controlling potw pass-through/interference due to compatible … presentation - option... ·...
TRANSCRIPT
Fishbeck, Thompson, Carr & Huber, Inc.
Controlling POTW
Pass-Through/Interference
Due to Compatible Pollutants
Jerald O. Thaler, P.E.
Option 3
Treatment at POTW
with Excess Capacity
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
Objective
If a POTW has available capacity, determine
how to achieve:
Accommodating special needs of SIUs
Enhancing revenues
Ann Arbor WWTP (Ann Arbor .com)
Using Available Capacity to Accommodate Special Needs of SIUs
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
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
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
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
Traditional Local Limits
MAHL = not-to-exceed mass to protect WWTP
MAIL = portion of MAHL available to SIUs
Allocate MAIL over total SIU flow
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
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
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
Example SAL Procedures
Local Limit (CLCL LIM) = 1,000 mg/L
Surcharge Threshold (CSURCH) = 250 mg/L
Background (CBKGD) = 110 mg/L
Classification for
BOD5
A
B
C
X…
(misc. other) B
where: X - Discharger to be regulated via SAL
Significant Industrial User
Acme Manufacturing
USA Automotive, Inc.
Standard Plating
Smith Foods
Discharge Flow,
gal/day
50,000
100,000
25,000
250,000
75,000
where: A - Surcharging Specific Discharger (>CSURCH & <CLCL LIM)
where: B - Nonsurcharging Specific Discharger (>CBKGD & <CSURCH)
where: C - Nonspecific Discharger (<CBKGD)
METROPOLITAN WWTP
INDUSTRIAL PRETREATMENT PROGRAM
Step 1 – Classify Dischargers
Status of Status ofApproved Approved
MAHL MAIL
Maximum Allowable Headworks Loading (MAHL) 16,500 lb/day
- Safety Factor @ 10% of MAHL 1,650 lb/day
- Background 9.500 mgd @ 110 mg/L 8,710 lb/day
Maximum Allowable Industrial Loading (MAIL) 6,140 6,400 lb/day
- Septage 0.000 mgd @ 1,000 mg/L 0 0 lb/day
- Allocated to SIUs 2,890 2,890 lb/day
Remaining 3,250 3,510 lb/day20% 21% of MAHL
Fraction
Acme Manufacturing 50,000 gpd @ 1,000 mg/L 420 lb./day 7%
USA Automotive, Inc. 100,000 gpd @ 250 mg/L 210 lb./day 3%
Standard Plating 25,000 gpd @ 110 mg/L 20 lb./day <1%
Smith Foods 250,000 gpd @ 1,000 mg/L 2,080 lb./day 34%
… (misc. other) 75,000 gpd @ 250 mg/L 160 lb./day 3%
Allocated to SIUs 2,890 lb./day
X
B
A
B
C
SIU
Classification
Significant
Industrial User
Allocated
Discharge Flow
Allocated
Concentration
Allocated
Discharge Mass
BOD5
METROPOLITAN WWTP
INDUSTRIAL PRETREATMENT PROGRAM
MASS ACCOUNTING FOR
Example SAL Procedures
Step 2 – Check MAHL/MAIL Status
Status of Status ofApproved Approved
MAHL MAIL
Maximum Allowable Headworks Loading (MAHL) 16,500 lb/day
- Safety Factor @ 10% of MAHL 1,650 lb/day
- Background 9.500 mgd @ 110 mg/L 8,710 lb/day
Maximum Allowable Industrial Loading (MAIL) 6,140 6,400 lb/day
- Septage 0.000 mgd @ 1,000 mg/L 0 0 lb/day
- Allocated to SIUs 4,980 4,980 lb/day
Remaining 1,160 1,420 lb/day7% 9% of MAHL
Fraction
Acme Manufacturing 50,000 gpd @ 1,000 mg/L 420 lb./day 7%
USA Automotive, Inc. 100,000 gpd @ 250 mg/L 210 lb./day 3%
Standard Plating 25,000 gpd @ 110 mg/L 20 lb./day <1%
Smith Foods 250,000 gpd @ 2,000 mg/L 4,170 lb./day 68%
… (misc. other) 75,000 gpd @ 250 mg/L 160 lb./day 3%
Allocated to SIUs 4,980 lb./day
BOD5
METROPOLITAN WWTP
INDUSTRIAL PRETREATMENT PROGRAM
MASS ACCOUNTING FOR
Classification Discharge Flow Concentration Discharge MassIndustrial User
SIU Significant Allocated Allocated Allocated
A
B
C
X
B
Example SAL Procedures
Step 3 – Select Appropriate SAL
Using Available Capacity to Enhance Revenues
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
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:
Surcharge Threshold
Should represent “normal” domestic sewage
Set by sampling of background location,
basis of design, and/or literature values
Not same as local limit
Metcalf & Eddy, Inc., Wastewater Engineering, 1991
Pollutant
Medium
Strength
mg/L
High
Strength
mg/L
BOD5 190 350
TSS 210 400
Ammonia-N 25 45
Total-P 7 12
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
BOD5 100% 0.19 0.01-0.50
TSS 98% 0.17 0.01-0.73
Ammonia-N 31% 0.41 0.14-4.98
Total-P 86% 1.51 0.27-4.79Complied by Mr. Jack Keys, ca. 2000
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
New Surcharge Rate Method
Apply state-of-the-art O&M Cost Software to
simulate effect of load increases
From results, calculate corresponding
surcharge rate
O&M Cost
Software
0
1
2
3
4
5
0 1 2 3 4
lb/d
ay
0
1
2
3
4
5
0 1 2 3 4
$/d
ay
0
1
2
3
4
5
0 1 2 3 4lb/day
$/d
ay
slope (Δ$/Δlb) = surcharge rate
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
Case Study -- Ionia WWTP
System Configuration
CapdetWorks®
Case Study -- Ionia WWTP
O&M Cost Breakdown
Case Study -- Ionia WWTP
Load Increase Simulations
BOD5
+0
+50
+100
+150
+0 +250 +500 +750
Nondomestic User Loading (lb/day)
O&
M C
ost ($
/da
y)
Slope ($/lb) = 0.11
TSS
+0
+50
+100
+150
+0 +250 +500 +750
Nondomestic User Loading (lb/day)
O&
M C
ost ($
/da
y)
•
Slope ($/lb) = 0.22
Ammonia-N
+0
+25
+50
+75
+0 +30 +60 +90
Nondomestic User Loading (lb/day)
O&
M C
ost ($
/da
y)
•
Slope ($/lb) = 0.22
Total-P
+0
+25
+50
+75
+0 +5 +10 +15
Nondomestic User Loading (lb/day)
O&
M C
ost ($
/da
y)
Slope ($/lb) = 4.43
Case Study -- Ionia WWTP
Summary
Observations Low cost to treat BOD5, TSS, and Ammonia-N
High cost to treat Total-P
Previously overcharging for BOD5 and TSS
Parameter Previous
Surcharge Rate $/lb
Updated Surcharge Rate
$/lb
BOD5 0.50 0.11
TSS 0.50 0.22
Total-P -- 4.43
Ammonia-N -- 0.22
Example SAL/Surcharge Revenue
Allocated Flow = 250,000 mgd
Surcharge Rate = $0.20 /lb
Extra-Strength BOD5 Surcharge – Smith Foods
METROPOLITAN WWTP
$0
$10,000
$20,000
$30,000
$40,000
0 500 1,000 1,500 2,000 2,500
Mo
nth
ly C
har
ge
Discharge Concentration, mg/L
CS
AL
CL
CL
LIM
CT
HR
ES
H
CB
KG
D
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
Questions & Discussion
Michigan Residents Are Stewards for
20% of the Earth’s Usable Fresh Water
NASA
Fishbeck, Thompson, Carr & Huber, Inc.
Thank You!