Principal Investigator: Charles E. Courchene

Email address: chuck.courchene@ipst.edu

Industry Partner: Timber Company, Rayonier Corp., Georgia-Pacific Corp.

The pulp and paper industry in the Southeast U.S. is facing increased competition from imported products and having to pay higher stumpage for southern pine timber because of reduced acreage for timber production and the increasing demand for wood. Wood costs need to be controlled if the Georgia pulp and paper industry is to remain competitive. Foresters are using more intensive management practices to increase wood fiber. These management practices include competition control, fertilization and shorter rotation to accelerate growth. The resulting increased growth of southern pines has the potential to reduce wood costs for paper production or at least slow the steady increase. To be cost-effective however, the fast grown trees cannot result in lower pulp yields or diminished final product.

A joint study by the University of Georgia, the Institute of Paper Science and Technology, and the USDA Forest Service along with collaboration from industry partners was undertaken to evaluate the wood and pulp quality from fast-grown loblolly and slash pine. The effects of planting density (400, 600, 800 TPA) and herbaceous competition control of 14 year loblolly pine in the Piedmont and herbaceous competition control and fertilization of 17 year slash pine in the Coastal Plain on wood properties, pulp yield and paper properties were examined. The properties of the young trees were compared to that of a 24 year loblolly plantation in the Piedmont and 24 year slash pine plantation in the Coastal Plain. Annual growth rates of 14 year loblolly increased 106-124% compared to 24 year slash control . Wood samples were quantified as to annual growth increments, percent latewood per growth ring, and the proportion of juvenile wood. The proportion of juvenile wood in the saw log stem was significantly higher in the young Piedmont trees compared to the Costal Plain trees. Three types of chips were prepared from each tree sample, chipping saw chips (CNS), whole stem chips, and top wood chips. The chips were screened and classified and specific gravity and bulk density measured. Within each chip type, the bulk density of the intensively managed younger trees was equal to or greater than the control. The top wood chips had a bulk density 18% lower than the CNS chips which may impact digester production when a large percentage of the top wood chips are used because of a reduced chip charge per digester cycle.

Both linerboard and sack kraft grade pulps were made from each of the chip sources in the laboratory and the handsheet strength tested. Within each chip type, there was not any adverse effect on pulp yield from the intensive management practices. The top wood samples with a higher proportion of juvenile wood had pulp yields that were 2-3% less than the CNS chip yields. Overall, there was no negative impact on handsheet strength from the intensive practices within each chip type. However, the top wood pulps with more juvenile wood fibers produced higher tensile and burst strength due to increased sheet bonding but lower tear strength because of the shorter fiber length.

The results of this study show that the Georgia pulp and paper industry can significantly increase pine growth using intensive forest management and rotations as short as 14 years and use the CNS chips or whole stem chips to manufacture linerboard and sack paper with no significant change in paper properties. Rotations less than 12-14 years in the Piedmont could result in significantly reduced pulp yields and changes in paper properties because trees under 12 to 14 years old have fiber properties similar to top wood chips. Timber companies are now adopting woody and herbaceous competition control and can expect increased growth rates on managed plantations.

Email address: covert@arches.uga.edu

Industry Partner: International Paper

To date, efforts to control fusiform rust have focused on the development of rust-resistant trees through selective breeding of pines. Although breeding has resulted in significant gains in resistance, fully resistant pine families have rarely been identified. In addition, fully resistant pines are not available in sufficient quantities to be employed operationally. Rust fungi that cause diseases on other host plants are notorious for their ability to overcome host resistance in the field, therefore, it appears unlikely that resistance to fusiform rust will remain effective indefinitely. In this context, it is important to consider alternative approaches for controlling fusiform rust and to concurrently improve our understanding of this host-pathogen interaction.

Our long-term research goals are twofold: 1) improve our understanding of how fusiform rust galls are formed and 2) create trees that are resistant to fusiform rust. As a first step towards these goals, molecular genetic techniques have been used to identify and isolate pine genes that are either turned on or turned off by fusiform rust infection. Analysis of these genes and their products should give us insight into the mechanisms of fusiform rust gall formation. Once these genes are in hand and characterized, there are a variety of genetic engineering strategies that could be implemented to create trees that are likely to be improved in their resistance to fusiform rust.

The experimental nature of this work makes it difficult to predict when results will be used by Georgia’s forest industry. However, if the first round of genetically engineered trees are improved in their disease resistance, they should be available for industry testing in 3-5 years.

Principal Investigator: Jeffrey F.D. Dean

E-mail address: jeffdean@uga.edu

Industry Partner: International Paper

As the pulp and paper industry continues to push for increased productivity, mills are increasingly forced to accept fast-grown southern pines containing significant amounts of "juvenile" and "compression" wood. These types of wood are considered to be of lower quality and are less desirable for pulp production than wood produced by more mature trees. Estimates suggest that pulp yields from juvenile trees (10-15 years old) may be 5-10% less than from a comparable dry weight of wood from mature trees. This project seeks to develop a means for identifying the genetic factors responsible for that 5-10% loss in yield.

To use genetic engineering for the efficient modification of complex traits, such as those governing wood quality, flowering and tree form, genes isolated from the trees themselves will be required. However, very few genes from trees have so far been isolated and characterized. As a means of efficiently identifying genes that have potential applications to forestry, particularly with respect to improving the quality of wood and fibers from southern yellow pines, we have employed a functional genomics technique, called Serial Analysis of Gene Expression (SAGE), to quantify unique DNA tags that represented each of the RNA transcripts expressed in selected woody tissues of loblolly pine. Literally, we are able to quickly "count" thousands of gene copies, and record the number of times a copy from each particular gene is present in the tissue. Our original expectations were to complete analyses of four classes of wood-forming tissues from loblolly pine, representing juvenile, mature, compression and opposite woods, by the end of FY99. As the project progressed we realized that in order to get statistically significant coverage we needed to revise upward (5x) our target for the number of SAGE tags to be counted from each SAGE library. This alteration in plans, coupled with technical difficulties in the preparation of libraries from some of the target tissues, has meant that we were unable to meet the original goals set for FY99 – 10,000 tags counted for each of the four tissue types. However, as of the filing date for this report, we have counted more 45,000 tags from a single library. These tags have enabled us to identify over 5800 unique genes that are expressed in cambial tissues producing juvenile wood, and we have begun to identify likely functions for many of the most highly expressed genes. Once we complete our analyses of the other three libraries, quantitative differences in tag frequency will allow us to identify genes whose altered expression may be linked to changes in wood quality. It is our expectation that cDNAs isolated using the information from our SAGE analyses will be useful for efforts to modify wood quality. The researchers involved in this work will interface with those working on a TIP3-funded project to improve transformation protocols for southern yellow pines in order that the effect of these novel genes on wood formation might be tested in transgenic pines at the earliest opportunity.

This project addresses the identification of novel genes involved in governing wood and fiber properties in loblolly pine, thereby addressing a biotechnology priority issue for the TIP3 program. Our goal is to develop informative databases cataloging pine genes and their relative expression in woody tissues having greater or lesser value to industry. Such databases will provide the starting point for several alternative methods improve wood quality in southern pines. For instance, genes identified as likely to control juvenile wood production might be used to genetically engineer trees that will produce less juvenile wood. Alternatively, genes whose expression is tightly correlated with wood quality might be used to monitor in real-time the effects of new silvicultural treatments on wood quality. As the databases are not yet complete, they have not been used by any companies.

Principal Investigator: David E. Kissel

Email address: dkissel@arches.uga.edu

Industry Partner: Union Camp

This research will determine the months of the year that urea fertilizers may be applied without significant loss of its nitrogen to the atmosphere. Any fertilizer lost will not be available to increase forest growth. Forestry managers generally follow the guidelines that urea may not be applied during the April through September time period, because it is widely believed by some managers that significant loss of ammonia from the applied fertilizer may occur back into the air due to higher temperatures. However, there is little information in forest situations about how much loss actually occurs during this time period. If losses are not as significant as believed by many scientists, fertilizer may be applied more efficiently during this time period by taking advantage of better weather, more daylight hours, and frequently lower urea fertilizer prices. More acres may be fertilized, thus leading to improved forest growth and fiber supply.

Our research will help solve this problem because during the past year, we have designed and built a device that will allow us to measure the amount of ammonia loss that actually occurs from urea following its application to the forest. In tests this summer, we have modified the measurement system to increase its measurement accuracy. In our most recent tests, we were able to measure over 98 % of the ammonia actually being lost in the forest. Later this year, additional units of the measurement devices that are now being built, will allow us to determine losses from as many as three fertilizer treatments at one time. With this capability, it will be possible to determine how important management factors such as smaller but more frequent applications of fertilizer will reduce the loss of ammonia from urea fertilizer applied in the forest. We expect to measure the loss of ammonia from surface applied urea once each month next year. We will carefully measure the environmental conditions at each application time, and we will determine how the temperature and conditions of humidity affect the amount of ammonia loss measured. The knowledge gained will allow us to know the amount of loss from urea fertilizer that is applied at different times, different rates of application and with different amendments that might reduce ammonia loss.

If the results of our research show that ammonia losses are low during the April through September period, then we can expect that more acres of mid-rotation southern pines will be fertilized for the following reasons: a. Fertilizer application equipment may be utilized for a greater portion of the year, which should reduce application costs, and b. Often, urea prices are reduced during the summer period, which will allow more urea to be purchased with a given amount of budgeted funds. The net result of these two factors will be more acres fertilized at the end of the mid-rotation time period, which will increase forest growth rates, resulting in earlier harvests and more production and profit per acre.

Genetic transformation methods for southern pine

Principal Investigator: Gary Peter

Email address: gary.peter@ipst.edu

Industry Partner: The Timber Company (Georgia Pacific)

The most productive Georgia Forestry lands are actively managed as tree plantations. The goal of most forestry operations is to maximize yields of high quality wood. Planting and farming practices known as silviculture seek to maximize tree growth rates. Tree growth rates need to be high and even increased for Georgia to remain economically competitive in the global forest products marketplace. The effects of high tree growth rates as well as specific silvicultural treatments on the wood and fiber properties are not well characterized. However, it is well known that if rotation times of pine were shortened by one half, then much of the wood and fibers would be from the juvenile wood. This juvenile wood shows a generally lower strength than mature wood and fibers. Therefore, if the strength of juvenile enriched wood and wood fibers from these high growth rate plantations are not good then the yield of valuable products for construction and container board grades from them could decrease dramatically. The effects of harvesting early and maximizing growth rates on wood and fiber qualities is of very significant concern because of the potentially widespread impacts on both solid wood and paper products. A key challenge to the future is to improve the strength of wood and wood fibers from this plantation grown juvenile wood. Small increases in strength may lead to billions of dollars/year.

The goals of this project were 1) to develop rapid methods for measuring key strength related fiber properties and to use these methods 2) to assess the impact of silvicultural practices on these key fiber properties on southern pine plantations. One of the most important properties for southern pine wood and fibers is strength. The strength of individual fibers is most strongly determined by the angle with which cellulose is deposited in the fiber secondary cell wall. This property is termed microfibril angle (MFA). The MFA of fibers from young, juvenile trees is inferior to older more mature trees, and this reduces the strength of the wood and paper products made from these younger juvenile trees.

We have successfully developed a cost effective and simple method for measuring the MFA of fibers. This opens a door, previously closed by cost, to developing a more complete under-standing of the role that silvicultural treatments have on determining MFA. We are using this new method to determine the impact of certain silvicultural variables, including planting density, fertilization and heribicide treatments, on the MFA and fiber length of loblolly and slash pine. We measured the MFA and fiber lengths, the other important contributor to strength, for 15 trees from two treated and two control sites. We are currently analyzing this data relative to the large amount of information available about these trees’ growth rates, solid wood, pulp yields and paper properties.

The information obtained by our studies is directly applicable by forest products and individual growers today. This information can help them decide what silvicultural practices to employ, some of which may improve the strength of juvenile wood.

Ensuring Fiber Supply Through Biotechnology: New Tissue Culture Tools from Gene Expression Studies

Email address: john.cairney@ipst.edu

Industry Partner: International Paper

Fiber is the most expensive single component in the paper making process. An inexpensive supply of fast-growing trees would redress the advantage currently enjoyed by foreign competitors. Somatic Embryogenesis (SE), a laboratory technique for plant embryo multiplication, allows thousands of plantlets to be produced in a small space in a short period of time. The potential for supplying trees to the industry has been recognized by many companies however, Loblolly Pine, the most important tree in the Southern US, is recalcitrant to the process. Improvement of SE will require 1) an understanding of the program of gene activity responsible for embryo development 2) development of hypothesis for SE improvement based on this understanding. 3) testing and implementation of improved protocols.

We have developed new techniques and have identified and cloned over 500 genes critical to embryo development. We have begun to assay the activity of these genes during natural embryo development in seeds on the tree and in embryos in the laboratory. We have used this information to create new hypotheses for pine embryo development which we have tested. Incremental improvements in embryo quality have resulted. We are now creating a database of gene activity during embryo development and will use this to continue the cycle of hypothesis-generation and evaluation. We receive considerable industrial input from Georgia-based pulp and paper companies during semi-annual visits and through discussions throughout the year.

The deployment of clones (e.g produced by SE) in plantations would produce 40-50% improvement in yield over unimproved forest and a 10-20% yield improvement over current improvement practices. A consensus of industry opinion is that the improvement in somatic embryogenesis could be worth a very significant amount; possibly hundreds of millions of dollars to the industry.

Principal Investigator: Rodney Will

Email address: rwill@arches.uga.edu

Industry Partner: Rayonier, Inc.

Georgia has the largest forest products industry in the country (approximately $18 billion in annual revenue). Feeding this industry is a readily available fiber supply grown on 23.6 million forested acres, the most of any state in South. However, estimates are that the harvest of softwood in Georgia exceeds growth by 5 percent. Because the competitiveness of the forest products industry in Georgia is based on a readily available and affordable fiber supply, more fiber per acre must be produced to make up for lost acreage and to meet future demands.

This is a two-year study to determine the mechanisms that control maximum stem volume on a per acre basis by examining the biotic and resource limitations that are incurred as the number of trees per acre increases. We are measuring carbon partitioning, intercepted radiation, nutrient concentrations and rates of physiological processes of intensively managed loblolly pine and slash pine stands planted in 1996 at 300, 900, 1500, and 1800 trees per acre. Six sets of stands at different locations on the Coastal Plain are being measured. This is an ongoing project is continuing through FY00 so all measurements are not completed and results are preliminary.

We anticipate this study will determine how maximum stem volume growth per acre of loblolly and slash pine stands is limited by external resources and by internal patterns of growth and carbon allocation as stocking density increases. Furthermore, we anticipate that the specific limiting resources or processes of loblolly and slash pine that can be targeted by silvicultural prescriptions and genetic selection to increase stem volume growth.

Measurements from the third growing season are completed. Increasing stocking density decreased the size of individual trees, but increased the per acre stem volume growth. Stocking density did not affect foliar nutrient concentrations, net photosynthetic rates, or respiration rates of foliage or stem. Intercepted radiation measured during the period of maximum leaf area was well correlated to stem volume growth. The lack of response in the capacity of carbon gain (photosynthetic rate or nutrient concentrations) or in carbon loss (respiration) indicate that growth on a per acre basis is driven mainly from increased leaf area and intercepted radiation. Although loblolly pine growth is greater, loblolly pine and slash pine appear to respond similarly to stocking density for most parameters. More information regarding the effects of stocking density on whole tree nutrient status, carbon partitioning, and leaf area dynamics will be determined during FY00.

Knowing what limits growth as stocking density increases will result in the development of management strategies that will manipulate key resources and mechanisms to increase stand growth rates. Depending on what limits growth, nutrients can be manipulated through the timing and application rate of fertilizer or carbon partitioning to stem or respiration can be manipulated through resource inputs or genetic selection. In addition, once the limiting mechanisms are determined, it may be possible to manipulate them through future genetic engineering. So far, it appears that management should focus on increasing leaf area. In addition, understanding what controls stem volume growth as density increases will provide information for a new generation of the growth and yield models that include mechanistic parameters.

Principal Investigator: C. Wayne Berisford

Email Address: berisford@bugs.ent.uga.edu

Industry Partner: Pine Tip Moth Research Consortium

The Nantucket pine tip moth, Rhyacionia frustrana (Comstock), is a serious pest of southern pine plantations. Larvae feed on growing shoots of loblolly, shortleaf, and Virginia pine seedlings and saplings, causing loss of growth, poor tree form, and reduced wood quality. Tip moth populations, and therefore extent of damage, vary among plantations, for reasons that are poorly understood. The goal of this study was to find environmental variables that are useful in predicting stand susceptibility to tip moth infestation, and develop an effective tip moth hazard rating system based on these variables.

Thirteen one-year-old and four two-year-old loblolly pine plantations were established as study sites in the Georgia coastal plain. Eight of the one-year-old and all two-year-old plantations were located in the southeastern Georgia coastal plain, in the Savannah area. The remaining five one-year-old plantations were located near Bainbridge in the southwestern Georgia coastal plain. Tip moth infestation rates, measured as percentage of infested shoots, were estimated at each study site for the purpose of serving as the response variable in predictive equations using several environmental variables as predictors. For the overwintering generation, infestation rates ranged from 2.8% to 77.4% (mean = 51.2) for the Savannah area sites, and 43.5% to 65.7% (mean = 53.4) for the Bainbridge sites. Summer generation infestation rates were much lower, ranging from 1.9% to 17.9% (mean = 8.2) at the Savannah area sites and from 6.8% to 26.4% (mean = 18.4) at the Bainbridge sites. Low variation in tip moth infestation levels combined with dramatic decreases in tip moth populations late in the season, precluded further pursuit of the problem in 1999.

In winter of 1999, when overwintering tip moth damage is obvious, we will begin attempts to identify potential study sites for the 2000 field season. Sites will be selected that show a high degree of variation in tip moth infestation rates. Once these sites are identified, potentially useful predictive variables (previous tip moth damage, foliar nutrients, site preparation and silvicultural treatments, soil pH, soil CaCO₃, soil profile, soil drainage class, soil texture, and proximity to susceptible pine plantations) will be measured at each site. Infestation rates will be monitored during each generation throughout the season to verify that differences in infestation rates are consistent over time. Multiple regression and/or multivariate statistical analyses will be used to identify variables that are useful in predicting tip moth infestation rates.

An accurate pre-planting tip moth hazard rating system could be economically beneficial by allowing forest managers to plan stand establishment in areas with low probability of moth infestation and by guiding them in selection of species to be planted. In addition, a post-establishment hazard rating system would make it possible for forest managers to concentrate tip moth control operations on those areas with a high probability of serious moth infestation, thus reducing control costs.

Principal Investigator: Pierre Brodeur

Email address: pierre.brodeur@ipst.edu

Industry Partner: Southeast Paper Manufacturing

In mills optimizing raw material usage and closing up water systems due to environmental regulations, efficient removal techniques are needed to remove accumulating solid suspensions. As a novel approach to solids removal, an in-line chemical flocculation/ultrasonic method to clarify a whitewater stream was investigated. The method first considers the use of flocculants to create larger size particles or flocs. Then, an ultrasonic field normal to the flow direction of the whitewater stream is applied to the flocs in such a way as to obtain two output streams: a clarified water stream and a stream of concentrated solids. A laboratory in-line ultrasonic separation system was used to demonstrate the clarification concept. Test conditions were determined to achieve a clean stream with less than 100 ppm of solids. Also, clarification efficiency close to 80% of the maximum possible clarification efficiency in the experimental setup was obtained.

An economic analysis was performed on a theoretical 6000 gpm ultrasonic whitewater clarifier. It was compared to a conventional dissolved air flotation (DAF) unit of the same size. The ultrasonic clarifier is estimated to cost 66% less than the DAF to purchase and install, and will cost 35% less to operate (considering both chemical and electrical costs).

Research is underway to develop a 100 gpm pilot-scale ultrasonic clarifier and perform a mill demonstration in collaboration with Southeast Paper Manufacturing and Beloit Corporation.

Principal Investigator: K.C. Das

Email address: kdas@bae.uga.edu

Industry Partner: Weyerhaeuser

The Pulp and Paper Industry generates over 4 million dry tons of sludge every year with more than 70% of this presently landfilled. Cost of landfill space is increasing and its applicability is becoming limited thus requiring alternative approaches. In 1993 a single Georgia mill produced 35,200 wet tons of knot rejects, 4,200 wet tons of boiler ash, 18,500 wet tons of primary sludge and 156,900 wet tons of wood yard debris. The total 214, 800 tons of solid waste were disposed at a nominal cost of $7/ton resulting in $1.5 million disposal cost for that year. It is anticipated that in the future landfill costs can reach $20/ton (current state municipal landfill cost average is $32/ton). At $20/ton the disposal costs for this milll can be as much as $4.3 million per year. This limited use of byproduct resources and significant cost of disposal together limits the economic and environmental viability of the industry.

Future (and present) work focuses on (1)quantifying odor released during composting and determining how to reduce it, (2)adding other mills to our research thus addressing additional unique industry solid wastes, (3)evaluating chlorinated organics presence and degradation.

Presently one mill has tested the composting process on-site to divert the solid waste from landfills to a value added compost. They have found that local farmers’ interest in the product is high and that the product works well in mine land reclamation. The economics of diversion is being evaluated and the mill is presently seeking independent contractors of composting. As additional markets for compost use develop, a larger number of mills are expected to utilize composting as an option. An average mill producing 50 tons of compostable waste per day can be expected to save about $500,000/yr through avoided landfill costs and product sales.

Principal Investigator: H. Jeff Empie

Email address: jeff.empie@ipst.edu

Industry Partner: Weyerhaeuser Company (Oglethorpe, GA)

Industry Competitiveness: Odor reduction is an increasing concern of communities located in the vicinity of a kraft pulp mill. The time has arrived whereby that characteristic sulfur-based odor no longer "smells like money." Previous technologies that have been investigated include incineration and wet scrubbing, neither of which is an acceptable route, with both technologies posing their own pollution problems.

The goal of this project is to use mill-generated green liquor dregs which are routinely sent to the landfill to reduce the odorous emissions from the mill waste gases down to a level where the odor is no longer detectable.

Installing a process step to reduce or eliminate odor from a kraft mill will increase production costs without an accompanying productivity or efficiency increase. To be able to implement a technology that employs a no-cost "catalyst" that is readily available (i.e. dregs), and does not produce a secondary waste stream that requires additional treatment, should make this technology an attractive low-cost alternative.

Findings to Date: Laboratory scouting experiments this past year used a packed bed reactor to determine the rate of sulfide removal from a pre-mixed feed gas of hydrogen sulfide in nitrogen and oxygen as a function of process operating parameters, including temperature, feed concentration, gas flow rate, and bed size. The effective lifetime of the bed was determined as measured by when it becomes ineffective in removing the sulfurous odor component. Based on typical mill production rates of both dregs and odorous gases, it was determined from the lab data that the dregs would have to be regenerated one time so that the daily mill dregs production can successfully treat the odorous gases continuously leaving the mill. A successful method to regenerate the spent dregs was developed.

Work is underway to reconfirm the laboratory results under actual operating conditions and establish the technical and economic feasibility of the technology. A mill scale trial will look at several different point sources of odor in the pulp mill. A skid-mounted packed bed unit will be constructed to sample and analyze gas flows from different locations around the mill.

Implementation by Industry: At the successful completion of this project, implementation should be immediate as all kraft mills produce green liquor dregs. The spent dregs no longer effective in removing the odorous components from mill waste gases would then be sent to the landfill. Hence, the only costs would be for capital equipment and for transportation of dregs to and from the packed bed reactors.

Principal Investigator: Arthur J. Ragauskas

Email address: arthur.ragauskas@ipst.edu

Industry Partner: Sunds Defibrator Inc

Competing industrial usage of Georgia’s water resources over the past decade have substantially increased the interest in low effluent, closed-cycle pulp and paper mill operations. Virtually, all pulp mills in the state of Georgia will need to examine their fresh utilization practices. A variety of research plans and technologies are being developed for the market place in response to these demands. Of the many technological challenges that must be addressed prior to completion of commercial closed-mill pulping and bleaching operations, control of non process elements (NPE) through-out the manufacturing process is one of the most urgent. A key component of NPE control strategy is a detailed description of the amounts of NPEs in the incoming wood supply for a mill.

Our studies evaluated the concentration of NPEs in a series of wood chips acquired from commercial pulping operations located throughout Georgia. These studies demonstrated that in both SW and HW chips the relative concentrations of NPEs is Ca> K> Mg> Mn > (Na, Ba) > Fe although the amounts of these materials were usually significantly higher in HW samples. Metals analysis also demonstrated that the bark had even higher amounts of Ca, K, and Mg. NPE analysis of mill and laboratory kraft pulps demonstrated that the NPE values in the wood chips are mirrored, to some extent, in the pulps, but clearly a variety of pulping process parameters influence the overall metals content of the pulps.

The results of these studies are of value to any mill in Georgia implementing modeling technology to evaluate how closed mill operations will impact pulping and/or bleaching operations. The experimental data acquired in this project determined the amounts of metals that are introduced into a pulp mill by the wood furnish. In addition, the results of this project demonstrated that the NPEs in the wood impact subsequent pulping operations. Our studies also established that significant amounts of NPEs could be introduced into the fiber line by the presence of residual bark on the wood chips. Clearly, for mills suffering from calcium or potassium problems, improved debarking technologies could aid their operations. The results of this study have been distributed to the eight mills participating in this study and a variety of pulp and paper manufacturing representatives from the state of Georgia.

Principal Investigator: Alan W. Rudie

E-mail address: alan.rudie@ipst.edu

Industry Partner: Georgia Pacific

Wood is the major source of these non-process elements in the mill. Calcium is present at about 1000 ppm in wood chips, and barium around 50 ppm. Although these numbers seem small, for a typical mill the calcium amounts to over two tons and the barium over 100 pounds each day. The calcium oxalate and barium sulfate scales are particularly troublesome because they are very hard and can only be removed by acid treatment. Removal of these scaling minerals requires a shutdown of the mill and can result in lost production if the build-up can not be handled within the normal maintenance schedule of the mill. We estimate the cost to Georgia mills at over 2.5 million dollars annually and this is assuming the mills can handle the problems without lost production.

This project is improving our understanding of why and how trace metals accumulate in a pulp mill fiber line. We are trying to determine what fraction of the metals is physically bound to fiber, what fraction is dissolved in process streams and what fraction is precipitated either as a solid material suspended in process filtrates, attached to process equipment (scale) or attached to pulp. We have discovered that calcium enters the bleach plant as calcium carbonate rather than physically bound to the unbleached fibers as initially expected. We have determined that manganese oxalate precipitates should also exist in the bleach plant, even though there have been no reports of this in any of the deposits analyzed by the industry. Our analysis suggests that calcium oxalate and barium sulfate precipitates should exist in nearly all bleach plants. This raises the question why some mills do not have problems with mineral scales. We have also demonstrated that a change in the process pH at the end of the chlorine dioxide bleach stage will help to transfer trace metals out of some bleach plants without reducing bleaching efficiency.

A new project by the same PI’s is now attempting to confirm the presence of precipitates in the bleach plant, and if found will begin to characterize their behavior. Of particular interest will be what controls the size and scaling tendency of the precipitates and how to use this to eliminate scale problems in mills.

Principal Investigator: Sujit Banerjee

Email address: s.banerjee@ipst.edu

Industry Partner: Hollingsworth & Vose

The pulp and paper industry uses large volumes of freshwater, and economic, environmental, and political pressures will force reduction of water use, especially at coastal and/or urban mills. Regulatory trends target the reduction of both wastewater discharge, and of the COD (Chemical Oxygen Demand) content of the effluent. Public perception of the industry as a large user of water further emphasizes the issue. Water usage can be minimized either through lower use, or through recycling. Pulp and paper manufacture is water-intensive. The easy gains, e.g. through control of spills have already been achieved, and we are at the point where further reduction will be achieved either through major process changes or through water reuse. This project addresses potential water recycling opportunities.

The focus of this project is to (a) define the quality of water necessary for various operations, (b) evaluate the quality available from various operations, (c) identify the technological and financial barriers required to match water need with availability, (d) develop the missing links, and (e) demonstrate and transfer the process. Most of the work was done at the Hollingsworth and Vose (H&V) facility at Hawkinsville, GA. Characterization of various streams at H&V has shown that the quality of the final effluent is comparable to that from the filtered Saveall, and that a part of the final effluent should be recyclable. Sources of recyclable water were identified at Tenneco, and at Cedar Springs.

We project that 12 mgd can be saved at H&V, Cedar Springs, and Tenneco for annual savings of $42K and $27K in water and treatment costs, respectively.

Principle Investigator: Yulin Deng

Phone Number: 404-894-5759

Industry Partner: Stone Container

Georgia is one of the nation’s leading producers of pulp and paper. With the increasingly restrictive environmental regulations, the investigation of the impacts of water closure on the paper properties and papermaking process, and the development of technologies to reduce fresh water consumption have been identified as a priority by Georgia Consortium for Technological Competitiveness for the pulp and paper industry.

Although totally closed water system has been developed by some paper mills in recent years and it may be the only way for a new mill to start up, Georgia paper mills have not successfully closed their water streams. The buildup of the dissolved electrolytes and contaminates in a closed white-water system, particular in the mills that use recycled pulp, results in a significant increase in anionic trash content, hardness of water, sticky deposition, and cationic polymer demand. All of these dissolved and colloidal substances may lead to a remarkable reduction in chemical additive efficiency, fiber bonding, and paper quality, and will significantly affect the wet-end operation. In order to increasingly use circulated water and to develop strategies for mill closure, it is very important to know how the accumulated trashes and contaminates will affect the papermaking process and paper products.

2. A mathematical model was established to predict the buildup of non-substantive materials in whitewater. A laboratory investigation utilizing a Formette Dynamique to simulate paper machine closure was also conducted to verify the model. The Formette made directional handsheets under dynamic conditions at consistencies closer to those found at mills. After each sheet was made, the whitewater was recycled for the next sheet. Two different levels of closure, 93% and 87% were investigated. Closure in this work was defined as the percentage of recycled whitewater in headbox furnish. The buildup of sodium and calcium in the whitewater were monitored and compared with the model prediction. The metals build up quickly and the closure level had a large impact on the final equilibrium.

3. The mill water closure will result in a significant increase of inorganic salts and organic anionic trashes in papermaking white water, which, in turn, affects the retention aid performance. The possible effects of the contaminants, including inorganic salts and organic materials, on the performance of different retention systems were examined in this study. Four retention systems, including a single cationic polyacrylamide (CPAM) system, a dual cationic polymer system of CPAM and polyamine (PAE), an anionic microparticle system (CPAM + bentonite), and a nonionic retention aid of polyethylene oxide (PEO) in combination with phenol-formaldehyde resin (PFR), were investigated. The results showed that the inorganic salts and organic substances will significantly affect the performance of cationic polymer and microparticle retention systems, but will have less effect on the retention efficiency of the PEO/PFR system. The results presented in this study suggest that, from a filler retention efficiency point of view, the nonionic PEO system is better than cationic polymers for the furnishes containing high inorganic salts and organic substances.

The results from this study will help Georgia mills to develop mill closure strategies, reduce the water consumption, save water recycle energy, increase the efficiency of chemical additives, and improve the paper products.

Principal Investigator: J. Y. Zhu

Email address: Junyong.Zhu@ipst.edu

Industry Partner: Georgia Pacific

Kraft mill odor has long been a public relation problem for many kraft mills in Georgia. With the increasingly restrictive environmental regulations posed by the federal agencies, gaining environmental competitiveness in pulp and paper mill operation is of strategic importance to the success of Georgia’s pulp and paper industry. Investigation of new technologies and processes to achieve a mill operation with minimum environmental impact to enhance quality of air effluents is identified as a priority by the Georgia Consortium for Technological Competitiveness for the pulp and paper industry. Reduction of the odorous gas emission in kraft mills will significantly improve the environmental competitiveness of Georgia pulp and paper industry, and will also improve public relation, with surrounding communities. When it is more economical feasible, odor reduction, instead of odor elimination, can improve significantly the air quality and the environment of a kraft mill since it will reduce the radius of the area being impacted by the odor emission.

The present research studied the feasibility of reducing odor gas production at its source – during kraft pulping without sacrificing pulp yield and quality. The odor gas formation data obtained in various pulping processes can be used to optimize operating processes to achieve minimum odor production, for example, a bleaching sequence may be designed differently now with the odor gas formation data. The next step will be to study the overall performance in terms of total reduced sulfide (TRS) formation and the pulp productivity and quality with the knowledge gained in the present study. Unfortunately, the project is not renewed. This report represents the final work of the project.

The odor formation data obtained in the present study can be immediately used by the industry to reduce odor formation through process redesign and optimization without sacrificing the pulp productivity and quality. The actual savings to the industry depends on how much a specific mill spends on odor treatment, which could be on the order of $100,000/yr per mill.