Research & Innovation
FOREST BIOTECHNOLOGY: The next revolution?
By Pulp & Paper Canada
Trees that grow 40 feet in 10 years, that grow two inches in diameter annually, that have branches only in the top five feet, that have no taper and which are square: not something from the new Star W...
By Pulp & Paper Canada
Trees that grow 40 feet in 10 years, that grow two inches in diameter annually, that have branches only in the top five feet, that have no taper and which are square: not something from the new Star Wars movie, but a possible reality in the future. This was the vision put forth by Dave Ellis, director of biotechnology, BC Research Inc., during the PacWest Conference forum.
Although this ideal tree is not a reality now, Ellis advised delegates to think of the “green revolution” between the 1960s and 1980s when food crop productivity rose between 100 and 400%. This was achieved through breeding for high-yield and disease-resistant crops, exactly what the forest products industry wants for its trees. He compared the increase in plantation forestry and agroforestry to the advances achieved in canola and other agricultural crops.
Biotechnology can be a management tool, Ellis stressed. “The opportunity is there to create value through biotechnology.” Demand for forest products will outpace supply by 2010. The long-term supply will depend upon sustainable management of the forest resources.
In the next 50 years, the world’s population will double, Ellis added. A two to three time increase in food production will be needed. Current worldwide farmland equals the landmass of South America. If the food production must be increased two- to threefold, a landmass the size of North and South America will be needed. Therefore, the world must either change the way it grows food or will have to plow more land for crops.
Another food revolution is needed. Yield is no longer increasing significantly due to a few reasons. These include physical limits, water scarcities and deteriorating soil conditions. The next revolution in agriculture will be the gene revolution, Ellis said. The rapid acceptance of genetically engineered crops is unprecedented. In 1985 there were no acres dedicated to genetically engineered crops; in 1998, there were 28 million acres planted.
Ellis sees a global shift in forestry toward plantations with more companies using clones.
There is a forest clonal program underway in BC and Ellis thinks that within five years, herbicide- or disease-resistant strains of species will be planted.
Other projects underway include studies into lignin biosynthesis, that is, trees with more uniform lignin, which is easier to remove. Cellulose is the topic of another study. It is similar in structure to starch so advances in potatoes were studied and the findings moved to trees in an effort to increase stem biomass.
There are concerns. Genetically engineered crops have been a subject of controversy and have met great opposition in some circles. What are the risks when genetically engineered trees are introduced to the wild? Will the implanted genes somehow get into the wild population and what are the consequences? Ellis said that scientists are working to ensure that these genes do not escape. Their reproductive abilities must be eliminated. The energy that goes into reproduction can be channeled into mass growth and, therefore, increase productivity.
Ellis also cited the recently announced joint venture on forest biotechnology (R&D News, p. 73).
Biotechnology is not for all sites, species or markets, Ellis cautioned. It is not a replacement for sound forest management. The questions of environmental risk — the effect of biodiversity, gene escape and sustainability — still must be addressed. But, all indicators point to huge potential.
One delegate noted that there is heavy resistance in Europe to genetically engineered canola. Will it be the same for trees? Ellis said that some resistance is expected but because trees are not a food crop, the concern may be mitigated. One mill delegate said customers are already asking if his company has genetically engineered products in its pulp.
Asked why Canada has been so slow to adapt this new technology, Ellis said it was puzzling that so few test plots have been allowed. He thinks it will come in eventually, noting that the industry is a “conservative” one.
Ellis was one of five speakers at the Forum, part of the program of the annual conference of the Pacific and West Coast (PacWest) branches of the Pulp and Paper Technical Association of Canada (PAPTAC), held in Whistler, BC, May 19-22.
Staying on the forestry end, Dag Rutherford is a registered professional forester working with KPMG. He spoke about Forest certification: Marketing tool or good forest management? Why be certified? Rutherford listed a few reasons such as pressure from non-governmental organizations (NGO), consumers and/or buyers groups. A lack thereof may be a barrier to markets. Finally, there is the possibility of adding a premium to certified products.
There are three forestry practice certification options: 1. ISO 14001, eight in Canada. 2. The Canadian Standards Association (CSA) SFM, one in Canada. 3. The Forest Stewardship Council (FSC), three in Canada.
The first two certify a management system. The FSC object of certification is the forest or product.
The CSA and ISO standards can be implemented together because they both use the same management framework. FSC certification is performance based.
Rutherford said the first few BC certifications will be subject to extensive scrutiny, which is not surprising. Some criticism is inevitable. He added that the “Leading bodies must get it right.” To have any validity, the audit must go beyond the documentation and assess the field implementation of a standard.
When selecting the appropriate standard, companies will need to consider market acceptance, flexibility, costs and quality of the actual registration process. The implementation of one standard does not necessarily preclude registration under another standard and there can be benefits to dual registration.
KRAFT PRICES ON THE RISE
Two speakers addressed markets and global competition. Charles Widman, Widman Associates, spoke principally about bleached kraft pulp. On the bright side, Widman said there seems to be a recovery on the way and he believes the recovery is sustainable. Inventories are in a better balance and there is little new capacity. By May 2000, he said he would not be surprised if the price of pulp was US$600 per tonne (t).
High production costs in BC are the main barrier to a sustained recovery. The costs are high, he added, because of the lack of flexibility in the workplace. Progress is being made in this area but BC still lags behind eastern Canada in the level of flexibility achieved in mills.
High taxation in BC is also a problem. “We’re not competitive,” Widman said. The sales tax on equipment is a disincentive to investment as is the BC Corporate Capital Tax. The lack of capital investment has hurt the BC forest products industry and Widman feels the level of technology in BC has fallen behind that found in eastern mills, particularly in the sawmill sector.
“We should welcome companies from the east,” Widman added, companies such as Tembec and Donohue which have made significant investments in BC recently. “We should seek more joint ventures, consolidations.”
Al Small, vice-president, paper marketing, Pacifica Papers, told delegates about Competing in the global economy. The industry must earn an adequate return over the business cycle to be able to attract new capital as required. Small said that the industry is competing for capital in world markets. Not earning a decent return will not have bankers flocking to the door to lend money.
There is an opportunity in groundwood printing papers, Pacifica’s strength, according to Small. The market is huge and growing and the US economy is still resilient and certain to grow.
Small also addressed the issue of the Canadian dollar, saying that the industry lives precariously on the weak dollar. “If the Canadian dollar were to rise to $0.75 (US), the full 40% of the top of the cost curve belongs to Canadian mills.”
Small also spoke about value-added grades, a strategic area for Pacifica. In 1993 at Pacifica (then MacMillan Bloedel), newsprint accounted for 65% of production. It now account
s for only 33%. The company has increased production of value-added grades by 300 000 t/y. Still, this is no guarantee to profitability. The challenge is that the future is not guaranteed. Demand for the industry’s products will grow. The question, Small said, is whether the industry can be profitable for the long-term.
It is possible to compete with a dollar valued at over US$0.70, but maintenance downtime, energy rates and corporate taxes must all decrease. The skills are there, Small said.
Organizers for the Process Control session on Friday morning worked hard to get four mill-based papers. The first, by Martin Pudlas, Northwood Pulp, looked at Model-based bleach plant control: Implementation at Northwood. Because pulp is now considered a commodity, the drive is to optimize existing equipment to reduce costs and increase profitability.
The project was on the B line, which was built in 1982. Its capacity is 800 t/d although it can “sprint” up to 1100 t/d. All the towers are upflow.
This project began in 1994. Existing controls were unreliable. When Northwood went to 100% chlorine dioxide substitution, brightness time was slower. The mill was using compensated brightness control but this is highly coupled to other process variables and the compensated brightness setpoint may vary depending upon residence time. The mill decided to study model-based control using either CEK control or percentage delignification control. It opted for the latter. Why? To take advantage of bleaching knowledge available and future bleaching knowledge.
The new approach uses bleaching kinetic models using online kappa number and ClO2 strength measurements. Kinetic models are based on the delignification and bleaching kinetics for the Do and Eop stages. The control objective was to share the load between the front end and back end of the bleach plant, i.e., maintain a constant percentage of delignification across the Do stage.
Results have been impressive. Uptime is greater than 95%. Chemical use is down 11% (conservative figure). CEK variability is down 56% from 0.9 to 0.4 and pulp strength has improved.
Patents are pending for the system in the US and Canada. Future work will study setpoint optimization for further savings, online brightness measurement and soda loss compensation.
David Osmond, Cariboo Pulp, described Slaker control using FTIR and conductivity. The bleached kraft pulp mill was used to develop and test a fourier transform infrared (FTIR) analyzer. It was a joint project between Cariboo, Paprican and Kvaerner Chemetics. It was applied to the digester and to the causticizer. It was found to be reliable and accurate in measuring effective alkali and carbonate levels — white, black and green liquors.
Cariboo wanted to compare conductivity with FTIR. Over a three-day period, results showed changing conductivities but no change in the causticizing efficiency. Conductivity is prone to interference and drift. FTIR is not but is an offline test. Cariboo tried to combine all the good points of each into one control strategy. The development of the FTIR analyzer and new control strategies have resulted in causticizing efficiency improving by 38% while effective alkali variability has dropped by 33%. The benefits of the new system include improved settling and clarification, more efficient lime conversion, more constant liquor production and lime quality changes are compensated for. Osmond said that the mill can maintain existing operations and increase the production rate or maintain production and move the causticizing efficiency values up.
Rick Harper, Pacifica Papers, described the Application of a new tuning method for valve position controllers at Pacifica’s Port Alberni, BC, mill. Objectives of the new control program were to stabilize the stock proportioner and wire pit consistencies and reduce machine moisture variability. The mill was having a lot of problems stemming from saveall consistency control. Therefore, it was trying to achieve: saveall to blend consistency to +/- 0.1%; saveall to blend flow to +/-25 Usgalpmin; tower level to +/- 4 ft (surge capacity).
The key to stabilizing the consistency control was to minimize interactions between the major/minor consistency loops and the level/consistency loops. In summary, Harper recommended that mills develop a clear control strategy, tune minor controllers aggressively, minimize the interaction with level control and avoid gap controllers.
Gerry Pageau, Howe Sound Pulp and Paper discussed a simple project that had a very good payback for the mill, in a paper titled A proven control scheme for vacuum drum washers. When the mill was rebuilt in the early 1990s, the 1962-era bleach plant was the only area left untouched. Orginally designed for 600 t/d, it can now run up to 1200 t/d with only one new tower. The twinned four-stage bleach plant has eight drum washers, four from 1962, which serve Eop and Dn stages, two 1997 washers serve the Do stage and two 1990 washers finish up in the D2 stage.
Why automate? It provides for easier operation, which makes for happier operators. Better washing means lower ClO2 and NaOH use on subsequent washers. Reduced defoamer use means lower operating costs. A possible saving of more than $2/adt could be achieved.
To achieve a good wash, the drum needs to be run at optimum speed, yet operators prefer a slower speed because it is safer. But too slow a speed means a lumpy mat. Too fast and the mat becomes too thin and can run under the doctor blade and back into the drum. The optimum mat is about one to 1.5 inches.
The new controls helped minimize tower dilution, maximize the possible evaporation and shower flow and minimize defoamer use.
Howe Sound installed flowmeters, consistency meters and the necessary programming. The consistency controllers are on the six downflow towers. This gives the mill a feed rate estimate to the washer. The speed controller determines the speed based on the feed rate. Dilution is controlled based on the feed and the speed is optimized.
Since installation, defoamer use has dropped to less than 0.2 kg/t from about 0.8 kg. Caustic and ClO2 use have also dropped and washing is better. Pageau said the mill has saved $688 000/y.
REMOVING THE NASTIES
Innovation in paper manufacturing innovations was the topic under discussion in the Friday afternoon session. Jack Sadler, UBC, looked at The different effects of white water dissolved and colloidal fractions on paper properties and effects of enzyme treatments on their removal. As mills move to closure, there is a build-up of contaminants that can have adverse effects on papermaking operations and the end product. Major dissolved and colloidal substances include carbohydrates, lignin, extractives and inorganics. The adverse effects of these substances include poor strength, pitch deposits, reduced brightness and reduced paper machine runnability. Dissolved and colloidal substances reduce fibre:fibre bonding and sheet consolidation. Resin and fatty acids reduce paper machine runnability because of lowered wet web strength.
The project involved the fungal removal of extractives by a three-day treatment at 30C. This removed all lignin, steryl esters and 75% of resin and fatty acids. However, the process length and temperature in the test conditions are not feasible in commercial applications.
In his conclusion, Sandler said the presence of high-level dissolved and colloidal substances will reduce quality. Fungal and fungal culture filtrate treatment can reduce the level of detrimental substances in white water.
Future work will assess the continuous operation of the treatment reactor. It will be scaled up to a pilot plant level. Sandler said the work is not claiming any benefits to properties but rather removing the detrimental effects.
A new use for chlorine dioxide, removing fluorescence from recycled fibre, was described by Teresa Znajewski, Sterling Pulp Chemicals. In one mill trial, the ClO2 removed fluorescence better than a quenching agent with less chemical needed.
In another mill, P-FAS bleaching was used to reach an ISO bri
ghtness of 86 to 89 with 3 to 4% fluorescence. The mill wanted to remove the fluorescence. In a laboratory trial, 0.4% ClO2 was applied to reach zero fluorescence with some expected brightness loss.
In a full-scale mill trial, the mill changed its bleaching to P-D and used a level of 0.2 to 0.5% ClO2. The mill was concerned about corrosion because a lot of 304 and 316 stainless steel was used in the piping. However, after two years of operation, there was no increase in corrosion.
Znajewski said that for a stand-alone DIP mill, the ClO2 must be made on site. She recommends a small-scale chlorite-based generator that is easy to install and has a low capital cost. There is no need for any ClO2 storage. The mill liked the system so much it removed its peroxide bleaching and went to all ClO2.
Alan Bird, Degussa, looked at the issue of permanent papers. He said there are two schools of thought. 1)Lignin shouldn’t be allowed anywhere near permanent papers; and, 2)why not?
New findings show that yellowing and strength losses are two separate mechanisms. Current standards usually limit lignin to less than 1% for a permanent paper designation.
A 1997 study led by the Canadian Conservation Institute and Paprican found that acidity is the most significant factor in paper degradation. Calcium carbonate improves stability of both lignin-free and lignin-containing papers. So, the lignin or no lignin question seems to have been answered and Bird said the debate may move onto optical properties. Acidity is the real reason for the historic poor performance of lignin-containing papers. Research findings should lead to greater freedom for papermakers to develop new grades and greater choice/freedom for paper buyers and users.
The second kraft pulp session was held Saturday morning. Pierre Brub, UBC, led off with a paper on the Treatment of evaporator condensate using a high temperature Mbr: Determination of maximum operating temperature and operating costs.
A large fraction of clear condensate and all foul condensate is sewered and treated as effluent. Some mills are now looking at re-using condensate. A membrane bioreactor is one possible method.
The objective of the study was to try to find the feasibility of removing methanol biologically from evaporator condensates at high temperature. Brub said other goals included finding the maximum feasible operating temperature and the economic feasibility of biologically treating condensate in a high-temperature membrane bioreactor. The method was compared to a steam stripper for a comparison of costs.
It was found that the cost of a membrane bioreactor would be cheaper than for steam stripping. If the mill could use a polymeric membrane, the costs would be even lower, but over the long-term, the effect of the polymeric is not known.
Raj Seth, Paprican, got things going with his paper, Measuring fibre strength of papermaking pulps. The direct measurement of the strength has been elusive. Two methods are traditionally used to measure the strength of papermaking pulps –viscosity and zero span tensile strength (ZSTS) of pulp handsheets. Why does ZSTS increase with beating or refining? Do the fires become stronger? Are the fibres more effectively gripped when better blended? Seth said it improves not because the fibres become stronger or better bonded but because they become straighter which enables them to transmit load. Bonding and fibre length have little to do with ZSTS.
The implications are that the fibres must be straight or straightened for the ZSTS test to reflect fibre strength and commercial fibres are seldom straight. The fibres can be swelled in a beater. As the fibres swell, the ZSTS reaches a plateau rapidly. These plateaus can be regarded as a reliable index of fibre strength. Seth then said that the argument for eliminating bonding by wetting is without foundation.
In his conclusions, Seth said that pulp viscosity is a poor predictor of fibre strength, that ZSTS of pulp handsheets is a reliable index of strength provided that the fibres are straight. Fibres can be straightened by gentle beating and swelling. The index of fibre strength relevant for product properties is the dry sheet ZSTS and not that of the rewetted sheets.
Fibre strength is one component of pulp quality. Other factors such as fibre length and coarseness also contribute. In response to a question, Seth said that unfortunately the practice of using wet ZSTS stems from ignorance.
A tough act to follow, Mike Schofield, Hercules PPD, did well with his paper, Yield improvement and strength maintenance – chemical additives strategies. The demand for bleached hardwood and softwood kraft pulps will continue to grow but the raw material is becoming scarce and costs will rise. As paper machine speeds and the use of DIP increase and basis weights drop, the strength a mill gets from bleached kraft pulp becomes more important.
However, Schofield said, the pulping paradox is that the harder mills work to delignify, the more pulp strength is lost. If kappa numbers rise, the load on the effluent treatment plant is increased, bleaching costs go up and so does the reject rate. Therefore, the question is how to maintain or decrease kappa number while maintaining fibre yield and properties.
Different chemical enhancement treatments have been used. Also, there have been some mechanical process changes.
Specialty chemical process enhancement (SCPE) can be used when mills need an incremental gain.
SCPE could be a surfactant-based digester addition and anthraquinone (AQ) or might be the use of wash aids. The former works by enhancing liquor penetration into the chips and it wets the hydrophilic surfaces of extractives. The combined benefits of an additive and AQ are that the efficiency of the AQ is improved and this can lead to reduced AQ consumption.
A wash aid in oxygen delignification can help reduce carryover because less alkali is used. The objective is to increase washing efficiency of drum and belt washers, increase water removal and reduce contaminant carryover.
John Kronis, Degussa-Huls, described how Caro’s acid can be a better choice for brightening chemical pulp than hydrogen peroxide. Development work on Caro’s acid is an ongoing effort at Degussa and Kronis said the company is very excited about its potential, comparing it to ozone in the 1960s, ahead of its time.
Caro’s acid has been used in delignification, Degussa’s Degox process. It can complement an ozone stage and may also be used as an activation stage. When used for brightening, Caro’s worked best when applied in the high-density storage. A small amount is need along with a little DTPA. Residuals are very low. No pH adjustment is needed. The final brightness is very stable
AND THE WINNERS ARE
At the closing dinner, awards for the best papers were given out. The winner of the H. R. MacMillan Award (Eagle Trophy) for best paper was Ralph Lunn, Celgar Pulp, for his paper: Is acid addition required on the Do bleaching stage? Based on the result of a survey of Canadian mills, as well as laboratory work, Do stages require additional acidification only when chlorine dioxide use is less than 1.5 times the saltcake carryover into the stage. The effect of acid addition can be assessed quickly in a mill trial.
Gerry Pageau, Howe Sound Pulp & Paper, earned first runner-up for his paper on the control scheme for washer. Second runner-up honors went to R.S. Chow, Alberta Research Council, for his paper, The characterization of anionic trash in the mechanical pulping process. The distribution of anionic trash in the process can be correlated to final brightness. For softwood and softwood/hardwood pulp blends, washing the pulp with white water (containing anionic trash) led to more efficient bleaching.
Jeff Guild, UBC Pulp & Paper Centre, earned best novice honors for his paper, Development of chemical conditioning program to enhance the dewaterability of pulp and paper mill waste activated sludge. A bench-scale sludge press was used to optimize both coagulant and flocculant addition to a coastal pulp mill’s sludge. A decreasing chemical
need was found with an increasing primary sludge fraction (vs. secondary). A sludge’s dewaterability decreases with age.
Ken Wilshire, Filter Innovations won the best supplier paper award for his paper Slime control in paper machine shower water systems with unique chemical-free electro-technology. The principles of electronic dispersion have been shown to be an effective way to prevent biological formations from occurring on paper machine shower nozzles. St. Laurent Paperboard used the equipment with success at its La Tuque, QC, mill.
Delegates had lots of choice at PacWest, perhaps too much. There were a record number of papers submitted and program organizers did their best to accept all, but this meant scheduling as many as three concurrent sessions including two on Saturday morning. Conference chairman Ron Sheel, Howe Sound Pulp and Paper, said the organizing committee wants to offer as much as possible, but that too many choices could have the effect of diluting the strength of the sessions. This in light of the fact that attendance was also down somewhat, which, as Sheels said, is the trend for conferences overall. Still, the technical content of the papers was strong with many mill-based presentations, and attendance at the sessions was good.
The “jury is still out” on the workshops which were held, Sheel added. They will be reviewed to see if they should be included again. The supplier poster presentations were a hit with delegates and well-positioned outside the session rooms. Sheel said he is waiting to hear what the suppliers have to say about the result but thinks the event will continue next year. Moving the event to the Chateau Whistler hotel from the convention centre also was successful as all events could be held in one building. To open the new millennium, Jasper Park Lodge will again host the conference.