P yrethroid Fate & Behavior in Publicly Owned Wastewater Treatment Works

1. Pyrethroid Fate & Behavior in Publicly Owned Wastewater Treatment Works Daniel M. Tessier Environmental Safety Assessment DuPont Crop Protection • On behalf of the Pyrethroid Working Group member companies: AMVAC, Bayer, Cheminova, DuPont, FMC, Syngenta, Valent

2. Key questions regarding pyrethroids as wastewater microcontaminants • urban sources ? • influent concentrations ? • degradation / partitioning during wastewater processing ? • is known efate behavior (determined for agricultural settings) relevant in wastewater / POTWs ? • are current analytical methods sufficient? • effect of various wastewater treatment processes? • effluent concentrations? • PWG sought to answer these questions via laboratory, pilot and plant-scale studies as well as monitoring of selected California POTWs

3. Generalized POTW Processes

4. 8 pyrethroids included in the studies

5. Bench-scale treatability study Post-screen influent fortified at nominal 5 mg/L (50 mg/L permethrin)

6. aerobic system anaerobic digester

7. Results – Primary Settling a. Ca 0.85 gal / 200 gal influent ‡ No sorption to solids during primary settling

8. Pyrethroid Removal in Anaerobic Reactor

9. Pyrethroid Distribution in the Aerobic System

10. Conclusions: Bench-scale experiment No sorption of pyrethroids to solids in primary settling (attributed to high DOC as alternate sorption compartment; short detention time) Anaerobic digestion (biodegradation) ca. 32 – 79% removal of pyrethroid input. Aerobic treatment - biodegradation + low sorption of pyrethroids to solids (13 – 51% remain in effluent) >90% removal of effluent residual pyrethroids via ultra-filtration Overall >90% removal in final filtered effluent

11. Plant-scale process modeling Water & biosolids (sludge) phases collected over 1 week period & analyzed for pyrethroid concentrations Data modeled via TOXCHEM+ (Hydromantis, Ontario, Canada)

12. Plant-scale process modeling:POTW schematic and sampling locations

13. TOXCHEM Representation of SRCSDPOTW

14. Pyrethroid concentrations following aerobic treatment and ultrafiltration

15. Model Predicted vs Measured Concentrations

16. Modeling Results- Pyrethroid Fate NB: Measured concentrations of deltamethrin, fenpropathrin and esfenvalerate were too low for comparison against predicted concentrations

17. Conclusions: Full Scale Sampling / Process Modeling Predicted concentrations in good agreement with measured values. Log Kow used in the model (4.8 to 5.9) were generally lower than literature values (Laskowski, 2002) Attributable to high aqueous DOC. Pyrethroid emissions to the atmosphere were predicted to be < 2.4% for all tested compounds Median removal for biodegradation ranged from 44% to 65% Median removal for sorption ranged from 30% to 42% Pyrethroid discharge to effluent ranged from 2.9 to 11.9%

18. Pyrethroid Monitoring at California POTWs • PWG and Tri-TAC developed a partnership beginning in August 2007 • Revised DPR requirement – July 15, 2011 • Monitor for group III pyrethroids in influent, effluent, biosolids • Monitor at least 20 POTWs in California • Submit analytical methods for influent, effluent and biosolids for eight pyrethroids

19. Study Design • 32 California POTWs • Varying size (volume of treated wastewater) • Location (urban to rural) • Treatment processes used (primary, secondary, tertiary) • Customer base (residential, industrial, commercial) • Population served • Facilities divided into 3 groups for sampling (north to south) • Samples • Influent (31)-consecutive grabs • Effluent (31)-consecutive grabs • Biosolids (24)-grabs, composited in laboratory

20. Study Design (cont.) • Samples analyzed for pyrethroids by two laboratories • Group III pyrethroids (permethrin, cypermethrin, bifenthrin, cyfluthrin, esfenvalerate, l-cyhalothrin, deltamethrin, fenpropathrin) • TSS, TOC and TS determined by one laboratory • Extensive QA program (SWAMP comparable)

21. Results: Influent - All Sites # of detects = number of results that are above the limit of detection

22. Results: Biosolids - All Sites # of detects = number of results that are above the limit of detection All results reported on a dry weight basis

23. Results: Effluent - All Sites # of detects = number of results that are above the limit of detection 3 sites contained no detectable residues of the 8 pyrethroid pesticides

24. Effect of Treatment Level on Effluent Concentration

25. Conclusions: POTW Monitoring • Pyrethroids are likely to be found in influents, effluents and biosolids from California POTWs • Effluent (31 sites) • Pyrethroids were detected in 28 of the 31 sites examined • Bifenthrin (82%) was the most frequently detected pyrethroid followed by cypermethrin (81%) and permethrin (65%) • Total pyrethroid residues ranged from non-detectable to a maximum residue of 190 ng/L

26. Overall Conclusions Pyrethroids are likely to be present in wastewater influent, effluent & biosolids. Bench-scale and plant scale studies indicate ca. 90% removal of pyrethroids from influent streams via sorption & biodegradation; this benchmark is reflected in real-world monitoring. POTW process parameters (e.g detention time, 1o vs 2o vs 3o treatment) anticipated to influence % removal; effective modeling procedures are available to predict pyrethroid fate in POTW matrices. Baseline data and assumptions from e-fate studies must be applied judiciously to POTW investigations (e.g, Kow; Koc).

27. Key Personnel • PWG /DuPont Crop Protection • Al Barefoot • Dan Tessier • HDR Engineering • Joe Cleary • Joy McGrath • Sacramento Regional Sanitation District • Heather Ramil • Kurt Ohlinger • ABC / Morse Laboratories • Kevin Clark • Coalition for Urban/Rural Environmental Stewardship • Jim Markle • Van Buuren Consulting, LLC • Beverly van Buuren • Hydromantis • Hugh Monteith