p.1 

OAR Box 1828 

Prepped by Ollie Stewart 

Document Number: 

308) IV-B-12 

Docket Number: 

A-83-27 

Printed 11/12/200811:12:59 AM Sheet 308 of 325 
P.2 

A-83-27 

IV-B-12 

MEMORANDUM 

DATE: April 14, 1987 

TO: Jim Eddinger, EPA/ISB 

FROM: J. Thomas Waddell and David M. White, Radian Corporation 

SUBJECT: Disposal of Sodium Scrubber Waste 

1.0 INTRODUCTION 

Options for disposal of sodium scrubber waste (SSW) were examined by 

EPA prior to proposal of new source performance standards (NSPS) for sulfur 

1 2 dioxide (SO-) emissions from coal and oil-fired boilers. ' During public 

review of the proposed standard (51 Federal Register. 22385, June 19, 1986), 

comments were received regarding potential problems associated with disposal 

of SSW. This memorandum summarizes recent additional work done to evaluate 

these comments. 

2.0 IMPACT OF BEST AVAILABLE TECHNOLOGY (BAT) GUIDELINES 

One commenter voiced concern over the impact of best available 

technology (BAT) water quality guidelines on discharges of liquid sodium 

scrubber effluent. This concern does not appear justified. BAT standards 

are specific to individual waste streams and industries and do not include 

effluent from the boiler and its support equipment. Therefore, this concern 

is not discussed further in this memo. 

3.0 ANALYSIS OF DISPOSAL OPTIONS 

To address comments received on the availability of and limitations on 

various waste disposal options, selected state environmental agencies were 

surveyed to evaluate possible constraints on discharging liquid SSW to a 

Progress Center/3200 E. Chapel Hill Rd./Nelson Hwy./P.O. Box 13000/Research Triangle Park. N.C. 27709/(919)541-9100 
P.3 

receiving water body (RWB) or publicly-owned treatment works (POTW). In 

1983 approximately 500 sodium scrubbers were in operation in the U.S. Of 

2 

this total, summary data were available for 357 units. Only 37 were 

located outside California. All the units in California, six units in 

Wyoming, one in Montana, and one in Texas were used to reduce S02 emissions 

from steam generators used for enhanced oil recovery (EOR) and minerals 

production. 

California defines SSW as a "designated" waste, meaning that although 

it is nonhazardous based on specified testing, it still poses a threat to 

state water quality objectives. Specifically, the high level of total 

dissolved solids (TDS) is felt to pose a hazard to the state's citrus 

industry. SSW from these units are disposed of by either 1) injecting the 

effluent into RCRA Class II wells as part of the EOR operations or 2) 

hauling it to natural or man-made salt ponds where liquid in the waste is 

evaporated by the sun. One petroleum industry source estimated the cost of 

disposal by evaporation (including haulage to the disposal site) is $50 to 

4 $60 per ton. 

The remaining 29 units were located at 19 plants throughout the U.S. 

Disposal procedures used by the units discussed above (deep well injection 

and evaporation ponds) are specific to EOR and arid regions with high net 

evaporation rates and are not possible for units located in many parts of 

the country. To determine how SSW would be handled in other regions, state 

water and solid waste regulators and POTW operators were contacted in four 

states (Michigan, Minnesota, New Hampshire, and North Carolina) based on 

comments received. Producers of SSW in these states have three disposal 

options: direct discharge to a RWB, discharge to a POTW, and disposal at a 

waste disposal site. Of the 19 plants, five discharged to a POTW, nine 

discharged to a RWB, and one used the SSW as a process feedstock (the method 

of disposal for the four remaining plants was not known). 

Discharge to a RWB is regulated through effluent guidelines established 

by each state. An effluent guideline is a concentration limit used in 

permitting a new source. The impact of a new source is evaluated by 

determining pollutant concentrations in the RWB if the discharge were to 
P.4 

occur. Waste streams already discharging into the RWB are included in the 

calculations. Of the states surveyed, the TDS concentration of the SSW was 

the most cited concern. The TDS effluent guidelines for these states range 

5 6 7 from 100 to 300 mg/l. ' ' In two of the states, specific examples were 

cited indicating discharge of a liquid waste with characteristics similar to 

5 6 SSW would not be permitted because TDS limits had already been reached. ' 

These cases, however, are site-specific. Although alternative S02 control 

options would be required in these and similar situations, sodium scrubbing 

remains a feasible option in many locations. 

POTW's discharging to a RWB must meet the same effluent guidelines as 

direct dischargers. The ability to discharge SSW to a POTW is therefore 

determined by the present loading on a given POTW. A specific case was 

identified in one state where a POTW could not accept SSW because of sulfate 

discharges from an existing industrial plant which uses sulfuric acid to 

Q 

wash glassware. Again, this case was site-specific. 

Disposal of SSW at waste disposal sites is possible in most states. 

These facilities must be lined to ensure that soluble sodium salts do not 

leach into adjacent groundwater. The cost of disposal at a lined facility 

q 

was estimated at $25 to $30 per ton by one commenter. In North Carolina, 

two lined facilities exist; however, neither facility is able to accept 

wastes from a new sodium scrubber due to existing commitments. Other 

states might have similar disposal site limitations. Where this is the 

case, additional disposal capacity could be constructed or alternative S0~ 

control options could be used. 

4.0 SECONDARY ENVIRONMENTAL IMPACTS 

In addition to comments on available disposal options, comments were 

also received regarding secondary environmental impacts from H~S emissions 

and the impact of TDS on TSS concentrations. Although the issue of H,S 

11 emissions was discussed in a previous memorandum, additional information 

was collected from a POTW in New Hampshire where H«S emissions are currently 

a problem because of high sulfate loadings from an existing industrial 
P.5 

g 

process. H2S is released from the POTW dewatering system whenever the 

wastewater stagnates and becomes acidic. It should be noted that the 

sulfate loading problem was not caused by a sodium scrubbing system. New 

Hampshire state officials also noted that H,S emissions could also occur 

upstream of the POTW if the sewer line became stagnant. 

Data submitted by Monsanto during the public comment period indicate 

the settlability of total suspended solids (TSS) can be adversely affected 

by high levels of TDS, especially at TDS levels above roughly 10,000 ppm. 

As a result, discharge of SSW has the potential to reduce the POTW's 

throughput capacity. To put this issue in perspective, the increased TDS 

level at a one million gallon per day capacity POTW resulting from a sodium 

scrubber is calculated in Table 1. Using SSW parameters from a 150 million 

Btu/hour boiler burning 3.5 percent sulfur fuel with a scrubber removal 

efficiency of 92 percent, the resultant increase in POTW effluent TDS is 

4,400 ppm. Whether this increased TDS level significantly affects an 

individual POTW will depend on the type of wastes received by the POTW and 

the TDS and TSS levels before addition of SSW. 

5.0 COST IMPACTS 

Where discharge to a POTW or RWB is not possible, SSW disposal costs 

may range from $25-60 per ton (equal to $110-$270 per thousand gallons of 

wastes) versus roughly $0.60 per thousand gallons when POTW disposal is 

12 possible. The impact of higher scrubber waste disposal costs on total 

annualized costs (i.e., operating and maintenance and annualized capital 

costs) is shown in Table 2 for a model 150 million Btu/hour steam generating 

unit burning a 0.6, 1.24, and 3.23 percent sulfur coal. Using a liquid 

waste disposal cost of $0.60 per 1,000 gallons, the total annualized cost 

for sodium scrubbing these three coals is $440,000, $550,000, and $827,000 

per year, respectively. If a liquid waste disposal cost of $100 per 1,000 

gallons is assumed, the total annualized cost roughly doubles to $746,000, 

$1,137,000, and $2,357,000 per year. At these costs, other S02 control 

technologies such as lime spray drying or dual alkali are likely to be 

selected based on cost as the preferred S02 control method. 
P.6 

6.0 CONCLUSIONS 

The application of sodium scrubbing systems may be limited in some 

cases by local or site-specific restrictions on waste disposal or by the 

costs required to meet these restrictions. This will require consideration 

of alternative waste disposal methods or S02 control options. While waste 

disposal restrictions will limit the application of sodium scrubbers at 

certain sites, a number of units are currently in operation. In fact, 

sodium scrubbers are more widely used on industrial boilers than any other 

scrubbing system. Thus, while sodium scrubbers may not be applicable in all 

cases, they are currently in use and their continued use is expected. 
P.7 

7.0 REFERENCES 

1. Technical Note from Berry, R. S., Radian Corporation, to the Industrial 

Boiler S02 Docket. January 25, 1984. Update of the Sodium Scrubber 

Wastewater Issue. 

2. Technical Note from Maddox, J. A., Radian Corporation, to the 

Industrial Boiler S02 Docket. September 6, 1984. Sodium Scrubber Data 

Sample and Analysis. 

3. Letter from Anton, E. C , California Water Resource Control Board, to 

Maddox, J. A., Radian Corporation. May 30, 1984. California Water 

Regulations. 

4. Telecon, May, P. A., Radian Corporation, with Ouellette, R., Shell Oil, 

October 28, 1986. Sodium Scrubber Effluent. 

5. Telecon, May, P. A., Radian Corporation, with Ramsey, D., North 

Carolina Department of Natural Resources. October 23, 1986. Sodium 

Scrubber Discharge Considerations. 

6. Telecon, May, P. A., Radian Corporation, with Allen, D., New Hampshire 

Water Control Board. October 29, 1986. Sodium Scrubber Discharge. 

7. Telecon, May, P. A., Radian Corporation, with Boerson, G., Michigan Air 

and Water Quality Control. October 29, 1986. Sodium Scrubber 

Discharge. 

8. Telecon, May, P. A., Radian Corporation, with Dakota, R., Merimac New 

Hampshire POTW, October 28, 1986. Facility Operation and Sodium 

Scrubber Effluent Impacts. 

9. Cogentrix, Inc., Comments of Cogentrix, Inc. (public comments on NSPS) 

to Docket No. A-83-27. 

10. Telecon, May, P. A., Radian Corporation, with Myer, W., North Carolina 

Department of Natural Resources, October 23, 1986. Waste Site Disposal 

of Scrubber Effluent. 

11. Technical Note from Martinez, J. A., Radian Corporation, to Sedman, C. 

B., U.S. EPA. April 2, 1984. H2S Emissions from Sodium Scrubbing 

Wastewater Streams in Sewer Systems. 

12. Laughlin, J. H., et al., Radian Corporation, Industrial Boiler S02 Cost 

Report, prepared for U.S. EPA, Research Triangle Park, NC, November 28, 

1984. 
P.8 

TABLE 1. CALCULATION OF TDS IMPACT ON MODEL POTW 

Model Parameters: 150 million Btu/hour steam generating unit 3.54 

weight percent coal sulfur content sodium scrubber 

at 92 percent S02 removal 

Scrubber Effluent Rate = 50.28 gpm 

= (50.28 gal/min) (ft3/7.48 ga l) (66.58 lb/ft3) 

(60 min/hr) (24 hr/day) 

= 644,466 lb/day 

TDS Concentration = 57,000 ppm (or 5.7 weight percent) 

TDS Rate - 36,735 lb/day 

Impact on 10 Gal/Dav POTW 

Total Flow Rate = (IO6 gal/day) (ft3/7.48 gal) (62.4 lb/ft3) 

8,342,250 lb/day 

(36,735/8, 

4,400 ppm 

Increase in TDS = (36,735/8,342,250) (IO6) 
P.9 

a 

TABLE 2. TOTAL ANNUALIZED COSTS FOR SODIUM SCRUBBERSa'

b 

Liquid Waste Coal Sulfur Content, (wt. %) 

Cost Rate 

($/l,000 gal) 0.6 1.24 3.23 

0.60 440 550 870 

100.0 746 1,137 2,357 

200.0 1,054 1,727 3,848 

All costs in $1000/year, 1985. 

Sodium scrubber installed on 150 million Btu/hr boiler. 

c Corresponds to coals in Summary of Regulatory Analysis with nominal 

sulfur contents of 1.2, 2.5, and 6.0 lb S02/million Btu.