Controlling POTW Pass-Through/Interference Due to Compatible Pollutants

Transcription

1 Fishbeck, Thompson, Carr & Huber, Inc. Controlling POTW Pass-Through/Interference Due to Compatible Pollutants Option 3 Treatment at POTW with Excess Capacity Jerald O. Thaler, P.E.

2 The Captive Loading Conundrum Many WWTPs experiencing lower flows and loads, leaving available capacity Many WWTPs also have local limits which are: Uniform not-to-exceed concentrations Applied to all nondomestic users, whether or not they discharge the particular pollutant Result = captive loading (on paper) that cannot be accessed

3 Objective If a POTW has available capacity, determine how to achieve: Accommodating special needs of SIUs Enhancing revenues Ann Arbor WWTP (Ann Arbor.com)

4 Using Available Capacity to Accommodate Special Needs of SIUs

5 Special Allocation Limits (SALs) Releasing captive loading via SALs can: Assist industries with special needs Promote local economy and protect jobs Improve asset utilization SALs most applicable to compatible pollutants Treatable via existing system Generally safe from toxic overloading

6 Special Allocation Limits (SALs) Extension of traditional local limits Option to allow alternate user-specific limits At discretion of WWTP management Provides ultimate in allocation flexibility Rapidly gaining acceptance in State Ann Arbor Bay City Flint Genesee County Lansing Wyoming

7 Current Example #1 Dairy facility considered locating in community Requested applicable local limits Assessed need and cost of pretreatment system Decided to instead locate in Indiana WWTP has available capacity To improve economic development opportunities in future, now implementing SALs

8 Current Example #2 Existing landfill expanding in community Involved major capital investment Would require expensive pretreatment system to meet ammonia local limit WWTP has available capacity To subcontract ammonia treatment to WWTP, now implementing SALs

9 Traditional Local Limits MAHL = not-to-exceed mass to protect WWTP MAIL = portion of MAHL available to SIUs Allocate MAIL over total SIU flow

10 SAL-based Local Limits Set aside portion of MAIL as reserve Allocate remaining MAIL over total SIU flow If assigned to SAL, deduct excess loading from reserve

11 USEPA Position on SALs May select any allocation method producing enforceable local limits which: Prevent pass-through and interference Comply with prohibitions in Federal regulations Subject to review by approval authority

12 MDEQ Position on SALs Legal authority in Sewer Use Ordinance Constraints Total influent mass cannot exceed MAHL Total allocated mass cannot exceed MAIL Assigned limit cannot exceed any applicable CSL Important to have accurate and up-to-date MAHLs/MAILs Approvable written procedures

13 Example SAL Procedures Step 1 Classify Dischargers METROPOLITAN WWTP INDUSTRIAL PRETREATMENT PROGRAM Local Limit (C LCL LIM ) = 1,000 mg/l Surcharge Threshold (C SURCH ) = 250 mg/l Background (C BKGD ) = 110 mg/l Significant Industrial User Acme Manufacturing USA Automotive, Inc. Standard Plating Smith Foods (misc. other) Discharge Flow, gal/day 50, ,000 25, ,000 75,000 Classification for BOD 5 A B C X B where: A - Surcharging Specific Discharger (>C SURCH & <C LCL LIM ) where: B - Nonsurcharging Specific Discharger (>C BKGD & <C SURCH ) where: C - Nonspecific Discharger (<C BKGD ) where: X - Discharger to be regulated via SAL

14 Example SAL Procedures Step 2 Check MAHL/MAIL Status SIU Classification A B C X B Status of Status of Approved Approved MAHL MAIL Maximum Allowable Headworks Loading (MAHL) 16,500 lb/day - Safety 10% of MAHL 1,650 lb/day - Background mg/l 8,710 lb/day Maximum Allowable Industrial Loading (MAIL) 6,140 6,400 lb/day - Septage ,000 mg/l 0 0 lb/day - Allocated to SIUs 2,890 2,890 lb/day Remaining 3,250 3,510 lb/day 20% 21% of MAHL Significant Industrial User METROPOLITAN WWTP INDUSTRIAL PRETREATMENT PROGRAM MASS ACCOUNTING FOR BOD 5 Allocated Discharge Flow Allocated Concentration Allocated Discharge Mass MAIL Fraction Acme Manufacturing 50,000 1,000 mg/l 420 lb./day 7% USA Automotive, Inc. 100, mg/l 210 lb./day 3% Standard Plating 25, mg/l 20 lb./day <1% Smith Foods 250,000 1,000 mg/l 2,080 lb./day 34% (misc. other) 75, mg/l 160 lb./day 3% Allocated to SIUs 2,890 lb./day

15 Example SAL Procedures Step 3 Select Appropriate SAL METROPOLITAN WWTP INDUSTRIAL PRETREATMENT PROGRAM MASS ACCOUNTING FOR BOD 5 Status of Status of Approved Approved MAHL MAIL Maximum Allowable Headworks Loading (MAHL) 16,500 lb/day - Safety 10% of MAHL 1,650 lb/day - Background mg/l 8,710 lb/day Maximum Allowable Industrial Loading (MAIL) 6,140 6,400 lb/day - Septage ,000 mg/l 0 0 lb/day - Allocated to SIUs 4,980 4,980 lb/day Remaining 1,160 1,420 lb/day 7% 9% of MAHL SIU Significant Allocated Allocated Allocated Classification Industrial User Discharge Flow Concentration Discharge Mass A B C X B MAIL Fraction Acme Manufacturing 50,000 1,000 mg/l 420 lb./day 7% USA Automotive, Inc. 100, mg/l 210 lb./day 3% Standard Plating 25, mg/l 20 lb./day <1% Smith Foods 250,000 2,000 mg/l 4,170 lb./day 68% (misc. other) 75, mg/l 160 lb./day 3% Allocated to SIUs 4,980 lb./day

16 Using Available Capacity to Enhance Revenues

17 Surcharges with SALs Extra-strength surcharges recover cost to treat concentrated wastes Not penalty or fine Use SAL as basis for calculating surcharge Condition of agreement Subcontracting portion of treatment capacity Often less expensive than pretreatment

18 Extra-Strength Surcharges Applicable only for compatibles Basis Threshold concentration (mg/l) Surcharge rate ($/lb) Example Assuming 250 mg/l threshold and $0.20/lb rate, surcharge for SIU discharging 0.25 mgd at 1,000 mg/l:

19 Surcharge Threshold Should represent normal domestic sewage Set by sampling of background location, basis of design, and/or literature values Pollutant Medium Strength mg/l High Strength mg/l BOD TSS Ammonia-N Total-P 7 12 Not same as local limit Metcalf & Eddy, Inc., Wastewater Engineering, 1991

20 Surcharge Rates Represent incremental treatment cost over normal domestic waste Important to have accurate and up-to-date representation of O&M costs MWEA IPP Committee Survey Pollutant POTWs with Surcharge (N=49) Median Rate $/lb Range of Rates $/lb BOD 5 100% TSS 98% Ammonia-N 31% Total-P 86% Complied by Mr. Jack Keys, ca. 2000

21 Surcharge Rates Wide range in survey was surprise Traditional calculation approach Rule-of-thumb estimates Surveys of other communities Assumed cost breakdown factors New method needed Improve accuracy; more site-specific Straightforward updates

22 lb/day $/day $/day New Surcharge Rate Method Apply state-of-the-art O&M Cost Software to simulate effect of load increases O&M Cost Software From results, calculate corresponding surcharge rate slope (Δ$/Δlb) = surcharge rate lb/day 3 4

23 O&M Cost Software Selected CapdetWorks (Hydromantis, Inc.) Wide range of unit operations for wastewater and biosolids Specify system configuration and influent quality, obtain: Steady state mass balance, with recycle streams Detailed O&M cost breakdown Windows-based; user friendly

24 Case Study -- Ionia WWTP System Configuration CapdetWorks

25 Case Study -- Ionia WWTP O&M Cost Breakdown

26 O&M Cost ($/day) O&M Cost ($/day) O&M Cost ($/day) O&M Cost ($/day) Case Study -- Ionia WWTP Load Increase Simulations BOD 5 TSS Slope ($/lb) = Slope ($/lb) = Nondomestic User Loading (lb/day) Nondomestic User Loading (lb/day) Total-P Ammonia-N Slope ($/lb) = Slope ($/lb) = Nondomestic User Loading (lb/day) Nondomestic User Loading (lb/day)

27 Case Study -- Ionia WWTP Summary Observations Parameter Previous Surcharge Rate $/lb Updated Surcharge Rate $/lb BOD TSS Total-P Ammonia-N Low cost to treat BOD 5, TSS, and Ammonia-N High cost to treat Total-P Previously overcharging for BOD 5 and TSS

28 Monthly Charge Example SAL/Surcharge Revenue METROPOLITAN WWTP Extra-Strength BOD 5 Surcharge Smith Foods Allocated Flow = 250,000 mgd Surcharge Rate = $0.20 /lb $40,000 $30,000 CBKGD CTHRESH CLCL LIM CSAL $20,000 $10,000 $ ,000 1,500 2,000 2,500 Discharge Concentration, mg/l

29 Perspective SALs can release captive loading Still protect against pass-through and interference Promote local economy/jobs by assisting SIUs with special needs Surcharges combined with SALs can enhance revenues Use SAL as basis for surcharge (i.e., subcontracting portion of treatment capacity) Important to have accurate and up-to-date MAHLs/MAILs and surcharge rates

30 Questions & Discussion Michigan Residents Are Stewards for 20% of the Earth s Usable Fresh Water NASA

31 Fishbeck, Thompson, Carr & Huber, Inc. Thank You!