Bioavailable Phosphorus in Advanced Phosphorus Removal Facility Effluent
Bioavailable Phosphorus in Advanced Phosphorus Removal Facility Effluent Phase II Study Bo Li, Michael T. Brett Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington 98195, USA; libo@u. washington. edu
INTRODUCTION • Effluent total phosphorus (TP) concentration 3 mg/L 250 mg/L!! 200 mg/L 100 mg/L 500µg/L 50µg/L 20µg/L What is left here? ?
INTRODUCTION • Phosphorus Characterization – Common Operational Categories: • • Total Phosphorus (TP) Total Reactive Phosphorus (TRP) Soluble Reactive Phosphorus (SRP) etc…. However…. These are all based on chemical analysis…
INTRODUCTION • Definition of Bio-available phosphorus (BAP) Phosphorus can be utilized by algae • Phosphate (PO 4 • …. -3) Recalcitrant P Inorganic P • Apatite • Al. PO 4 • Fe. PO 4 Organic P • Polyphosphate • Inositol hexakisphophate • L-α-phosphatidyl choline • phosphoenol pyruvate
METHODS PHASE I STUDY – Spokane Region • • Spokane City Pilot Plant City of Coeur d’Alene Post Falls Liberty Lake Hayden Area Regional Sewer Board Inland Empire Paper Spokane River
PHASE I RESULTS – Effluent TP vs. BAP% • Previous study on effluent TP vs. BAP% – Spokane City Pilot Plant (Three alum additions + filtration process) A very strong statistical correlation between the effluent TP and BAP% KEY NOTE • As more chemicals were added, the BAP% in the effluent declined.
PHASE I RESULTS – Effluent TP vs. BAP% • P bioavailability in Spokane Regional WWTP effluents KEY NOTE • • BAP% varied in effluents from different advanced nutrient removal facilities Less than 60% of P in the effluents are bioavailable.
METHODS WERF national • 21 P species – inorganic P, humic substances • 75 samples from 17 Plants Treatment Process Category EBPR without chemical addition MBR Processes Single stage tertiary Dual stage tertiary *EBPR: Enhanced Biological P removal *MBR: Membrane Biological Reactor Plants 3 2 6 6 Chemical Addition √ √ √
WERF national RESULTS – P species • Bioavailability of P species: P Species Reactivity Bioavailability Al-P, Fe-P 90% Apatite DNA, RNA Humic Substances KEY NOTE ≈15% • Not all P are created equal • Can’t estimate Bioavailable P merely based on chemical analysis
WERF national RESULTS – Effluent TRP vs. BAP RESULTS • Find the best predictor of BAP – TRP vs. BAP KEY NOTE • TRP is a conservative measure of BAP! *TRP: Total Reactive P
WERF national RESULTS –– Effluent BAP% TRP vs. BAP TP RESULTS • BAP% & TP results KEY NOTE • Intensive chemical P removal processes were used to achieve low TP concentrations.
PHASE IICONCLUSIONS STUDY – Objective 1 Lake Spokane CE-QUAL-W 2 model • CBODP – Phosphorus associated with Carbonaceous Biochemical Oxygen Demand (CBOD) BAP = CBODP*(1 -e-kt) • Assumptions: – CBODP = TP – SRP – k. CBODP = k. TP-SRP *SRP: Soluble Reactive P
PHASE CONCLUSIONS II STUDY– Objective 1 Lake Spokane CE-QUAL-W 2 model CBODP Decay rate (k. CBODP) Corresponding Source Point Sources Non-Point Sources Decay rate, day-1 Liberty Lake WWTP Spokane WWTP Coeur D‟Alene WWTP Post Falls STP Inland Empire Paper Kaiser Aluminum Hayden POTW summer discharge (for scenarios) 0. 0456 0. 0736 0. 0792 0. 066 0. 0186 0. 1275 0. 0838 AVE 0. 07 Organic matter from Washington Tributaries Lake Coeur D‟Alene CBOD 0. 066 0. 13 AVE 0. 10 0. 0838
PHASE IICONCLUSIONS STUDY – Objective 1 • Objective 1: Determine dissolved phosphorus mineralization rates • Hypothesis: The mineralization rate for the recalcitrant dissolved P for Spokane region WWTP effluents is likely to be different with the original value assumed by current TMDL model. • Task: The algal dissolved P uptake experimental design can determine conservative dissolved organic P mineralization rates for any Spokane region effluent type. These mineralization rates can be integrated into the current Long Lake TMDL model.
PHASE CONCLUSIONS II STUDY– Objective 1 • Objective 1: Determine dissolved phosphorus mineralization rates • Experimental Design: Sample Autoclaved P Bioassay Dissolved P analysis (Days 0, 1, 2, 4, 8, 14 and 21) Dissolved P mineralization rate Selenastrum capricornutum Initial concentration: 200, 000 cells/ml. Incubate for 21 days. Continuous Illumination Temperature: 24 ± 2ºC Shake at 110 rpm.
PHASE CONCLUSIONS II STUDY– Objective 1 • Objective 1: Determine dissolved phosphorus mineralization rates • Experimental Design: Sample Autoclaved P Bioassay Dissolved P analysis (Days 0, 1, 2, 4, 8, 14 and 21) Dissolved P mineralization rate BAP = BAP%*TDP*(1 -e-kt) BAP%, K *TDP: Total Dissolved P
PHASE CONCLUSIONS II STUDY– Objective 1 • Objective 1: Determine dissolved phosphorus mineralization rates • Experimental Design: Sample Autoclaved P Bioassay Dissolved P analysis (Days 0, 1, 2, 4, 8, 14 and 21) Dissolved P mineralization rate BAP% = 75%, k = 1. 1 day-1 BAP% = 43%, k = 1. 5 day-1
PHASE CONCLUSIONS II STUDY– Objective 2 • Objective 2: Resolving issues on bioassay methods from the Phase I Spokane BAP study • Hypothesis: Ecology and EPA concerned that some of the very low effluent %BAP results we reported were at least partially a result of nutrient co-limitation (e. g. , by nitrogen) and/or effluent toxicity. • Task: We will conduct experiments to determine whether the low %BAP we have previously determined for Spokane region dischargers is partially an artifact of nutrient colimitation and/or effluent toxicity.
PHASE CONCLUSIONS II STUDY– Objective 2 • Objective 2: Resolving issues on bioassay methods from the Phase I Spokane BAP study • Experimental Design: amended with all of other nutrients Sample amended with all of other nutrients +P P Bioassay Bioavailability of P in the effluents
PHASE CONCLUSIONS II STUDY– Objective 3 • Objective 3: The role of Humics in dissolved nutrient recalcitrance • Hypothesis: It is hypothesized that both recalcitrant dissolved organic nitrogen (r. DON) and dissolved organic P (r. DOP) will be associated with large molecular weight size fractions, (> 10 kilo Daltons; k. Da). • Task: We will use ultra-filtration to size fractionate the "dissolved" or colloidal portion of effluents with a high proportion r. DON and r. DOP to determine whether nutrient recalcitrance is associated with a high proportion of nutrients in the large molecular weight size range associated with colloidal humic substances (i. e. , > 10 k. Da).
PHASE CONCLUSIONS II STUDY– Objective 3 • Objective 3: Comparison of the humic hypothesis for r. DON and r. DOP • Experimental Design: Sample Ultrafiltration (3, 10, 30 and 100 k. Da) Filtrate P and N analysis DON and DOP concentration in each size range
PHASE CONCLUSIONS II STUDY– Objective 3 • Objective 3: Comparison of the humic hypothesis for r. DON and r. DOP • Experimental Design: Sample Ultrafiltration (3, 10, 30 and 100 k. Da) Filtrate P and N analysis DON and DOP concentration in each size range Problem: 3 k. Da membrane might filter out some fractions of PO 4
ACKNOWLEDGEMENTS Water Environment Research Foundation (WERF) Nutrient Challenge Program Spokane River Stewardship Partners (SRSP)
QUESTIONS?
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