Enzyme Applications in Pulp and Paper: An Introduction to Applications Dr. Richard Venditti Associate Professor - Director of Graduate Programs Department of Wood and Paper Science Biltmore Hall Room 1204 Raleigh NC 27695-8005 Tel. (919) 515-6185 Fax. (919) 515-6302 Email: [email protected] Slides courtesy of Phil Hoekstra. Endo-Beta 1,4 Xylanase Enzymes • Are proteins that catalyze chemical reactions • Biological cells need enzymes to perform needed functions • The starting molecules that enzymes process are called substrates and these are converted to products Endo-Beta 1,4 Xylanase Cellulase enzyme which acts on cellulose substrate to make product of glucose. Endo-Beta 1,4 Xylanase Enzymes • Are extremely selective for specific substrates • Activity affected by inhibitors, pH, temperature, concentration of substrate • Commercial enzyme products are typically mixtures of different enzymes, the enzymes often complement the activity of one another Endo-Beta 1,4 Xylanase Types of Enzymes in Pulp and Paper and Respective Substrates • Amylase --- starch • Cellulase --- cellulose fibers • Protease --- proteins • Hemicellulases(Xylanase) ---hemicellulose • Lipase --- glycerol backbone, pitch • Esterase --- esters, stickies • Pectinase --- pectins Endo-Beta 1,4 Xylanase Enzyme Applications in Pulp and Paper • Treat starches for paper applications • Enhanced bleaching • Treatment for pitch • Enhanced deinking • Treatment for stickies in paper recycling • Removal of fines • Reduce refining energy • Cleans white water systems • Improve softness in tissue • Clean outs Endo-Beta 1,4 Xylanase Starch Conversion for Surface Coatings • Amylases are used to cleave starch molecules to reduce the viscosity • Used for surface sizing and for starch in coatings • Not used for dry strength agent additive Endo-Beta 1,4 Xylanase Bleaching • Hemicellulases (xylanases) are used to cleave hemicelluloses in fiber, making the bleaching process more effective • May be able to reduce bleaching chemicals by up to 30% • Can improve brightness Endo-Beta 1,4 Xylanase Pitch treatment • Lipases used to control pitch in pulping processes • Converts tri-glycerides to fatty acids which are more stable in water, won’t deposit as much Endo-Beta 1,4 Xylanase CH2 –--------- CH –---------CH2 Triglycerides OOO Ester-Bonds C=O C=O C=O (CH2)15 CH3 (CH2)15 CH3 (CH2)15 CH3 glycerol Fatty acids CH2 –--------- CH –---------CH2 │ OH OH OH OH │ C=O │ (CH2)15 CH3 Endo-Beta 1,4 Xylanase Deinking • Paper recycling inks and stickies attach to fibers at the surface of the fibers, stuck to microfibrils • Cellulase and hemicellulase enzymes hydrolyze these microfibrils, releasing the adhesives • Esterases help breakdown ink particles • Enzyme assisted DI reported to remove 30-60% more toners • Enzyme assisted DI reported to improve brightness by 4-5 points Endo-Beta 1,4 Xylanase Control and Removal Methods for Stickies – Use of environmentally benign adhesive (recyclable adhesive) – Avoidance: Control of recovered paper quality – Mechanical removal: screening and water clarification – Chemical control: polymers surfactants, others – Passivation with inorganics – Enzyme hydrolysis – Physical adsorption to paper fibers: retention – Dispersion – Protection: treatment of equipment to limit deposits – Mill shut down for clean-up Endo-Beta 1,4 Xylanase CLASSIFICATION OF STICKIES PRIMARY SECONDARY (Formed in (Change in pulper) environment, pH, temp., etc.) Endo-Beta 1,4 Xylanase MACRO VS MICRO STICKIES Macrostickies Retained on 6-cut (0.15 mm) slotted screen* Microstickies Accepted by 6-cut (0.15 mm) slotted screen* * Trend is towards 0.10 mm or 0.075 mm slottedEndo-Beta screen 1,4 Xylanase Stickies Control • Microstickies in dilution water recirculate back into the systems • Microstickies agglomerate under shear and pH changes and contribute to macrostickies, secondary stickies • Reducing microstickies will make a significant impact on macrostickies • Ability to measure both micro and macro is important Endo-Beta 1,4 Xylanase Endo-Beta 1,4 Xylanase Without Proper Water Clarification (<20% reduction): “ re-introduction of stickies” Endo-Beta 1,4 Xylanase Enzymes as stickies treatment • Esterases used to break ester bonds in polymers used in toners and adhesives • Improved paper cleanliness • Less deposits, less clean up on PM • Can be used as substitute for talc or solvent based dispersants Endo-Beta 1,4 Xylanase -(CH2 – CH - CH2 –CH -CH2 – CH )n - PVAc OOO Ester-Bonds C=O C=O C=O CH3 CH3 CH3 PVAlcohol Acetic acid -(CH2 – CH )- CH2 –CH -CH2 – CH )n - │ OH OH OH OH │ C=O │ CH3 Endo-Beta 1,4 Xylanase polyvinyl acetate Hydrophobic Surface -(-CH2CH-)n- OCOCH3 without Esterase with Esterase Agglomerates of PVAc polyvinyl alcohol + acetic acid -(-CH CH-)n- OH 2 OH HO OH HO OH OH OH OH OH + CH COOH OH HO 3 HO OH OH OH OH OH HO OH OH OH HO OH OH OH OH OH OH OH OH HO OH OH OH OH OH OH OH HO OH OH OH OH HO Polyvinyl alcohol OH OH OH OH OH Hydrophilic Endo-Beta 1,4 Xylanase Impact on stickies chemistry • Optimyze has two impacts on stickies – Cleaves ester bonds to reduce size of stickies – Surfaces on smaller stickies are converted to alcohol groups • Alcohol groups are less tacky • Alcohol groups are polar, which allow DAF polymers to grab onto them for removal Endo-Beta 1,4 Xylanase Electron micrographs Untreated Treated Endo-Beta 1,4 Xylanase Optimyze Plus 735 trial data stickies transfer on reel samples during Optimyze Plus 735 evaluation 160 1.2 count 140 PPM 1 BLX dosage 120 0.8 100 80 0.6 stickies 60 0.4 40 BLX 13064dosage (lb/t) 0.2 20 0 0 2/12 3/4 3/24 4/13 5/3 5/23 Endo-Beta 1,4 Xylanase Caustic replacement: neutral deinking for newsprint deinking • Caustic is used in pulping recycled fibers to swell fibers, improving paper making potential • Cellulase enzymes can be used in conjunction with or as a substitute for the caustic to swell fibers • Neutral deinking has some advantages including less COD in the white water, lower costs Endo-Beta 1,4 Xylanase Decrease energy in refining • Cellulase enzymes cause partial depolymerization of cellulose and swelling of fibers, more flexible fibers • Reduction of fines • Improves efficiency of refining, can decrease energy consumption or obtain improved strength at higher freeness • Often better runnability or less dryer energy required Endo-Beta 1,4 Xylanase Fibrillation 3/3/2010 Endo-Beta 1,4 Xylanase Fiber Modification • Enzymes can assist this de-lamination process • Conditions fiber for refining • Reduces refining energy • Changes the refining curve • Old rules do not apply • Laboratory Testing Endo-Beta 1,4 Xylanase Case History • MILL: Quebec • FIBER: Recycled/Softwood Kraft • GRADE: Napkin • GOAL: Increase tensile strength to middle of specification, reduce kraft fiber usage • METHODS: Treated MOW stock at the pulper with 0.5 to 1.0 kg/tonne BZM 2545, about 3 hours of contact time Endo-Beta 1,4 Xylanase Machine Trial of Buzyme 2545 in Napkin grade 45 275 40 270 35 30 265 25 SWK Usage 260 Tensile 20 Kraft Usage (%) Usage Kraft Tensile Strength Tensile 15 255 10 250 5 0 245 Pre-trial Trial Endo-Beta 1,4 Xylanase Machine Trial of Buzyme 2545 in Napkin grade 25 300 250 20 200 15 SWK Usage 150 Tensile 10 Kraft Usage (%) Usage Kraft Tensile Strength Tensile 100 5 50 0 0 Pre-trial Trial Refining energy reduced Endo-Beta 1,4 Xylanase Results: Machine Trial of Buzyme 2545 in Napkin grade • Reduced kraft from 40% to 0% of furnish • Increased tensile to a “comfortable” range • Refining energy reduced 14% • Drainage is better, but cannot take advantage of it, due to drive limitations Endo-Beta 1,4 Xylanase Hydrolysis of fines • Fines build up in water loop in PM and cause drainage, formation and paper properties problems • Cellulase enzymes hydrolyze these fines, making them soluble, improving PM ops • Can run PM faster (up to 10% faster in some cases?) Endo-Beta 1,4 Xylanase Softness in tissue • Cellulase enzymes improve softness by hydrolyzing cellulose in fibers, creating weak spots in fibers, making fibers flexible • Softness increases of up to 25% • P&G has several patents, some donated to NCSU Endo-Beta 1,4 Xylanase Case History • MILL: Quebec • FIBER: 95% SWD/5% Recycled Fiber • GRADE: Premium Bath • GOAL: Reduce refining energy, increase softness and bulk, maintain tensile • METHODS: Treated stock at the pulper with 0.5 to 1.0 kg/tonne BZM 2545, about 3 hours of contact time Endo-Beta 1,4 Xylanase Bulk vs. Tensile Buzyme 2535 vs. Glyoxylated Polyacrylamide 11 Average Bulk to Tensile 10 Increase of 3.5% 9 B/BW 8 7 12 14 16 18 20 22 GMT/BW Buzyme 2535 Gloxylated PAM Linear (Buzyme 2535) Linear (Gloxylated PAM)Endo-Beta 1,4 Xylanase Results • Shut down refiners • Maintained tensile • Bulk/basis weight increased by avg. of 3.5% • Able to reduce BWT due to increase in tensile • Machine speed increase of 100 FPM, due to better drainage Endo-Beta 1,4 Xylanase ROI for Fiber Modification • Reduction in refiner energy • Less fines generation – Better drainage – Softer feel – Less dusting – Cleaner white water • Reduction in starch or CMC • Fiber substitution – Could use more MOW, less virgin Endo-Beta 1,4 Xylanase Improved biodegradability of pulp mill waste water • Cellulases and Hemicellulases used to degrade cellulose and other high molecular weight polymers • COD/BOD ratio of domestic sewage 2:1 • COD/BOD ratio of paper mill waste water up to 5:1 • Hydrolysis of cellulose fines by enzymes to lower molecular weight sugars that are more biodegradable Endo-Beta 1,4 Xylanase Clean Ups / Boil Outs • Amylase to treat starch deposits in clean ups of starch preparation/application equipment • Protease used as biodispersants or enzyme boil-outs, cleave protein molecules in deposits and solubilize deposits Endo-Beta 1,4 Xylanase Summary • Enzymes are green chemicals that can improve operations in pulp and paper • Wide variety of enzymes, must be applied with understanding of how they work • Several widely accepted applications, starch, bleaching, clean ups • Future: high valued functionalized fibers, improved pulping, specialized paper properties, conversion of wastes to fermentable sugars.