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The Optimization of Low-Cost Phosphorus Removal from Wastewater Using Co-Treatments with Constructed Wetlands John Leader Soil & Water Science Department.

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Presentation on theme: "The Optimization of Low-Cost Phosphorus Removal from Wastewater Using Co-Treatments with Constructed Wetlands John Leader Soil & Water Science Department."— Presentation transcript:

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2 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 Soil and Water Science Department Laboratory Wetland Biogeochemistry

3 Outline of talk 1.Intro. & Background 2. Lab Studies 3. Column Studies 4. Mesocosms 5. 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 WETLANDS 1.) 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

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13 Humate Super Mag Tampa Fe DWTR GRU Ca DWTR

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16 Lab Studies Conclusions six substrates had potential for use as co- treatments 1.Aluminum #1 2. SuperMag 3. Humate product 4. Fe-DWTR 5. Ca-DWTR 6. 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

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19 DRU - Digested Dairy Wastewater [SRP]3.8 - 15.6 mg/L [TP]33 - 43 mg/L pH6.7 – 7.4 TSS2390 mg/L “DOC” (NPOC)453 mg/L DO0.09 mg/L (~1%) Conductivity4.5 mS/cm Salinity2.2 ppt Redox(Eh)- 45 mV

20 GRU – Secondary Municipal Effluent [SRP]0.44 – 1.8 mg/L [TP]0.47 – 2.5 mg/L pH6.7 – 7.4 TSS< 1 mg/L “DOC” (NPOC)< 7 mg/L DO> 8 mg/L (~100%) Conductivity0.7 mS/cm Salinity0.3 ppt Redox(Eh)> +350mV DRU - Digested Dairy Wastewater [SRP]3.8 - 15.6 mg/L [TP]33 - 43 mg/L pH6.7 – 7.4 TSS2390 mg/L “DOC” (NPOC)453 mg/L DO0.09 mg/L (~1%) Conductivity4.5 mS/cm Salinity2.2 ppt Redox(Eh)- 45 mV

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

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27 ( ………… all GRU Columns remained aerobic ……..… ) Facultative Anaerobes Fe 3+  Fe 2+ Facultative Anaerobes Mn 4+  Mn 2+ Facultative Anaerobes & Aerobes NO 3 -  NH 3 O 2  H 2 O ( 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

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

34 DRU - Anaerobic Digester Effluent (ADE): or GRU Effluent: Co-Treatment Reactors (CTR): Constructed Wetland Mesocosms CWM): pH DRU: ~7~ 7.5~ 8 GRU: ~7~ 7.5~ 7 TSS (mg/L) DRU: 239022968 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) Note Methane Flare

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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) DRUControl 0.274 Lime0.287 Iron0.290 GRUControl0.008GRU CTR’s alone:0.003 Lime0.0090.023 Iron0.0100.049

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

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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 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 Laboratory Wetland BiogeochemistrySoil and Water Science Department


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