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HomeMy WebLinkAboutNC0000272_Evergreen Response to EPA Comment Color Reduction_20120410 evergreen".I& Canton Off ice packaging 175 Molia Srreer• Canfonr NC 28716 PSD 28-12 10 April 2012 CERTIFIED MAIL Tom Belnick RETURN RECEIPT REQUESTED Supervisor, Complex NPDES Permitting Unit 7008 3230 0002 2591 1656 Division of Water Quality North Carolina Department of Environment and Natural Resources 1617 Mail Service Center Raleigh,North Carolina 27699-1617 Subject: Response to EPA Comments dated 22 March 2012 February 2012 Update to the Color Reduction Implementation Plan NPDES Permit NC0000272 Blue Ridge Paper Products Inc. Canton Mill Dear Mr. Belnick— Attached is our response to EPA comments received by the DWQ on 22 March 2012 and forwarded to us for evaluation. The EPA comments concern the expedited evaluation of TRW "A List" Recommendations under Part I Condition A.(8.), Item 10 of the NPDES permit as documented in the February 2012 Update to the Color Reduction Implementation Plan. Very truly yours, BLUE RIDGE PAPER PRODUCTS INC. DOING BUSINESS AS EVERGREEN PACKAGING Paul Dickens Nick McCracken Manager—Environmental Affairs Water Compliance Coordinator 828-646-6141 828-646-2874 paul.dickens�eve�ack.com nick.mccracken�eve�ack.com Attachment: Response to EPA comments dated 22 March 2012 concerning the February 2012 Update to the Color Reduction Implementation Plan cc (w/enclosure): DWQ ARO Color Team, Internal Distribution fresh by design. --X1 Doing Business in California as Evergreen Beverage Packaging F:\SHARE\Water Files\Color Reports 2010 Prmt\Color Reduction Implementation Plan\E-Sign Response to EPA Comments on the Updated Color Reduction Implementation Plan Apr 2012.doc eve r nTMcff Canton Office packaging 175 Main weer• Canton, NC 28716 Attachment — 10 April 2012 Blue Ridge Paper Products Inc. dba Evergreen Packaging (BRPP)response to EPA comments dated 22 March 2012 concerning the February 2012 Update to the Color Reduction Implementation Plan EPA Comment— First regarding BMPs • We continue to believe in the importance we have always accorded to BMPs, as noted below. However, it is puzzling that the list of BMPs shows hardly any improvements in the long term reductions of color, as one would anticipate. Moreover, we do not see estimates or data addressing any benefits that may accrue to implementing the evaluated BMPs and in so doing reduce variability/spikes in effluent color. BRPP Response— Prevention of wastewater effluent color is a priority for Canton Mill operations every day. Evergreen Packaging and the Canton Mill Color Team agree that Best Management Practices (BMPs) are critical to this priority. BMPs are most effective when they are mill specific, and are tracked, evaluated and implemented on an ongoing basis. In response to the EPA comment, "... it is puzzling that the list of BMPs shows hardly any improvements in the long term reduction of color, as one would anticipate." Evergreen Packaging would note that at the high level of effluent color prevention the Canton Mill has already achieved, new BMPs contribute more to operational reliability and control of process variability than to significant effluent color reduction. BMPs implemented during the period 2006 - 2011 have improved process variability compared to the period 2001 - 2005 as indicated by the standard deviation in secondary effluent color for these periods (table below). Specifically, BMP improvements since 2006 resulted in tighter (less variable) color performance during normal operating conditions and during planned outages. Period Standard Deviation of Canton Mill Secondary Effluent Color, lbs/da 2001 - 2005 17,318 2006 - 2011 10,843 fresh by design Doing Business in California as Evergreen Beverage Packaging Attachment- BRPP Response Page 2 EPA Comment- Second, regarding process changes • There appear to be notable differences in what was accomplished in lab studies (e.g., PITC) versus mill trials. We most certainly understand that lab results don't always successfully translate to full scale. However, the differences in changes in wastewater color are neither well explained nor documented, beyond assertions that they will not work. For example, the PITC work omits the inevitable increase in pulp yield due to the higher Kappa number at the digester exit with 2-stage OD. This would reduce bleaching chemical use as noted by McDonough (caustic and C102) and thus operating costs, not increase them; moreover the reduction in color was asserted to be less than 1000 Ibs/day, but there is no basis for this improbable assertion; McDonough shows noticeable reduction in color formation but there is not sufficient data available to calculate the impact on final effluent. • An appreciable amount of color is from the CRP; with less chemical usage in bleaching due to 2- stage OD, noted just above, CRP will have less to remove; this was not considered BRPP Response- Concerning results of the full scale-trials of enhanced extraction (peroxide fortification) compared to laboratory simulation of this process,the 90-day trials in 3rd quarter of 2011 clearly did not reduce bleach plant effluent color or result in bleach plant chemical cost savings. Concerning the laboratory studies of second stage oxygen delignification on pine,the mill took care to simulate how this technology might be applied as a retrofit to the existing pulp digestion,washing and bleach plant systems - including the Minerals Removal Process - without causing adverse effect on bleached pulp strength. To quantify the potential color benefits from 2-stage 02 delignification (00) compared to single stage delignification (0), an independent lab (Pruyn's Island Technical Center or PITC) was utilized to simulate the process using Canton Mill wood chips and brown stock pulp. A third party expert (McDonough) was retained to validate and summarize the outcome of the work. For the lab study plan, two operating strategies for digester wood cooking were considered - 26 kappa and 30.5 kappa. 26 kappa cooking strategy The first strategy was to maintain the current kappa number out of the digesters (26) for both 0 and 00 and take the benefits from the additional 02 delignification stage to target a 3-4 kappa number reduction entering the bleach plant. With this option,the data showed that color was reduced in the Do stage and Eo stage by 295 and 550 units, respectively (McDonough report Table 2, pages 2-3). The color reduction in the D1 stage was minimal (McDonough report Table 2, pages 2-3). [Note -the Do and D1 stages referred to in the PITC and McDonough reports simulate the D1 and D2 stages at the Canton Mill. The Eo stage in the lab studies simulates the Eo stage at the Canton Mill.] Attachment- BRPP Response Page 3 Bleaching chemicals were reduced as reported in the same table referenced above. The final pulp viscosity was reduced from 17.4 for 0 pulp to 14.5 for 00 pulp (McDonough report Table 2 pages 2-3). McDonough states on page 12 of report, "Analysis of mill data suggests that the viscosity reduction that would result from adding a second stage of oxygen delignification is likely to have pulp strength implications. Utilization of two-stage oxygen mill pulp may be expected to lead to lower final viscosity than the current 11.3 - 11.5 mPa.s and correspondingly lower physical strength properties." Based on the tests for physical properties,the following quote from page 5 of McDonough's report summarizes the results: "Figure 3 shows the relationship between tearing resistance and tensile strength for each of four pulp types. It is apparent that, at a tensile index of 70 N.m/g the 26 Kappa pulp after two oxygen stages had a roughly 15% lower tear relative to the base case (single-oxygen stage applied to 26 Kappa pulp). The "mill bleached" pulp had lower tear strength than the lab single-oxygen stage pulp. This may be explained by the harsher physical treatment of mill pulp due to blow valves, pumps and other process equipment." McDonough summarizes the lower strength implications on page 12 as follows: the 26 kappa 00 pulp developed lower tensile and tear tests resulting from reduced specific bond strength of the fibers, leading to increased beating requirements and denser sheets. The 15% reduction in pulp strength from applying second stage oxygen delignification to the existing Canton Mill process has serious commercial implications. Evergreen customer requirements for product specifications would be negatively impacted,to the point of losing business for unacceptable quality. Therefore,the 26 kappa strategy is not a viable option. 30.5 kappa cooking strategy The second strategy was to raise the Kappa number out of the digesters to 30.5 and utilize the 00 delignification process to reduce the Kappa number to its current level entering the bleach plant. With this strategy,the color in Do and Eo was reduced by 250 and 190 units, respectively (McDonough report Table 2, pages 2-3). This small reduction in color was with pulp that was one (1) Kappa unit below single stage delignification (12.4 vs 13.4). At this rate of approximately 60% delignification (McDonough report Table 1, page 2),we don't expect it to be obtainable with the viable second stage delignification system designs commercially available to retrofit to the existing Canton Mill process. The 16% C102 reduction referenced by the first full paragraph on page 12 of McDonough's report is again based on the 1 Kappa unit lower 00 pulp entering the bleach plant. The C102 chemical savings would not be realized for a targeted 13.4 Kappa number 00 pulp entering the bleach plant. The 00 stage also increased NaOH charge by 50% over 0 stage (McDonough report Table 1, page 2) ultimately increasing overall chemical costs for the process. The 30.5 kappa strategy did produce pulp that has virtually the same viscosity and strength properties as compared to the 0 pulp (McDonough report page 12). However, at this kappa range the unbleached yield increase out of the digesters would be minimal and "the increase in unbleached yield would be at least partially lost in the more extensive delignification that results from increased degree of oxygen delignification associated with Attachment- BRPP Response Page 4 the switch from single-stage oxygen to two-stage oxygen" (McDonough e-mail, 3/30/12). On the lab data basis,this strategy would not provide the significant color benefit that is desired. Calculation of Bleach Plant Effluent Color Reduction The following table outlines calculation of potential bleach plant effluent color reduction and secondary effluent color reduction based on the laboratory simulations of second stage oxygen delignification on pine. The laboratory results must be adjusted for the effect of pine bleach filtrate recycling with the Minerals Removal Process (MRP). The minimum closure and internal recycling rate is 50% and is used as a conservative (low) estimate in the calculation table. The average MRP closure rate in 2011 was 80.8%, substantially greater than the conservative calculation. The McDonough report and discussion above demonstrate that the 26 kappa strategy is not commercially viable due to adverse effect on pulp strength. The calculation of potential filtrate and effluent color reduction documented below demonstrate that the potential secondary effluent color reduction benefit of second stage oxygen delignification on pine with both the 26 kappa strategy(not commercially viable) and 30.5 kappa strategy is less than 1000 lbs per day. Digester Cooking Strategy 26 kappa- 00 30.5 ka pa - 00 Canton Mill Pine Bleach Filtrate D1 stage Eo Stage D1 Stage Eo Stage Color reduction compared to existing 295 550 250 190 single stage delignification, PCUs. 2011 filtrate flow, m d 0.25 0.11 0.25 0.11 Potential filtrate color reduction 615 505 521 174 without MRP, lbs/da * Total 1120 695 MRP closure, percent 50 50 Potential filtrate color reduction 560 348 considering MRP closure, lbs/da Potential secondary effluent color reduction based on 15% color 476 296 removal in activated sludge, lbs/da *Color lbs/day=PCUs x flow(mgd) x 8.34, this is the calculation of color mass used in the Canton Mill NPDES permit, see Permit condition A.(8.) item 2. Summary on cooking and color reduction While two-stage oxygen delignification would certainly be part of any new Kraft pulp mill, retrofit of this technology to an existing process that is optimized for specific commercial products - such as the Canton Mill - requires great care. Addition of a second oxygen delignification stage on pine is not a good retrofit for additional color reduction. Adjustments to cooking for pulp strength necessary to make commercially viable pulp for Attachment- BRPP Response Page 5 the fiber-based liquid packaging products manufactured by Evergreen Packaging negate potential chemical use and color benefits from the two-stage oxygen delignification process. The 2010 laboratory work to simulate retrofit of second stage oxygen delignification on pine was specifically designed to address TRW comments on previous work in 2001 as well as update economics and potential color reduction. Based on the simulation of realistic operating strategies to apply this technology to the Canton Mill, Evergreen Packaging concluded that second stage oxygen delignification on pine is not technically, operationally or economically feasible. Chloride Removal Process (CRP) EPA commented that color reduction from reduced CRP purge rate related to bleach plant chemical reduction should be considered. While this is theoretically correct, the CRP purge rate for chloride control is driven more by MRP closure rate and chemical demand associated with recycled non-process elements than by pre-bleach kappa. Additionally, the 26 kappa cooking strategy outlined above while producing some bleach plant chemical savings is not commercially viable due to adverse effect on pulp strength and final product quality. The 30.5 kappa cooking strategy-which is necessary to preserve pulp strength by holding pre-bleached kappa the same as the existing process-does not reduce bleach plant chemical use and subsequently would not reduce CRP purge rate. References from the February 2012 Color Reduction Implementation Plan PITC 2011 a-Report 2010-081 -Laboratory Cooking and Bleaching for Evergreen Packaging Canton,NC, Pruyn's Island Technical Center, January 31, 2011. McDonough 2011 -Laboratory Study of Likely Effects of Installing Two-Stage Oxygen Delignification at Evergreen Packaging's Canton Mill, Thomas J. McDonough, consultant to Evergreen Packaging, June 29, 2011.