1. Natural and Engineering Factors that Affect Disinfection Byproduct Concentrations in the Home Boning Liu and David Reckhow Department of Civil and Environmental Engineering, University of Massachusetts, Amherst, MA 01003

2. 2  Intro & DBP Issue  Factors affecting DBP formation  Information Gaps  Field Studies  Design  Municipal system  Home impacts  Conclusions Let’s make some disinfection byproducts!

3. HOCl + natural organics (NOM) Oxidized NOM and inorganic chloride Aldehydes Chlorinated Organics TOX THMs HAAs The THMs MCL 80µg/L The Precursors!

4. 4  Raw water NOM levels (e.g., TOC)  Specific precursor content of the RW NOM  NOM removal  Disinfection regime  type & dose  location in plant  contact time & temperature  pH  Degradation and formation in DS

5. Water Heater City Water Drinking Showering & Washing Dermal & Inhalation Beverage Preparation Food Preparation Ingestion Ingestion & Inhalation Clothes Washing Dermal & Inhalation Ingestion & Inhalation Human Exposure Activity Major Routes Dish Washing Dermal & Inhalation EPA regulation based

6.  Inhalation in the shower produces highest blood level and response is fast 6 Gordon et al., 2006 [Env. Hlth Persp.114:514-521]

7. Data from the Mills Plant (CA) August 1997 (courtesy of Stuart Krasner) Regulated DBPs But, the Bad Stuff is probably somewhere here

8.  What is the extent of diurnal variations in regulated and non-regulated DBPs?  In mains, near storage tanks, in dead ends  How does actual exposure compare to expectations from compliance testing?  Hot water effects(tankless vs. tank heater)  Non-regulated DBPs

9. dd 9

11.  Relatively low TOC 11

12. 12  Recent DBP levels have dropped due to new WTP

13.  Intensive sampling over 2 days  Monitor cold water  Plant effluent: system entry  Distribution system location unaffected by storage and dead end  Monitor hot water  Measure regulated and non-regulated DBPs  THMs, HAAs, residual chlorine, temp  TOX, HANs, CP, TCP

14.  Don’t try this at home

15.  dsa 15 Field Site #1 Total transit time is around 18-30 hours

19.  temp 19

22.  Northampton, MA

23. 23  Percentage of Unknown TOX little changed  50% for cold water  45% for hot water

24.  If TCAA decarboxylation isn’t the explanation, then what?  Answer: Shift in reaction pathway for common THM/TCAA intermediate 24 THMsTriHAAs Simplified from: Reckhow & Singer, 1985 [Water Chlorination: Environmental Impact and Health Effects, Vol 5, pp1229-1257.]

26.  Key intermediate  Concentrations are well known

28.  Northampton, MA

29.  Rocky Hill Cohousing Community, Northampton, MA  Uniform construction: completed 2005  Study date: late July 2010  18 homes participated  8 tankless gas heaters, 10 conventional tank heaters

30. tankless heaters No storage tank On-Demand, save energy, how about Disinfection byproducts?

31.  2 day sampling  Temperature controlled  Chlorine residual/pH measured at each site  Samples quenched, cooled down and transported to lab for DBP analysis  Simulated experiments

32. Reading is after flushing when temperature is stabilized Hot Water: 50-60 C Cold Water: 18-22 C

33. Heavy water usage

34.  Delta value, ratio

35. 

39.  Water Heaters substantially change the DBP levels and character  Some increase many fold  THMs, DiHAAs, Chloropicrin  Some show little change  TriHAAs  Some decrease  Dichloroacetonitrile, Trichloropropanone  For most, we simply don’t know  Tankless heaters have a smaller affect  High temperatures shift reaction pathways  TriHAA → THM  Other products formed?  What does this mean to exposure studies?  Need to look at other DBPs and develop models  Hypothesis: DBP increase is related to chlorine residual at time of heating 39

40.  Northampton (MA) DPW - Water Division  David Sparks, superintendent  Alex Roseweir, Doug Ducharme, Paul Petersen  Northampton Rocky Hill cohousing community  18 anonymous home owners 40

43. Total Chlorine Residual  Mixed cold water from cohousing homes, incubated at 53 o C(average T of hot tap)  Incubated water effluent from water treatment plant

44. TTHM DHAA THAA Immediately 53 o C

45. pH=6.7, temperature 60 o C, TCAA standard solution. Calculated K=( 0.0169 +/- 0.0025 )/hr

46. MCL: 60µg/L

47. 47  Less than with the hot tap

48. 48  Little difference between hot and cold

49. 49  Higher terminal levels in cold tap