Passive Phosphorus Removal Systems

Transcription

1 Passive Phosphorus Removal Systems Chad Penn, Josh Payne, Jeff Vitale: Oklahoma State University Josh McGrath: University of Maryland Delia Haak: Illinois River Watershed Partnership

2 P FILTER BACKGROUND AND BENEFITS

3 Target: Dissolved P Soils built up with legacy P will continue to release dissolved P for many years Conventional best management practices do little for DP Objective: construct P removal structures to trap dissolved P in runoff and tile drainage

4 Mehlich-3 Phosphorus (mg kg -1 ) Need for P filters High soil P concentrations contribute to long-term, slow P leak This is referred to as a legacy P issue Coale, F.J. and R. Kratochvil 2011: Unpublished data

5 Justification of cost for construction Current BMPs only slightly effective for DP losses DP: sustained transport for several years $$ DP: 100% biologically available

6 P Removal Structure Theory High P water PSM layer Clean water is released Drainage layer

7 3 Necessary Components Effective PSM in sufficient quantity P-rich water must flow through PSM Ability to retain and replace PSM

8 Example by-product PSM s Acid mine drainage treatment residuals Drinking water treatment residuals Bauxite mining and production waste (red mud) Fly ash Foundry Sand Steel slag waste Waste recycled gypsum

9 Selection Process for PSMs Material Availability Particle size distribution and bulk density Cost & Transportation Potential contaminants Sorption characteristics Sodium Soluble salts Total, acid soluble, and water soluble heavy metals Hydraulic conductivity Physical Properties

10 Cartridge Filter? Portable, easy to install Does not work! Limited amount of PSM

11 Confined Bed Good for large filter Ideal for drainage swales that require high peak flow and non restricted drainage Achieved through shallow PSM with large surface area

12 3 tons >6.35 mm EAF slag, treated 150 acres, 25% overall dissolved P removal after 8 months Confined Bed Example Structure has handled flow rates over 100 gpm Overflow weir

13 Confined Bed Example Structure re-loaded with >0.5 mm slag 33% overall removal after 18 months Still handles high flow rate Overflow weir

14 Similar to bed, but without confinement Allows large amount of material to be used Use flow control to build head Low cost Probably best option for ditches Tile Drain

15 Easily switch out material Modular design integrates with flow control Agri-Drain Small ditches or pond overflow Drawback: Small amount of material Box Filter

16 Storm Drain Filter

17 P removed (g kg -1 ) Performance and Lifetime It depends: Site conditions PSM Design P concentration (mg L -1 ) Retention time (min)

18 DESIGN GUIDANCE

19 General Design Approach Input Output Site hydrology 1. Peak flow rate 2. Annual flow volume 3. Dissolved P level 4. Max footprint P removal & lifetime 1. Target P removal (%) 2. Target lifetime PSM characterization 1. P sorption 2. Safety 3. Physical properties Design parameters 1. Area 2. Mass of PSM 3. Depth of PSM + + Model

20 Model Verification Ability to predict design curve is key Accuracy of inputs Golf course structure UMD structures on Eastern Shore Pilot scale structure Laboratory flow-through experiments conducted on new materials

21 Pilot Scale Filter

22 Cumulative P removed (mg kg -1 ) Example Pond Filter Data Measured Predicted P added (mg kg -1 )

23 P removed (mg kg -1 ) Example Golf Course Structure P added (mg kg -1 )

24 EXAMPLE DESIGN

25 Design: Poultry farm in OK Green Creek proposed structure location flow direction poultry houses

26 Design: Poultry farm in OK

27 Site Conditions Drainage area: 9 acres Slope: 6% Curve #: 78 Peak flow rate, 2yr-24hr storm: 16 cfs Annual flow volume: 9 acre-ft Typical dissolved P: 1 to 2 mg L -1 Annual dissolved P load: 49 lbs (22 kg) Assumed 2 mg P L -1 Goal: remove 45% of annual P load

28 Sizing the Structure: design curve for potential PSMs Measured directly via flow-through sorption tests or predicted based on chemical and physical properties Unique to each PSM, inflow concentration, and retention time

29 Structure design: impact of PSM characteristics Need to handle peak flow rate Need to handle P load

30 Structure design: impact of PSM characteristics Need to handle peak flow rate Need to handle P load

31 Potential design options to meet given P removal and 16 cfs flow PSM Mass (Mg) Cumulative year 1 removal (%) Lifetime (yrs) Hydraulic conductivity (cm s -1 ) Area (m 2 ) PSM depth (cm) WTR * AMDR Fly ash 3 (plus 95% sand) (mixed with 95% sand) >6.35 cm slag Treated > 6.35 cm slag **

32 Completed Structure

33 Completed Structure

34 Completed Structure

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36 Design: Tile drained field in IN 40 acre tiled drained field to bio-reactor Peak flow rate: 80 gpm Typical P concentration: 0.2 to 0.5 mg L -1 Annual P load: 0.5 kg (from 1 mil L yr -1 ) Hydraulic head: cm (over 90 ft length) Target removal: 3 year lifespan, 25 or 50% Maximum area: 400 sq ft Material: Sieved Slag

37 Design: Tile drained field in IN

38 Design: Tile drained field in IN

39 Design: Tile drained field in IN

40 Design Options: sieved slag Target 25% removal (yr) Mass (tons) Depth (in) Head (in) Peak flow (gpm) Total lifetime (yr) Cumulative removal (%) Area (sq ft) Not enough area

41 Design Options: coated slag Target 50% removal (yr) Mass (tons) Depth (in) Head (in) Peak flow (gpm) Total lifetime (yr) Cumulative removal (%) Area (sq ft) Not enough area

42 Additional Support Design software currently being created Provide interactive design guidance based on user inputs Will be made available to NRCS NRCS Standard will be completed after software is completed Commercialization may be key to dissemination

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44 Comparison to other BMPs In the short term there is no BMP that can appreciably reduce soluble P losses where flow cannot be reduced P mining with hay crops or corn to reduce soil P levels Sharpley et al. (2009): only 4.6 mg/kg decrease per year in Mehlich-3 P with continuous corn Not very fast

45 Comparison to other BMPs Treatment wetlands Require excessive retention time (days), thus requires many acres of space if high flow rates are to be treated inefficient P is not really removed from the system

46 ECONOMICS

47 Economics Example: Westville Metal & custom fabrication: $2677 ¼ carbon steel Slag transportation, sieving, coating: $853 Earth work for pad & berms: $846 Paint, seed, & erosion mat: $613 TOTAL: ~ $5000 Includes profit from private companies except for metal painting and installation Annual renewal estimated at $1213

48 Economics Example: Westville Year $ P removal (lbs.) Cumulative P removal cost ($/lb P)

49 Economics Economics will vary greatly between locations Westville structure could have been constructed for less money by using other materials Consider that it costs a waste water treatment plant dollars/lb P removed Easier to remove P at a high P concentration, point source

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