United States Environmental Protection Agency Water Engineering Research Laboratory Cincinnati OH 45268 Research and Development EPA/600/S2-87/006 Apr. 1987 oEPA Project Summary Alternative Disinfectants and Granular Activated Carbon Effects on Trace Organic Contaminants Wayne E. Koffskey and Benjamin W. Lykins, Jr. A study was conducted to evaluate the effects of alternative disinfectants on drinking water quality at Jefferson Parish, Louisiana, and the ability of granular activated carbon (GAC) to re- move disinfection byproducts and specific organic compounds. Bacterio- logical information was collected on the influent and effluent of sand and GAC columns. Four parallel pilot-column process streams were dosed with a different disinfectant (ozone, chlorine dioxide, monochloramine, and chlorine) and compared with a fifth pilot-column stream that was not disinfected. After 30 minutes of disinfectant contact time, the water in each process stream was passed through parallel sand, GAC, and duplicate GAC filters, each with 20 min- utes of empty bed contact time (EBCT). Samples collected from each process stream were analyzed for total organic carbon (TOC), total organic halide (TOX), 10 volatile organics, 65 solvent- extractable hydrocarbons, 26 chlori- nated hydrocarbon insecticides, hetero- trophic plate count (HPC), total coliforms, and dissolved oxygen. To simulate distribution conditions, ali- quots of each column effluent were dosed with monochloramine and free chlorine and analyzed for TOX and 10 volatile organics after storage for 5 days at river water temperature. The process train that yielded the least dissolved organic contaminants was predisinfection with ozone fol- lowed by GAC filtration and postdisin- fection with monochloramine. This Project Summary was devel- oped by EPA's Water Engineering Re- search Laboratory, Cincinnati, OH, to announce key findings of the research project that is fully documented in a separate report of the same title (see Project Report ordering information at back). Introduction The Mississippi River along with its tributaries drains nearly two-thirds of the continental United States and sup- plies a source of drinking water to many cities located along its banks, including Jefferson Parish. The waters of the Mis- sissippi River and its tributaries also re- ceive vast quantities of industrial and municipal wastes as well as agricultural run-off that create various levels (ng/L) of trace organic contamination. In addi- tion, significantly higher levels (mj/L) of organic contamination form when chlo- rine is used in disinfection. Therefore, a research project, funded jointly by the U.S. Environmental Protection Agency (EPA) and Jefferson Parish, was ini- tiated to determine the effect of apply- ing various disinfectants (ozone, chlo- rine dioxide, monochloramine, and chlorine) to clarified and filtered water followed by GAC adsorption. Pilot-Column Plant At the raw water intake of Jefferson Parish (located on the east bank above the mouth of the Mississippi River), raw water is pumped to four separate treat- ment plants. Nondisinfected clarified water was applied to the pilot-column ------- plant by the Permutit III plant (Figure 1). Raw river water was clarified with di- allyldimethylammonium chloride and/ or dimethylamine type cationic poly- mers and fluoridated with fluosilicic acid before entering the pilot-column system. The clarified water was then fil- tered through one of two pressure sand filters and divided into five process streams. Each disinfected process stream con- sisted of a 30-minute disinfectant con- tact chamber followed by parallel filtra- tion through a sand column, a GAC column, and a duplicate GAC column. The duplicate column was used to de- termine variability between GAC columns within the same process stream. The configuration of the non- disinfected process stream was identi- cal to that of the disinfected process streams except that the disinfectant contact chamber was eliminated. All materials used to construct the pilot-column system (pumps, pressure sand filters, plumbing, contact cham- bers, and columns) were composed of stainless steel, teflon, or glass. Plastic flow totalizers were installed at the end of each process stream, but all samples were taken upstream. Each pilot column was constructed from 6-in. ID x 10-ft glass pipe with 150 Ib/in.2 stainless steel flange ends and a teflon/stainless steel screen underdrain. The pilot columns were charged with 6.8 ft of either sand or GAC media to obtain a 20-minute EBCT with a flow of 0.5 gpm. Each disinfectant contact chamber was constructed from 12.75-in. OD (0.18-in. wall) stainless steel pipe with stainless steel blind flanged or capped ends. The chlorine dioxide, monochlor- amine, and chlorine contact chambers were 10 ft in height in order to produce 30 minutes of disinfectant contact time with a flow of 2 gpm. The ozone contact chamber was 11 ft in height and de- signed for countercurrent operation with the water entering at the top of the contact chamber and the ozone gas stream entering on the bottom. The water and ozone gas influent lines were oriented such that the influent water would be in contact with the ozone gas stream for 30 minutes. Ozone gas exit- ing the contact chamber was reduced by passage through a heated pelletized nickel oxide column to prevent conden- sation. Ozone was generated from com- pressed dry air using an electrically powered ozone generator with a maxi- mum output capacity of 0.25 Ib/day. Chlorine dioxide was generated using two solutions, one containing sodium chlorite and sodium hypochlorite and the other containing sulfuric acid. Adding a 50% excess of sulfuric acid ad- justed the pH of the final solution to 4. i— Cationic Polymer Fluosilicic Acid Mississippi River Mile 105.4 AMP Chloramines Filtration Regenerative Permutit III Turbine Clarifier Pumps ted - J_ T >- 1 c T Ozor Cont hart 1. T- ie — act iber rt T -4- -r T Chlo Diox J 1 T. r//?e-» ide i r f T T Mom ".hlor ] "} T amine ( 1 T Chlorine -*l r T j l T r T y 1 T n 1 Pressure Sand Filters Legend cm- GAC 1- Sand to Waste Figure 1. Pilot-column system flow schematic 2 These two solutions were pumped tc gether and received in-line mixing in small generating tower constructed c teflon shavings and glass. All compc nents that came into contact with chic rine dioxide were made of teflon o glass. This method generated a 96°/ yield of chlorine dioxide. Chlorine ga was fed to both the monochloramim and chlorine process streams usini teflon eductors. Ammonia was added ii the form of an ammonium hydroxidi solution by pumping into the chlo ramine process stream ahead of thi chlorine eductor. Disinfectant Effectiveness After 30 minutes, ozone residuals av eraged 0.5 mg/L as O3 and chlorine dioxide 0.5 mg/L as CI02. The average 30-minute residual for chlorite was slightly higher than that of chlorine dioxide at 0.6 mg/L as CI02. Essentiallv all of the chlorite resulted from the re duction of chlorine dioxide during the 30-minute contact period. This was de- termined by data generated from the chlorine dioxide demand analyses per- formed in a batch mode using deionized carbon filtered water and nondisin- fected pilot-column influent water. The average concentrations of chlorine dioxide constituents in deionized car- bon filtered water were 1.6 mg/L CI02, 0.0 mg/L CIO2, 0.2 mg/L CI2, 0.1 mg/L NH2CI, and 0.1 mg/L NHCI2. Those resid- uals observed after 30 minutes of con- tact time with the influent water of the pilot column were 0.7 mg/L CIO2, 0.6 mg/L CIO2, 0.1 mg/L CI2, 0.2 mg/L NH2CI, and 0.1 mg/L NHCI2. An average chlorine dioxide demand of 0.9 mg/L as CIO2 was seen with 0.6 mg/L or 67% re- duced to chlorite. Thirty-minute monochloramine resid- ual averaged 2.1 mg/L as NH2CI or 1.4 mg/L as CI2. A dichloramine residual was also observed averaging 0.4 mg/L as NHCI2. The average 30-minute chlo- rine residual for the chlorine process stream was 1.0 mg/L as CI2 with an aver- age monochlorine residual of 0.2 mg/L as NH2CI and an average dichloramine residual of 0.3 mg/L as NHCI2. The pres- ence of 0.1 to 0.2 mg/L of naturally oc- curring ammonia nitrogen produced chloramines. After 30 minutes of disinfectant con- tact time, ozone exhibited the highest level of disinfection followed by chlo- rine dioxide and chlorine whereas monochloramine was somewhat less effective. Chlorine dioxide, chlorine, and monochloramine became equallv ------- effective after filtration through the sand columns. As ozonated water passed through the sand column, the geometric mean for the HPC rose from 8 to 4594 CFU/mL, indicating a biologi- cally activated sand column. Whereas the geometric means for the HPC in- creased across the sand columns for all of the disinfected process streams, it de- creased for the nondisinfected process stream. Because each disinfectant be- came ineffective in the first portion of each GAC column, the geometric mean of the HPC in the effluent of each disin- fected GAC column increased to a level similar to that observed for the nondis- infected influent water of the pilot- column system. Most of the colonies picked from the heterotrophic plates were gram positive. Of the gram nega- tive bacteria identified, Pseudomonas, Alcaligenes, Moraxella, and Acineto- bacter calcoaceticas were observed most frequently. Some positive col- iforms were observed, especially at the beginning of the study. Organic Products TOC and TOX surrogates were evalu- ated during this study. After 30-minute disinfection contact time, average TOC concentrations were 3.3, 3.0, 3.3, 3.4, and 3.3 mg/L for nondisinfected, ozone, chlorine dioxide, monochloramine, and chlorine, respectively. After sand filtra- tion, the ozone stream showed a 0.5 mg/L concentration reduction. The TOC concentrations of the other streams were comparable to their influent val- ues. GAC effluent concentrations at steady state (180 days) were 2.7 mg/L TOC for all disinfection streams exept ozone (2.2 mg/L). Average instantaneous TOX concen- trations after 30-minute disinfectant contact time were 25, 15, 85, 117, and 263 ng/L for nondisinfected, ozone, chlorine dioxide, monochloramine, and chlorine, respectively. TOX byproducts were formed after disinfectant addition except for the ozonated stream, where an average 10 (xg/L reduction was seen. Instantaneous TOX concentrations in the sand column effluents were com- parable to their respective influents. GAC effluent instantaneous TOX con- centrations were influenced by the amount applied to the columns. Higher influent produced higher effluent con- centrations. Flame ionization detection and elec- tron capture chromatograms provided an overall indication of the effect of using various disinfectants. Compared to nondisinfected water, chlorination produced the most peaks followed by chloramination, chlorine dioxide, and ozone. (Figures 2 and 3). For the volatile organics detected (tri- halomethanes, 1,2-dichloroethane, dichloromethane, trichloroethylene, 1,1,2-trichloroethane, and carbon tetra- chloride), only the trihalomethanes were affected by disinfection. Average trihalomethane concentrations after 30 minutes of contact time were 1, 1, 1,4, and 34 g/L for nondisinfected, ozone, chlorine dioxide, monochloramine, and chlorine, respectively. GAC removed the trihalomethanes formed by chlori- nation for about 60 days until break- through and for about 80 days for those formed by chloramination. The nonvolatile organics identified in the pilot system influent consisted of 28 chlorinated hydrocarbons, 16 alkylben- zenes, 8 alkanes, 7 phthalates, 6 chlorobenzenes, 3 nitrobenzenes, 2 alkylaldehydes, tributylphosphate, triphenylmethane, 4-nonylphenol, and d-fenchone. The herbicide atrazine and the insecti- cide alachlor were present in the influ- ent to the pilot system throughout the study. Influent atrazine concentrations ranged from 23 to 249 ng/L with an aver- age of 80 ng/L. The influent atrazine concentration was not affected by chlo- rine dioxide, chloramine, or chlorine disinfection. Compared with the nondis- infected influent, however, ozonation removed an average of 83% of the atrazine. Alachlor levels in the nondisin- fected influent of the pilot column ranged from 13 to 593 ng/L with an aver- age of 127 ng/L. Alachlor was also unaf- fected by chlorine dioxide, chloramine, or chlorine disinfection, but its concen- tration was reduced an average of 84% by ozonation. Other chlorinated hydrocarbon insec- ticides (CHIs) were evaluated as a total sum of all the individual CHIs monitored during the study except atrazine and alachlor. The total CHI concentration in the nondisinfected influent ranged from 18 to 88 ng/L with an annual average of 36 ng/L. The concentration of these sub- Nondis- infected -JUUU- Chlorine Dioxide JLJ, jJLl I JUX Chlorine -I 1 1 3 Figure 2. Flame ionization GC profiles after idsinfeciton (runday 87). Ozone Chlorine dULJL Mono- chloramine Chlorine Figure 3. Electron capture GC profiles after disinfection frunday 87). 3 ------- stances was unchanged after disinfec- tion except for ozonation, which pro- duced an average total CHI reduction of 57%. The total alkylbenzene concentration in the nondisinfected influent ranged from 59 to 10,300 ng/L with an average of 590 ng/L. Thirty minutes of disinfec- tant contact time with chlorine dioxide, chloramine, and free chlorine produced an increase in the total alkylbenzene concentration of 11%, 14%, and 100%, respectively. Treatment with ozone, however, reduced the total alkylben- zene concentration by 52%. The total alkane concentration in the nondisin- fected influent averaged 50 ng/L with a range of 10 to 150 ng/L. Ozonation re- duced the concentratio'n of the total alkanes by an average of 35%. Addition of the other disinfectants had no effect on the total alkane concentration. The total phthalate concentrations in the nondisinfected influent ranged from 70 to 470 ng/L with an average of 180 ng/L. Ozonation produced an average total phthalate reduction of 1 1 %. No sig- nificant changes in total phthalate levels occurred for the other disinfectants. Total chlorobenzene concentrations in the nondisinfected influent ranged from 4 to 304 ng/L with an average of 100 ng/L. Nitrobenzene concentrations ranged from a minimum of 0.1 ng/L for 2-nitrotoluene to 260 |o.g/L for 2,4- dinitrotoluene. Ozonation produced an average of 68% concentration reduction for total chlorobenzene and 61% for total nitrobenzene. Conversely, chlori- nation resulted in a 75% increase in total chlorobenzene and a 43% increase in total nitrobenzene. Two alkylaldehydes, octanal and nonanal, were quantified. The total con- the nondisinfected influent ranged from below detection (<0.1 ng/L) to 37 ng/L with an average of 14.4 ng/L. An aver- age uniform increase in the total alkyl- aldehyde of 144% was observed in the ozonation system, whereas a relatively nonuniform increase of 56% occurred for the chlorine system relative to the nondisinfected influent. No significant changes in the concentration of total chlorobenzene, total nitrobenzene, and the alkylaldehydes were noted for the other disinfectants. Sand filtration had some effect on the total alkylbenzenes, total phthalates, total chlorobenzenes, and total alkyl- aldehydes, with lower concentrations in the effluent as compared to the influent. On the average, GAC removed me cnio- rinated hydrocarbons 90% to 97%, total alkylbenzenes 40% to 45%, total alkanes 44% to 52%, total chlorobenzenes 93% to 96%, and total nitrobenzenes 81% to 92% for the 1-year operational period The removal of total phthalates by GAC averaged 44% to 50% for about 25C days before the ozonated stream brokt through. Ozone appears to be the disinfectan of choice because lower concentration: of organics were detected during it: use. More research is needed, however to understand what happens to the or ganics after ozonation. Are these organ ics oxidized and destroyed; are the^ converted to other organics that are more biodegradable; are they more water soluble and not extractable, mak ing them difficult to detect? The full report was submitted in par tial fulfillment of Cooperative Agree ment No. C8806925 by Jefferson Parish Louisiana, Department of Public Utili ties, under the sponsorship of U.S. Envi ronmental Protection Agency. Wayne E. Koffskey is with the Parish Department of Public Utilities, Jefferson. LA 70121- the EPA author Benjamin W. Lykins. Jr., (also the EPA Project Officer, see below) is with the Water Engineering Research Laboratory, Cincinnati, OH 45268. The complete report, entitled "Alternative Disinfectants and Granular Activated Carbon Effects on Trace Organic Contaminants," (Order No, PB 87-146 700/ AS; Cost: $24.95, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Water Engineering Research Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 t u iicae twu i launmi rl. United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 BULK RATE POSTAGE & FEES P EPA PERMIT No G-3! Official Business Penalty for Private Use S300 EPA/600/S2-87/006 0169064 It 60604 ------- |