Totally Chlorine Free Study

Prepared by Brian Parsons, Process Engineer CSF November 29, 2016

Table of Contents:

Section 1 - Executive Summary………………………………………………….…….page 3 Section 2 - Facility Description Site Overview ……………………………………………………………..page 4 Permit Requirements…………………………………………………..page 5 Performance against permit…………………………………………page 8 Section 3 – CSF Product Requirements Overview…………………………….page 11 Section 4 – Current ECF Bleaching Process……………………………………….page 12

Section 5 - Comparing ClO2 to its TCF Counterparts………………………….page 13 Section 6 – Market Study for TCF Product………………………………………..page 18 Section 7 - Estimated Cost for Conversion from ECF to TCF………………page 18 Section 8 – Conclusions……………………………………………………………………page 18 Section 9 – References…………………………………………………………………….page 19

Section 1: Executive Summary

Section S12 of the Cosmo Specialty Fibers’ NPDES permit (WA 0000809) required the submittal of a “comprehensive analysis of converting to a totally chlorine free (TCF) bleaching process. This analysis must include complete technology conversion description, itemized cost to convert, detailed market outlook/viability for TCF product. The analysis must specify the capital cost to convert and the predicted product sales impacts and long term economic viability resulting from the conversion.” CSF has conducted a study on whether or not it can/should convert from elemental chlorine free (ECF) bleaching to totally chlorine free (TCF) bleaching. The facility has found that the conversion is not economically viable for the following reasons:

 Permit limits for AOX, TCDD, and TCDF have been achieved with the current ECF bleaching sequence.  The TCF replacements for chlorine dioxide (ozone and peracetic acid) are not suitable for bleaching chemistry requirements of Cosmo Specialty Fibers’ production of dissolving pulp, due to their inability to achieve product purity due to either degradation of cellulose fiber (in the case of ozone) or the significantly slower removal of lignin from the pulp (in the case of peracetic acid).  Dissolving pulp product specifications cannot be produced without Chlorine Dioxide.  There is no market demand for TCF products in the Dissolving pulp businesses which Cosmo Specialty Fibers competes in.  TCF bleaching is not considered AKART for producing pulp used in all of the industries supplied by Cosmo Specialty Fibers  The capital costs for converting the facility to TCF is not reasonable and the increased operating costs associated with the new oxidants would significantly impact profitability.

The proceeding sections of this document we will outline these issues in greater detail.

Section 2: Facility Description

OVERVIEW:

Facility Location Map

History

The mill is in Cosmopolis, Washington on the south bank of the Chehalis River. Weyerhaeuser constructed the mill in 1957 as a paper grade sulfite process pulp mill. In 1962, Weyerhaeuser started converting the mill to produce dissolving and specialty grade pulp. The mill is capable of producing 550 tons per day of dissolving and paper grade pulp. Weyerhaeuser continued to operate the mill until September 2006, when production shut down. The company mothballed the equipment the following year in anticipation of selling the mill. In August 2010, an investor group, The Gores Group purchased the mill from Weyerhaeuser and named it Cosmo Specialty Fibers. CSF resumed operation in May 2011. The company ended production of paper grade pulps the mill now produces dissolving pulp, specifically acetate, viscose, ether and other limited specialty grades. [1]

Industrial Processes

Cosmo Specialty Fibers is an acid bisulfite pulp mill. It produces dissolving pulp from softwood chips for a variety of customers around the world. Currently the facility incorporates the use of elemental chlorine free bleaching (ECF) to produce its pulp; this means, that it uses Chlorine Dioxide in the bleaching of its pulp.

Pulp production varies based on market demand. Cosmo uses a magnesium bisulfite cooking acid in its pulping process. The mill has nine batch digesters for cooking primarily hemlock wood chips. The pulp exiting the digesters goes into dump tanks and a multi-stage, countercurrent brown stock washer system. The mill bleaches the pulp using a sequence of caustic, oxygen, chlorine dioxide, and hydrogen peroxides. Cosmo processes the pulp in the machine building to make the final product. [1]

The pulping process generates spent cooking liquid called “brown liquor.” The spent liquor, which contains lignin, separates from the pulp in a countercurrent washer system. The mill further processes the brown liquor in evaporators and concentrators to form the “red liquor” and then burns the red liquor in recovery boilers no. 1, 2, and 3 for energy. The mill recovers magnesium oxide and sulfur dioxides from the recovery boilers flue gas and reuses the chemicals to make more cooking acid. The facility supplements the remaining cooking acid by burning sulfur at the acid plant and adding magnesium to the process. [1]

The mill receives its water from the City of Aberdeen’s industrial water supply at Lake Aberdeen. The water flows to Cosmo’s filter plant via an underground pipe. The filter plant processes the water for uses in the mill’s pulping and bleaching process, machine room, and power boilers. [1]

PERMIT REQUIREMENTS:

Federal and state regulations require that effluent limits in an NPDES permit must be either technology- or water quality-based. [1]

Technology-Based Effluent Limits

Technology-based effluent limits are either set by regulations or developed on a case-by-case basis. Federal effluent guidelines in 40 CFR 430 Subpart D set limits for the dissolving sulfite pulp subcategory. These guidelines defined the Best Practicable Technology (BPT) and were published in the Federal Register on November 1982 and March 30, 1983. In the December 17, 1986 Federal Register, the guidelines also define the Best Conventional Pollutant Control Technology (BCT) to be the same as BPT. Both BCT and BPT are dated more than ten years ago. For BCT and BPT older than ten years, Ecology needs to determine if the limits are still valid and equivalent to “all known available and reasonable treatment” (AKART). To determine AKART, Ecology considered three things:

• The current treatment technologies compared to technologies available when the federal effluent guidelines were established.

• The pollutants loading to the wastewater treatment system.

• The treatment system’s capability of meeting the federal effluent guidelines.

Federal effluent guidelines in 40 CFR 430 Subpart D defines best available technology economically achievable (BAT) for pentachlorophenol and trichlorophenol. Cosmo does not use chlorophenolic- containing biocides. Therefore, these guidelines do not apply were not used to set technology-based limit for these pollutants. [1]

EPA has not promulgated federal effluent guidelines for the bleaching process at dissolving pulp sulfite mills. Ecology used best professional judgment in consultation with the EPA Region 10 to determine technology-based limits and AKART for the bleach plant effluent. [1]

AKART Determination with Respect to the Bleaching Process

EPA has not indicated a date for the promulgation of the effluent guidelines to address the bleaching process at sulfite mills that produces dissolving pulp. Because such mills are unique, it is unlikely that new effluent guidelines will be promulgated in the near future. Therefore, Ecology made the AKART determination using the 1998 effluent guidelines for the sulfite specialty grade (40 CFR 430 Subpart E), and in consultation with EPA staff at Region 10 and headquarters. The use of the 1998 effluent guidelines is still appropriate because specialty grade has a high alpha cellulose content of 91 or above ISO brightness, close to the characteristics of dissolving pulp. [1]

Available effluent guidelines define best available technology economically achievable (BAT) for several processes similar but not identical to the process used at Cosmo. The mill currently uses ECF technology, which consists of chlorine dioxide, oxygen delignification, and caustic wash to bleach dissolving pulp. Dissolving pulp is almost pure alpha-cellulose with far fewer impurities than paper and specialty pulps; this level of purity is more difficult and costly to achieve with totally chlorine free (TCF) bleaching. According to EPA, there are no mills using TCF technology to make the same products as Cosmo. Because no new or untried technology is used to define AKART, ECF with oxygen delignification continues to define AKART for a dissolving sulfite mill like Cosmo. [1]

In the future, improved technology or changes in market demands or regulations may make TCF bleaching feasible. Therefore, Ecology required this TCF study be completed in the current permit cycle. [1]

Technology-Based Limit with Respect to the Bleaching Process

As of the date of this permit, the EPA has not promulgated effluent guidelines for the bleaching process of dissolving sulfite pulp bleaching. Until guidelines are promulgated, Ecology used the 1998 guidelines for specialty grade sulfite pulp (40 CFR 430.54). These guidelines represent AKART (see section above). The compliance point is at the bleach plant effluent. The guidelines specify monitoring and limits for chlorinated organic compounds, including dioxins, associated with ECF bleaching method. Table 11 contains BAT limits for each pollutant. The basis for specific pollutants are shown in the paragraphs below. [1]

Technology-Based Limits for Bleach Plant Effluent

Federal effluent guidelines Pollutant Monitoring limits 40 CFR 430 Subpart E 2,3,7,8-TCDD Daily max < 10 pg/L 2,3,7,8-TCDF Daily max < 10 pg/L Trichlorosyringol Daily max < 2.5 μg/L 3,4,5-Trichlorocatechol Daily max < 5.0 μg/L 3,4,6-Trichlorocatechol Daily max < 5.0 μg/L 3,4,5-Trichloroguaiacol Daily max < 2.5 μg/L 3,4,6-Trichloroguaiacol Daily max < 2.5 μg/L 4,5,6-Trichloroguaiacol Daily max < 2.5 μg/L 2,4,5-Trichlorophenol Daily max < 2.5 μg/L 2,4,6-Trichlorophenol Daily max < 2.5 μg/L Tetrachlorocatechol Daily max < 5.0 μg/L Tetrachloroguaiacol Daily max < 5.0 μg/L 2,3,4,6-Tetrachlorophenol Daily max < 2.5 μg/L Pentachlorophenol Daily max < 5.0 μg/L AOX Daily max (*) AOX Monthly average (*) (*) 40 CFR 430 Subpart E has not set a numerical limit for AOX. Ecology set technology-based limits using the treatment system performance data. TABLE 11. Technology-Based Limits for Bleach Plant Effluent – NPDES Fact Sheet page 20 of 100[1]

2,3,7,8-TCDD The 1998 effluent guidelines for sulfite specialty grade subcategory (40 CFR 430.54) set a limit of 10 pg/L for 2,3,7,8-TCDD. This value is based on a minimum level using test method 1613. Due to improvements in the method, the lab can achieve a 5 pg/L detection limit, thereby meeting the 10 pg/L minimum level. The mill’s NPDES permit requires it to comply with less than 10 pg/L minimum level at the bleach plant effluent. [1]

2,3,7,8-TCDF The previous permit included a 2,3,7,8-TCDF limit of 31.9 pg/L at the bleach plant effluent. This value was derived from the bleached paper grade Kraft subcategory limit of 31.9 pg/L (40 CFR 430.24) instead of the specialty grade sulfite subcategory limit of 10 pg/L (40 CFR 430.54). Ecology used the 31.9 pg/L because, at the time, the EPA method 1613 could not meet a detection limit of 10 pg/L due to interference. Both the mill and EPA analyzed the bleach plant effluent for dioxins and furans for the purpose of promulgating limits for the sulfite pulping subcategory. The decision to use the less stringent limit of 31.9 pg/L was based on the determination that Cosmo mill was the best performer in the sulfite subcategory. The determination was from verbal conversation with the EPA. [1]

For the 2015 permit, Ecology re-evaluated the limit using current lab performance and the most up-to- date quarterly monitoring results from 2011 and 2012. Recent results showed the lab can achieve a detection limit between 1 and 3 pg/L for 2,3,7,8-TCDF. Ecology consulted with the state’s Manchester Laboratory about method 1613. Ecology recognizes labs cannot always meet a detection limit of 1 pg/L due to matrix interference. However, it judged that labs can reasonably and consistently meet a detection limit of 5 pg/L or lower. Therefore, Ecology went back to the specialty grade sulfite subcategory limit of 10 pg/L minimum level for the permit compliance limit. This minimum level achieves both AKART and a detection limit of 5 pg/L. [1]

AOX (Absorbable Organic Halides) The 1998 effluent guidelines for sulfite specialty grade subcategory (40 CFR 430.54) did not have an AOX limit. The EPA reserved a placeholder for AOX limits in the guidelines. Because there were no guidelines available, the previous permit set technology-based limits using the mill’s treatment performance. The 2007 permit limits are 2,180 lbs/day monthly average and 2,720 lbs/day maximum daily. These limits were derived from the treatment system performance prior to 2006. The average monthly limit was based on a 95th percentile AOX data. The maximum daily limit was based on a 99th percentile data. [1]

There are two sources for AOX: 1) the bleaching process; and 2) the reaction with hypochlorite added to treat fecal coliform. The existing AOX limits reflect the treatment the mill must achieve to minimize AOX in the discharge and, at the same time, treat fecal coliform to meet the permit limits. Therefore, Ecology retained the AOX limits from the previous permit in the current, 2015 permit. [1]

Chloroform The 1998 federal effluent guidelines for specialty grade sulfite pulp (40 CFR 430 Subpart E) did not contain limits for chloroform. The guidelines also reserved a placeholder for this pollutant. As a result, Ecology continued to require the mill to sample and report the concentration in the Bleach Plant effluent, but proposed no effluent limit. [1]

Performance against NPDES Permit Limits: Cosmo Specialty Fibers has neither exceeded the maximum daily limit nor the monthly average listed for AOX above since start-up. Some of the higher values seen in 2016 are most likely caused by the change in disinfection protocol for Fecal coliform control, which has caused more Sodium Hypochlorite to be used in various parts of the Effluent system. This can be seen in Graph 1, on the next page.

Cosmo Specialty Fibers' Outfall AOX 3000

2500

2000

1500

1000 CSF Outfall AOX

Daily Daily (lbs/day)AOX CSF Daily AOX Limit 500

Date

Graph1

There is also no evidence of CSF exceeding the maximum daily limits for TCDD in its bleach plant effluent. This can be seen in Graph 2 below:

Cosmo Specialty Fibers' Bleach Plant's Eff TCDD

4 CSF Bleach Plant Eff TCDD CSF Bleach Plant TCDD Limit

2 TCDD TCDD From Bleach Plant (pg/L) 0

Date

Graph 2

Finally, since the startup of the mill, Cosmo Specialty Fibers has only had one occurrence of exceeding the limit for its bleach plant’s effluent TCDF level. That result was thoroughly investigated, with no root cause determined. This can be seen in the graph below:

Cosmo Specialty Fibers' Bleach Plant's Eff TCDF

14 12 10 8 6 CSF Bleach Plant Eff TCDF 4 CSF Bleach Plant Eff TCDF Limit

2 TCDF TCDF FromBleach Plant (pg/L) 0

Date

Graph 3

Section 3: Cosmo Specialty Fibers Product Overview

Overview:

The pulp manufactured by Cosmo Specialty Fibers is used exclusively as Dissolving Pulp market. This type of pulp is either dissolved to make regenerative cellulose (e.g. viscose and lyocell) or is cellulose converted to cellulose derivatives (e.g. acetate and ethers)[2][3]. Quality wise, dissolving pulp is different from paper grade pulp in that dissolving pulp contains high-purity cellulose, high brightness, and high reactivity towards specific chemicals [2][4]. The pulp made at Cosmo Specialty Fibers is used in a variety of end uses; such as Viscose, Microcrystalline Cellulose, Acetate, etc.

Viscose:

The pulp Cosmo Specialty Fibers produces for its viscose customers is used in applications such as, textiles, tire cord, cellophane, etc [2]. Most of the customers for these grades operate out of China, where the viscose market is on the rise [2]. The mill makes multiple grades for these customers with a variety of different specific product qualities. One of the most important quality parameter for these grades is cellulose purity, which is measured in the industry as R18. One of the major things that dictates what the specifications for Cosmo Specialty Fibers’ viscose pulp’s R18 value is China’s anti- dumping tariff, which states that all imported market pulp to China has a R18 value between 87% and 94.0%. If a producer sends products with purity levels outside of those values to China, a tariff is assessed against them [5].

Microcrystalline Cellulose:

The pulp produced for microcrystalline cellulose (or MCC for short) customers, is used as fillers for pharmaceuticals and food. Like viscose, one of the important quality measurements of the MCC pulp is cellulose purity. Other important quality attributes of the pulp are: the low amount of natural resin extractives, the low amount of contaminants/impurities present in the pulp, the brightness of the pulp, and the high density of the sheet. [6]

Acetate:

The pulp produced for acetate customers is used to create cellulose acetate, used in films and cigarette filters. The key quality attributes of these grades are their very high cellulose purity, high brightness, and high degree of polymerization (which is measured as the pulp’s viscosity) [3].

Section 4: Current CSF ECF Bleaching Processes

Overview:

Currently Cosmo Specialty Fibers has two stages that use on-site generated chlorine dioxide as the main bleaching chemical. The first of these stages is also the first bleaching stage and is mainly used as a delignification step. This stage removes most of the residual lignin left in the pulp after being cooked in the digesters (aka the Pulping Process). Following the first chlorine dioxide step is an oxygen delignification reactor coupled with a NaOH extraction, which removes the carboxylic acid structures created in the first Chlorine Dioxide stage from the pulp [7]. After this stage is the second Chlorine Dioxide stage. This is another delignification step, which essentially removes any remaining lignin from the pulp by converting it into carboxylic acid structures that will then be extracted in the bleach cells by more NaOH.

Onsite Generation of Chlorine Dioxide:

As mentioned in the overview, Cosmo Specialty Fibers produces chlorine dioxide onsite using a chlorine dioxide Generator. This generator employs the method known as the Solvay Process for producing chlorine dioxide. The overall reaction of the Solvay Process can be seen in Figure 1 below.

퐶퐻3푂퐻 + 4푁푎퐶푙푂3 + 2퐻2푆푂4 → 4퐶푙푂2 + 퐻퐶푂푂퐻 + 2푁푎2푆푂4 + 3퐻2푂 Figure 1 [3].

Chlorine dioxide gas produced in the reaction above is absorbed from the generator with water creating a solution of chlorine dioxide in water. This solution is then stored in a tank while it waits to be dosed in the two chlorine dioxide stages.

Description of 1st Chlorine Dioxide Stage:

The first Chlorine Dioxide stage happens to be the first stage in the facility’s Bleaching Process. It also happens to be the primary delignification stage in the Bleach Process. In this stage the solution of chlorine dioxide in water is introduced to the pulp in a static mixer. The pulp is then reacted with the chlorine dioxide in a continuous vessel just downstream from the mixer. After passing through the reactor the pulp is washed with shower water. Filtrate from this washing process is collected and stored in a vessel below the washer for reuse. Any excess filtrate is overflowed from this tank to a deaeration tank before being sent to the settling ponds.

Description of 2nd Chlorine Dioxide Stage:

The second chlorine dioxide stage is the 3rd stage in the facility’s Bleaching Process. It is also the final delignification stage in the Bleaching Process. In this stage the solution of chlorine dioxide in water is introduced to the pulp at an agitated in-line mixer. The pulp is then reacted with the chlorine dioxide in a continuous vessel downstream from the mixer. After passing through the reactor the pulp is washed with shower water. Just as in the first chlorine dioxide stage the filtrate from this washing process is collected and stored in a vessel below the washer for reuse. Any excess filtrate from this stage is also overflowed from the collection vessel and sent to the same de-aeration tank before being sent to the settling ponds.

Section 5: Comparing ClO2 to its TCF Counterparts

Overview:

Currently the bleaching process at Cosmo Specialty Fibers is elemental chlorine free or ECF, utilizing chlorine dioxide in two stages for delignification. The reaction between the chlorine dioxide and the pulp during these stages is called oxidation with electrophiles [7]. This process is required to take place under acidic conditions [7]. That being said, to become totally chlorine free (TCF) the facility would have to find a chemical that could conduct oxidation with electrophiles under acidic conditions. Two such chemicals might be Ozone and Peracetic Acid [7]. To see if in fact they can do what chlorine dioxide does chemically with pulp all three processes will be discussed over the course of this section. Also, discussion will be had on what types of equipment changes would be needed to implement ozone and/or peracetic acid (this includes any onsite chemical generation, mixing vessels, and reactor vessels).

Chlorine Dioxide:

How chlorine dioxide reacts with the lignin in the pulp by oxidizing it and converting it into carboxylic acid groups was discussed in earlier; so now an in depth look into the chemical reaction process will be done for chlorine dioxide.

The first step in chlorine dioxide bleaching is the “abstraction” of hydrogen from a phenol group resulting in the generation of chlorite anion [7]. This chlorite anion can regenerate chlorine dioxide while under acidic conditions; but under alkaline conditions the chlorite anion is more likely to form chlorate, which will slow the rate of delignification [7]. In addition, the reaction with the phenol group also results in the formation of phenoxy radical [7]. After the initial reaction the phenoxy radical is further oxidized by chlorine dioxide to produce an opened ring carboxylic acid [7]. It might also undergo side chain elimination, producing a quinone [7]. This first stage process is illustrated in the figures below, which are from the text “Pulp Bleaching Today,” by Hans Ulrich Suess.

Figure 2: the initial reaction of ClO2 with the phenol groups of lignin results in the abstraction of hydrogen creating a penoxy radical which either reacts further with ClO2 to make carboxylic acids (lower reaction) or converts via side chain elimination to quinone (upper reaction) [7].

In order for the reaction(s) in Figure 2 to work, free phenol groups must be present. This is where one of the benefits to using chlorine dioxide comes into play. This benefit is that the inorganic reaction products of chlorine dioxide are capable of additional reactions with lignin. For example, after abstraction of hydrogen from the free phenol group the formation of hypochlorous acid (HOCl) and chloronium ion (Cl+) are formed. The chloronium ion then conducts cleavage of ether groups which leads to the formation of a free phenol group [7]. This cleavage of ether groups is demonstrated in the figure below, also from the text “Pulp Bleaching Today,” by Hans Ulrich Suess.

Figure 3: (Hans, 76)

This production of free phenol groups allows chlorine dioxide to carry out the reaction illustrated in Figure 2, and thus continue the oxidation of lignin [7].

In addition to reacting with free phenol groups, chlorine dioxide can also react with phenol ethers within the lignin [7]. This reaction is much slower than the reaction between chlorine dioxide and free phenol groups; indicating that chlorine dioxide is more selective towards free phenol groups [7]. The reaction between chlorine dioxide and phenol ethers is illustrated in the figure below, which is from the text “Pulp Bleaching Today,” by Hans Ulrich Suess.

Figure 4: the reaction products are 1.4 quinones, aryl ether cleavage and ring openings to muconic acid derivatives [7]. After knowing all of these reactions, it is apparent that chlorine dioxide is incredibly selective towards reacting with lignin. In fact, chlorine dioxide will react very fast with lignin at the beginning of the oxidation process [7]. As the reactive sites in lignin are consumed the reaction becomes slower until it reaches an end point where the no amount of excess chlorine dioxide will break the lignin down further

[7]. Once the end point is reached the oxidized lignin will need to be extracted in a NaOH stage [7]. Now that the chemistry behind chlorine dioxide bleaching has been covered, it is now known what characteristics will be needed to replace it as a bleaching agent in Cosmo Specialty Fibers’ process. Ergo, to replace chlorine dioxide a bleaching chemical would not only need to react in similar ways with the lignin, but will also have to be as selective towards lignin.

Ozone:

One possible replacement for chlorine dioxide is ozone. Much like chlorine dioxide, ozone would have to be produced onsite [7]. It is generated by the silent electrical discharge of pure oxygen [7]. For most pulp mills that produce excess electricity this generation would not be much of a cost center; however, Cosmo Specialty Fibers does not produce an excess of electricity and therefore the generation would become a significant cost center for the facility.

Ozone is a very reactive compound and as such must be added to the pulp in a well-mixed manner. The reason for this is because if ozone were to become pocketed within the pulp it would cause significant quality damage to the surrounding pulp [7]. As such a normal static mixer and a basic inline chemical mixer (both of which are used in our process to mix chlorine dioxide with the pulp at Cosmo Specialty Fibers) will not suffice for mixing ozone with the pulp. Instead ozone is typically added to the pulp in the reactor vessel itself which requires the pulp to be medium to high consistency and high turbulence within the reactor [7].

From a chemical standpoint ozone reacts to both lignin and cellulose in multiple ways [7]. The main reactions that occur between ozone and lignin are: hydroxylation, oxidation into quinones, side chain cleavage, and 1.3 dipolar cycloaddition [7]. These reactions can be seen in the figure below, which is from the text “Pulp Bleaching Today,” by Hans Ulrich Suess.

Figure 5: The reactions are in the order as listed in the paragraph above. [7]

As mentioned before, ozone will react with cellulose fiber. It does this by causing chain oxidation of the cellulose [7]. This can be detrimental to the facilities products since it is very important for dissolving pulp to have high cellulose purity and oxidation can harm this. One such product is the standard viscose grade. As discussed in Section 3, The Ministry of Commerce of China has established anti-dumping

15 regulations on imports for their dissolving pulp industry that specifically target low end viscose cellulose purity [5]. The implementation of an ozone stage may result in a drop in overall purity of the mill’s pulp which could either put the product dangerously close to or within the limits of this regulation, which would result in the facility’s customers getting a tariff placed on them. This could not only result in the customer passing on the cost to Cosmo Specialty Fibers but could result in a significant negative hit to the reputation of the mill and loss of business. Degradation of cellulose would also be a problem for our high purity Viscose, Acetate, and our MCC grades all of which require a significantly higher cellulose purity level as compared to our standard viscose grade.

In addition to oxidizing cellulose chains, ozone also oxidizes any ethers, alcohols, and carbonyl structures creating new carbonyl or carboxyl structures [7]. It also reacts with the double bonds on hexenuronic acid [7]. Based on the plethora of things ozone will react with, it is safe to say it is not specifically selective when it comes to what it reacts with. Because of its non-selective nature and high reactivity, bleaching in ozone would likely result in further loss in the degree of polymerization (measured by the viscosity of the pulp) of the pulp especially for softwood pulps, which contain lesser amounts of hexenuronic acids than hardwood pulps [3]. This is a huge issue when it comes to the Acetate (and other high viscosity) grades which require the mill’s pulp to be produced with a high degree of polymerization. Furthermore, it is clear that the reactions ozone has with the pulp will change the chemistry of the pulps for all of Cosmo Specialty Fibers’ grades. Because of this, if the facility were to switch to ozone at even one of the chlorine dioxide stages, it would have to get its products requalified with all of its customers, which again would be detrimental to the mill.

Peracetic Acid:

Unlike chlorine dioxide and ozone, peracetic acid does not necessarily have to be produced using onsite generation; however, it is expensive to purchase due to the fact that all of the compounds found in the solution (peracetic acid, hydrogen peroxide, acetic acid…) contribute to the cost [7]. This cost could be lowered by purchasing distilled peracetic acid, but unfortunately there is only one supplier in the world and they reside in Finland [7]. This makes onsite generation the cheaper option in the long run [7]. Peracetic acid is produced by mixing hydrogen peroxide and acetic acid [7]. The production of peracetic acid can be accelerated in the presence of a strong acid like sulfuric acid [7].

Chemically, peracetic acid reacts with lignin by way of hydroxylation with the aromatic systems of lignin [7]. The hydroxylation of the aromatic systems leads to the oxidation of the reactant and thus generating phenolic groups. These phenolic groups are then easily oxidized into quinones, which are then cleaved into carboxyl acids [7]. This reaction process is displayed in the figure on the next page, which is from the text “Pulp Bleaching Today,” by Hans Ulrich Suess.

Figure 6: [7]

Unlike chlorine dioxide, peracetic acid does not react with lignin very fast [7]. In fact, if the peracetic acid reactor temperature falls below about 60oC, the reaction will become very slow resulting in a negative effect on pulp brightness [7]. Most likely the slower reactivity with lignin and the temperature constraints are why peracetic acid is not used at the front end of bleaching processes. That being said, peracetic acid is typically used before a hydrogen peroxide stage towards the end of the bleaching process [7]. Still, this is only done to increase the effectiveness of the peroxide to brighten the pulp [7] and it would likely require more energy in the form of steam to replicate the delignification ability of chlorine dioxide in the last chlorine dioxide stage in Cosmo Specialty Fibers bleaching process.

Section 6: Market Study

As mentioned in Section 2, Cosmo Specialty Fibers is an Acid Bisulfite mill that produces exclusively dissolving pulp from softwood chips. From research into the markets the facility competes in, there is no evidence of a softwood sulfite mill that produces dissolving pulp with totally chlorine free bleaching [2][3][8][9]. In fact, in the dissolving pulp industry the only TCF mills that could be found were those that produced pulp using hardwood [8]. Also, while there are mills that produce viscose with TCF (which are most likely hardwood sulfite or prehydrolysis kraft), there are no dissolving pulp mills that produce either MCC or Acetate pulp [3]; therefore, the change to TCF bleaching would eliminate Cosmo Specialty Fibers from these markets, which would limit the mill’s viability. Section 7: Estimated Cost for Conversion from ECF to TCF

Research was done on the cost of converting CSF process to TCF bleaching, even though product quality cannot be achieved with this sequence. Two separate cost estimates were found. One of these estimates was for the conversion of a magnesium bisulfite mill in Australia that produced paper grade pulp. That estimate was approximately $145Million to convert the facility to TCF bleaching back in 1997 [10]. Another cost estimate came from a TCF article in the mid ‘90s that suggested it would cost about $96Million to convert an existing paper grade mill to TCF [11]. Both of these estimates were done for paper grade mills, and the current cost would be substantially higher in 2016 dollars, however we did use the estimates as an order of magnitude capital cost. From an operating cost estimate, as mentioned in section 5, Cosmo Specialty Fibers would have to buy electricity to generate ozone. The estimated energy needed to generate ozone is 7-8kWh/kg of ozone [12]. This would add an estimated $3.65 of incremental cost for generating ozone. In conclusion, the capital cost of converting and the additional cost of operations from implementation of TCF bleaching stages are not reasonable for Cosmo Specialty Fibers to incur. Section 8: TCF Study Conclusions

It is not reasonable for Cosmo Specialty Fibers to convert its bleaching process from elemental chlorine free (chlorine dioxide based) to totally chlorine free. First, the facility is and continues to operate below the maximum discharge limits, set by the current NPDES permit, for absorbable organic halogenated matter, tetrachloro-dibenzo dioxins, and furans. Second, both ozone and peracetic acid (the alternatives to chlorine dioxide) are not suitable chemically to replace chlorine dioxide in Cosmo Specialty Fibers’ bleaching process, for a number of quality specific reasons. For instance, ozone degrades cellulose leading to the lowering of cellulose purity in the pulp, which does not agree with the quality standards of the dissolving pulp we produce. Also, peracetic acid is not a strong enough oxidizer to match the capabilities of chlorine dioxide at both the front and at the second to last stage of the mill’s bleaching process. Furthermore, TCF bleaching is not currently considered to be AKART (all known and reasonable technologies) for acid bisulfite dissolving pulp mills that produce products for viscose, microcrystalline cellulose, and acetate pulp from softwood chips. In addition, the cost for converting to totally chlorine free is unreasonably expensive, and more costly to operate. Based on all of these reasons, it is not economically viable for Cosmo Specialty Fibers to convert to TCF bleaching.

Section 9: References

[1] Washington State, Department of Ecology. “Fact Sheet for NPDES Permit WA0000809: Cosmo Specialty Fibers.” April 2, 2015.

[2] Liu et al. “Review: Dissolving Pulp,” BioResources 11(3). 2016. 7902-7916.

[3] Sixta, Herbert. “Handbook of Pulp.” Weinheim, Germany: Wiley-VCH GmbH & Co. KGaA, 2006. Pages 251, 742, 830, 882, 1022, 1025-1026, & 1028.

[4] Leithem, Phyllis C. et al. “Reduced Chlorine Usage in the Production of Sulfite Dissolving Pulp.” Tappi Press Conference (1994). Atlanta Georgia. 669-713.

[5] The People’s Republic of China, Import and Export Fair Trade Bureau of the Ministry of Commerce. “Ruling 20131106.” Doc number: 2013 75. November 6, 2013.

[6] Lester Van Groeningen (CSF Contractor for Product Development). Internal Document re Micro Crystalline Cellulose.

[7] Suess, Hans Ulrich. “Pulp Bleaching Today.” Berlin, Germany: The Deutsche Nationalbibliothek, 2010. Pages 13, 27, 30, 45, 74-78, 96-97, 153-154, 158-159, & 161.

[8] Sixta, Herbert. “Comparative Evaluation of TCF Bleached Hardwood Dissolving Pulps.” Lenzinger Ber. 79 (2000), pages 119-128.

[9] U.S. Environmental Protection Agency. “Market Study of Molecular Chlorine Free and Totally Chlorine free Bleached Paper.” December 1992.

[10] “Magnefite Pulping Process for Chlorine Free Bleaching” Infohouse. http://infohouse.p2ric.org/ref/10/09463.htm. June 1997.

[11] Johnston, Paul A. et al. “Towards Zero-Effluent Pulp and Paper Production: The Pivotal Role of Totally Chlorine Free Bleaching.” Greenpeace International, Amsterdam. November 28, 1996.

[12] Hostachy, Jean-Christophe et al. “Pulp Bleaching with Ozone Industrial Achievements & Perspectives.” Mcilvaine Co. Northfield, IL.