Publications by authors named "Yuefeng F Xie"

36 Publications

Kinetics and mechanism of haloacetaldehyde formation from the reaction of acetaldehyde and chlorine.

Chemosphere 2021 Jun 18;283:131253. Epub 2021 Jun 18.

School of Environment, Tsinghua University, Beijing, 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA17057, USA.

Haloacetaldehydes (HALs) are the third prevalent group of disinfection by-products (DBPs) by weight in drinking water, and their cytotoxicity and genotoxicity are higher than regulated DBPs. In order to understand their formation mechanism during chlorination and ozonation-chlorination, this study examined the reaction kinetics of chloral hydrate (CH), dichloroacetaldehyde (DCA), chloroacetaldehyde (CA) and acetaldehyde by chlorine at different pH values and chlorine doses. The results showed that the reaction rate constants increased with pH and chlorine dose, except that the degradation of CH would not be affected by the presence of free chlorine. At the same pH and chlorine dose, the half-lives of CH, DCA, CA and acetaldehyde were in the order of CH > acetaldehyde ≫ DCA > CA. A kinetic model used to predict the formation of HALs and chloroform during chlorination of acetaldehyde was developed, and the predicted data fitted well with the measured data. As pre-ozonation could oxidize natural organic matter to acetaldehydes, the concentration of acetaldehyde formed after pre-ozonation was used to calculate the HAL yields during ozonation-chlorination by the kinetic model, which fitted the experimental results well. The kinetic model elucidated that the formation mechanism of HALs was a stepwise substitution process on the α-hydrogen of acetaldehyde during chlorination.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131253DOI Listing
June 2021

Study on the influence of operational and management processes of a water reclamation plant since COVID-19 situation.

Environ Pollut 2021 Apr 28;285:117257. Epub 2021 Apr 28.

Xi'an High-Tech Institute, Shaanxi, Xi'an, 710025, China.

Reusing treated wastewater can effectively alleviate water shortages and water contamination problems but depends on ensuring the safety of the reclaimed water that is produced. The operating and management conditions for water reclamation plants in China have been changed since the outbreak of the COVID-19 epidemic in China at the end of 2019 to prevent emerging viruses being spread through wastewater treatment processes and the reclaimed water that is produced. Removal of pathogens and trace organic compounds (e.g., pharmaceuticals and personal care products and endocrine disrupting chemicals) in a real water reclamation plant after the start of COVID-19 epidemic was studied. Disinfection byproduct formation caused by chlorine being added to meet disinfection requirements was also assessed. The pathogenic microorganism concentrations in effluent were <2 (most probable number)/L, and the removal rates for most trace organic compounds were >80% when advanced treatments were performed using ozone, ultraviolet light, and chlorine doses of 2 mg/L, 20.5 mJ/cm, and 2-3 mg/L, respectively. The main disinfection byproduct produced at a chlorine dose of 2 mg/L and a residence time of 1 h was chloroform (at concentrations <15 μg/L). The results indicated that the water reclamation processes with modified conditions gave high pathogen and trace organic compound removal rates and reasonably well-controlled disinfection byproduct concentrations.
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http://dx.doi.org/10.1016/j.envpol.2021.117257DOI Listing
April 2021

Optimization of ozone dosage in an ozone contact tank using a numerical model.

Environ Sci Pollut Res Int 2021 Apr 15. Epub 2021 Apr 15.

School of Environment, Tsinghua University, Beijing, 100084, China.

Ozone has been widely applied in drinking water and wastewater treatment plants, and it is essential to determine the ozone dosage and its ratio in ozone contact tank to increase the ozone absorption and utilization rates. Batch experiments were performed to determine the first-order reaction rate coefficient of ozone (k) in different raw water qualities. Results showed that k had an exponential decaying relationship with the ozone consumption amount (ΔO). Based on the ozone mass transfer and decomposition kinetics, a numerical model was developed to optimize the total ozone dosage and its ratio in three aeration parts by calculating the ozone absorption and utilization rates in an ozone contact tank. The ozone absorption rate was little affected by the water quality, and an even distribution of ozone could greatly increase the ozone absorption rate. However, the ozone utilization rate was tightly related with the water quality. For waters that consumed ozone quickly, ozone should be dosed equally in three aeration parts to increase the ozone utilization rate up to 94.3%. Otherwise, more ozone should be dosed in the first aeration part. An increase in ozone utilization rate would induce an increase in the degree of water purification. This model could give theoretical support for the determination of ozone dosage and its ratio in water treatment plants rather than experience.
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http://dx.doi.org/10.1007/s11356-021-13917-3DOI Listing
April 2021

A Facile and Scalable Fabrication Procedure for Thin-Film Composite Membranes: Integration of Phase Inversion and Interfacial Polymerization.

Environ Sci Technol 2020 02 22;54(3):1946-1954. Epub 2020 Jan 22.

Department of Chemical Engineering , KU Leuven , Celestijnenlaan 200F , B-3001 Leuven , Belgium.

Conventional dense thin-film composite (TFC) membranes evince a universally low water permeability, the increase of which typically relies on introducing additional transport channels based on intricate steps within a membrane preparation process. In this study, we reported a novel and simplified procedure for the fabrication of high-performance TFC membranes. Specifically, the dissolution of aqueous monomers in the casting solution was utilized for the following interfacial polymerization (IP). Since the monomers diffused to the water bath during phase inversion, the control of precipitation time enabled an effective regulation of the monomer concentration in the formed polymeric substrates, where the IP reaction was initiated by the addition of the organic phase. The entire and uniform embedment of aqueous monomers inside the substrates contributed to the formation of ultrathin and smooth selective layers. An excellent separation performance (i.e., water permeability: 34.7 L m h bar; NaSO rejection: ∼96%) could be attained using two types of aqueous monomers (i.e., piperazine and β-cyclodextrin), demonstrating the effectiveness and universality of this method. Compared to the conventional immersion-based process, this novel procedure shows distinct advantages in reducing monomer usage, shortening the production cycle, and achieving a more superior membrane performance, which is highly promising for large-scale membrane manufacture.
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http://dx.doi.org/10.1021/acs.est.9b06426DOI Listing
February 2020

The haloacetic acid leap in effluent of a biologically active carbon filter experiencing a disinfectant switch.

Chemosphere 2020 Apr 21;244:125435. Epub 2019 Nov 21.

Department of Chemistry, Indiana University of Pennsylvania, Indiana, 15705, PA, USA. Electronic address:

Water utilities must disinfect their water despite the formation of carcinogenic disinfection byproducts (DBPs) such as haloacetic acids (HAAs) upon chlorination. Although employment of a biologically active carbon (BAC) filtration process is able to reduce the HAA level preventively by removing the HAA precursors and correctively by removing the already-formed HAAs, this research reported an HAA leap in a bench-scale BAC filter effluent upon a disinfectant switch from chlorine to chloramine, posing a pressure of meeting the stringent HAA regulations. The HAA6 (sum of six HAAs) tripled from a 5 μg/L base level to a maximum of 17 μg/L during progressive switches with 3 chloramine doses at 5, 25, and 50 mg/L. Dichloroacetic acid (DCAA) accounted for the majority of the leap, which also influenced the bromine substitution factor during the HAA formation. Filtration of distilled water using heat-deactivated media evidenced slight HAA desorption and suggested potential roles of soluble microbial products from biofilms as new HAA precursors for a real BAC filter experiencing a disinfectant switch.
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http://dx.doi.org/10.1016/j.chemosphere.2019.125435DOI Listing
April 2020

Synergistic effects of combining ozonation, ceramic membrane filtration and biologically active carbon filtration for wastewater reclamation.

J Hazard Mater 2020 01 23;382:121091. Epub 2019 Aug 23.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China; Environmental Engineering Programs, Pennsylvania State University, Middletown, PA, 17057, USA.

In this study, we proposed to apply an integrated process which is comprised of in situ ozonation, ceramic membrane filtration (CMF) and biologically active carbon (BAC) filtration to wastewater reclamation for indirect potable reuse purpose. A pilot-scale (20 m/d) experiment had been run for ten months to validate the prospect of the process in terms of treatment performance and operational stability. Results showed that the in situ O + CMF + BAC process performed well in pollutant removal, with chemical oxygen demand, ammonia, nitrate nitrogen, total phosphorus and turbidity levels in the treated water being 5.1 ± 0.9, 0.05 ± 0.01, 10.5 ± 0.8, <0.06 mg/L, and <0.10 NTU, respectively. Most detected trace organic compounds were degraded by>96%. This study demonstrated that synergistic effects existed in the in situ O + CMF + BAC process. Compared to pre-ozonation, in situ ozonation in the membrane tank was more effective in controlling membrane fouling (maintaining operational stability) and in degrading organic pollutants, which could be attributed to the higher residual ozone concentration in the tank. Because of the removal of particulate matter by CMF, water head loss of the BAC filter increased slowly and prolonged the backwashing interval to 30 days. BAC filtration was also effective in removing ammonia and N-nitrosodimethylamine from the ozonated water.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121091DOI Listing
January 2020

Mechanism of ozonation enhanced formation of haloacetaldehydes during subsequent chlorination.

Chemosphere 2019 Dec 14;236:124361. Epub 2019 Jul 14.

School of Environment, Tsinghua University, Beijing, 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA, 17057, USA.

Haloacetaldehydes (HAs) are the third prevalent group of disinfection by-products of great health concern. A bench-scale study was performed to investigate the formation and speciation of HAs in raw and treated waters after chlorination and ozonation-chlorination. Pre-ozonation resulted in enhanced HA formation during subsequent chlorination, and the HA yields from ozonation-chlorination were 1.66 and 1.63 times higher than that from chlorination of raw and treated waters. The mechanism about the increase of HA formation during ozonation-chlorination was systematically investigated in this study. The results showed that acetaldehyde formed after ozonation was the dominant precursor for the enhanced HA formation during subsequent chlorination. Increase in pH and chlorine dose increased HA formation during acetaldehyde chlorination. Based on the kinetic studies on the HA formation during acetaldehyde chlorination and the HA stabilities with and without free chlorine, it was found that chlorine was incorporated into the α-hydrogen in acetaldehyde to form a sequence of mono-, di- and tri-chloroacetaldehyde. During this process, these three chlorinated acetaldehydes would also undergo base-catalyzed hydrolysis through decarburization and dehalogenation pathways. This study elucidated that acetaldehyde formed after ozonation resulted in the increase of HA formation during subsequent chlorination. This study also revealed the formation pathway of HA during chlorination of acetaldehyde, which would help to minimize HA formation at drinking water plants.
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http://dx.doi.org/10.1016/j.chemosphere.2019.124361DOI Listing
December 2019

Impacts of Metal-Organic Frameworks on Structure and Performance of Polyamide Thin-Film Nanocomposite Membranes.

ACS Appl Mater Interfaces 2019 Apr 26;11(14):13724-13734. Epub 2019 Mar 26.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment , Tsinghua University , Beijing 100084 , China.

Metal-organic frameworks (MOFs), a class of hybrid organic-inorganic materials, have recently attracted tremendous interests in the fabrication of thin-film nanocomposite (TFN) membranes with exceptional permselectivity. However, the structure-performance relationship of such membranes, which is a function of both MOF type and membrane fabrication procedure, has not been elucidated in the literature. In this study, three types of hydro-stable MOFs, namely, MIL-53(Al), NH-UiO-66, and ZIF-8, were used to fabricate TFN nanofiltration membranes via both blending (BL) and preloading interfacial polymerization methods. Results show that the incorporation of MOFs could enhance water permeability of TFN membranes to 7.2 L/(m·h·bar) at most ( TFN-BL-0.10%), about 1.3 times of the corresponding thin-film composite membranes, without sacrificing their selectivity to reject NaCl (>40%) and xylose (>65%). Membrane characterization revealed that MOFs decreased the cross-linking degree while increasing the membrane thickness, surface negative charge, and roughness of the polyamide active layer. MIL-53(Al) were found to bind with polyamide via reacting with piperazine, whereas weaker polyamide-MOF interactions were observed for NH-UiO-66 and ZIF-8. This difference, along with the hydrophilicity of MOF particles, explained the varied permselectivity of different TFN membranes. Compared to pristine polyamide membranes, the TFN membranes demonstrated higher or comparable efficiencies in removing a set of six pharmaceuticals (PhACs), which were determined by the molecular properties of PhACs and membrane structure. The findings of this study deepen our understanding of the roles that MOFs play in regulating membrane performance, promoting molecular design of MOF-incorporated TFN membranes via precise control of MOF-polymer interactions.
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http://dx.doi.org/10.1021/acsami.9b01923DOI Listing
April 2019

Enhanced organic removal for shale gas fracturing flowback water by electrocoagulation and simultaneous electro-peroxone process.

Chemosphere 2019 Mar 16;218:252-258. Epub 2018 Nov 16.

Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.

Colloids and organics in shale gas fracturing flowback water (SGFFW) during shale gas extraction are of primary concerns. Coagulation combined with oxidation might be a promising process for SGFFW treatment. In this study, a novel electrocoagulation-peroxone (ECP) process was developed for SGFFW treatment by simultaneous coagulation and oxidation process with a Al plate as the anode and a carbon-PTFE gas diffusion electrode as the cathode, realizing the simultaneous processes of coagulation, HO generation and activation by O at the cathode. Compared with electrocoagulation (EC) and peroxi-electrocoagulation (PEC), COD removal efficiency mainly followed the declining order of ECP, PEC and EC under the optimal current density of 50 mA cm. The appearance of medium MW fraction (1919 Da) during ozonation and PEC but disappearance in ECP indicated that these intermediate products couldn't be degraded by ozonation and PEC but could be further oxidized and mineralized by the hydroxyl radical produced by the cathode in ECP, demonstrating the hydroxyl radical might be responsible for the significant enhancement of COD removal. The pseudo-first order kinetic model can well fit ozonation and EC process but not the PEC and ECP process due to the synthetic effect of coagulation and oxidation. However, the proposed mechanism based model can generally fit ECP satisfactorily. The average current efficiency for PEC was 35.4% and 12% higher than that of ozonation and EC, respectively. This study demonstrated the feasibility of establishing a high efficiency and space-saving electrochemical system with integrated anodic coagulation and cathodic electro-peroxone for SGFFW treatment.
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http://dx.doi.org/10.1016/j.chemosphere.2018.11.055DOI Listing
March 2019

Impacts of shale gas production wastewater on disinfection byproduct formation: An investigation from a non-bromide perspective.

Water Res 2018 11 19;144:656-664. Epub 2018 Jul 19.

Environmental Programs, The Pennsylvania State University, Middletown, PA, 17057, USA. Electronic address:

The rapid rise of shale gas development has triggered environmental and human health concerns due to its impacts on water resources, especially on disinfection byproduct (DBP) formation upon chlorination. Despite the recently reported results on bromide, the effects of non-bromide ions in production wastewater at extremely high levels are vaguely defined. In this study, we investigated the effects of production wastewater, with bromide and non-bromide species, on the formation of DBPs when production wastewater was spiked into surface waters at various percentages. Results showed that the introduction of debrominated production wastewater led to increased formation of some chlorinated DBP species in selected surface water and wastewater. As the spiking percentage of debrominated production wastewater increased, the chlorinated DBP species increased. The contributions of individual cations to DBP formation followed a sequence of magnesium > calcium > barium at 0.10% spiking percentage due to the different catalytic effects of their chelates with organic precursors. The study of anions suggested that the discharge of treated production wastewater containing elevated sulfate may further enhance DBP formation. The significance of this study lies in the fact that in addition to bromide concerns from production wastewater, non-bromide species also contributed to DBP formation. The gas production wastewater management decision should consider the negative impacts from both bromide and non-bromide species to better protect the receiving water resources.
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http://dx.doi.org/10.1016/j.watres.2018.07.048DOI Listing
November 2018

Formation of disinfection by-products under influence of shale gas produced water.

Sci Total Environ 2019 Jan 5;647:744-751. Epub 2018 Aug 5.

Department of Chemistry, Indiana University of Pennsylvania, Indiana, PA 15705, USA. Electronic address:

Accidental spills and surface discharges of shale gas produced water could contaminate water resources and generate health concerns. The study explored the formation and speciation of disinfection by-products (DBPs) during chlorination of natural waters under the influence of shale gas produced water. Results showed the presence of produced water as low as 0.005% changed the DBP profile measurably. A shift to a more bromine substitution direction for the formation of trihalomethanes, dihaloacetic acids, trihaloacetic acids, and dihaloacetonitriles was illustrated by exploring the individual DBP species levels, bromine substitution factors, and DBP species fractions, and the effect was attributable to the introduction of bromide from produced water. The ratio of dichloroacetic and trichloroacetic acids also increased, which was likely affected by different bromination degrees at elevated bromide concentrations. Increasing blend ratios of produced water enhanced the formation of DBPs, especially the brominated species, while such negative effects could be alleviated by pre-treating the produced water with ozone/air stripping to remove bromide. The study advances understandings about the impacts of produced water spills or surface discharges regarding potential violation of Stage 2 DBP rules at drinking water treatment facilities.
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http://dx.doi.org/10.1016/j.scitotenv.2018.08.055DOI Listing
January 2019

Adsorption of pharmaceuticals onto isolated polyamide active layer of NF/RO membranes.

Chemosphere 2018 Jun 16;200:36-47. Epub 2018 Feb 16.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.

Adsorption of trace organic compounds (TrOCs) onto the membrane materials has a great impact on their rejection by nanofiltration (NF) and reverse osmosis (RO) membranes. This study aimed to investigate the difference in adsorption of various pharmaceuticals (PhACs) onto different NF/RO membranes and to demonstrate the necessity of isolating the polyamide (PA) active layer from the polysulfone (PS) support layer for adsorption characterization and quantification. Both the isolated PA layers and the PA+PS layers of NF90 and ESPA1 membranes were used to conduct static adsorption tests. Results showed that apparent differences existed between the PA layer and the PA+PS layer in the adsorption capacity of PhACs as well as the time necessary to reach the adsorption equilibrium. PhACs with different physicochemical properties could be adsorbed to different extents by the isolated PA layer, which was mainly attributed to electrostatic attraction/repulsion and hydrophobic interactions. The PA layer of ESPA1 exhibited apparently higher adsorption capacities for the positively charged PhACs and similar adsorption capacities for the neutral PhACs although it had significantly less total interfacial area (per unit membrane surface area) for adsorption compared to the PA layer of NF90. The higher affinity of the PA layer of ESPA1 for the PhACs could be due to its higher capacity of forming hydrogen bonds with PhACs resulted from the modified chemistry with more -OH groups. This study provides a novel approach to determining the TrOC adsorption onto the active layer of membranes for the ease of investigating adsorption mechanisms.
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http://dx.doi.org/10.1016/j.chemosphere.2018.02.088DOI Listing
June 2018

Effects of conventional ozonation and electro-peroxone pretreatment of surface water on disinfection by-product formation during subsequent chlorination.

Water Res 2018 03 11;130:322-332. Epub 2017 Dec 11.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address:

The electro-peroxone (E-peroxone) process is an emerging ozone-based electrochemical advanced oxidation process that combines conventional ozonation with in-situ cathodic hydrogen peroxide (HO) production for oxidative water treatment. In this study, the effects of the E-peroxone pretreatment on disinfection by-product (DBP) formation from chlorination of a synthetic surface water were investigated and compared to conventional ozonation. Results show that due to the enhanced transformation of ozone (O) to hydroxyl radicals (OH) by electro-generated HO, the E-peroxone process considerably enhanced dissolved organic carbon (DOC) abatement and significantly reduced bromate (BrO) formation compared to conventional ozonation. However, natural organic matter (NOM) with high UV absorbance, which is the major precursors of chlorination DBPs, was less efficiently abated during the E-peroxone process than conventional ozonation. Consequently, while both conventional ozonation and the E-peroxone process substantially reduced the formation of DBPs (trihalomethanes and haloacetic acids) during post-chlorination, higher DBP concentrations were generally observed during chlorination of the E-peroxone pretreated waters than conventional ozonation treated. In addition, because of conventional ozonation or the E-peroxone treatment, DBPs formed during post-chlorination shifted to more brominated species. The overall yields of brominated DBPs exhibited strong correlations with the bromide concentrations in water. Therefore, while the E-peroxone process can effectively suppress bromide transformation to bromate, it may lead to higher formation of brominated DBPs during post-chlorination compared to conventional ozonation. These results suggest that the E-peroxone process can lead to different DBP formation and speciation during water treatment trains compared to conventional ozonation.
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http://dx.doi.org/10.1016/j.watres.2017.12.019DOI Listing
March 2018

A comparison of genotoxicity change in reclaimed wastewater from different disinfection processes.

Chemosphere 2018 Jan 4;191:335-341. Epub 2017 Oct 4.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.

Effluents before disinfection from four wastewater reclamation plants were treated with chlorine (Cl), ozone (O), chlorine dioxide (ClO), medium-pressure ultraviolet (MPUV) and four different combinations of the above, to evaluate the effect of disinfection processes on the genotoxicity removal by the SOS/umu test. Results showed that the genotoxicity increased after MPUV irradiation (10-100 mJ/cm), but declined when adopting other disinfection processes. The effectiveness of genotoxicity reduction by five chemical disinfectants was identified as: O > pre-ozonation with Cl ≈ ClO > combination of ClO and Cl > Cl. The sequential combination of MPUV, Cl and O reduced the genotoxicity to a level similar to the source water. The influence of differential disinfection process varied on iodinated wastewater, which is closely related to the competitive reactions between disinfectants, iodine and dissolved organic matters. The removal of genotoxic pollutants and the formation of genotoxic disinfection by-products are the two major factors that lead to the change in genotoxicity during disinfection.
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http://dx.doi.org/10.1016/j.chemosphere.2017.10.024DOI Listing
January 2018

Role of adsorption in combined membrane fouling by biopolymers coexisting with inorganic particles.

Chemosphere 2018 Jan 29;191:226-234. Epub 2017 Sep 29.

School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW, 2052, Australia.

This study was conducted in order to obtain a better understanding of the combined fouling by biopolymers coexisting with inorganic particles from the aspects of fouling index, fouling layer structure and biopolymer-particle interactions. Calcium alginate was used as the model biopolymer and FeO, AlO, kaolin, and SiO were used as model inorganic particles. Results showed that the combined fouling differed greatly among the four types of inorganic particles. The differences were attributed particularly to the different adsorption capacities for calcium alginate by the particles with this capacity decreasing in the order of FeO, AlO, kaolin and SiO. Particle size measurement and electron microscopic observation indicated the formation of agglomerates between calcium alginate and those inorganic particles exhibiting strong adsorption capacity. A structure was proposed for the combined fouling layer comprised of a backbone cake layer of alginate-inorganic particle agglomerates with the pores partially filled with discontinuous calcium alginate gels. The filterability of the fouling layer was primarily determined by the abundance of the gels. The strength of physical interaction between calcium alginate and each type of inorganic particle was calculated from the respective surface energies and zeta potentials. Calculation results showed that the extent of physical interaction increased in the order of AlO, FeO, kaolin and SiO, with this order differing from that of adsorption capacity. Chemical interactions may also play an important role in the adsorption of alginate and the consequent combined fouling. High-resolution XPS scans revealed a slight shift of electron binding energies when alginate was adsorbed.
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http://dx.doi.org/10.1016/j.chemosphere.2017.09.139DOI Listing
January 2018

The role of solubility on the rejection of trace organics by nanofiltration membrane: exemplified with disinfection by-products.

Environ Sci Pollut Res Int 2017 Aug 22;24(22):18400-18409. Epub 2017 Jun 22.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.

Interactions of trace organic compounds (TOrCs) with polymeric nanofiltration (NF) membrane can affect their rejection. It is desirable to investigate whether solubility which depends on the free energy of interaction between these solutes and water correlates with rejection/adsorption and the potential to be incorporated in the partitioning terms of current NF model. A total of ten neutral disinfection by-products (DBPs) were selected as the model compounds for TOrCs to comprehensively investigate the role of solubility on rejection and adsorption. Pearson correlation analysis indicated that the correlation between MW and rejection ratio was highly significant (r = 0.778, p = 0.008) and that between solubility and rejection ratio was moderately significant (r = -0.636, p = 0.48) in a cross-flow system. By fitting Freundlich equation from adsorption isotherm experiment, the adsorption affinity (K ) of DBPs was roughly correlated with their solubility with regard to the comparison of n value with 1. α was then introduced as a parameter of solute-membrane interaction from the perspective of partitioning term in the hydrodynamic model. Exponential relationship can be observed between the solubility and α, demonstrating the possibility of incorporating solubility into the partitioning terms in NF model to accurately predict the rejection of DBPs.
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http://dx.doi.org/10.1007/s11356-017-9282-0DOI Listing
August 2017

Mechanism and kinetics of halogenated compound removal by metallic iron: Transport in solution, diffusion and reduction within corrosion films.

Chemosphere 2017 Jul 6;178:119-128. Epub 2017 Mar 6.

Energy and Environment International Centre, School of Energy and Power Engineering, Beihang University, Beijing, 100191, PR China.

A detailed kinetic model comprised of mass transport (k), pore diffusion (k), adsorption and reduction reaction (k), was developed to quantitatively evaluate the effect of corrosion films on the removal rate (k) of halogenated compounds by metallic iron. Different corrosion conditions were controlled by adjusting the iron aging time (0 or 1 yr) and dissolved oxygen concentration (0-7.09 mg/L DO). The k values for bromate, mono-, di- and tri-chloroacetic acids (BrO, MCAA, DCAA and TCAA) were 0.41-7.06, 0-0.16, 0.01-0.53, 0.10-0.73 h, with k values at 13.32, 12.12, 11.04 and 10.20 h, k values at 0.42-5.82, 0.36-5.04, 0.30-4.50, 0.30-3.90 h, and k values at 14.94-421.18, 0-0.19, 0.01-1.30, 0.10-3.98 h, respectively. The variation of k value with reaction conditions depended on the reactant species, while those of k, k and k values were irrelevant to the species. The effects of corrosion films on k and k values were responsible for the variation of k value for halogenated compounds. For a mass-transfer-limited halogenated compound such as BrO, an often-neglected k value primarily determined its k value when pore diffusion was the rate-limiting step of its removal. In addition, the value of k might influence product composition during a consecutive dechlorination, such as for TCAA and DCAA. For a reaction-controlled compound such as MCAA, an increased k value was achieved under low oxic conditions, which was favorable to improve its k value. The proposed model has a potential in predicting the removal rate of halogenated compounds by metallic iron under various conditions.
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http://dx.doi.org/10.1016/j.chemosphere.2017.03.006DOI Listing
July 2017

Azo compound degradation kinetics and halonitromethane formation kinetics during chlorination.

Chemosphere 2017 May 23;174:110-116. Epub 2017 Jan 23.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Environmental Engineering Programs, Penn State University, Middletown, PA 17057, USA.

The chlorination of azo compounds can produce halonitromethanes (HNMs), which have attracted increasing concern due to their high genotoxicity. By impacting the speciation of chlorine and azo compounds, pH impacts apparent second-order rate constants of Methyl Orange (MO, 27.5-1.4 × 10 M s), Acid Orange II (AO, 16.7-99.3 M s), and Acid Red 1 (AR 1, 3.7-72.5 M s) (pH range 6.3-9.0). The two-compartment first-order model successfully described the chloropicrin (TCNM) formation kinetics, suggesting that both fast- and slow-reacting precursors of TCNM are generated from the chlorination of azo compounds. The ratios between fast and slow formation rate constants for MO and AO were 15.6-5.4 × 10, while that of AR 1 was 9.8-19.4 (pH range 6.5-9.0). The fraction of the fast-reacting TCNM precursors decreased with increasing pH for MO and AO; while that for AR 1 decreased when pH increased from 6.5 to 8.0, and then increased when pH increased from 8.0 to 9.0. The impact of pH on TCNM formation was also precursor-specific. The highest molar yields of TCNM predicted from the model in this study were 2.4%, 2.5%, and 1.5% for MO, AO, and AR 1, respectively. The study demonstrates that azo compounds are important HNM precursors, and pose a potential threat to drinking water safety.
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http://dx.doi.org/10.1016/j.chemosphere.2017.01.098DOI Listing
May 2017

Effect of bromide on the transformation and genotoxicity of octyl-dimethyl-p-aminobenzoic acid during chlorination.

J Hazard Mater 2017 Feb 15;324(Pt B):626-633. Epub 2016 Nov 15.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.

Octyl-dimethyl-p-aminobenzoic acid (ODPABA), one of the most commonly used organic UV filters, can undergo considerable transformation in water when entering into the disinfection process. The impacts of bromide on degradation kinetics, formation and speciation of transformation products, regulated disinfection by-products (DBPs) as well as genotoxicity changes during ODPABA chlorination were investigated in this study. Results indicated that the reaction of ODPABA with chlorine followed pseudo-first-order and second-order kinetics. Adding bromide noticeably enhanced the degradation rate of ODPABA, but reduced the impact of chlorine dose. Four halogenated transformation products (Cl-ODPABA, Br-ODPABA, Cl-Br-ODPABA and Br-ODPABA) were detected by LC-MS/MS. Mono-halogenated products were stable during 24-h chlorination, while di-halogenated products constantly increased. The total yields of trihalomethanes (THMs) and haloacetic acids (HAAs) were both low, but predominated by bromine substitution at high levels of bromide. In addition, SOS/umu tests showed that genotoxicity was generated after ODPABA chlorination, which was increased at least 1.5 times in the presence of bromine. Whereas, no significant genotoxicity variation was observed following bromide concentration change.
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http://dx.doi.org/10.1016/j.jhazmat.2016.11.035DOI Listing
February 2017

Characterization of haloacetaldehyde and trihalomethane formation potentials during drinking water treatment.

Chemosphere 2016 Sep 17;159:378-384. Epub 2016 Jun 17.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.

Haloacetaldehydes (HAs) are the third prevalent group of disinfection by-products (DBPs) of great health concern. In this study, their formation and speciation during chlorination were investigated for raw and process waters collected at three O3-biological activated carbon (BAC) advanced drinking water treatment plants. The results showed that all HA formation potentials (HAFPs) were highly enhanced whenever ozone was applied before or after conventional treatment. Sand filtration and BAC filtration could substantially reduce HAFPs. Trihalomethanes (THMs) were also measured to better understand the role of HAs in DBPs. Very different from HAFPs, THMFPs kept decreasing with the progress of treatment steps, which was mainly attributed to the different precursors for HAs and THMs. Brominated HAs were detected in bromide-containing waters. Chloral hydrate (CH) contributed from 25% to 48% to the total HAs formed in waters containing 100-150 μg L(-1) bromide, indicating the wide existence of other HAs after chlorination besides CH production. In addition, bromide incorporation factor (BIF) in HAs and THMs increased with the progress of treatment steps and the BIF values of THMs were generally higher than those of HAs. The BAC filtration following ozonation could significantly reduce HA precursors produced from ozonation but without complete removal. The brominated HAFPs in the outflow of BAC were still higher than their levels in the raw water. As a result, O3-BAC combined treatment was effective at controlling the total HAs, whereas it should be cautious for waters with high bromide levels.
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http://dx.doi.org/10.1016/j.chemosphere.2016.05.088DOI Listing
September 2016

Effect of capacitive deionization on disinfection by-product precursors.

Sci Total Environ 2016 Oct 7;568:19-25. Epub 2016 Jun 7.

Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha, Hunan 410082, China; Department of Chemistry, Indiana University of Pennsylvania, Indiana, PA 15705, USA. Electronic address:

Formation of brominated disinfection by-products (DBPs) from bromide and natural organic matter upon chlorination imposes health risks to drinking water users. In this study, capacitive deionization (CDI) was evaluated as a potential process for DBP precursor removal. Synthetic humic acid and bromide containing saline water was used as model water prior to CDI treatment. Batch experiments were conducted at cell voltages of 0.6-, 0.9-, and 1.2V to study the influence of CDI on the ratio of bromide and dissolved organic carbon, bromine substitution factor, and DBP formation potential (FP). Results showed beneficial aspects of CDI on reducing the levels of these parameters. A maximum DBPFP removal from 1510 to 1160μg/L was observed at the cell voltage of 0.6V. For the removed DBPFP, electro-adsorption played a greater role than physical adsorption. However, it is also noted that there could be electrochemical oxidations that led to reduction of humic content and formation of new dichloroacetic acid precursors at high cell voltages. Because of the potential of CDI on reducing health risks from the formation of less brominated DBPs upon subsequent chlorination, it can be considered as a potential technology for DBP control in drinking water treatment.
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http://dx.doi.org/10.1016/j.scitotenv.2016.05.219DOI Listing
October 2016

Chlorination of oxybenzone: Kinetics, transformation, disinfection byproducts formation, and genotoxicity changes.

Chemosphere 2016 Jul 14;154:521-527. Epub 2016 Apr 14.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.

UV filters are a kind of emerging contaminant, and their transformation behavior in water treatment processes has aroused great concern. In particular, toxic products might be produced during reaction with disinfectants during the disinfection process. As one of the most widely used UV filters, oxybenzone has received significant attention, because its transformation and toxicity changes during chlorine oxidation are a concern. In our study, the reaction between oxybenzone and chlorine followed pseudo-first-order and second-order kinetics. Three transformation products were detected by LC-MS/MS, and the stability of products followed the order of tri-chloro-methoxyphenoyl > di-chlorinated oxybenzone > mono-chlorinated oxybenzone. Disinfection byproducts (DBPs) including chloroform, trichloroacetic acid, dichloroacetic acid and chloral hydrate were quickly formed, and increased at a slower rate until their concentrations remained constant. The maximum DBP/oxybenzone molar yields for the four compounds were 12.02%, 6.28%, 0.90% and 0.23%, respectively. SOS/umu genotoxicity test indicated that genotoxicity was highly elevated after chlorination, and genotoxicity showed a significantly positive correlation with the response of tri-chloro-methoxyphenoyl. Our results indicated that more genotoxic transformation products were produced in spite of the elimination of oxybenzone, posing potential threats to drinking water safety. This study shed light on the formation of DBPs and toxicity changes during the chlorination process of oxybenzone.
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http://dx.doi.org/10.1016/j.chemosphere.2016.03.116DOI Listing
July 2016

Pathway fraction of bromate formation during O₃ and O₃/H₂O₂ processes in drinking water treatment.

Chemosphere 2016 Feb 23;144:2436-42. Epub 2015 Nov 23.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.

Ozone process has been widely used for drinking water treatment recently. In the oxidation process, bromate is formed by three pathways, i.e., the direct pathway, the direct-indirect pathway and the indirect-direct pathway. This study developed a method to calculate the percentage of these three pathways for bromate formation during O3 process and O3/H2O2 process. Two kinds of water, distilled water containing bromide (DW) and surface water from the Yellow River (SW) were selected as raw rater. The result showed that in natural water systems, the direct-indirect pathway was dominant for bromate formation during the oxidation process. When 3 mg L(-1) O3 was used as the only oxidant, nearly 26% of bromide ion was transferred into bromate in two kinds of water after 80 min. The dominant pathway in DW was the direct pathway (48.5%) and the direct-indirect pathway (46.5%), while that was the direct-indirect pathway (68.9%) in SW. When O3/H2O2 were used as oxidants, as the H2O2 dosage increased, the fractions of bromate formation by direct pathway and direct-indirect pathway decreased, while that by indirect-direct pathway increased. The conversion ratio from bromide to bromate first kept stable or increased, then decreased and reached its minimum when [H2O2]/[O3] ratio was 1.0 in DW and 1.5 in SW. Under this condition the indirect-direct pathway took the largest fraction of 70.7% in DW and 64.0% in SW, respectively.
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http://dx.doi.org/10.1016/j.chemosphere.2015.11.022DOI Listing
February 2016

Effects of metal ions on disinfection byproduct formation during chlorination of natural organic matter and surrogates.

Chemosphere 2016 Feb 23;144:1074-82. Epub 2015 Oct 23.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Civil and Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.

The effects of calcium, cupric, ferrous and ferric ions on the formation of trihalomethanes (THMs) and haloacetic acids (HAAs) were investigated using natural organic matter (NOM), small molecular weight NOM surrogates and natural water samples. The results showed that the effects were greatly dependent on the disinfection byproduct (DBP) precursor structure and molecular weight, and metal ions species. While using NOM as precursors, addition of 4.00 mM calcium ions increased the formation of THMs, dihaloacetic acids (DHAAs) and trihaloacetic acids (THAAs) by 24-47%, 51-61% and 15-25%, respectively. Addition of cupric ions at 0.02 mM increased the formation of THMs and DHAAs by 74-83% and 90-100%, respectively, but decreased the formation of THAAs by 26-27%. Similar effect was not observed when 0.04 mM ferrous or ferric ions were added. The effects of calcium and cupric ions on DBP formation were generally more evident for the NOM surrogates than that for NOM. The primary catalytic effect of calcium ions was due to complexation and less sensitive to molecular structure or weight, while that of cupric ions was attributed to redox reactions and greatly dependent on molecular structure. Both ferric and ferrous iron had substantial effects on the DBP formation of surrogates (citric acid and catechol in particular), which implied that the catalytic effects of ferric and ferrous iron mainly depended on molecular weight. The catalytic effect of cupric ions was also observed on natural water samples, while the effects of calcium, ferrous and ferric ions on natural water samples were not evident.
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http://dx.doi.org/10.1016/j.chemosphere.2015.09.095DOI Listing
February 2016

Biologically active carbon filtration for haloacetic acid removal from swimming pool water.

Sci Total Environ 2016 Jan 19;541:58-64. Epub 2015 Sep 19.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.

A biologically activate carbon (BAC) filter was continuously operated on site for the treatment of haloacetic acids (HAAs) in an outdoor swimming pool at an average empty bed contact time (EBCT) of 5.8 min. Results showed that BAC filtration was a viable technology for direct removal of HAAs from the pool water with a nominal efficiency of 57.7% by the filter while the chlorine residuals were 1.71 ± 0.90 mg/L during the study. THMs and TOC were not removed and thus were not considered as indicators of the effectiveness of BAC filtration. Increased EBCT in the range of 4.5 and 6.4 min led to improved HAA removal performance, which could be best fit by a logarithmic regression model. BAC filtration also affected the HAA speciation by removing more dichloroacetic acid (DCAA) than trichloroacetic acid (TCAA), resulting in a lower ratio of DCAA/TCAA in the filtered effluent. However, the observation of an overall constant ratio could be attributable to a complex formation and degradation mechanism occurring in swimming pools.
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http://dx.doi.org/10.1016/j.scitotenv.2015.09.059DOI Listing
January 2016

Trihalomethane hydrolysis in drinking water at elevated temperatures.

Water Res 2015 Jul 8;78:18-27. Epub 2015 Apr 8.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.

Hydrolysis could contribute to the loss of trihalomethanes (THMs) in the drinking water at elevated temperatures. This study was aimed at investigating THM hydrolysis pertaining to the storage of hot boiled water in enclosed containers. The water pH value was in the range of 6.1-8.2 and the water temperature was varied from 65 to 95 °C. The effects of halide ions, natural organic matter, and drinking water matrix were investigated. Results showed that the hydrolysis rates declined in the order following CHBrCl2 > CHBr2Cl > CHBr3 > CHCl3. THM hydrolysis was primarily through the alkaline pathway, except for CHCl3 in water at relatively low pH value. The activation energies for the alkaline hydrolysis of CHCl3, CHBrCl2, CHBr2Cl and CHBr3 were 109, 113, 115 and 116 kJ/mol, respectively. No hydrolysis intermediates could accumulate in the water. The natural organic matter, and probably other constituents, in drinking water could substantially decrease THM hydrolysis rates by more than 50%. When a drinking water was at 90 °C or above, the first order rate constants for THM hydrolysis were in the magnitude of 10(-2)‒10(-1) 1/h. When the boiled real tap water was stored in an enclosed container, THMs continued increasing during the first few hours and then kept decreasing later on due to the competition between hydrolysis and further formation. The removal of THMs, especially brominated THMs, by hydrolysis would greatly reduce one's exposure to disinfection by-products by consuming the boiled water stored in enclosed containers.
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http://dx.doi.org/10.1016/j.watres.2015.03.027DOI Listing
July 2015

Effect of dissolved oxygen concentration on iron efficiency: Removal of three chloroacetic acids.

Water Res 2015 Apr 29;73:342-52. Epub 2015 Jan 29.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China; Environmental Programs, The Pennsylvania State University, 777 West Harrisburg Pike, Middletown, PA 17057, USA.

The monochloroacetic, dichloroacetic and trichloroacetic acid (MCAA, DCAA and TCAA) removed by metallic iron under controlled dissolved oxygen conditions (0, 0.75, 1.52, 2.59, 3.47 or 7.09 mg/L DO) was investigated in well-mixed batch systems. The removal of CAAs increased first and then decreased with increasing DO concentration. Compared with anoxic condition, the reduction of MCAA and DCAA was substantially enhanced in the presence of O2, while TCAA reduction was significantly inhibited above 2.59 mg/L. The 1.52 mg/L DO was optimum for the formation of final product, acetic acid. Chlorine mass balances were 69-102%, and carbon mass balances were 92-105%. With sufficient mass transfer from bulk to the particle surface, the degradation of CAAs was limited by their reduction or migration rate within iron particles, which were dependent on the change of reducing agents and corrosion coatings. Under anoxic conditions, the reduction of CAAs was mainly inhibited by the available reducing agents in the conductive layer. Under low oxic conditions, the increasing reducing agents and thin lepidocrocite layer were favorable for CAA dechlorination. Under high oxic conditions, the redundant oxygen competing for reducing agents and significant lepidocrocite growth became the major restricting factors. Various CAA removal mechanisms could be potentially applied to explaining the effect of DO concentration on iron efficiency for contaminant reduction in water and wastewater treatment.
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http://dx.doi.org/10.1016/j.watres.2015.01.027DOI Listing
April 2015

Effects of ozonation on disinfection byproduct formation and speciation during subsequent chlorination.

Chemosphere 2014 Dec 29;117:515-20. Epub 2014 Sep 29.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Environmental Engineering Programs, The Pennsylvania State University, Middletown, PA 17057, USA.

Ozone has been widely used for drinking water treatment recently. This study was conducted to investigate the effect of dosing ozone on the formation potentials and speciation of disinfection by-products (DBPs, brominated DBPs in particular) during subsequent chlorination. Trihalomethanes (THMs), trihaloacetic acids (THAAs), dihaloacetic acids (DHAAs), dihaloacetonitriles (DHANs), chloral hydrate (CH)and trichloronitromethane (TCNM) were included. The results showed that the yields of THMs, THAAs and DHAAs reached the maxima at 1.83, 0.65 and 0.56 μM, respectively, corresponding to an ozone dose approximately at 2 mg L(-1). The formation potentials of CH and TCNM increased, while that of DHAN decreased, with the increase of ozone dose up to 6 mg L(-1). The bromide incorporation factor values of THMs, THAAs, DHAAs and DHANs increased from 0.62, 0.37, 0.45 and 0.39 at O3=0 mg L(-1) to 0.89, 0.65, 0.62 and 0.89 at O3=6 mg L(-1), respectively. It indicated that the use of ozone as a primary disinfectant may cause a shift to more brominated DBPs during subsequent chlorination, and the shift may be more evident with increased ozone dose. The total percentage of brominated DBPs (as bromide) reached the maximum value of 55% at 2 mg L(-1) ozone dose.
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http://dx.doi.org/10.1016/j.chemosphere.2014.08.083DOI Listing
December 2014

Haloacetic acid removal by sequential zero-valent iron reduction and biologically active carbon degradation.

Chemosphere 2013 Jan 15;90(4):1563-7. Epub 2012 Oct 15.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China.

An innovative haloacetic acid (HAA) removal process was developed. The process consisted of a zero-valent iron (Fe(0)) column followed by a biologically active carbon (BAC) column that were efficient in degrading tri- and di-HAAs, and mono- and di-HAAs, respectively. The merit of the process was demonstrated by its performance in removing trichloroacetic acid (TCAA). An empty bed contact time of 10 min achieved nearly complete removal of 1.2 μM TCAA and its subsequent products, dichloroacetic acid (DCAA) and monochloroacetic acid (MCAA). HAA removal was a result of chemical dehalogenation and biodegradation rather than physical adsorption. Preliminary kinetic analyses were conducted and the pseudo-first-order rate constants were estimated at ambient conditions for Fe(0) reduction of TCAA and biodegradation of DCAA and MCAA by BAC. This innovative process is highly promising in removing HAAs from drinking water, swimming pool water, and domestic or industrial wastewater.
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http://dx.doi.org/10.1016/j.chemosphere.2012.09.046DOI Listing
January 2013

Formation of disinfection by-products: effect of temperature and kinetic modeling.

Chemosphere 2013 Jan 29;90(2):634-9. Epub 2012 Sep 29.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.

The temperature of drinking water fluctuates naturally in water distribution systems as well as often deliberately heated for household or public uses. In this study, the temperature effect on the formation of disinfection by-products (DBPs) was investigated by monitoring the temporal variations of twenty-one DBPs during the chlorination of a humic precursors-containing water at different temperatures. It was found that chloroform, DCAA, TCAA, DCAN and CH were detected at the considerable level of tens of μg L(-1). The three regulated DBPs (chloroform, DCAA and TCAA) were found increasing with both contact time and water temperature, while the five typical emerging DBPs (DCAN, CH, TCNM 1,1-DCPN and 1,1,1-TCPN) revealed the significant auto-decomposition in addition to the initial growth in the first few hours. Increasing water temperature could enhance the formation rates of all the eight detected DBPs and the decomposition rates of the five emerging DBPs. Further, a kinetic model was developed for the simulation of DBP formation. The validity and universality of the model were verified by its excellent correlation with the detected values of each DBP species at various temperatures. The formation rates of 1,1-DCPN and 1,1,1-TCPN, and the decomposition rate of 1,1,1-TCPN were faster as compared to the other DBPs. And the formation reaction activation energies of CH, DCAN and 1,1-DCPN were relatively large, indicating that their occurrence levels in the finished water were more susceptible to temperature variations.
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http://dx.doi.org/10.1016/j.chemosphere.2012.08.060DOI Listing
January 2013