Nutrients: Site Specific Criteria Can Yield Major Cost Benefits. AWW & WEA 2013 Conference

Transcription

1 Nutrients: Site Specific Criteria Can Yield Major Cost Benefits AWW & WEA 2013 Conference Rex Robbins, PE; Jim Malcolm FTN Associates, Ltd.

2 Presentation Topics Nutrients 101 Numeric Criteria AR Criteria - Permit Limits SSC and AR Historical Option Changes in Permit Limits Can = $$$ Savings for Compliance

3 Nutrients 101 Macronutrients in Aquatic Systems Nitrogen (N) Phosphorus (P) Nutrients are needed for Aquatic Life Too much Aquatic Life = eutrophication

4 Nutrient Affects Aquatic Life Uptake depends on light, oxygen, and availability of nutrients Limiting nutrient Freshwater and estuaries typically phosphorus limited, Marine typically nitrogen limited

5 Nutrient Criteria Clean Water Act requires states to Establish water quality criteria to protect designated uses of waterbodies Set enforceable limits in NPDES permits based on those criteria Criteria can be narrative or numeric Arkansas: narrative criteria for nutrients free from (objectionable, nuisance, )

6 Numeric Criteria are Coming to AR! ADEQ currently developing them.. Surrounding states developing them. (Mississippi TP: mg/l; TN: mg/l) AR Town Branch TMDL In Stream Target of 0.1 mg/l TP (EPA) AR NACA WWTP Permit Limit 0.1 mg/l TP

7 Why Don t We Already Have Nutrient Criteria??

8 AL Prodcution Conventional Pollutant Criteria Development Conventional Pollutant Less is More Conventional Pollutant Concentration

9 Desirable AL Production Nutrient Criteria Development Levels that support and do not impair desirable AL Nutrients Criteria Levels that begin to promote undesirable AL, Benefit Impairment Nutrient Concentration

10 Numeric Nutrient Criteria Will result in Permit Limits on the amount of N and P allowed to be discharged to a waterbody Levels will probably be based on measurable indicators of aquatic health Dissolved oxygen Algae, phytoplankton, periphyton Water clarity

11 Implementation of the Criteria Unknowns How will criteria be written in standards? How will criteria be incorporated into permits? How will monitoring data be collected and assessed?

12 New Water Quality Criteria Lead to New NPDES Permit Limits!!!!

13 You May Have New Permit Limits That You Can t Meet Surprise!

14 Fact or Fiction? New or better treatment is your only option to meet new or more stringent permit limits.

15 Fiction! Many Other Compliance Tools Exist Including: Alternate Engineering: Indirect Discharger Evals/Limits Source Control/Product Substitution Recycle/Reuse Modify the discharge Alternate Discharge Location Site Specific Criteria Site Specific Permit Limits

16 Site Specific?????? Designated Beneficial Uses Were Developed to Meet CWA Goals Aquatic Life Protection / Propagation (Fishable) Recreation in and on the Water (Swimmable) Others.

17 Water Quality Criteria Are Developed to Attain DBUs! Key Points: Criteria for pollutants are usually developed by EPA and usually apply to large geographic areas, Site specific conditions can mitigate adverse effects of pollutants and criteria can be over protective.

18 AR - Long History of SSC to Modify Existing Criteria.. Minerals (sulfate, chloride, TDS) - Based on ER least disturbed streams - POTW, Industrial effluents, reclaimed mine site runoff can easily exceed ER values! Temperature Ambient Temp frequently exceed ecoregional criteria (e.g. 86 F)! Metals: Bioavailabity varies widely with hardness/other factors Nutrients????; Time will tell.

19 (1) DBUs, (2) Criteria and (3) Permit Limits Oh My! Permit Limits are developed to Meet Criteria Permit Limits can be over-protective

20 Example: Dell Power Plant

21 Designated Uses Seasonal Channel Altered Delta Fishery Perennial Channel Altered Delta Fishery Primary and Secondary Contact Recreation Domestic Drinking Water Supply Industrial and Agricultural Water Supply

22 Water Quality Criteria Temperature: 32 C (89.6 F) Delta 5 F TDS: 411 mg/l Sulfate: 37 mg/l

23 Modifications Approved Previous Modified Temperature 89.6 F 95 F Temperature +/- 5 F No delta 5 F TDS 411 mg/l 1,200 mg/l Sulfate 37 mg/l 480 mg/l Drinking Water Use Assigned By Default (not existing) Removed (necessary for TDS and SO4 modifications)

24 Applicability Metals, Nutrients, Minerals, Temp Incorrect 303(d) listings Industrial, Municipal Discharges

25 Criteria Changes Can = Changed Permit Limits so How Can Different Permit Limits Save Me $$$$?

26 Nutrient removal from wastewater

27 Treatment of Nutrients Nutrient Removal from wastewater Biological Chemical Physical (Nutrient Removal, WEF Manual of Practice No. 34)

28 N and P in Raw Sanitary Wastewater Nitrogen 40 mg/l of TN Organic N..15 mg/l Ammonia N 25 mg/l Nitrite...0 mg/l Nitrate..0 mg/l Phosphorus

29 Limits of Technology vs. Criteria Limit of Technology 3 mg/l TN 0.3 mg/l TP (Jeyanayagam, 2005) (WEFTEC mg/l) Criteria TN: mg/l TP: mg/l

30 WWTPs in ARKANSAS Typical systems in AR are not designed for nutrient removal: Aerated Lagoons TN = 14 to 20 mg/l TP = 3 to 5 mg/l Activated sludge TN = 4 to 11 mg/l (with denitrification) TP = 3 to 5 mg/l

31 Nitrogen Removal Nitrification (ammonia is oxidized to nitrate) Autotrophic bacteria do this Requires oxygen and consumes alkalinity (lowers ph) NH 4 + NO 2 - NO 3 -

32 Nitrogen Removal Denitrification (nitrate reduced to N 2 gas) Heterotrophic bacteria do this Anoxic conditions Requires a carbon source Produces alkalinity NO 3 - N 2 (gas)

33 Activated Sludge Systems Single-sludge system w/ no dentrification Pre-denitrification system (MLE)

34 Biological P Removal Phosphorus accumulating organisms (PAOs) Amount of P in Biomass Typical = 1.5 to 2.5% In PAOs = 6 to 8%

35 Chem P Removal Precipitation with a metal salt (aluminum or iron) or lime Lots of sludge Can be added on to existing plants

36 AS System with Chem. P Removal

37 Level Treatment Level Objectives BOD (mg/l) TSS (mg/l) TN (mg N/L) TP (mg/p/l) <30 < <30 < <30 < <30 <30 2 <0.02 Falk, M.W., et al. (2011) Striking a Balance Between Nutrient Removal and Sustainability. WERF Research Project under Nutrient Challenge, NUTR1R06n.

38 What will it Cost? (Capital Costs Only) 1 (No N/P Removal) _ 2 (8 mg/n/l;1 mg P/L) $3.40/gallon 3 (4-8 mg N/L; mg P/L) $5.10/gallon 4 (3 mg N/L; <0.1 mg P/L) $6.00/gallon 5 2 mg N/L; <0.02 mg P/L) $12.50/gallon Falk, M.W., et al. (2011) Striking a Balance Between Nutrient Removal and Sustainability. WERF Research Project under Nutrient Challenge, NUTR1R06n.

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40 Summary Nutrient criteria are coming to AR Dischargers have options for meeting upcoming NDPES permit limits Site-specific criteria may be an option Small changes in NDPES permit limits can = large savings for dischargers. Collaborative solutions are needed

41 Questions? Hopefully You Heard Something Useful