency followed the order of steel pipe > ductile iron pipe > polyethylene (PE) pipe. Seven intermediates were identified during ENO chlorination, and the primary oxidation reaction involved the cleavage of the piperazine group. Finally, it was found that the potential for chlorine toxicity in treated drinking water in the presence of ENO is higher than it is without this pollutant.
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http://dx.doi.org/10.1016/j.scitotenv.2019.04.275DOI Listing
August 2019

Characteristics and mechanism of dimethyl trisulfide formation during sulfide control in sewer by adding various oxidants.

Sci Total Environ 2019 Jul 10;673:719-725. Epub 2019 Apr 10.

College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310027, China.

The addition of chemical agents to control the production of hydrogen sulfide (HS) is currently the principal technology used to control odor emissions from sewers. In this study, laboratory reactors were used to investigate the change in dimethyl trisulfide (DMTS) concentrations when dosing with oxidant to control sulfide in sewers. Our results show that the intermittent addition of oxidant leads to sulfide regeneration and increased DMTS formation. Additional experiments were conducted to investigate the processes that result in the formation of DMTS. The results indicate that the polysulfide produced after oxidant addition was a key intermediate in DMTS production. Enzymatic methylation of polysulfide was an important process in DMTS formation. Dimethylsulfoxide (DMSO) was observed in the reactor when oxidant was again added but it was reduced to DMTS when the oxidant was depleted. There are side-effects of adding oxidant, and alternative control measures for volatile sulfur compounds (VSCs) need to be investigated further.
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http://dx.doi.org/10.1016/j.scitotenv.2019.04.131DOI Listing
July 2019

The release mechanism of heavy metals from lab-scale vertical flow constructed wetlands treating road runoff.

Environ Sci Pollut Res Int 2019 Jun 15;26(16):16588-16595. Epub 2019 Apr 15.

The Institute of Municipal Engineering, The College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, Zhejiang, China.

Constructed wetlands (CWs) have been applied to remediate heavy metal pollution effectively in practice. However, the heavy metal release from CWs has not been paid enough attention. In this study, a 5-month experiment was carried out with three parallel lab-scale vertical flow constructed wetlands (VFCWs) with zeolites as fillers. The artificial rainwater was pumped into VFCWs to study the release characteristic and mechanisms of heavy metals (Cu, Zn, Cr, and Pb). The results showed that significant amounts of Zn and Cu were released from the VFCWs at the end of the experiment while Pb and Cr rarely escaped. The upper layer (0-30 cm) of the VFCWs was the most effective area for heavy metal removal due to the presence of sediments, but it was also the most active area for heavy metal release. To explain this result, the sediments were analyzed before and after being leached by the tap water. The results indicated that Zn and Cu existed mainly in the exchangeable state, and they had strong leachability and bioavailability, causing its releases. Also, competitive adsorption of different metals meant that the metal ions with strong adsorption to zeolite caused the metal ions with weak adsorption to be desorbed from zeolites, and thus, a large amount of Zn escaped from VFCWs. The escape of heavy metals from CWs illustrated that it should be paid more attention in the management.
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http://dx.doi.org/10.1007/s11356-019-05097-yDOI Listing
June 2019

A novel method: using an adenosine triphosphate (ATP) luminescence-based assay to rapidly assess the biological stability of drinking water.

Appl Microbiol Biotechnol 2019 Jun 10;103(11):4269-4277. Epub 2019 Apr 10.

College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058, Zhejiang, China.

The rapid and credible evaluations of the microbial stability of a drinking water distribution system (DWDS) are of great significance for ensuring the safety of drinking water and predicting microbial pollution. Conventional biostability assessment methods mainly focus on bacterial regrowth or evaluation of the level of nutrients that support bacterial regrowth. However, such methods are time-consuming and have many limitations. An adenosine triphosphate (ATP) assay can rapidly measure all active microorganisms and is known to be a useful method to assess the microbial activity of drinking water. The measurement of ATP has been used for more than a decade in the field of drinking water research. This article reviews the application of an ATP luminescence-based method to assess the biostability of drinking water and discusses the feasibility of ATP measurement as a parameter for quickly evaluating this criterion. ATP measurement will help researchers and water managers better monitor the biological stability of drinking water from the source to the consumer's tap. This review covers the: (1) principle and application of the ATP measurement in drinking water quality assessment; (2) comparison of the merits and demerits of several methods for evaluating the biostability of drinking water; (3) discussions on using ATP measurement in evaluating biostability; and (4) improvements in the use of ATP measurement in evaluating biostability. At the end of this review, recommendations were given for better application of the ATP measurement as a parameter for monitoring the microbial quality of drinking water.
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http://dx.doi.org/10.1007/s00253-019-09774-3DOI Listing
June 2019

Impact of UV irradiation on Chlorella sp. damage and disinfection byproducts formation during subsequent chlorination of algal organic matter.

Sci Total Environ 2019 Jun 20;671:519-527. Epub 2019 Mar 20.

Erdos City Anxintai Environmental Protection Technology Co. Ltd, Erdos 017000, China.

The frequent occurrence of algal blooms in surface water has attracted more and more attention, which caused many water quality problems, including disinfection byproducts (DBPs). Algal organic matter (AOM) including intracellular organic matter (IOM) and extracellular organic matter (EOM), was a well-known precursor to DBPs formation in drinking water. This study evaluated the effect of ultraviolet (UV) irradiation on the cell integrity, IOM release and DBPs formation during subsequent chlorination of Chlorella sp. Results showed the damage rates of algal cells increased to 40.1% after the high UV irradiation of 528 mJ/cm, which contributed to the release of IOM. In addition, UV irradiation was effective in reducing the formation of haloacetic acids (HAAs) both in AOM and IOM, but promoted the formation of nitrogenous DBPs (N-DBPs) from AOM in subsequent chlorination. Furthermore, neutral pH exerted a positive effect on the formation of DBPs. UV irradiation decreased the bromine substitution factor (BSF) value of AOM at a high bromide level. The BSF values increased with increasing of the concentration of bromide. Moreover, more amino acids and low molecular weight precursors were produced after UV irradiation in filtered supernatant, which contributed to the formation of N-DBPs with algal chlorination. Overall, this information demonstrated pre-oxidation of UV irradiation could be used to treat the algal-rich drinking water.
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http://dx.doi.org/10.1016/j.scitotenv.2019.03.282DOI Listing
June 2019

A Greedy Sampling Design Algorithm for the Modal Calibration of Nodal Demand in Water Distribution Systems.

Environ Model Softw 2019 Feb;2019:1-3917571

Department of Civil Engineering, Zhejiang University, Hangzhou 310058, China.

This paper presents a greedy optimization algorithm for sampling design to calibrate WDS hydraulic model. The proposed approach starts from the existing sensors and sequentially adds one new sensor at each optimization simulation step. In each step, the algorithm tries to minimize the calibration prediction uncertainty. The new sensor is installed in the location where the uncertainty is greatest but also sensitive to other nodes. The robustness of the proposed approach is tested under different spatial and temporal demand distribution. We found that both the number of sensors and the perturbation ratio affect the calibration accuracy as defined by the average nodal pressure deviation itself and its variability. The plot of the calibration accuracy versus the number of sensors can reasonably guide the trade-off between model calibration accuracy and number of sensors placed or the cost. This proposed approach is superior in calibration accuracy and modeling efficiency when compared to the standard genetic algorithm (SGA) and Monte Carlo Sampling algorithm (MCS).
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http://dx.doi.org/10.1155/2019/3917571DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7433793PMC
February 2019

Real-Time Water Distribution System Hydraulic Modeling Using Prior Demand Information by Formal Bayesian Approach.

J Water Resour Plan Manag 2019 ;145(12)

Dept. of Civil Engineering, Zhejiang Univ., Hangzhou 310058, China.

Real-time water distribution system (WDS) hydraulic models are used in water utilities to facilitate the planning and operation of the water distribution system. As a critical model input, spatiotemporally varying nodal water demands significantly affect the performance and applicability of such WDS models. Thus, real-time nodal demands must be calibrated for reliability before their use. The main difficulty for real-time calibration is the lack of observed data sufficient to determine thousands of nodal demands accurately in a network. To address the difficulty, this study proposes a formal Bayesian approach to determine nodal demands in WDS hydraulic modeling by explicitly taking prior water demand information into account and coupling more information to constrain the nodal water demand modeling. Application of the approach on a simple hypothetical network and a field network in a city of eastern Zhejiang Province, China demonstrates that by adding prior information, the nodal demand can be uniquely determined in real time. The approach limits uncertainty propagation and improves the robustness of the real-time model calibration and analysis.
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http://dx.doi.org/10.1061/(asce)wr.1943-5452.0001137DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7898116PMC
January 2019

Sulfadiazine destruction by chlorination in a pilot-scale water distribution system: Kinetics, pathway, and bacterial community structure.

J Hazard Mater 2019 03 24;366:88-97. Epub 2018 Nov 24.

School of Civil and Environmental Engineering, Georgia Institute of Technology, USA.

Sulfadiazine (SDZ) has been frequently detected in surface waters in recent years. We evaluated the kinetics, mechanisms, intermediate products and bacterial community structure that result from the reaction of SDZ with free chlorine (HOCl/OCl). We examined this in a pilot-scale water distribution system. Neutral pH had the fastest rate of destruction of SDZ. A second-order reaction constant for the destruction of SDZ by chlorine increased with increasing concentration of free chlorine (FC). For different pipe materials, the rate of SDZ degradation decreased as follows: stainless steel (SS) pipe > polyethylene (PE) pipe > ductile iron (DI) pipe. Based on the less complex bacterial diversity and more chlorine-resistant by 16S ribosomal ribonucleic acid (rRNA) gene analysis, SS pipe and PE pipe were more suitable in SDZ degradation in water distribution system (WDS) than DI pipe. In addition, the transformation products from SDZ chlorination were identified by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry, and the products included SO extrusion products, haloacetic acids and trihalomethanes. Toxicity tests further confirmed that the toxicity of SDZ chlorination was higher both in low FC (0.7 mg/L) and high FC (1.3 mg/L) in WDS.
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http://dx.doi.org/10.1016/j.jhazmat.2018.11.096DOI Listing
March 2019

Degradation of sulfonamides and formation of trihalomethanes by chlorination after pre-oxidation with Fe(VI).

J Environ Sci (China) 2018 Nov 2;73:89-95. Epub 2018 Feb 2.

College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310027, China. Electronic address:

Sulfonamides are used in human therapy, animal husbandry and agriculture but are not easily biodegradable, and are often detected in surface water. Sulfamethazine (SMZ) and sulfadiazine (SDZ) are two widely used sulfonamide antibiotics that are used heavily in agriculture. In this study, they were degraded in an aqueous system by chlorination after pre-oxidation with ferrate(VI) (FeO, Fe(VI)), an environmentally friendly oxidation technique that has been shown to be effective in degrading various organics. The kinetics of the degradation were determined as a function of Fe(VI) (0-1.5mg/L), free chlorine (0-1.8mg/L) and temperature (15-35°C). According to the experimental results, SMZ chlorination followed second-order kinetics with increasing Fe(VI) dosage, and the effect of the initial free chlorine concentration on the reaction kinetics with pre-oxidation by Fe(VI) fitted a pseudo-first order model. The rate constants of SDZ and SMZ chlorination at different temperatures were related to the Arrhenius equation. Fe(VI) could reduce the levels of THMs formed and the toxicity of the sulfonamide degradation systems with Fe(VI) doses of 0.5-1.5mg/L, which provides a reference for ensuring water quality in drinking water systems.
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http://dx.doi.org/10.1016/j.jes.2018.01.016DOI Listing
November 2018

A comparative analysis for the development and recovery processes of different types of clogging in lab-scale vertical flow constructed wetlands.

Environ Sci Pollut Res Int 2018 Aug 9;25(24):24073-24083. Epub 2018 Jun 9.

The Institute of Municipal Engineering, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, Zhejiang, 312058, People's Republic of China.

Clogging is a major operational and maintenance issue associated with the use of constructed wetlands. In this study, four lab-scale vertical flow constructed wetlands (VFCW) were used to fully understand the development mechanisms of various types of clogging and their recovery characteristics. The VFCWs were fed with glucose solution, starch suspension with and without bacteriostat, glucose, and starch mixed solution, respectively, to simulate Bio-clogging, organic particle clogging (Op-clogging), inert particle clogging (Ip-clogging), and the combination of Bio-clogging and Op-clogging (C-clogging). Resting operations with water decline were applied to relieve the clogging in the VFCWs. The results indicate that Op-clogging occurred first, followed by C-clogging and Bio-clogging. Ip-clogging took the longest time to develop and did not occur by the end of this study. The microscope analysis found that the extracellular polymeric substances (EPS) bonded the starch particles together to form a dense membrane-like structure and promoted the clogging process. In addition, surface clogging was observed in all four experimental beds. Op-clogging occurred much closer to the surface than those caused by soluble organic matter and inert particles. Furthermore, the growth of biofilm caused significant decline in hydraulic conductivity, whereas its influence on porosity was relatively slight. Moreover, applying resting operation with water decline was effective for recovery from Bio-clogging, Op-clogging, and C-clogging in VFCWs except for Ip-clogging. The results also implied the recovery rates through applying resting operation with water decline were much higher than that with constant water level.
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http://dx.doi.org/10.1007/s11356-018-2418-zDOI Listing
August 2018

An efficient multi-objective optimization method for water quality sensor placement within water distribution systems considering contamination probability variations.

Water Res 2018 10 20;143:165-175. Epub 2018 Jun 20.

College of Civil Engineering and Architecture, Zhejiang University, 866 Yuhangtang Rd, Hangzhou, 310058, China.

Water quality security within water distribution systems (WDSs) has been an important issue due to their inherent vulnerability associated with contamination intrusion. This motivates intensive studies to identify optimal water quality sensor placement (WQSP) strategies, aimed to timely/effectively detect (un)intentional intrusion events. However, these available WQSP optimization methods have consistently presumed that each WDS node has an equal contamination probability. While being simple in implementation, this assumption may do not conform to the fact that the nodal contamination probability may be significantly regionally varied owing to variations in population density and user properties. Furthermore, the low computational efficiency is another important factor that has seriously hampered the practical applications of the currently available WQSP optimization approaches. To address these two issues, this paper proposes an efficient multi-objective WQSP optimization method to explicitly account for contamination probability variations. Four different contamination probability functions (CPFs) are proposed to represent the potential variations of nodal contamination probabilities within the WDS. Two real-world WDSs are used to demonstrate the utility of the proposed method. Results show that WQSP strategies can be significantly affected by the choice of the CPF. For example, when the proposed method is applied to the large case study with the CPF accounting for user properties, the event detection probabilities of the resultant solutions are approximately 65%, while these values are around 25% for the traditional approach, and such design solutions are achieved approximately 10,000 times faster than the traditional method. This paper provides an alternative method to identify optimal WQSP solutions for the WDS, and also builds knowledge regarding the impacts of different CPFs on sensor deployments.
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http://dx.doi.org/10.1016/j.watres.2018.06.041DOI Listing
October 2018

The dependence of chlorine decay and DBP formation kinetics on pipe flow properties in drinking water distribution.

Water Res 2018 Sep 27;141:32-45. Epub 2018 Apr 27.

College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310027, China.

Simultaneous chlorine decay and disinfection byproduct (DBP) formation have been discussed extensively because of their regulatory and operational significance. This study further examines chemical reaction variability in the water quality changes under various hydrodynamic conditions in drinking water distribution. The variations of kinetic constant for overall chlorine decay (k) and trihalomethane (THM) formation were determined under stagnant to turbulent flows using three devices of different wall demand and two types of natural organic matters (NOM) in water. The results from the comparative experiments and modeling analyses show the relative importance of wall demand (k), DBP-forming chlorine decay (k), and other bulk demand (k) for pipe flows of Re = 0-52500. It is found that chlorine reactivity of virgin NOM is the overriding factor. Secondly, for tap water NOM of lower reactivity, pipe flow properties (Re or u) can significantly affect k, the THM yield (T), formation potential (Y), and the time to reach the maximum THM concentration (t) through their influence on kinetic ratio k(k+k). These observations, corroborating with turbidity variations during experiments, cannot be explained alone by chlorine dispersion to and from the pipe wall. Mass exchanges through deposition and scale detachment, most likely being flow-dependent, may have contributed to the overall chlorine decay and DBP formation rates. Thus for the simultaneous occurrence of chlorine decay and DBP formation, model considerations of NOM reactivity, pipe types (wall demand), flow hydraulics, and their interactions are essential.
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http://dx.doi.org/10.1016/j.watres.2018.04.048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6800165PMC
September 2018
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