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Ecological Engineering: Nutrient Uptake Patrick Corbitt Kerr University of Notre Dame It has been said that streams are the gutters down which flow the.

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Presentation on theme: "Ecological Engineering: Nutrient Uptake Patrick Corbitt Kerr University of Notre Dame It has been said that streams are the gutters down which flow the."— Presentation transcript:

1 Ecological Engineering: Nutrient Uptake Patrick Corbitt Kerr University of Notre Dame It has been said that streams are the gutters down which flow the ruins of continents. L.B. Leopold et al

2 Stormwater Management: The Industry Direction  Quantity  (-) Water Supply (Irrigation, Drinking Water,…)  (+) Flooding (Rate or Volume?)  Quality  Importance  Safe for humans (Acute vs Chronic)  Ecosystem Conscious  Aesthetics  Components  Groundwater vs Surface Water  Type of Pollutants  Pollutant Source: Urban or Rural  Sediment & Watercourse Stability Image from

3 Stormwater Pollutants  Sediment  Nutrients (Nitrogen, Phosphorus, Organic Matter)  Microorganisms (e.g. Coliform Bacteria)  Toxic Substances  Pesticides  Salt (Chloride)  Oil and Grease (e.g. Polycyclic aromatic hydrocarbons (PAHs))  Heavy Metals (e.g. Lead, Zinc, Copper)  Heat  Litter

4 Nutrients  Nutrients: Chemicals that an organism needs to live and grow.  Macronutrients:  Carbon (C)  Nitrogen (N)  Phosphorus (P)  If the aquatic ecosystem requires nutrients, why then are nutrients considered a pollutant?  An oversupply of nutrients to a certain species can result in excessive growth; thereby choking out other species.  The Solution is …. Balance.

5 Algae (Phytoplankton) Blooms  Upper left: Cyanobacterial (blue-green algal) bloom in the Gulf of Finland region of the Baltic Sea.  Upper right: Dinoflagellate red tide bloom near the Japanese Coastline (Sea of Japan).  Lower left: Cyanobacterial bloom in the St Johns River Estuary, near Jacksonville, Florida.  Lower right: Mixed cyanobacterial-chlorophyte bloom in North Island, New Zealand Image from

6 Hypoxia  Means “Low Oxygen”  Algae blooms consume oxygen  (0 mg/L) is “anoxia”  Called “Dead Zones” because animals can’t survive  Kills mobile animals like fish  Kills shellfish and other less mobile animals  Nursery habitat is destroyed  Releases stored pollutants  Chemical reaction between hypoxic water and bottom sediments  Overall ecosystem is stressed (Birds, mammals, too!) Image from: srwqis.tamu.edu/hot-topics/hypoxia.aspx

7 Gulf of Mexico Hypoxia Image from:

8 The Mississippi River Basin: N & P Yield Image from:

9 Percent N & P Contribution by State Image from:

10 Sources: Nitrogen & Phosphorus Image from:

11  Macro-Scale vs Micro-Scale:  Hydrosphere, Lithosphere, Atmosphere, Biosphere  Water Cycle  Conservation of Mass & Energy  Ecosytem Components:  Solar Energy ( Light / Temperature )  Producers  Consumers  Decomposers  Water  Soil / Water / Air Chemistry The Nutrient (Biogeochemical) Cycle Image from: ga.water.usgs.gov/edu/watercyclehi.html

12 Nutrient Cycling: Carbon  Organic (O)  Has C  Inorganic(I)  Dissolved (D)  Particulate (P) Image from:

13 Nutrient Cycling: Nitrogen  State Changes  Nitrification(Gain O)  De-Nitrification (Lose O)  Fixation ( N 2 Uptake)  Assimilation( NH 4, NO 3 Uptake)  Mineralization  Assimilatory Uptake  Structural Synthesis  Dissimilatory Uptake  Bacteria obtain Energy Image from:

14 Nutrient Cycling: Phosphorus  Uptake  Autotrophic  Heterotrophic  Mineralization  Bacterial Activity  Adsorption  Balance  Water Column  Sediment Imagefrom:

15 Nutrient Transport: Spiraling Concepts and Methods for Assessing Solute Dynamics in Stream Ecosystems Stream Solute Workshop Journal of the North American Benthological Society, Vol. 9, No. 2. (Jun., 1990), pp

16  Ecosystems change spatially  Seeks a dynamic balance between form & function  The watercourse changes  Width, Depth, Velocity, Sediment Load, Canopy Cover, Temperature, Flow Characteristics  The stream community & biogeochemical processes conform to the new structure. River Continuum Concept (RCC)

17 Nutrient Uptake (U) Image from:  Definition: The total flux of nutrient from the water column to the stream bottom, expressed on the basis of stream bottom area (e.g., mg/m²/hr)  Biotic & Abiotic  Element Cycling  Rate  Pathways  Residence Time

18 Biotic Uptake  Stoichiometry of Organic Matter  Redfield Ratio: C:N:P = 106:16:1  Not Phytoplankton  Silica  Diatoms Image from: labs.psc.riken.jp/pnbmrt/Research_English.html

19 Abiotic Uptake  Some nutrients adsorb to sediment particles.  Adsorption capacity varies  By nutrient and chemical state:  Phosphorus (H 2 PO - 4 ) is most adsorptive  By Media:  Capacity dependent on makeup and chemical properties  pH, total and reactive calcium, total and reactive Fe, Al oxide  Capacity also increases as:  Size & Density decreases  Porosity and Surface Area increases  Not Permanent -> Desorption Image from:

20 How does this relate to us as Professional Civil Engineers?

21 The Design Process:  What conditions are we considering?  Existing or Pre-Existing  Proposed or Ultimate  What is our design criteria?  Quantity:  Typically: Peak Discharge (Match α -yr Post to ß-yr Pre)  But sometimes ….Volume  Recharge (Re V ), Channel Protection (CP V ), Overbank Flood Protection (Q p ), Extreme Flood (Q f )  Quality:  Water Quality Standards: What Format?  Waterbody Type or Waterbody Specific?  Concentration, Load, or Indicator (Clarity or Chl-a)?

22 The Water Quality Challenge  Who’s leading the charge?  Environmental Groups  EPA  Coastal States: Maryland, Florida, etc.  Who/What is being targeted?  Point versus Non-Point Sources  Urban Areas (Agricultural/Rural has largely been avoided)  Construction Practices: Erosion & Sediment Control  Stormwater BMPs: New Construction & Retrofits  Stream Restoration  How do we design stormwater BMPs?  Uniform Sizing Criteria: (Performance Based?)  Water Quality Volume (WQ V )

23 WQv ( A Standard Solution?)  Methods:  Post-Conditions vs Pre-Conditions Difference  Post-Conditions Total  Regression Equation: function of P, I, and A  WQ V = [(P)(R V )(A)]/12 Where:  WQ V = Water Quality volume (acre-feet)  P = Precipitation (inches)  Rainfall necessary to facilitate full movement of pollutants (“First Flush”)  A = Drainage Area (acres)  R V = Volumetric Runoff Coefficient = (I)  I = Percent Impervious Area (%)  Function of Load and BMP Performance (Pollutant Specific)

24 The Water Quality Volume  Issues:  Regression equation doesn’t account for non-impervious area  Are nutrient-laden areas being considered?  For storms greater than P, can WQ V be targeted?  Consider a 100% Impervious Site, designed for P = 1”:  P is a function of Duration, Time of Concentration, and Land Cover  Peak Water Quality Flowrate (Q WV ) P = 1”P > 1” 100% Treated Any Duration Duration Dependent WQV”

25 What to do with the Water Quality Volume?  Suppose we account for the “First Flush” and can isolate all the pollutants by that WQ V, what are our goals?  Ideally we wish to TREAT the water?  In Water/Wastewater:  We have effluent criteria defined by concentration and load  We measure (sample) both influent and effluent  We alter it chemically and mechanically  But, most importantly, though, we can remove mass (SLUDGE)  Why is sludge removal so important?  Some pollutants can be broken down but unless N, P, Heavy Metals, etc. are removed from the system and assuming steady flow the load in will equal the load out.  If removal is the ultimate goal, then how?

26 Removing N & P  N & P come in many different forms. Which do we target?  Perhaps, we should first identify ways to remove nutrients, and maybe that will decide for us… Image from:

27 General Ways to Remove Pollutants  Separation is the first step to pollutant removal.  Methods of separation we know from water/wastewater treament:  1) Screening  2) Skimming  3) Settling  4) Filtering  Can’t use active treatment systems or mechanical means  Typically referred to as a Pre-Treatment.  Pollutants are separated WITHIN the system. Full Removal requires maintenance (Typically considerable).  These methods will often FAIL under HIGH flows.

28 Screening  Typically refer to as trash racks  We focus on the Inlet Image from: Image from:

29 Skimming  Solution:  Submerged Outlets  High flow overflow?  Use Bypass Control Structures  Reduces both size of structure and effectiveness Image from: figure4.41.gif Image from:

30 Settling  Theoretical Solutions:  Force it with a vortex  Inhibit (re-)suspension  Slow Flow (Long Release Time)  Not Turbulent (Wide/Deep)  Long Paths (Baffles, Islands, L:W)  Design Options:  SW Manual Criteria  Length to Width Ratio  1.5:1 to 3:1  Forebay  (Typically at least 10% WQ v )  Use Stoke’s Law  Need to know influent load

31 Stoke’s Law Equation:  V S = settling velocity (cm/s)  g = gravity (m/s²)  ρ S and ρ W = densities of the particle and water (g/cm³)  µ = dynamic viscosity  d = effective particle diameter Particle TypeDensity (g/cm³)Diameter (µm) Settling Velocity (m/d) Phytoplankton – – 1.9 Particulate Organic Carbon1.02 – – >64,0.2 - >2.3 Clay Silt

32 Applying Stoke’s Law  Solids Budgeting  Simple Solution  Complex Solution

33 Resuspension  Bed Scour is a function of shear stress  Shear Stress is a function of velocity gradient, therefore consider the :  Velocity of the flow path  Orbital Velocity (from wind forced waves)  Wind Velocity  Depth  Fetch  Affects both aeration and suspension Image from:

34 Sediment Transport  Sediment Balance  Bed Load  Suspended Load  Costly to Model Image from: cals.arizona.edu/.../riparian/chapt4/p7.html Image from: medinaswcd.org/streams.htm

35 Fluvial Geomorphology Image from:

36 Transient Storage  A) Surface Transient Storage (STS)  B) Hyporheic Transient Storage (HTS)  Nutrient Uptake Increases as:  Transient Storage Increases  Geomorphic Features  Hydralic Gradient  Velocity/Flow Decreases  Turbulence Increases  Depth Decreases  Residence Time Increases

37 Surface Transient Storage  Non- Advective:  Stagnant  Turbulent  Boundary Layer  Receives Light  Aerobic

38 Hyporheic Zone  Underground  No Light  Driven by Hydraulic Gradient  Moves Oxygen into Bed/Bank  Leaves Bed/Bank as anaerobic Image from:

39 Filtration versus Infiltration  Filters  Not Vegetated  Replaceable Media  Infiltration  Groundwater Recharge  Reduces Nutrient Load  Leaches Pollutants into GW

40 Outlet Filters  Vertical Perforated Riser  Slow release (Essentially orifice equation times # of holes)  Concentric (Not Focused) Image from:

41 Example of an Underground Sand Filter  Montrose Parkway – Phase I  Urban Setting: No room for pond or above ground BMPs  Solution: Underground Sand Filter… Quality Solution: Quantity SSF: Separator Sand Filter

42 Choosing the best method

43 BMP Performance  How do we measure performance?  Load or Concentration  How do we rate performance?  Reduction % or Final Effluent Result

44 Comparing Pollutant Removal Efficiencies among Different BMPs

45 Dry versus Wet methods  Dry > Wet  Filtration/Infiltration  Groundwater Recharge  In-basin vegetation in addition to perimeter  BioRetention  Dry < Wet  Less effective for oils, greases, & hydrocarbons  Disturbance of Bottom Sediments  Leaching

46 Combination Facilities  2+ facilities  Target different pollutants  Pre-Treat for Next BMP  Start at Source  Grass Channels instead of Curb, Gutter, & Sewers Image from: Image from:

47 Pond Depth (Shallow or Deep)  Shallow:  Pros:  More Vegetation  Higher oxygen content  Greater Wetted Contact Area  Cons:  More bottom disturbance -> Greater Turbidity  Thermal Increase  Wider Pond: Less Canopy Cover  Deep  Pros:  Cooler Water  Less Disturbance  Cons:  Stratification and Anoxia  Less Wetted Contact Area  Less Vegetation

48  State Requirements (Min, Max) (GA)  Max Depth: (GA: 8 ft )  Min Depth: (GA: 3ft to 4ft)  Design for maximum depth to avoid Anoxia (FL)  If TP is known, calculate chyl-a: TP = total P concentration (µg/l) Chyl-a = chlorophyll-a (mg/m³)  Calculate Mean Secchi Disk Depth SD = Secchi disk depth (m)  Calculate Depth of DO  For Deeper Depths Aeration or Mixing is Required Pond Depth Design

49 Maximizing Nutrient Uptake Summary  Pre-Treat  Screen, Skim, Settle, Filter (abiotic Uptake)  Treat (Biotic Uptake)  Healthy Ecosystem  Biodiversity  Vegetation (Diversify)  Plan Form Features (Abnormal Geometry)  Habitat (In-Pond Features)  Pore Diffusivity  Bed/Bank Material  Construction Methods  Can’t rely on maintenance!

50 Case Studies: Austin, TX

51 Case Studies: Auckland, New Zealand

52 Case Studies: St. Paul, MN

53 Case Studies: Aurora, CO

54 Case Studies: Runaway Bay, NC

55 Case Studies: 91

56 Case Studies: 90

57 Case Studies: 77

58 Case Studies: Mosquitos

59 Case Studies: 98

60 Resources

61 National Aquarium


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