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Final Report: Evaluation of the Efficacy of a New Secondary Disinfectant Formulation Using Hydrogen Peroxide and Silver and the Formulation of Disinfection By-Products Resulting From Interactions with Conventional Disinfectants
EPA Grant Number: R825362Title: Evaluation of the Efficacy of a New Secondary Disinfectant Formulation Using Hydrogen Peroxide and Silver and the Formulation of Disinfection By-Products Resulting From Interactions with Conventional Disinfectants
Investigators: Batterman, Stuart A. , Fattal, Badri , Lev, Ovadia , Mancy, Khalil H. , Shuval, Hillel , Wang, Shuqin , Warila, James , Zhang, Lianzhong
Institution: University of Michigan , Hebrew University
EPA Project Officer: Rosenthal, Sheila
Project Period: June 15, 1997 through June 14, 2000 (Extended to June 14, 2001)
Project Amount: $594,346
RFA: Drinking Water (1997)
Research Category: Drinking Water
Description:
Objective:This research addressed two critical issues associated with the use of a new secondary disinfectant formulation utilizing hydrogen peroxide (H2O2) and silver (Ag+): (1) the efficacy of the formulation to provide long-term residual disinfection, including the control of coliform bacteria, bacterial regrowth, and slime/biofilm control; and (2) the identification and quantification of disinfection by-products (DBPs) that may result from interactions with conventional chlorine- and oxidant-based disinfectants. The research encompassed a sequence of laboratory and modeling studies aimed at evaluating the effectiveness of the alternative disinfectant in a range of source waters and utility system characteristics. The secondary disinfectant is one of the few nonchlorine-based disinfectants that can provide long-term residual disinfection in drinking water systems. By combining two or more disinfection agents, it may be possible to lower concentrations of each component, reduce exposures, minimize the formation of toxic and undesirable DBPs, and thus minimize health risks associated with disinfection.
The approach consisted of: (1) a laboratory evaluation of microbial disinfection efficacy, including optimal formulation of the secondary disinfectant and optimal doses of primary and secondary disinfectants; (2) a laboratory evaluation of DBP formation resulting from interactions with various primary disinfectants; (3) an evaluation and possible field-scale demonstration of the combined disinfectant; and (4) related studies designed to evaluate potential risks and other aspects associated with the proposed disinfectant and any formed DBPs. These components were designed to provide a comprehensive evaluation of the microbial disinfection efficiency and DBP formation potential of the new disinfectant.
The overall research goal was to develop information regarding disinfection efficacy and DBPs of the alternative disinfectant for different source waters as well as environmental and utility conditions. Effects on DBPs of the primary disinfectants and any new by-product formation were quantified, as were optimum dosages and pathogen inactivation of the new formulation. The research results are suitable for use in exposure and risk assessments and to support future policies and decisions regarding disinfection approaches.
Summary/Accomplishments (Outputs/Outcomes):Disinfection Efficacy. Investigations emphasized the inactivation performance of a combined disinfectant comprised of hydrogen peroxide and silver or copper ions for target indicator microorganisms in both synthetic high quality water and for high TOC water (TOC = 6 mg/L). Die-off kinetics were evaluated upon exposure to hydrogen peroxide, silver or copper ions alone, and in combinations. Target or model organisms included bacteria (Escherichia coli-B and Escherichia coli-K12), bacteriophage (MS2), and a pathogenic virus (Polio 1). Special efforts were devoted to assess the impact of the combined disinfectant and its components on biofilm formation under prolonged continuous operation. The following key results were obtained:
- Bacterial Inactivation. The combination of hydrogen peroxide and
silver ions, rather than each one separately, was the most effective in
inactivating E. coli-B and E. coli-K12; silver ions alone were more effective
than hydrogen peroxide alone. In general, the bacterial inactivation performance
of the combined disinfectant was slow compared to chlorine-based disinfectants
(e.g., 3-log reductions (99.9 percent) of E. coli-B at pH 7 and 24 C using
30-ppm hydrogen peroxide and 30-ppb silver ions (an optimized formulation)
required an exposure of 88 min). Water quality significantly affected the
inactivation of E. coli. The first-order Chick Watson coefficient of
inactivation of E. coli-B with water containing 6 mg/L TOC was reduced by
three-fold compared to synthetic water (e.g., 0.078 vs. 0.024 L/min for exposure
to 30 mg/L hydrogen peroxide and 30 ppb silver ions at pH 7 at ambient
temperature). Inactivation performance of the combined disinfectant increased at
basic pH (e.g., log activation increased by two-fold by increasing the pH from 6
to 9 using the optimized formulation). Finally, inactivation performance
increased with temperature (e.g., two-fold increase in log inactivation of E.
coli resulted by increasing the temperature from 4 to 24 C for a 1-hour exposure
to the optimized formulation).
The inactivation performance of hydrogen peroxide and copper ions showed much more significant synergistic effect for all combinations that were examined in comparison to the combined disinfectant using hydrogen peroxide and silver. For example, inactivation of E. coli-B at pH 7 after 1 hour of exposure at room temperature to 125 ppb copper ions showed less than 1-log reduction. However, 4.3 logs reduction were obtained during the same time interval in combination with 30 ppm hydrogen peroxide.
- Viral Inactivation. The combined disinfectant showed rather low viral inactivation kinetics. Approximately 6 hours were necessary to achieve 4 logs inactivation of MS2 bacteriophage at 24 C and pH 7 using a rather high concentration of the combined disinfectant, 100 ppm hydrogen peroxide and 100 ppb silver ion. The inactivation of the MS2 virus was achieved exclusively by the hydrogen peroxide ingredient. The virus was either unaffected or even protected by the presence of the silver ions. The inactivation of Polio 1 was even lower, 0.15 log reduction was obtained by 12 hours exposure to the combined disinfectant, again using 100 ppm hydrogen peroxide and 100 ppb silver ion.
- Biofilm Control. Biofilm control was evaluated for the combined disinfectant (comprised of hydrogen peroxide and silver ion) and each of its components. Biofilm growth was investigated on uncoated and CaCO3 coated galvanized iron samples over prolonged exposure duration. The CaCO3 film did not significantly affect biofilm development. The combined disinfectant using 30 ppm hydrogen peroxide and 30 ppb silver ion was as effective in preventing film growth as hydrogen peroxide alone (30 ppm). Both compositions showed significant biofilm prevention as compared to silver ions alone. However, biofilm control using approximately 1 ppm of chlorine was considerably higher than that for the combined disinfectant. The bacteria that survived after 48 hours disinfection with hydrogen peroxide and the combined disinfectant showed high catalase activity, hinting that hydrogen peroxide and the combined disinfectant may have a rather limited effectiveness in continuous operation. Results of these laboratory studies indicated that full-scale field demonstrations, originally envisioned and investigated during the course of this research, would not be warranted in the field conditions.
Disinfection By-Products. The addition of the secondary disinfectant following the use of chlorine or ozone as a primary disinfectant produces very dramatic reductions in DBP formation. With chlorine, the secondary disinfectant quenches the formation of trihalomethanes (THMs) and haloacetic acids (HAAs), two sets of DBPs that have been priorities for control and regulation. This quenching occurs due to the reduction of chlorine to chloride by hydrogen peroxide, which halts further reaction of chlorine with dissolved organic matter and other DBP precursors. The reduction in DBPs resulting from the primary and secondary disinfectants applies to a wide range of temperatures, pH, bromide concentrations, and DOC levels. When used with ozone, hydrogen peroxide also quenches formation of THMs and reduces, though not as strongly, formation of inorganic by-products (e.g., bromate). Applying the hydrogen peroxide/silver ion formulation 1 to 4 min after ozonation started, for example, nearly stopped the formation of bromoform (CHBr3) and reduced bromate (BrO3-) formation by 13 to 82 percent, depending on the water characteristics and the ozonation parameters. Changing the hydrogen peroxide/silver addition time altered the ozone exposure (C x T value) and affected the magnitude of reduction of the ozonation by-products. Preliminary results suggest that an ammonia addition at the beginning of ozonation followed by an hydrogen peroxide/silver ion addition shortly afterwards could increase ozone exposure and further reduce by-product formation.
The addition of hydrogen peroxide appears to form several aldehydes and ketones at low levels that resemble those formed by the ozonation of water. A total of 13 aldehydes (formaldehyde, acetaldehyde, propanal, butanal, pentanal, hexanal, heptanal, octanal, nonanal, decanal, glyoxal, methyl glyoxal, and 5-keto-1-hexanal) and 6 ketones (acetone, butanone, hexanone-2, hexanone-3, dimethyl glyoxal, and 3-methylcyclopentanone) were identified as H2O2 disinfection by-products in synthetic water. The same group of compounds (except for dimethyl glyoxal) was identified in natural water. Aldehyde formation is a strong function of hydrogen peroxide concentration, and no formation is observed with hydrogen peroxide concentrations below 4 mg/L. Formaldehyde and acetaldehyde concentrations peaked to nearly 30 and 15 g/L, respectively, after 6 to 7 days, while levels of other aldehydes continued to increase, suggesting complex dynamics.
Risks and Related Studies. Widespread use of the combined disinfectant, if practical, might result in potential for uptake of silver ions by fish and humans and potential health risks. An ecological model was constructed to simulate partitioning between water and sediment, uptake by algae, invertebrates and fish (trout and carp), and risks to humans from fish consumption. Monte-Carlo simulations were used to represent the uncertainty and variability of input parameters. The modeling effort used a variety of scenarios, including "worst case" conditions in which receiving waters provided small amounts of dilution and subsistence fishers consumed large amounts of high trophic level feeders. Results suggest that risks are minimal under all likely scenarios. Other risk-related studies describe partitioning of formed trihalomethanes among various biological compartments, and describe the loss of trihalomethanes during the preparation of beverages. These results can be used to improve exposure assessments of DBPs.
Potential Practical Applications. The experimental research showed that the combined disinfectant offers synergistic effects on the inactivation of E. coli that generally increased with higher temperature and pH and decreased in secondary and tertiary effluents; however, no increased virucidal action was observed and biofilm control efficacy over long periods was limited. Used as a secondary disinfectant following either chlorination or ozonation, the hydrogen peroxide provided a strong quenching effect on the major by-products. Although limited production of additional disinfection by-products was observed on some waters, these studies suggest that the combined disinfectant may be appropriate for use as long-term secondary residual disinfectant for relatively high quality water in some circumstances. This research also suggests that a multiple component disinfectant combination applied sequentially (e.g., ozone, ammonia, and hydrogen peroxide) might provide effective inactivation and reduced by-product formation.
Journal Articles on this Report: 8 Displayed | Download in RIS Format
| Other project views: | All 19 publications | 9 publications in selected types | All 9 journal articles |
| Type | Citation | ||
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Armon R, Laot N, Lev O, Shuval H, Fattal B. Controlling biofilm formation by hydrogen peroxide and silver combined disinfectant. Water Science and Technology 2000;42(1-2):187-192. |
R825362 (1999) R825362 (Final) |
not available |
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Batterman S, Zhang LZ, Wang SQ. Quenching of chlorination disinfection by-product formation in drinking water by hydrogen peroxide. Water Research 2000;34(5):1652-1658. |
R825362 (1999) R825362 (Final) |
not available |
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Batterman S, Huang AT, Wang S, Zhang L. Reduction of ingestion exposure to trihalomethanes due to volatilization. Environmental Science and Technology 2000;34:4418-4424. |
R825362 (1999) R825362 (Final) |
not available |
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Batterman S, Zhang L, Wang S, Franzblau A. Partition coefficients for the trihalomethanes among blood, urine, water, milk and air. Science of the Total Environment 2002;284(1-3):237-247. |
R825362 (Final) |
not available |
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Glezer V, Harris B, Tal N, Iosefzon B, Lev O. Hydrolysis of haloacetonitriles: linear free energy relationship, kinetics and products. Water Research 1999;33(8):1938-48. |
R825362 (1999) R825362 (Final) |
not available |
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Liberti L, Lopez A, Notamicola M, Bamea N, Pedahzur R, Fattal B. Comparison of advanced disinfecting methods for municipal wastewater reuse in agriculture. Water Science and Technology 2000;42(1-2):215-220. |
R825362 (1999) R825362 (Final) |
not available |
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Pedahzur R, Katzenelson D, Barnea N, Lev O, Shuval HI, Fattal B, Ulitzur S. The efficacy of long-lasting residual drinking water disinfectants based on hydrogen peroxide and silver. Water Science and Technology 2000;42(1-2):293-298. |
R825362 (1999) R825362 (Final) |
not available |
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Warila J, Batterman S, Passino-Reader DR. A probabilistic model for silver bioaccumulation in aquatic systems and assessment of human health risks. Environmental Toxicology and Chemistry 2001;20(2):432-441. |
R825362 (1999) R825362 (Final) |
not available |
drinking water, watersheds, exposure, risk, ecological effects, viruses, bacteria, pathogens, environmental chemistry, engineering, risks, ecological effects, DBPs, viruses, bacteria, treatment, environmental chemistry, aquatic. , Water, Scientific Discipline, RFA, Drinking Water, Chemical Engineering, Analytical Chemistry, Environmental Engineering, Environmental Chemistry, drinking water system, drinking water contaminants, treatment, water quality, exposure and effects, microbiological organisms, bacterial mutagen, secondary disinfection formulation, DBP risk management, alternative disinfection methods, chlorine-based disinfection, monitoring, chemical byproducts, disinfection byproducts (DPBs), emerging pathogens, pathogens, public water systems, microbial risk management, exposure, microbial contamination, water treatment, hydrogen peroxide, community water system, Silver
Relevant Websites:
http://www.sph.umich.edu/~stuartb/index.html 
Progress and Final Reports:
1999 Progress Report
Original Abstract