### Memorandum 20 February 2007 Page 1

TO: Airport Deicing Administrative Record

FROM: Mary Willett and Mark Briggs, ERG

DATE: August 2010

SUBJECT: Estimated Capital and O&M Costs for Anaerobic Fluid Bed Treatment of

ADF Contaminated Stormwater

EPA and ERG collected both influent and effluent samples from the anaerobic fluid bed (AFB) treatment system installed at the Albany International Airport in Albany, New York. The actual sampling data is provided in the Albany Sampling Episode Report. Based on the removal efficiency of the AFB for many of the pollutants of concern (POCs) and its demonstrated performance at two airports (Albany and Akron),

EPA and ERG believe the AFB is one of the viable treat ment alternatives for stormwater contaminated with aircraft deicing fluid (ADF). This memorandum pres ents the methodology that will be used to estimate costs for airports to install and operate ABF reacto rs to treat stormwater contaminated with ADF.



### AFB Technology Description

The AFB treatment system uses a vertical, cylindrical tank in which the ADF contaminated stormwater is pumped upwards through a bed of granular activated carbon -- small pieces with irregular surfaces -- at a velocity sufficient to fluidize, or suspend, the medi a. Treatment of organic carbon in the ADF contaminated stormwater comes via a thin film of microorganisms that grows and coats each granular activated carbon particle, providing a vast surface area for biological growth. The anaerobic microorganisms occur naturally in sediment, peat bogs, cattle intestines, and even brewer's yeast. Breakdown products from the AFB treatment system include methane, carbon dioxide and new biomass. Effluent from the AFB can be discharged to a local POTW or, in most cases, directly to surface water.

The range of influent soluble COD concentrations that can be efficiently treated by an AFB system is approximately 2,000 to 128,000 mg/L. For both the low concentration threshold and high concentration threshold, the AFB system can manage brief excu rsions outside the 2,000 to 128,000 mg/L range. However, the treatment for high concentrations can not be sustained for long. EPA understands this concentration range should be used as a guide for sel ecting an appropriate treatment technology for ADF contaminated runoff. For example, for concentra tions greater than 128,000 mg/L COD (approximately 8% propylene glycol), recycling technologies such as evaporation would be a more appropriate choice 1

.

AFB treatment reactors are designed to operate at a near constant influent COD load. Operation at a near

constant COD load results in a more stable bacter ial population, improving the treatment efficiency and increasing the predictability of the effluent quality. Op erating AFB systems to treat collected deicer runoff in an aviation setting, as opposed to other industrial settings, requires additional control measures to achieve

near constant COD load because of the wide fluctuati on in COD influent concentration. Simple storagebased equalization, although important in the desi gn of the overall treatment system, may not provide a

1 Airport Council International – North America comments on EPA’s Proposed Rule for Effluent Guidelines for the Airport Deicing Category.

### Memorandum August 2010 Page 2

sufficient dampening of concentrations to allow stead y-state operation. Therefore, added controls are required that are designed so that influent COD con centrations are measured on an ongoing basis and the influent flow rates to the AFB are adjusted to achieve the desired COD loading.

Treating wastes using an anaerobic biological system as compared to an aerobic system offers several advantages. The anaerobic system requires much less energy since aeration is not required and the anaerobic system produces less than 50 percent of the sl udge of an aerobic process. In addition, because the biological process is contained in a sealed reactor, odors are eliminated. Figure 1 is a diagram showing the major components of a typical AFB treatment system 2

.

Figure 1. Typical Anaerobic Fluid Bed Trea tment System for Treatment of Stormwater Contaminated by ADF

Figure 2 is a process flow diagram showing how an AF B treatment system has been integrated into an existing airport for treatment of ADF contaminated storm water 3 . For this airport, ADF contaminated stormwater was collected at the deicing pads and deli vered to mixed equalization tanks which dampen flow

2 US Department of Defense, ESTCP, Mineralization of TNT, RDX, and By-Products in an Anaerobic Granular

Activated Carbon Fluidized Bed Reactor, April 2003.

3 Rick McQueen and Tim Arendt, Development of a Dicer Management System for Akron-Canton Airport

### Memorandum August 2010 Page 3

and concentration excursions. ADF contaminated st ormwater is then pumped from the equalization tanks to the AFB reactors for removal of COD. Although Figure 2 shows two mixed equalization tanks, airports have the flexibility to install any combination of tanks or stormwater ponds to provide adequate equalization prior to AFB treatment. In addition, th e AFB reactor treatment system consists of two AFB reactors and two media-solids separation units. Th e paring of AFB reactors and media-solids separation units allows the system to be operated in either pa rallel or series modes to support treatment requirements

under different conditions. The use of two reactors is also important to achieve redundancy. The size and cost of the reactors and separators have the most di rect relationship to COD load removed of the various
system components 4 . Other cost components included with the overall cost of the AFB treatment reactor system include activated carbon media, interior suppor t systems, treatment building, and exterior treatment
support systems.

Figure 2. Deicer Management Process Block Diagram



### Available Capital Cost Data

Two airports have provided insta lled capital and operating costs for AFBs to treat ADF contaminated stormwater; Albany International Airport (Albany) and the Akron-Canton Airport (Akron) in Canton, Ohio. According to Albany, the installed cost fo r their deicing stormwater treatment system is approximately $8.1 million dollars (2006 $) 5 . This cost does not include equalization tanks or ponds prior to the AFB, additional storm water piping to transfer ADF impacted stormwater from areas of generation to the storage tanks or ponds, or purchase of additional land to accommodate the AFB treatment reactors. These additional costs (see memorandums on tank costs and pi ping costs), must also be added to the total

4 Airport Council International – North America comments on EPA’s Proposed Rule for Effluent Guidelines for the Airport Deicing Category.

5 Installed cost for treatment system were verbally provided by Mark Sobel during the Albany Sampling Episode. Costs were escalated by 18.07 percent to adjust costs from 1999 dollars to 2006 dollars using Bank of Canada Consumer Price Index Calculator (http://www.b ankofcanada.ca/en/rates /inflation_calc.html). North Deicing

Pad

South Deicing

Pad BOD Monitoring/

Flow Diversion

Storage

Tank Storage

Tank

Anaerobic Fluidized

Bed Reactor Treatment System

To Stream

### Memorandum August 2010 Page 4

cost for a complete AFB treatment system. The Albany treatment system is designed to treat approximately 5,200 lbs/day of chemical oxygen demand (COD) at an average influent concentration of 5,000 mg/L. The Akron AFB reactors are designed to treat approximately 3,400 lbs/day of COD at an average influent concentration of 19,000 mg/L. Based on the design C OD loading and average influent concentration, the Akron AFB treatment system can process approximately 21,600 gal/day (15 gal/min) of ADF contaminated stormwater. Installed capital costs for the AFB treatment system at Akron is estimated to be approximately $3.3 million (2006 $), and does not include collecti on and storage costs. Table 1 shows the design information for both the Albany and Akron AFB treatment systems 6 . The information provided in Table 1 shows the Akron-Canton AFB system is designed for a lower COD loading than Albany, but a higher COD and propylene glycol concentration. Design loading rates (lbs COD/ft 3 media) for Akron are also lower than the actual loading rates at Albany.



### Table 1. Akron-Canton Airport Treatment System Design Basis Versus Albany AFB 6

Parameter Akron-Canton AFB Design Albany International Airport

Performance Data Load 3,400 lbs COD/day 2,000 lbs PG/day 5,200 lbs/day COD 3,100 lbs/day PG/day Flow Rate 15 gpm 100 gpm Influent Concentrations 19,000 mg/L COD 11,120 mg/L PG 5,000 mg/L COD 3,000 mg/L PG Effluent Concentrations <340 mg/L COD < 1 mg/L PG 500 mg/L TSS (from reactors) 50 mg/L TSS (after solids removal) <340 mg/L COD <1 mg/L PG 200 mg/L TSS

Number of Reactors 2 2

Reactor Dimensions 10 feet di ameter x 32 feet high 14 f eet diameter x 32 feet high
Volume Per Reactor 2,515 cu bic feet 3,425 cubic feet

Methane Production Rate 6.1 cubic feet/lb COD removed @

80 o F 6.75 cubic feet/lb COD removed @

80 o F PG: Propylene Glycol



### Anaerobic Fluid Bed Capital Cost Methodology

As indicated in industry comments to the proposed rule, the capital cost approach which uses a linear relationship between ADF use and ADF percent capture to predict costs does not consider minimum capital costs for small systems or the economy of scale for larger systems. All AFB treatment systems, regardless of size, will require basic components such as chemical dosing systems, gas handling systems, sludge handling systems, storage tanks, in-line monitoring equipment, and process control systems. For many of these components, cost is independent of treatment system size 7

.

6 Rick McQueen and Tim Arendt, Development of a Dicer Management System for Akron-Canton Airport

7 Airline Transport Association of Amer ica, Inc. comments on EPA’s Proposed Rule for Effluent Guidelines for the Airport Deicing Category.

### Memorandum August 2010 Page 5

To assist EPA with developing costs for small AFB treat ment reactors, industry developed a cost curve that shows a more appropriate genera l relationship between cost and COD load for Primary Treatment Components for systems designed to treat between 500 and 7,000 lbs/day of COD. As shown in the figure below that was provided in industry comments 8 (Figure 1), the cost per pound of COD removal increases rapidly for smaller load removal systems because of the economy of scale with the reactor and separator system, and the cost for support buildings and facilities is relatively constant and not tied to COD loading.



### Figure 1. AFB Reactor Capital Cost for Treating

ADF Contaminated Stormwater

y = 275101x -0.6279

0 1000 2000 3000 4000 5000 6000 7000

0 2000 4000 6000 8000

COD Loading (lbs/day)Capital Cost ($/lbCOD/day)

Using the equation in Figure 1, EPA can roughly pred ict the installed capital cost for an AFB reactor (excluding storage, collection, and possible land costs) if the COD loading is known. The example below shows how the cost model will estimate costs for an AFB treatment system.



### Installed Capital Cost Example:

Applied ADF (Type 1 propylene gl ycol): 417,000 gallons/season 9
ADF/COD Conversion Factor: 14.28 lbs COD/gal Type I ADF Estimated ADF Capture Efficiency for Block and Pump System: 40 percent Treatment System Operating Period: 194 days/yr 10

Avg. COD Loading = 417,000 gal/season x 14.38 lbs C OD/gal x 0.40 x 1/194 days = 12,363 lbs COD/day

Cost for COD Removal: 275,101 x (12,363) -0.6279 = $741/lb COD/day

Installed Capital Cost for AFB: 12,363 lb s COD/day x $741/lb COD/day = $9.2 million

8 Airport Council International – North America comments on EPA’s Proposed Rule for Effluent Guidelines for the Airport Deicing Category.

9 Average annual applied ADF from all airports reporting to questionnaire

10 Average operating days per year provided by Albany International Airport from 1998 to 2006

### Memorandum August 2010 Page 6

For the airport costing model, the amount and type of ADF applied, and the deic ing season operating period will be obtained from the survey database. The estimat ed ADF capture efficiency will vary depending of the type of collection method. For example, airports that utilize centralized deicing pads have an estimated capture efficiency of approximately 60 percent 11 . If the airport uses a storm sewer block-and-pump type system and glycol collection vehicles (GCVs), the estim ated capture efficiency will be approximately 40
percent 12 . If an airport only uses GCVs, the estimated captu re efficiency will be approximately 20 percent.



### Annual Operating and Maintenance Costs

Annual operating and maintenance (O&M) costs were provided for both the Akron and Albany treatment reactors. According to Albany, thei r annual O&M cost is approximately $510,000/year to operate the AFB. Akron has recently constructed their AFB and does not have actual operating data. Akron provided estimated annual O&M costs to be $195,000/year. Si nce annual operating costs for the AFB are directly

related to the annual amount of ADF use and the capture percentage, ERG decided to normalize annual AFB reactor annual operating costs to these two factors. Table 3 shows the AFB reactor annual O&M costs normalized to annual ADF usage for Albany and Akron.

Table 3. Normalized Annual O&M Costs for the Anaerobic Fluid Bed Reactors

Annual

ADF

Use (gal/yr) Estimated

Percent Capture 1 Annual ADF Captured Annual O&M

Cost (2006 $/yr) 1 Normalized

Annual

O&M Cost ($/gal ADF recovered) Albany 125,775 92 115,713 $510,000 $4.40 Akron 60,264 60 36,200 $195,000 $5.39 Average: $4.90 1. Airport deicing loadings database

To estimate annual costs, the annual ADF use will be multiplied by the percent capture and the average

annual O&M cost as shown below.

Annual AFB Treatment Reactor O&M: ADF Use (gal/yr) x Percent Capture x $4.90



### Annual O&M Cost Example:

Applied ADF (Type 1 propylene gl ycol): 417,000 gallons/season 13
Estimated ADF Capture Efficiency for Block and Pump System: 40 percent Annual O&M Cost: 417,000 gal x 0.4 x 4.90 = $816,000/year

11 Average capture efficiency for Albany, Denver an d Pittsburgh airports having centralized deicing.

12 General Mitchell International Airport WPDES Permit Requirement.

13 Average annual applied ADF from all airports reporting to questionnaire

### Memorandum August 2010 Page 7

The annual O&M costs in the above example do not include costs for collection, transfer or storage of the

ADF contaminated stormwater.



### Cost Methodology Limitations

EPA recognizes that using the number of operating days in the equation to calculate COD load to the AFB and ultimately estimate costs is simplistic. The size of the actual treatment system at any specific airport will depend on a variety of factors such as method of stormwater collection a nd frequency, duration and intensity of deicing events, and ge neral airport operations. Depending on these factors, the AFB treatment system design engineers and airport management will n eed to make trade-offs between the size of treatment and storage. EPA is not attempting to design an AFB treatment system for any specific airport, but is instead using limited information such as annual ADF usage to predict estimated capital and operating costs

to within + 30% of actual costs. EPA recognizes that specific airport constraints may underestimate or overestimate costs for AFB treatment systems, but wh en taken as a whole for the entire industry, costs

should be within + 30% of actual costs.