MEMORANDUM 

TO: Steam Electric Rulemaking Record 

FROM: Mark Briggs and Danielle Lewis, ERG

DATE: September 30, 2015

SUBJECT: Analysis of Polishing Filter Costs for FGD Effluent 

Per EPA’s request, ERG prepared an estimate of the capital and annual costs that would be incurred by a 

steam electric power plant if final polishing filters were added to the flue gas desulfurization (FGD)

wastewater treatment train as is done at Keystone Generating Station, one of the model plants for 

determining mercury and arsenic limitations and standards for FGD wastewater based on chemical 

precipitation. To estimate capital costs for the polishing filters, ERG contacted FiltraSystems Inc. located 

in Farmington Hills, Michigan and requested “book” prices for three sizes of cartridge filter systems. The 

attached product information brochure provided by FiltraSystems shows the cartridge filter systems. 

Using the “book” prices for a single cartridge filter system provided by FiltraSystems (DCN SE06320 – 

SE06322 and SE06330), ERG estimated installed capital costs for a steam electric facility. These 

installed capital costs are provided in the table below. 

Table 1. Estimated Installed Capital Cost for a Polishing Filter System at Steam Electric Plants 

Cartridge 

Filtration 

Unit Design 

Flow 

(gpm) 

FiltraSystems 

Cost per Unit 

Number of 

Systems 

Required at 

Facility a

Total 

Equipment 

Cost b

Installation 

Cost c

Indirect 

Costs d

Total 

Installed 

Capital 

Cost 

70 $1,270 2 $2,540 $2,540 $2,180 $7,260

180 $3,750 2 $7,500 $7,500 $6,450 $21,500

300 $4,540 2 $9,080 $9,080 $7,800 $26,000

1,200 $18,400 2 $36,900 $36,900 $31,700 $106,000

a - Assume a redundant unit on standby for use during cartridge filter change-out. 

b - Total equipment cost include an initial 2 boxes of 20 cartridge filters (replacement filters are $150/box). 

c - Installation cost assumed to be 100% of total equipment cost. 

d - Indirect costs are 43% of the total equipment cost plus installation cost, consistent with EPA’s cost 

methodology for FGD wastewater treatment systems. 

The cartridge filter systems provided by FiltraSystems, Inc. are fully assembled and the 180, 300, and

1,200 gpm systems are manufactured with 316 stainless steel that is appropriate for high chloride waste 

streams. The 70 gpm system quoted by FiltraSystems is manufactured with 304 carbon steel and therefore

ERG increased the quoted cost by 39 percent to account for 316 stainless steel.1

 Cartridge filters are sized 

to remove particles larger than 10 microns.2

 

1

 Percentage increase based on the difference in cost for a FiltraSystems Inc.180 gpm unit constructed with 304 

stainless steel versus a FiltraSystems Inc. 180 gpm unit constructed with 316 stainless steel. 

2

 The filtration unit can filter smaller particles by using filter cartridges of different micron ratings. For example, 

according to the vendor, a 1-micron filter could be used instead without any increase in cost. 
Memorandum 

September 30, 2015 

Page 2 

To estimate annual operating and maintenance (O&M) costs for the cartridge filter system, ERG assumed 

that the existing effluent pump already included in the FGD wastewater treatment system cost is sufficient 

to pump water through the cartridge filters. ERG also assumed that one unit would require complete 

cartridge filter replacement on a weekly basis, and that general operating labor and other maintenance 

materials would be approximately 6 percent of the installed capital cost. The table below shows the 

estimated annual operating and maintenance cost for the three sizes of cartridge filtration units from 

FiltraSystems, Inc. 

Table 2. Estimated Annual Operating and Maintenance Costs for a Polishing Filter System at 

Steam Electric Plants 

Cartridge 

Filtration Unit 

Design Flow 

(gpm) 

Filter 

Cartridges 

per System a

Estimated 

Filter 

Cartridges 

per Year 

Annual Filter 

Cartridge 

Replacement Cost b

Annual 

Operating Labor 

and Equipment 

Cost c

Estimated 

Total Annual 

O&M Cost 

($/yr) 

70 7 364 $2,730 $440 $3,170

180 12 624 $4,680 $1,290 $5,970

300 20 1,040 $7,800 $1,560 $9,360

1,200 80 4,160 $31,200 $6,330 $37,500

a - Number of cartridge filters per filter system from FiltraSystems, Inc. 

b - Cost is based on $7.50 per cartridge from FiltraSystems, Inc. The system evaluated for this cost estimate is based on 

using 10-micron filters; however, according to the vendor the cost for 1-micron filter cartridges would be the same. 

c - Annual operating labor and equipment based on 6% of installed capital cost per Perry’s Chemical Engineers Handbook, 

Sixth Edition. 

ERG compared the added capital cost for a polishing filter to the overall estimated capital cost for a FGD 

treatment system, and found the costs are minimal. ERG first indexed the total capital costs and total 

O&M costs from Table 1 and Table 2 to 2010 dollars, using the RSMeans construction cost indexing 

values for 2015 and 2010 (DCN SE06331). Next, using the indexed capital and O&M costs, ERG 

developed a relationship between the design flow rate and the total installed capital cost and total annual 

O&M costs for the polishing filter. 

 Total Polishing Filter Capital Cost = 77.431× FGD Wastewater gpm + 1739.9 EQ (1) 

 Total Polishing Filter O&M Costs = 27.632 × FGD Wastewater gpm + 363.08 EQ (2) 

ERG then used Equation 1 and Equation 2 to estimate the capital and O&M costs to install a polishing 

filter for each plant discharging FGD wastewater. 

The estimated installed capital cost for a chemical precipitation system treating approximately 180 gpm of 

FGD wastewater is approximately $17 million dollars. The installed capital cost for an additional 

polishing filter treating the same flow is approximately $19,000 in 2010 dollars, or 0.09 percent of the 

total capital cost.3 Results are similar for annual O&M costs. The estimated annual cost for a chemical 

precipitation system treating approximately 180 gpm of FGD wastewater is approximately $1,000,000/yr 

and the annual cost for the polishing filter is $5,300 per year, or 0.5 percent of the total annual O&M 

cost.4 

 

3

 The cost for a polishing filter are an even smaller percentage of the total cost for a treatment system that includes 

both chemical precipitation plus biological treatment, less than 0.06 percent. 

4

 The annual cost for the polishing filters is less than 0.4 percent of the total annual cost for the chemical 

precipitation plus biological treatment system. 
Memorandum 

September 30, 2015 

Page 3 

For plants with a flow rate greater than 1,200 gpm, ERG assumed that multiple filters would be installed 

and the wastewater flow would be equally split between them. For example, a plant with a flow rate of 

2,200 gpm would require two filters with a design flow of 1,200 gpm each.5 This plant is costed for a total 

of 4 filters (two operating and two spare) to be consistent with the methodology described above. 

Finally, ERG estimated the industry-level cost for all plants discharging FGD wastewater to install and 

operate polishing filters, ERG estimates a total capital cost of $1,750,000 and an annual O&M cost of 

$608,000. On an industry-level, polishing filter costs represent less than 0.25 percent of total capital costs 

and 0.9% of annual O&M costs for chemical precipitation. When compared to industry-level costs for 

chemical precipitation plus biological treatment, polishing filter costs represent 0.1% of total capital costs 

and 0.6% of annual O&M costs. 

 

5

 Of the 69 plants discharging FGD wastewater, the largest discharge flow is 2,170 gpm. ERG estimates a capital 

cost of $170,000 and annual O&M cost of $60,300 for the polishing filters needed to handle this flow rate.