E-mail Correspondence with AF&PA (Sulfide Discharges – O’Shaughnessy)

From: "O'Shaughnessy, Niall" <noshaugh@rocktenn.com> 

Sent: Monday, June 13, 2011 8:00 AM 

To: Sabol, Elizabeth 

CC: Acker, Ken G.; Butler, Nina-Mary; Schwartz, Jerry 

Subject: FW: FW: Request for 2009 DMR Data Clarification 

See the responses to you questions below. Let me know if you have any other questions or need clarifications on the 

answers below. 

Niall O'Shaughnessy, PE 

RockTenn 

3700 Crestwood Parkway 

Suite 850 

Duluth, GA 30096 

770-570-1607 (office) 

770-361-7359 (cell) 

noshaugh@rocktenn.com 

From: Elizabeth Sabol [mailto:Elizabeth.Sabol@erg.com] 

Sent: Wednesday, June 08, 2011 8:26 AM 

To: O'Shaughnessy, Niall 

Subject: RE: FW: Request for 2009 DMR Data Clarification 

Niall, 

 

As discussed on the phone, the following questions are listed as follow-up to the responses provided in early March 

2011 regarding 2009 sulfide discharges at the facility. 

 

For the sulfide discharges confirmed: 

 

1. What processes at the facility contribute to the sulfide discharges? Please explain why sulfide is used or a 

byproduct of this process. 

The mill uses a kraft pulping process. The kraft process uses a sodium-based alkaline 

pulping solution (liquor) consisting of sodium sulfide (Na2

S) and sodium hydroxide 

(NaOH) in 10 percent solution. This liquor (white liquor) is mixed with the wood chips 

in a reaction vessel (digester). The output products are separated wood fibers (pulp) and 

a liquid that contains the dissolved lignin solids in a solution of reacted and unreacted 

pulping chemicals (black liquor). The black liquor undergoes a chemical recovery 

process to regenerate white liquor for the first pulping step. Overall, the kraft process 

converts approximately 50 percent of input furnish into pulp. 

The kraft chemical recovery process consists of the following general steps: 

Black liquor concentration Residual weak black liquor from the pulping process is 

concentrated by evaporation to form "strong black liquor.” After brown stock washing in 

the pulping process, the concentration of solids in the weak black liquor is 

approximately 15 percent; after the evaporation process, solids concentration can range 

from 60 - 80 percent. In some older facilities, the liquor then undergoes oxidation for 

odor reduction. The oxidation step is necessary to reduce odor created when hydrogen 
sulfide is stripped from the liquor during the subsequent recovery boiler burning process. 

Almost all recovery furnaces installed since 1968 have non-contact evaporation 

processes that avoid these problems, so oxidation processes are not usually seen in mills 

with modern recovery furnaces. Common modern evaporator types include multiple 

effect evaporators as well as a variety of supplemental evaporators. Odor problems with 

the kraft process have been the subject of control measures. 

Recovery boiler The strong black liquor from the evaporators is burned in a recovery 

boiler. In this crucial step in the overall kraft chemical recovery process, organic solids 

are burned for energy and the process chemicals are removed from the mixture in molten 

form. Molten inorganic process chemicals (smelt) flow-through the perforated floor of 

the boiler to water-cooled spouts and dissolving tanks for recovery in the recausticizing 

step. 

Energy generation from the recovery boiler is often insufficient for total plant needs, 

however, so facilities augment recovery boilers with fossil-fuel-fired and wood-wastefired boilers (hogged fuel) to generate steam and often electricity. Industry-wide, the 

utilization of pulp wastes, bark, and other papermaking residues supplies 65 percent of 

the energy requirements of pulp and paper companies. 

Recausticizating Smelt is recausticized to remove impurities left over from the furnace 

and to convert sodium carbonate (Na2CO3) into active sodium hydroxide (NaOH) and 

sodium sulfide (Na2

S). The recausticization procedure begins with the mixing of smelt 

with "weak" liquor to form green liquor, named for its characteristic color. 

Contaminant solids, called dregs, are removed from the green liquor, which is mixed 

with lime (CaO). After the lime mixing step, the mixture, now called white liquor due 

to its new coloring, is processed to remove a layer of lime mud (CaCO3

) that has 

precipitated. The primary chemicals recovered are caustic (NaOH) and sodium sulfide 

(Na2

S). The remaining white liquor is then used in the pulp cooking process. The lime 

mud is treated to regenerate lime in the calcining process. 

Calcining In the calcining process, the lime mud removed from the white liquor is 

burned to regenerate lime for use in the lime mixing step. The vast majority of mills 

use lime kilns for this process, although a few mills use fluidized bed systems in which 

the reactants are suspended by upward-blowing air. 

2. Are there any treatment technologies in place for the sulfide? 

There are no specific treatment technologies in place for sulfide treatment, however, 

the wastewater is treated across the mill’s wastewater treatment ponds before being 

discharged. 

3. Are both sulfide and flow measurements taken at the same location in the process? If not, is a smaller 

flow associated with the sulfide discharge? 

Yes. The sulfide and flow measurement represent the effluent being discharged to the 

receiving stream. 

4. Please provide a description of Outfall 001. 
The effluent from the treatment ponds is routed through a 30-inch effluent pipeline 

where it is discharged subsurface into the Pee Dee River. The Pee Dee River has a 

daily minimum flow of 673 cfs and a minimum mean flow of 3,480 cfs (1996 thru 

2010). The effluent sample is collected from the wastewater where it enters the 30-

inch pipeline. Flow is measured using a venturi flow device in the pipeline. 

5. Are the sulfide concentrations reported in 2010 similar to the 2009 concentrations? 

Yes. 

 

I appreciate your timely response to the questions listed above. Also, please call me directly (703-633-1659) if you 

have any questions or to discuss the answers. 

 

I look forward to hearing from you. 

 

Thanks, 

Elizabeth 

Elizabeth A. Sabol 

Environmental Engineer 

Eastern Research Group, Inc. 

14555 Avion Parkway, Suite 200 

Chantilly, VA 20151 

elizabeth.sabol@erg.com

Phone:703-633-1659