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Wu L, Liu S, Liu H. Dichloramine Hydrolysis in Membrane Desalination Permeate: Mechanistic Insights and Implications for Oxidative Capacity in Potable Reuse Applications. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:13157-13167. [PMID: 38996057 PMCID: PMC11270831 DOI: 10.1021/acs.est.4c04547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/25/2024] [Accepted: 06/25/2024] [Indexed: 07/14/2024]
Abstract
Dichloramine (NHCl2) naturally exists in reverse osmosis (RO) permeate due to its application as an antifouling chemical in membrane-based potable reuse treatment. This study investigated mechanisms of background NHCl2 hydrolysis associated with the generation of oxidative radical species in RO permeate, established a kinetic model to predict the oxidative capacity, and examined its removal efficiency on trace organic contaminants in potable reuse. Results showed that NHCl2 hydrolysis generated transient peroxynitrite (ONOO-) and subsequently dissociated into hydroxyl radical (HO•). The maximal HO• exposure was observed at an RO permeate pH of 8.4, higher than that from typical ultraviolet (UV)-based advanced oxidation processes. The HO• exposure during NHCl2 hydrolysis also peaked at a NH2Cl-to-NHCl2 molar ratio of 1:1. The oxidative capacity rapidly degraded 1,4-dioxane, carbamazepine, atenolol, and sulfamethoxazole in RO permeate. Furthermore, background elevated carbonate in fresh RO permeate can convert HO• to carbonate radical (CO3•-). Aeration of the RO permeate removed total carbonate, significantly increased HO• exposure, and enhanced the degradation kinetics of trace organic contaminants. The kinetic model of NHCl2 hydrolysis predicted well the degradation of contaminants in RO permeate. This study provides new mechanistic insights into NHCl2 hydrolysis that contributes to the oxidative degradation of trace organic contaminants in potable reuse systems.
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Affiliation(s)
- Liang Wu
- Environmental
Toxicology Program, University of California, Riverside, California 92521, United States
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Sitao Liu
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Haizhou Liu
- Environmental
Toxicology Program, University of California, Riverside, California 92521, United States
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
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Zheng S, Li J, Yan W, Zhao W, Ye C, Yu X. Biofilm formation and antioxidation were responsible for the increased resistance of N. eutropha to chloramination for drinking water treatment. WATER RESEARCH 2024; 254:121432. [PMID: 38461606 DOI: 10.1016/j.watres.2024.121432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 03/04/2024] [Accepted: 03/05/2024] [Indexed: 03/12/2024]
Abstract
Chloramination is an effective strategy for eliminating pathogens from drinking water and repressing their regrowth in water distribution systems. However, the inevitable release of NH4+ potentially promotes nitrification and associated ammonia-oxidizing bacteria (AOB) contamination. In this study, AOB (Nitrosomona eutropha) were isolated from environmental water and treated with two disinfection stages (chloramine disinfection and chloramine residues) to investigate the occurrence mechanisms of AOB in chloramination. The results showed that N. eutropha had considerable resistance to monochloramine compared to Escherichia coli, whose inactivation rate constant was 19.4-fold lower. The higher resistance was attributed to high levels of extracellular polymer substances (EPS) in AOB, which contribute to AOB surviving disinfection and entering the distribution system. In AOB response to the chloramine residues stage, the respiratory activity of N. eutropha remained at a high level after three days of continuous exposure to high chloramine residue concentrations (0.5-1.5 mg/L). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) suggested that the mechanism of N. eutropha tolerance involved a significantly high expression of the intracellular oxidative stress-regulating (sodB, txrA) and protein-related (NE1545, NE1546) genes. Additionally, this process enhanced EPS secretion and promoted biofilm formation. Adhesion predictions based on the XDLVO theory corroborated the trend of biofilm formation. Overall, the naturally higher resistance contributed to the survival of AOB in primary disinfection; the enhanced antioxidant response of surviving N. eutropha accompanied by biofilm formation was responsible for their increased resistance to the residual chloramines.
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Affiliation(s)
- Shikan Zheng
- College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen, 361102, China
| | - Jianguo Li
- College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen, 361102, China
| | - Wanli Yan
- College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen, 361102, China
| | - Wenya Zhao
- College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen, 361102, China
| | - Chengsong Ye
- College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen, 361102, China.
| | - Xin Yu
- College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China; Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen, 361102, China.
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3
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Pham H, Wahman DG, Fairey JL. Closing Dichloramine Decomposition Nitrogen and Oxygen Mass Balances: Relative Importance of End-Products from the Reactive Nitrogen Species Pathway. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:2048-2057. [PMID: 38238190 PMCID: PMC10832998 DOI: 10.1021/acs.est.3c08088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/18/2023] [Accepted: 12/28/2023] [Indexed: 01/31/2024]
Abstract
In drinking water chloramination, monochloramine autodecomposition occurs in the presence of excess free ammonia through dichloramine, the decay of which was implicated in N-nitrosodimethylamine (NDMA) formation by (i) dichloramine hydrolysis to nitroxyl which reacts with itself to nitrous oxide (N2O), (ii) nitroxyl reaction with dissolved oxygen (DO) to peroxynitrite or mono/dichloramine to nitrogen gas (N2), and (iii) peroxynitrite reaction with total dimethylamine (TOTDMA) to NDMA or decomposition to nitrite/nitrate. Here, the yields of nitrogen and oxygen-containing end-products were quantified at pH 9 from NHCl2 decomposition at 200, 400, or 800 μeq Cl2·L-1 with and without 10 μM-N TOTDMA under ambient DO (∼500 μM-O) and, to limit peroxynitrite formation, low DO (≤40 μM-O). Without TOTDMA, the sum of free ammonia, monochloramine, dichloramine, N2, N2O, nitrite, and nitrate indicated nitrogen recoveries ±95% confidence intervals were not significantly different under ambient (90 ± 6%) and low (93 ± 7%) DO. With TOTDMA, nitrogen recoveries were less under ambient (82 ± 5%) than low (97 ± 7%) DO. Oxygen recoveries under ambient DO were 88-97%, and the so-called unidentified product of dichloramine decomposition formed at about three-fold greater concentration under ambient compared to low DO, like NDMA, consistent with a DO limitation. Unidentified product formation stemmed from peroxynitrite decomposition products reacting with mono/dichloramine. For a 2:2:1 nitrogen/oxygen/chlorine atom ratio and its estimated molar absorptivity, unidentified product inclusion with uncertainty may close oxygen recoveries and increase nitrogen recoveries to 98% (ambient DO) and 100% (low DO).
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Affiliation(s)
- Huong
T. Pham
- Department
of Civil Engineering, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - David G. Wahman
- Drinking
Water Treatment and Distribution Branch, Water Infrastructure Division,
Center for Environmental Solutions & Emergency Response, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, United States
| | - Julian L. Fairey
- Department
of Civil Engineering, University of Arkansas, Fayetteville, Arkansas 72701, United States
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Woo Y, Cruz MC, Wuertz S. Selective Enrichment of Nitrososphaera viennensis-Like Ammonia-Oxidizing Archaea over Ammonia-Oxidizing Bacteria from Drinking Water Biofilms. Microbiol Spectr 2022; 10:e0184522. [PMID: 36445127 PMCID: PMC9769795 DOI: 10.1128/spectrum.01845-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 11/08/2022] [Indexed: 12/03/2022] Open
Abstract
Ammonia-oxidizing archaea (AOA) can oxidize ammonia to nitrite for energy gain. They have been detected in chloraminated drinking water distribution systems (DWDS) along with the more common ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB). To date, no members of the AOA have been isolated or enriched from drinking water environments. To begin the investigation of the role of AOA in chloraminated DWDS, we developed a selective approach using biofilm samples from a full-scale operational network as inoculum. A Nitrososphaera viennensis-like AOA taxon was enriched from a mixed community that also included Nitrosomonas-like AOB while gradually scaling up the culture volume. Dimethylthiourea (DMTU) and pyruvate at 100 μM were added to promote the growth of AOA while inhibiting AOB. This resulted in the eventual washout of AOB, while NOB were absent after 2 or 3 rounds of amendment with 24 μM sodium azide. The relative abundance of AOA in the enrichment increased from 0.2% to 39.5% after adding DMTU and pyruvate, and further to 51.6% after filtration through a 0.45-μm pore size membrane, within a period of approximately 6 months. IMPORTANCE Chloramination has been known to increase the risk of nitrification episodes in DWDS due to the presence of ammonia-oxidizing microorganisms. Among them, AOB are more frequently detected than AOA. All publicly available cultures of AOA have been isolated from soil, marine or surface water environments, meaning they are allochthonous to DWDS. Hence, monochloramine exposure studies involving these strains may not accurately reflect their role in DWDS. The described method allows for the rapid enrichment of autochthonous AOA from drinking water nitrifying communities. The high relative abundance of AOA in the resulting enrichment culture reduces any confounding effects of co-existing heterotrophic bacteria when investigating the response of AOA to varied levels of monochloramine in drinking water.
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Affiliation(s)
- Yissue Woo
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- Singapore Centre for Environmental Life Sciences Engineering, Interdisciplinary Graduate Programme, Nanyang Technological University, Singapore, Singapore
- School of Civil and Environmental Engineering, Nanyang Technological University, Singapore, Singapore
| | - Mercedes Cecilia Cruz
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Stefan Wuertz
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- School of Civil and Environmental Engineering, Nanyang Technological University, Singapore, Singapore
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Wu L, Patton SD, Liu H. Mechanisms of oxidative removal of 1,4-dioxane via free chlorine rapidly mixing into monochloramine: Implications on water treatment and reuse. JOURNAL OF HAZARDOUS MATERIALS 2022; 440:129760. [PMID: 35969953 DOI: 10.1016/j.jhazmat.2022.129760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 08/04/2022] [Accepted: 08/09/2022] [Indexed: 06/15/2023]
Abstract
Free chlorine (HOCl) and monochloramine (NH2Cl) are two of the most commonly used water disinfectants in water treatment; however, the capability of rapid mixing of HOCl into NH2Cl to induce oxidative reactions for efficient removal of contaminants remains largely unknown. In this study, 1,4-dioxane (1,4-D) removal was quantified during the rapid mixing of HOCl into NH2Cl, to evaluate the effects of solution pH and HOCl-to-NH2Cl ratio, and to identify mechanisms by which reactive species are generated in the system. Results showed that the highest 1,4-D removal was observed at the near-neutral pH of 6 with the HOCl-to-NH2Cl molar ratio of 1. Hydroxyl radical (HO•) contributed to 60-70 % of 1,4-D degradation and its generation was initiated by the hydrolytic decay of NH2Cl and NHCl2 upon HOCl addition to NH2Cl with rapid mixing, and subsequent transformation of peroxynitrite (ONOO-) and peroxynitrous acid (ONOOH). The results also confirmed that the presence of dissolved oxygen was required to form ONOO-/ONOOH, and ONOO- was a crucial precursor for reactive radical generation. These findings provide insight into the reaction mechanism associated with the system of rapidly mixed HOCl into NH2Cl with the potential optimization and application for efficient trace organics removal in water treatment and reuse.
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Affiliation(s)
- Liang Wu
- Environmental Toxicology Program, University of California, Riverside, CA 92521, USA; Department of Chemical and Environmental Engineering, University of California, Riverside, CA 92521, USA
| | - Samuel D Patton
- Environmental Toxicology Program, University of California, Riverside, CA 92521, USA; Department of Chemical and Environmental Engineering, University of California, Riverside, CA 92521, USA
| | - Haizhou Liu
- Environmental Toxicology Program, University of California, Riverside, CA 92521, USA; Department of Chemical and Environmental Engineering, University of California, Riverside, CA 92521, USA.
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Pham HT, Wahman DG, Fairey JL. Updated Reaction Pathway for Dichloramine Decomposition: Formation of Reactive Nitrogen Species and N-Nitrosodimethylamine. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:1740-1749. [PMID: 33448793 PMCID: PMC7951990 DOI: 10.1021/acs.est.0c06456] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The N-nitrosodimethylamine (NDMA) formation pathway in chloraminated drinking water remains unresolved. In pH 7-10 waters amended with 10 μM total dimethylamine and 800 μeq Cl2·L-1 dichloramine (NHCl2), NDMA, nitrous oxide (N2O), dissolved oxygen (DO), NHCl2, and monochloramine (NH2Cl) were kinetically quantified. NHCl2, N2O, and DO profiles indicated that reactive nitrogen species (RNS) formed during NHCl2 decomposition, including nitroxyl/nitroxyl anion (HNO/NO-) and peroxynitrous acid/peroxynitrite anion (ONOOH/ONOO-). Experiments with uric acid (a ONOOH/ONOO- scavenger) implicated ONOOH/ONOO- as a central node for NDMA formation, which were further supported by the concomitant N-nitrodimethylamine formation. A kinetic model accurately simulated NHCl2, NH2Cl, NDMA, and DO concentrations and included (1) the unified model of chloramine chemistry revised with HNO as a direct product of NHCl2 hydrolysis; (2) HNO/NO- then reacting with (i) HNO to form N2O, (ii) DO to form ONOOH/ONOO-, or (iii) NHCl2 or NH2Cl to form nitrogen gas; and (3) NDMA formation via ONOOH/ONOO- or their decomposition products reacting with (i) dimethylamine (DMA) and/or (ii) chlorinated unsymmetrical dimethylhydrazine (UDMH-Cl), the product of NHCl2 and DMA. Overall, updated NHCl2 decomposition pathways are proposed, yielding (1) RNS via NHCl2→HNO/NO-→O2ONOOH/ONOO- and (2) NDMA via ONOOH/ONOO-→UDMH-ClorDMANDMA.
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Affiliation(s)
- Huong T Pham
- Department of Civil Engineering, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - David G Wahman
- U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, United States
| | - Julian L Fairey
- Department of Civil Engineering, University of Arkansas, Fayetteville, Arkansas 72701, United States
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Maestre JP, Wahman DG, Speitel GE. Monochloramine Cometabolism by Mixed-Culture Nitrifiers under Drinking Water Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:6240-6248. [PMID: 27196729 DOI: 10.1021/acs.est.5b05641] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Chloramines are the second most used secondary disinfectant by United States water utilities. However, chloramination may promote nitrifying bacteria. Recently, monochloramine cometabolism by the pure culture ammonia-oxidizing bacteria, Nitrosomonas europaea, was shown to increase monochloramine demand. The current research investigated monochloramine cometabolism by nitrifying mixed cultures grown under more relevant drinking water conditions and harvested from sand-packed reactors before conducting suspended growth batch kinetic experiments. Four types of batch kinetic experiments were conducted: (1) positive controls to estimate ammonia kinetic parameters, (2) negative controls to account for biomass reactivity, (3) utilization associated product (UAP) controls to account for UAP reactivity, and (4) cometabolism experiments to estimate cometabolism kinetic parameters. Kinetic parameters were estimated in AQUASIM with a simultaneous fit to the experimental data. Cometabolism kinetics were best described by a first-order model. Monochloramine cometabolism kinetics were similar to those of ammonia metabolism, and monochloramine cometabolism accounted for 30% of the observed monochloramine loss. These results demonstrated that monochloramine cometabolism occurred in mixed cultures similar to those found in drinking water distribution systems; therefore, monochloramine cometabolism may be a significant contribution to monochloramine loss during nitrification episodes in drinking water distribution systems.
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Affiliation(s)
- Juan P Maestre
- University of Texas at Austin , Department of Civil, Architectural and Environmental Engineering, 301 East Dean Keeton Street, Stop C2100, Austin, Texas 78712, United States
| | - David G Wahman
- United States Environmental Protection Agency , Office of Research and Development, Cincinnati, Ohio 45268, United States
| | - Gerald E Speitel
- University of Texas at Austin , Department of Civil, Architectural and Environmental Engineering, 301 East Dean Keeton Street, Stop C2100, Austin, Texas 78712, United States
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Wahman DG, Speitel GE. Hydroxylamine addition impact to Nitrosomonas europaea activity in the presence of monochloramine. WATER RESEARCH 2015; 68:719-730. [PMID: 25462776 DOI: 10.1016/j.watres.2014.10.054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 09/24/2014] [Accepted: 10/24/2014] [Indexed: 06/04/2023]
Abstract
In drinking water, monochloramine may promote ammonia–oxidizing bacteria (AOB) growth because of concurrent ammonia presence. AOB use (i) ammonia monooxygenase for biological ammonia oxidation to hydroxylamine and (ii) hydroxylamine oxidoreductase for biological hydroxylamine oxidation to nitrite. In addition, monochloramine and hydroxylamine abiotically react, providing AOB a potential benefit by removing the disinfectant (monochloramine) and releasing growth substrate (ammonia). Alternatively and because biological hydroxylamine oxidation supplies the electrons (reductant) required for biological ammonia oxidation, the monochloramine/hydroxylamine abiotic reaction represents a possible inactivation mechanism by consuming hydroxylamine and inhibiting reductant generation. To investigate the abiotic monochloramine and hydroxylamine reaction's impact on AOB activity, the current study used batch experiments with Nitrosomonas europaea (AOB pure culture), ammonia, monochloramine, and hydroxylamine addition. To decipher whether hydroxylamine addition benefitted N. europaea activity by (i) removing monochloramine and releasing free ammonia or (ii) providing an additional effect (possibly the aforementioned reductant source), a previously developed cometabolism model was coupled with an abiotic monochloramine and hydroxylamine model for data interpretation. N. europaea maintained ammonia oxidizing activity when hydroxylamine was added before complete ammonia oxidation cessation. The impact could not be accounted for by monochloramine removal and free ammonia release alone and was concentration dependent for both monochloramine and hydroxylamine. In addition, a preferential negative impact occurred for ammonia versus hydroxylamine oxidation. These results suggest an additional benefit of exogenous hydroxylamine addition beyond monochloramine removal and free ammonia release, possibly providing reductant generation.
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Affiliation(s)
- David G Wahman
- United States Environmental Protection Agency, Office of Research and Development, Cincinnati, OH 45268, USA.
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