Grantee Research Project Results
2000 Progress Report: Pilot Studies of the Ozonation/FBT Process for the Control of Disinfection Byproducts in Drinking Water
EPA Grant Number: R826829Title: Pilot Studies of the Ozonation/FBT Process for the Control of Disinfection Byproducts in Drinking Water
Investigators: Masten, Susan J.
Institution: Michigan State University
EPA Project Officer: Hahn, Intaek
Project Period: July 15, 1998 through May 14, 2001 (Extended to August 15, 2001)
Project Period Covered by this Report: July 15, 1999 through May 14, 2000
Project Amount: $424,734
RFA: Drinking Water (1998) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
Objective:
This project involves investigating a combined ozonation/biological fluidized bed treatment (FBT) for the removal of trihalomethanes (THM) and other disinfection byproduct (DBP) precursors from drinking water. The ultimate goal of the project is to develop an economical and simple processing system for the control of DBPs in drinking water. This project also aims at developing design criteria for the proposed ozonation/FBT system.The goals of this project are being accomplished through bench-scale and pilot-scale studies. The studies are being conducted using three very distinct source waters: (1) Lake Erie water collected at the Monroe Water Filtration Plant (Monroe, MI); (2) Huron River water collected at the Ann Arbor Water Treatment Plant (Ann Arbor, MI); and (3) Lake Lansing water (East Lansing, MI). Lake Erie water has a low total organic carbon (TOC) concentration of approximately 2 mg/L. Huron River water has a TOC concentration of 6-8 mg/L and is typical of rivers across the United States. Although Lake Lansing water does not provide source water to any treatment plant, it has been selected because of high TOC concentration (9-11 mg/L).
Progress Summary:
Several experimental systems have been developed to accomplish the goals of this project. These include a bench-scale ozonation system, bench-scale biodegradation system, and a pilot-scale ozonation/FBT system.The bench-scale ozonation system has been developed to investigate the kinetics of ozonation of naturally occurring organic matter (NOM) in selected source waters and, particularly, the effect of ozonation pathways on the formation of both DBPs and biodegradable organic matter. The biodegradation kinetics of raw and ozonated waters was being studied using bench-scale biofiltration and FBT systems. The pilot-scale ozonation/FBT system was developed to evaluate the performance of the combined ozonation and FBT process for the control of DBP precursors in drinking water.
The effect of ozonation reaction pathways on the formation of both DBPs and biodegradable organic carbon was investigated. The study showed that the production of OH radicals relative to ozone dose adjusted for alkalinity was the greatest in water with the lowest TOC concentration (Lake Erie water) and the lowest in water having highest TOC concentration (Lake Lansing water). This suggests that organic matter in selected source waters acted more as a scavenger, rather than a promoter of radical reactions. The study also demonstrated that direct ozone reactions favor the production of biodegradable organic carbon, whereas radical reactions result in the removal of organic carbon. These findings were important in developing optimization strategies for the combined ozonation/FBT system.
In biodegradation studies, we identified several parameters that described the kinetics of the removal of organic matter during biodegradation. This included: (1) EBCTmin, which represented the minimum empty bed contact time (EBCT) required to remove rapidly biodegradable organic carbon ("fast" BDOC); (2) BDOCslow, which represented the amount of BDOC that at least remained after biodegradation at EBCTmin; and (3) Rmax, which was defined as the maximum rate of the biodegradation of "fast" BDOC.
The results of these experiments demonstrated that the source waters selected for this study were very distinctive, not only in terms of the total organic carbon matter content but also in terms of the amount of potentially biodegradable organic carbon. Essentially, all organic matter in Lake Erie water was refractory organics, i.e. not subject to biodegradation. Huron River water contained approximately 20 percent of potentially biodegradable organic matter, whereas nearly half of the organic matter in Lake Lansing could be biodegraded.
The study showed that ozonation of Lake Erie water at doses up to 3 mg/mg C did not result in the production of biodegradable organic carbon. Ozonation of Huron River water resulted in an increase of BDOC concentration from 1.2 mg/L in raw water to 2.8 mg/L in water ozonated at a dose of 1 mg/mg C. However, the concentration of BDOCslow also was increased after ozonation.
The results of biodegradation experiments with ozonated Lake Lansing water were surprisingly different from those with ozonated Huron River water. Unlike Huron River water for which no significant changes in biodegradation kinetics were observed at doses greater than 0.5 mg/mg C, the biodegradation parameters for ozonated Lake Lansing water were affected by ozone doses to a much greater extent. Ozonation of Lake Lansing water at a dose of 0.75 mg/mg C resulted in an increase in BDOC concentration from 5.04 to 6.06 mg/L. Ozonation at ozone doses of 1.5 and 3 mg/mg C resulted in the formation of additional 0.8 and 1.33 mg/L BDOC, respectively. An increase in ozone dose resulted in an increase in Rmax and a decrease in EBCTmin.
The most striking difference between Huron River water and Lake Lansing water was observed with respect to "slow" BDOC. The concentration of BDOCslow in Lake Lansing water decreased with an increase in ozone dose, compared to Huron River water in which BDOCslow increased at a dose of 0.5 mg/mg C and leveled off at higher ozone dosages.
The significance of these findings stems from the fact that, in the United States, control of biodegradable organic matter produced from ozonation is usually accomplished by rapid filtration with an EBCT of 15-20 minutes. Although the results of the experiments suggest that these filters are capable of removing "fast" BDOC from ozonated water, slowly biodegradable organic matter would remain in the filter effluent. This remaining biodegradable organic matter may cause bacterial regrowth in the distribution system. As such, the control of slowly biodegradable organic carbon produced or remaining after ozonation may be critical for the design of water treatment systems employing ozonation.
Future Activities:
We are initiating pilot-scale studies of the ozonation/FBT system. The 1 gpm pilot-scale system will be installed on November 28, 2000, at the Monroe Water Treatment Plant in Monroe, Michigan. We are, unfortunately, behind schedule due to unforeseen problems with the firm originally awarded the contract for the construction of the pilot-scale system. The new contract was awarded to Ace Technologies, Cincinnati, OH, a small minority-owned business. They have constructed the system, and as stated above, will install it on November 28, 2000.We anticipate testing the system at Monroe until April 2001, when the system will be moved to the Ann Arbor Plant. We anticipate that testing will be completed in Ann Arbor in October, when the system will be moved to a third location.
Although all necessary kinetic data and operating information has been generated, we will continue bench-scale studies with selected source waters. These studies will be directed towards further optimizing parameters for ozonation and biodegradation to increase the efficiency of the combined ozonation/FBT system.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
Other project views: | All 14 publications | 4 publications in selected types | All 4 journal articles |
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Yavich AA, Masten SJ. Modeling the kinetics of the reaction of ozone with natural organic matter in Huron River water. Ozone: Science & Engineering 2001;23(2):105-119. |
R826829 (2000) R826829 (Final) |
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Yavich AA, Masten SJ. Use of ozonation and FBT to control THM precursors. Journal of the American Water Works Association 2003;95(4):159-171. |
R826829 (2000) R826829 (Final) |
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Supplemental Keywords:
drinking water, ozone, biological treatment, naturally occurring organic matter, disinfection by-products, RFA, Scientific Discipline, Geographic Area, Water, Environmental Chemistry, Analytical Chemistry, Drinking Water, Environmental Engineering, EPA Region, public water systems, lake erie, trihalomethanes, disinfection by-products, detroit, monroe, ann arbor, disinfection byproducts (DPBs), regulated DBP, organic matter, biological treatment, michigan, community water system, fluidized bed treatment, DBP precursors, surface water, huron river, treatment, NOM, microbial risk management, naturally occurring organic matter, Wyoming, DBP risk management, water quality, drinking water contaminants, water treatment, DBPs, Region 5, drinking water system, disinfection, ozonation, THMsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.