Expert insights on use of enzymes as a driver of Pulp and Paper’s future

Buckman has a longstanding collaboration with Novozymes, a world leader in biosolutions. This liaison underscores benefits of the use of enzymes for paper-based products. An interview with Greg DeLozier, senior staff scientist at Novozymes, offers updates – and myth-busting – on the state of enzymes in paper production.

Question #1: Use of enzymes in the tissue production process is well known, but similar applications in paper-based packaging require a different set of important insights to adapt the technology to the manufacturing process. What are the key characteristics of enzymes being used in paper-based packaging production?

Recycling trends have been very favorable in recent years resulting in the growth of enzyme applications in the packaging segment. The enzymes that are used in packaging applications add value through selective modification of pulp and fiber. Enzymatic modification of the fiber surfaces improves the strength properties of pulps and thereby the potential for reduced energy, chemicals and even fiber to produce packaging materials. While there are modest differences to account for differences in objectives, fiber type, pH, temperature, consistency, and retention times, the enzymes used in packaging mills are quite similar to the ones used in tissue mills. And like tissue applications, enzymatic applications within the packaging mill can address multiple issues, particularly those encountered when using recycled fiber. Furnishes containing a significant proportion of recovered fiber suffer from excessive debris and contaminants which absorb additives in an unfavorable way, adversely impact dewatering and accumulate as machine deposits. Certain enzymes have been developed specifically to target these problematic elements and thereby improve the efficacy of wet-end chemicals, the on-machine performance of the furnish and the structure, strength and quality of the finished products.

Question #2: Enzymes are known for reducing operating costs in pulp mill bleaching operations or improving deposit control in recycled board mills. Are there other areas where you see significant results?

Enzymes have been used effectively to control certain types of deposits. One class of enzyme targets pitch associated with mechanical pulp production or use; another class targets contaminants – stickies – associated with recycled fiber. Another class prevents biological deposits that may accumulate in the paper machine or in the final product. These deposit control enzymes have been applied for decades, yet there is still opportunity for growth. In fact, new deposit control enzymes have recently been introduced into the market to contend with the increasingly broad range of contaminants encountered in recovered fiber. Enzymatic modification of starch for sizing and coating applications, one of the oldest applications of enzymes in paper and board manufacture, continues to improve production economy and provide greater control over starch properties. New fiber modification enzymes with greater tolerance for the normal conditions within market pulp mills and virgin board mills are currently adding value within these growth segments.

Question #3: Many people working in the industry believe that enzymes are “alive” and could present risks to the production and quality of paper-based packaging. How do you address this?

All enzymes are protein. Enzymes are simply three-dimensional biological molecules comprised of amino acids. As such, enzymes do not grow, replicate or reproduce. They are there for a short time to modify the fiber surface or disrupt the formation of deposits. And then they eventually degrade into harmless fragments of protein, peptides and amino acids. They do not end up in the product. Enzymes are distinctly different from other wet-end chemical technologies in that they do not become a part of the fiber or the finished product. Unlike chemical processes, enzymes use the natural components of the fiber to introduce new properties. And unlike mechanical processes – for example, mechanical refining – the relatively large enzyme molecules act at the accessible surfaces of the fiber and do not affect the integrity of the bulk of the fiber wall.

Question #4: How do you address the topic of enzymes performing too slowly or unpredictably in full-scale applications in pulp and paper production?

As enzymes must encounter and then react with their preferred substrates, the desired benefits may develop slower than conventional chemistries and/or mechanical processes. Typically, enzymes should be applied in a manner that quickly and uniformly distributes them at or near the point of application to maximize contact with their substrates within the available residence time. Note that mill closure and water circuits (e.g. feedback loops) may allow enzymes to cycle-up within mill operations. In such instances, target benefits may be obtained with relatively low dosing levels of enzyme.  As enzymes diffuse throughout the pulp within a storage tank or tower – directly influenced by flow rates and flow patterns – or cycle-up to an ideal concentration within mill circuits, their impact may be perceived as relatively slow. That said, there are several places throughout pulp and paper operations where enzymes can be applied to deliver the greatest benefit in the shortest amount of time. Before recommending enzymes, it is important to determine the proper application point. Ideally, enzyme-based products should not require process modification. Enzymes should be able to tolerate the conditions at and downstream of the point of application and require no or minor process modification to deliver the benefit. A suboptimal response may indicate that the best application location was not found. Changes and swings in process conditions may affect the performance of the enzymes as well. A thorough knowledge of the system will assist in the identification of issues within the process which could hinder or even deactivate the enzymes. Another important factor is the composition of the enzymatic product. Products prepared using single or rational blends of two or more enzymes can be applied with greater control over their performance. However, products based on ill-defined or minimally-processed enzymes may be associated with greater risks due to unknown, undesirable, and unpredictable side-activities. Knowing as much as possible is critical to the selection and delivery of the proper enzymes to maximize performance.

Question #5: How can enzymes help producers of packaging grades, and what are the main benefits of using them in the production process?

Enzyme applications seek to enhance the runnability and strength potential of conventional furnishes. By acting only on outer surfaces of the fiber and creating new functionalities from the natural constituents at the fiber surface, the enzymes influence subsequent interactions between fibers and wet-end chemistry. The resultant fiber properties reduce production costs and foster new strength-structure relationships in finished products. Strength requirements can be realized with less energy, chemistry or even fiber (e.g. light-weighting). Increased content of recycled fiber within a furnish provides more opportunity for further valorization through enzymatic applications. Enzymatic upgrading of recovered fiber and mitigation of contaminants may allow the reduced use of virgin fiber in blended furnishes.

Question #6: Today’s packaging grade producers are looking for more sustainable products. Sustainability is influenced by the raw inputs including fiber and chemistry. Can enzymes help, and if so, how?

Enzymes are produced naturally using fermentation – similar to the production of wine and beer.  As enzymes are not derived from fossil sources, their production is nearly carbon neutral. The minor carbon footprint of enzyme products is greatly offset by the reduced footprint afforded though their application. Improving the runnability of the furnishes reduces the energy requirements in the drying section. Imparting desirable optical properties in pulps and building strength in paper and board with less energy and chemical inputs reduces the carbon intensity of the mill. Moreover, enzyme applications that increase the use of recycled fiber reduces the relatively greater carbon contributions of virgin fiber. Whenever enzyme application enables a reduction of energy, water, chemical or fiber input, a sustainable benefit is obtained.

Question #7: How do you see regulatory developments impacting choices for more sustainable materials, including chemistry? Do you believe enzymes would have an opportunity in this field?

Since enzymes don’t become a part of a final product, the applicability of current and future regulations in the pulp, paper and board industry is likely to differ from chemical additives. However, enzymes are used across multiple industries where regulations are increasingly stringent. Near-term regulatory decisions could present unintended challenges. Ideally, the enzymatic solutions will be recognized as safe and sustainable options and compliant with current and future regulatory obligations. When used according to guidance, enzymes are relatively easy to defend and promote as preferred solutions in many industries – including pulp, paper and board.

Question #8: Do you see enzymes providing greater value in virgin or recycled paper and board production? What advice would you give for both types of manufacturers?

Enzymes can provide strong, positive results in recycled paper and board applications – especially in the packaging and graphic segment – as there is a strong interest in recovering the original desirable attributes of virgin fiber. Enzymatic deposit control is another area closely linked to the processing and use of recovered fiber. The most common enzymatic applications within operations producing and consuming virgin fiber are pre-bleaching and market pulp fiber modification – at the producer and consumer. Through localized activity at the fiber surface, enzymes are able to modify virgin fiber in a manner that is very different from chemical or mechanical processes. These fibers acquire attributes that cannot be obtained through chemical additives or mechanical means. The biggest challenge I see in the market is ensuring that the mill is able to take full advantage of the novel attributes introduced by the enzyme to fiber, pulps and furnishes. Comprehension of the underlying mechanisms of enzymatic fiber modification and deposit control is key to maximize the range and degree of value provided by enzymatic applications.

For information on Buckman’s enzymatic technologies for Pulp & Paper applications, please visit our webpage.