The Optimization of Low-Cost Phosphorus Removal from Wastewater Using Co-Treatments with

2. Wetland Biogeochemistry Laboratory Soil and Water Science Department The Optimization of Low-Cost Phosphorus Removal from Wastewater Using Co-Treatments with Constructed Wetlands John Leader Soil & Water Science Department Wetland Biogeochemistry Lab Exit Seminar November 10th, 2004 4:00 pm Florida Gym Rm.270

3. Outline of talk • Intro. & Background • Lab Studies • Column Studies • Mesocosms • Overall Conclusions

4. 1. INTRODUCTION & BACKGROUND • PROBLEM • Excess P discharged to surface waters threatens to water quality • Constructed wetlands can treat wastewater but are a finite sink for P • NEED FOR RESEARCH ON CONSTRUCTED WETLANDS1.) cost (increased size required for P removal) • 2.) performance (sometimes unpredictable) • 3.) sustainability (P “dead end”, export of P)

5. CENTRAL HYPOTHESIS • Optimizing hydrology & co-treatments could be a low-cost way to enhance CW performance • Ideal co-treatments would be widely-available, non-toxic by-products & useful soil amendments, once saturated with P

6. Hypotheses • materials will differ in abilities to remove & retain P • physico-chemical characteristics that affect performance will differ • co-treatments will affect wetland plants • Objective • eliminate materials at each stage until two are left for the mesocosm study

7. Overall Experimental Approach • Lab, column & mesocosm studies progressively lead toward a better understanding of the biogeochemical & practical factors of P removal with a co-treatment & wetland system • Results at each stage inform the system design for P removal from municipal & agricultural wastewater

8. 2. Lab Studies Approach - P sorption & desorption, kinetics, extracted metals, turbidity, & other parameters which might predict performance Materials/Methods -numerous by-products will be acquired & tested in the lab as described in the following slides

13. Super Mag Tampa Fe DWTR Humate GRU Ca DWTR

16. Lab Studies Conclusions • six substrates had potential for use as co-treatments • Aluminum #1 • SuperMag • Humate product • Fe-DWTR • Ca-DWTR • Coated Sand • coarse sand a relatively inert media for experimental columns • HRT & P loading rates suggested

17. Column Studies • Approach • co-treatment & sand column units to simulate major features & conditions of larger scale • apply wastewater at realistic volumes & rates • controls, replication, complete randomized design • Materials/Methods • By-product bottles paired with sand columns • Wastewater batch applied for 1-month • Effluent P measured with other parameters of wastewaters, substrates & sands, pre/post- loading

19. DRU - Digested Dairy Wastewater • [SRP] 3.8 - 15.6 mg/L • [TP] 33 - 43 mg/L • pH 6.7 – 7.4 • TSS 2390 mg/L • “DOC” (NPOC) 453 mg/L • DO 0.09 mg/L (~1%) • Conductivity 4.5 mS/cm • Salinity 2.2 ppt • Redox (Eh) - 45 mV

20. DRU - Digested Dairy Wastewater • [SRP] 3.8 - 15.6 mg/L • [TP] 33 - 43 mg/L • pH 6.7 – 7.4 • TSS 2390 mg/L • “DOC” (NPOC) 453 mg/L • DO 0.09 mg/L (~1%) • Conductivity 4.5 mS/cm • Salinity 2.2 ppt • Redox (Eh) - 45 mV • GRU – Secondary Municipal Effluent • [SRP] 0.44 – 1.8 mg/L • [TP] 0.47 – 2.5 mg/L • pH 6.7 – 7.4 • TSS < 1 mg/L • “DOC” (NPOC) < 7 mg/L • DO > 8 mg/L (~100%) • Conductivity 0.7 mS/cm • Salinity 0.3 ppt • Redox (Eh) > +350mV

21. All received the same DRU wastewater with [SRP] = 9 mg/L

22. All received the same GRU wastewater with [SRP] = 0.44 mg/L

27. ( ………… all GRU Columns remained aerobic ……..… ) Facultative Anaerobes Fe3+  Fe2+ Facultative Anaerobes Mn4+  Mn2+ Facultative Anaerobes & Aerobes NO3-  NH3 O2  H2O ( 492-599 mV ) ( 424-590 mV ) ( 444-564 mV ) ( 481-585 mV ) (100-172 mV; Except Iron DWTR = 290 mV ) (77-150 mV; Except Iron DWTR = 288 mV ) (72-347 mV; Iron DWTR = 298 mV ) (164-437 mV; Iron DWTR = 298 mV )

28. Column Studies Conclusions • Fe & Ca DWTR characteristics suggested overall suitability for use as co-treatments • coarse sand performance suggested it would be suitable as root bed media for vertical flow wetland

30. 4. Mesocosms • Experimental approach • CTR & CWM simulate features & conditions of large scale co-treatment & wetland system • apply wastewater at realistic volumes & rates to co- treatments & controls • replication, complete randomized design • Materials and methods • by-products placed in CTR paired with CWM; wastewater was applied for one year • effluent P were regularly measured with other parameters of the wastewaters, substrates, sands, & plants pre/post-loading

31. CTR & CWM - CONSTRUCTION & OPERATION

32. Mesocosm Tank Construction

33. Dairy Research Unit (DRU) Gainesville Regional Utilities (GRU) Agricultural Wastewater Municipal Wastewater Co-Treatment Reactors (CTR) & Constructed Wetland Mesocosms (CWM)

34. Note Methane Flare DRU - Anaerobic Digester Effluent (ADE): or GRU Effluent: Constructed Wetland Mesocosms CWM): Co-Treatment Reactors (CTR): pH DRU: ~7 ~ 7.5 ~ 8 GRU: ~7 ~ 7.5 ~ 7 TSS (mg/L) DRU: 2390 229 68 GRU: (below detection limit; < 1 mg/L) Redox (mV) DRU in CWM-Flooded: -147 to “Drained”: + 95 GRU in CWM-Flooded: +136 to “Drained”: + 440 (NOTE: +350 aerobic … +150 Fe reduction … -200Sulfate reduction … -300methanogenesis)

37. Mass Rates of Phosphorus in Influent and Effluents of Systems Mean P mass-loading rates(g m-2 day-1) DRU 0.49 GRU 0.01 Mean P mass-removal rates(g m-2 day-1) DRU Control 0.274 Lime 0.287 Iron 0.290 GRU Control 0.008GRU CTR’s alone:0.003 Lime 0.0090.023 Iron 0.0100.049

38. New Hypothesis to Test reducing the TSS in DRU WW with a wetland cell first, will greatly improve the efficiency of P removal by CTR

39.  Co-Treatment First Small or no difference between treatments & controls with dairy wastewater Wetland First Large difference between treatments & controls with dairy wastewater

46. MESOCOSM CONCLUSIONS • CWM paired with CTR removed P as well or better than controls • Ca & Fe CTR removed P from municipal & agricultural WW reducing loading to CW • TSS reduce P removal efficiency • TSS can be reduced by CW with increased efficiency of CTR • CTR had no apparent neg. & perhaps small pos. impact on wetland plants • Fe removed P from WW even when anaerobic • Bulrush stems & roots accumulate more P with higher loading rates

47. 5. Overall Conclusions • system design relatively simple, reliable & adaptable • multiple CW & CTR cells likely to reduce TP to lower levels • CTR performance declined over time but easily refilled • many potential by-products available for P removal from WW • CW are complex systems - designers, builders & operators should be aware of critical biogeochemical factors affecting performance

48. Wetland Biogeochemistry Laboratory Soil and Water Science Department • ACKNOWLEDGEMENTS • Dr. Reddy • Dr. Wilkie • Committee Members Dr. Harris, Dr. Koopman, Dr. Annable • Dr.’s Pant, Bonczek, White, Clark • Dr. K. Portier • Students: Carrie Miner, Todd Osborne, Jeff Higby, Ed Dunne, Lance Riley (Fisheries), Johnny Davis (Microbiology) • FL Department of Agriculture & Consumer Services • UF DRU & GRU • Final Substrates from * GRU Murphree DWT Plant * Hillsborough River DWT Plant • SWSD - Yu Wang, Gavin Wilson, Ron Elliot, Scott Brinton, Larry Schwandes, Keith Hollein & many other students & staff • Dr. Murphy (Counseling Center) & Dr. Darby (Infirmary) • My wife Lesley & my parents for their patience & love