Next Hurdle: 1,2,3-Trichloropropane. Kevin Berryhill

Transcription

1 Next Hurdle: 1,2,3-Trichloropropane Kevin Berryhill

2 Agenda 1. Background 2. Origin of TCP 3. Regulations 4. Treatment Alternatives 5. Treatment Cost

3 Where Does TCP Come From? Notification Level established after TCP s discovery at the Burbank Superfund site primary possible contaminating activity appearing to be hazardous waste sites

4 Where Has TCP Been Found?

5 Where Does TCP Come From?

6 Significant Impact on Rural Areas Agricultural origin Agriculture occurs in rural areas Rural areas have small water systems Small water systems have no money

7 An Underreported Problem? California UCMR ( ) Prior to DLR=0.005 µg/l Sample at source or entry point <150 connections exempt EPA UCMR 3 ( ) Systems > 10,000 people 800 representative PWSs Sample at entry point MRL = 0.03 µg/l Private Wells

8 Laboratory Analytical Constraints Detection Limit = 5 ng/l Equal to the notification level 7 times greater than the PHG Specific California-approved analytical methods Sanitation and radiation laboratories purge and trap GC/MS Sanitation and radiation laboratories liquid-liquid extraction GC/MS EPA (accuracy must be demonstrated by laboratory) EPA (accuracy must be demonstrated by laboratory) USEPA methods and are not adequate for TCP

9 Why Regulate TCP? Carcinogen Recognized as human carcinogen by California Classified as likely to be by the EPA 0.7 ppt health goal based on 1 in a million cancer risk Known toxin 100% man-made Byproduct of chemical synthesis Does not degrade naturally In wine there is wisdom, in beer there is freedom, in water there is TCP -Benjamin Franklin Denser than water

10 How is TCP Currently Regulated? Notification Level µg/l (1999) PHG µg/l (2009) TCP is not regulated by the U.S. EPA MCL 0.8 µg/l (mid-80s) MCL 0.6 µg/l (2005) MCL currently under review

11 Regulatory Process Draft MCL in day comment period 30 day administrative review Effective within 5 months Up to 6 months to sample

12 Treatment Alternatives There is no Best Available Technology (BAT) for TCP Look at what works for other VOCs Air stripping / packed tower aeration Reverse osmosis (RO) Advanced oxidation processes (AOP) Granular activated carbon (GAC)

13 Air Stripping Chemical Molecular Weight Henry s Law Constant (atm-m 3 /mol) Dibromochloropropane (DBCP) Methyl tertiary-butyl ether (MTBE) Tetrachloroethylene (PCE) Trichloroethylene (TCE) ,2,3-Trichloropropane (TCP) The lower the Henry s Law constant, the poorer the treatment performance 10 26% Removal

14 Reverse Osmosis At least one operational RO treatment plant removing TCP Bench-scale study (Fronk, Lykins & Carswell, 1990) Several membranes tested 39 to 85% rejection of TCP Brine disposal issues RO is a very expensive way to achieve incomplete removal of TCP

15 Advanced Oxidation AOP is likely to be a technically viable treatment alternative Ozone More viable for higher influent levels HiPOx study (Dombeck and Borg, 2005) Peroxide UV

16 Potential AOP Byproducts Tratnyek, P.G., V. Sarathy, and J.H. Fortuna. (2008) Fate and Remediation of 1,2,3-Trichloropropane. In Proceedings of the Sixth International Conference on Remediation of Chlorinated and Recalcitrant Compounds

17 Biological Treatment Natural biodegradation is insignificant Bacterial directed evolution studies are in in work. Even superbugs could require days or weeks to act.

18 Granular Activated Carbon (GAC)

19 Granular Activated Carbon Effective for almost all organic contaminants Reliable Simple All existing TCP removal plants use GAC

20 Existing GAC Facilities Existing GAC treatment facilities removing TCP include: Alhambra, CA Burbank Operable Unit, CA Fresno, CA Glendale, CA Honolulu, HI Kaanapali, HI Maui, HI Oceanside, CA San Jerardo, Salinas, CA Tustin, CA

21 GAC Vessel Configuration Carbon characteristics Series vs. parallel Empty bed contact time (EBCT)

22 Carbon Characteristics Substrate material Coconut Coal (anthracite, bituminous, lignite) Peat Adsorption properties (iodine number, molasses number, tannin value) Gradation, uniformity Hardness, abrasion resistance

23 Empty Bed Contact Time (EBCT) V(gal) Q(gal/minu te) minutes Raw Water Exhausted GAC Higher EBCT Lower EBCT Exhausted GAC Mass Transfer Zone Mass Transfer Zone Unutilized GAC Unutilized GAC Treated Water

24 Series vs. Parallel? Raw Water Exhausted GAC Mass Transfer Zone TCP is coming out of the filter, but This carbon still has capacity left Treated Water TCP detected

25 Series vs. Parallel? Lead Vessel Lag Vessel Exhausted GAC Mass Transfer Zone Unutilized GAC No TCP Treated Water Treated Water The second vessel will allow us to more fully utilize the carbon in the first vessel

26 When Do You Replace Carbon? Lead Vessel Lag Vessel Exhausted GAC Detected at 5 ng/l Already at 0.7 ng/l PHG? PHG < DLR TCP slips through monitoring Replace carbon in lead vessel based on 50% or 75% sample port in lag vessel

27 Carbon Usage Chemical Molecular Weight Log Octanol-Water Partition Coefficient (K ow ) Dibromochloropropane (DBCP) Methyl tertiary-butyl ether (MTBE) Tetrachloroethylene (PCE) Trichloroethylene (TCE) ,2,3-Trichloropropane (TCP) Usage Rate Prediction Methods Computer modeling Bottle point adsorption isotherms Rapid small-scale column testing (RSSCT) Small-scale pilot or bench studies Full-scale testing A value of 0.1 lb GAC / 1,000 gallons has been assumed pending a site specific water quality evaluation and testing

28 Bottle Point Isotherm Multiple bottles with different carbon weights added

29 Rapid Small Scale Column Test (RSSCT) Most practical way to estimate carbon usage Logistics Two 55-gallon drums of water 6 weeks Approximately $8,500 per test Limitations Inherent assumptions in model Snapshot in time Neglects biological activity Neglects GAC bed backwashing One batch of carbon Apply a factor of safety!

30 Pilot Testing More accurate than RSSCT Accounts for variations in raw water quality Captures biological effects Long-term test (Hopefully!)

31 Water Quality Considerations Background TOC= 250,000 ng/l TCP levels may not significantly affect carbon usage rates Background organics may be more critical DBCP is often found in the same well TCP = 5 ng/l

32 Nitrate Spikes Source water nitrate > 22 mg/l (as NO3) Effect similar to chromatographic peaking Occurs following shutdowns and backwashes Handled by: Nitrate monitoring Flush-to-waste

33 GAC Site Appurtenances Access for delivery Washwater disposal Initial washing Backwashing for head loss reduction Aesthetic considerations

34 Next Steps Recommendations for Utilities: Explore funding sources for construction and operation of the treatment system Factor into rates Responsible party Grant & SRF funding once MCL is established Measure TOC Compile NO 3 (nitrate) data Develop accurate production data Consider RSSCT testing

35 Kevin Berryhill (559)