Overview of Drinking Water Treatment and Byproduct

Transcription

1 verview of Drinking Water Treatment and Byproduct Compounds David Cwiertny Associate Professor Department of Civil and Environmental Engineering Director, Sustainable Water Development Graduate Program University of Iowa Director, Environmental Policy Research Program University of Iowa Public Policy Center

2 Chemical added = Quality Change Potential for unwanted reactions and byproduct formation

3 Why do we disinfect? John Snow Today: strict regulations for pathogen control in SDWA (e.g., 99.99% virus removal) CDC John Leal Jersey City, NJ (1908)

4 Disinfection byproducts result from unwanted reactions of disinfectants Natural organic matter (NM) Chlorine-based Disinfectants Cl 2 (g) Cl (free chlorine) Cl 2 (chlorine dioxide) N 2 Cl (combined chlorine) + = Disinfection Byproducts or DBPs (regulated, emerging & next generation)

5 Regulated DBPs: TMs and AAs Stage 1 and Stage 2 Disinfectants and Disinfection Byproduct Rules Category Trihalomethanes (TM4) aloacetic acid (AA5) Species Chloroform Bromoform Dichlorobromomethane Dibromochloromethane Monochloroacetic Acid (MCAA) Monobromoacetic Acid (MBAA) Dichloroacetic Acid (DCAA) Dibromoacetic Acid (DBAA) Trichloroacetic Acid (TCAA)* *

6 Compliance trends for DBPs: Nationally

7 Compliance trends for DBPs: Nationally (in Small Systems) CWSs serving between 500 and 10,000 people are far more likely to experience DBP violations than are either very small or larger systems. In fact, 56% of all DBP violations occurred in small and medium CWSs, even though those size categories account for only 36% of all systems

8 Compliance trends for DBPs: Iowa

9 Compliance trends for DBPs: Iowa Iowa by the numbers (CY 2016): 453 PWS with Any Violation 77 PWS with ealth-based Violation Focus on ealth-based Violations 246 total violations Rule Violations Radionuclides 87 Total Coliform Rule 41 Nitrates 36 Surface Water Treatment Rule 27 Arsenic 22 Revised Total Coliform Rule 10 Groundwater Rule 9 Stage 2 DBP 6 Volatile rganic Contaminants 4 Long-term 1 Enhanced Surface Water Treatment Rule 3 ther Inorganic Contaminant 1

10 Emerging byproducts: Nitrosamines and Iodinated DBPs Category Species NDMA Iodoform Nitrosoamines alonitromethanes (NMs) N-nitrosodimethylamine (NDMA) N-nitrosomethylethylamine (NMEA) N-nitrosodiethylamine (NDEA) N-nitroso-di-n-propylamine (NDPA) N-nitroso-di-n-butylamine (NDPA) N-nitroso-di-phenylamine (NDPhA) N-nitrosopyrrolidine (NPIP) N-nitrosopiperidine (NPIP) Chloronitromethane (CNM) Bromonitromethane (BNM) Bromodichloronitromethane (BDCNM) Dibromochloronitromethane (DBCNM) Trichloronitromethane (TCNM) Dichloronitromethane (DCNM) No federal MCL (on CCL3 & UCRM 2) California public health goal of 3 ng/l in drinking water (based on a 1 in 10-6 lifetime excess cancer risk) aloacetonitriles (ANs) Chloroacetonitrile (MCAN) Bromoacetonitrile (MBAN) Dichloroacetonitrile (DCAN) Dibromoacetonitrile (DBAN) Bromochloroacetonitrile (BCAN) Trichloroacetonitrile (TCAN) Iodo/bromo acetic acid Iodoacetic Acid (IAA) Bromoacetic Acid (BAA) Iodo methanes Iodoform

11 Next generation byproducts: Chlorine will react with most anything Susan Richardson University of South Carolina RLV Lecture: What is my drinking water?: Revealing the chemicals we can t see Dr. Susan Richardson Friday, ctober 13, 3:30 p.m. 101 Becker Communication Studies Building University of Iowa Iowa City, IA Iopromide

12 Next Generation Byproducts: Environmental Designer Drugs Chlorination of Glucocorticoid Steroids cortisol GC to GC cortisone GC to Androgen adrenosterone Endogenous to Synthetic GC Endogenous to Synthetic GC Androgen to Androgen 11b-hydroxyboldione GC to Androgen prednisolone GC to GC prednisone GC to Androgen d1-adrenosterone Chlorinated Derivative 9-chloro-prednisolone Chlorinated Derivative Cl 9-chloro-prednisone Chlorinated Derivative chloro-d1-adrenosterone

13

14 ptions for controlling DBP formation in water treatment ption 1: Precursor treatment ption 2: Alternative disinfection (UV, ozone) Compared to chlorine, ozone destroys a wider range of micro-organisms, produces fewer byproducts and more effectively removes unpleasant tastes and odors.

15 Concluding thoughts Disinfection of drinking water was one of the greatest public health advances of the 20 th century Today, we have the luxury (but also the responsibility) to focus on control of byproducts n balance, Iowa PWSs are effective in controlling DBP formation and limiting public health violations of SDWA Federal regulations for emerging DBPs (e.g., NDMA) is long overdue, so we shouldn t be complacent and must be prepared Next-generation DBPs: istory has long taught us that what we put into environment can (will?) find it s way into our water supplies and treatment facilities. Can chlorination amplify biological effects of EDCs, pesticides, industrial chemicals, etc. that may be in source water? Is ozonation or UV a better way forward? If so, how?