This glossary explains terminology used in the Forest Products, Pulp, Paper & Packaging sector, with a focused reference for the Pulp & Fiber Practice. It helps executives and practitioners interpret pulp grades, production processes, fiber quality, chemical recovery, environmental controls, certification, safety, and performance metrics.
A B C D E F G H I L M N O P R S T U V W X Z
| A | |
| AA | Active Alkali: The combined sodium hydroxide and sodium sulfide content of kraft white liquor, usually expressed as sodium oxide. It is a principal basis for setting the cooking chemical charge. |
| AD | Anaerobic Digestion: Biological treatment that decomposes organic matter without oxygen, reducing high-strength wastewater loads while potentially producing usable biogas. |
| ADMT | Air-Dry Metric Tonne: A commercial pulp unit conventionally representing one metric tonne at 90% dry fiber content. It standardizes invoicing and comparisons across pulp shipments with differing moisture levels. |
| AF&PA | American Forest & Paper Association: The United States trade association representing pulp, paper, packaging, tissue, and wood-products manufacturers on policy, sustainability, safety, and industry statistics. |
| AOX | Adsorbable Organically Bound Halogens: A wastewater parameter measuring halogenated organic compounds that adsorb onto activated carbon. It is particularly relevant to monitoring and controlling bleach-plant effluent. |
| APC | Advanced Process Control: Supervisory control methods that optimize digesters, bleaching lines, evaporators, recovery boilers, and other interacting processes beyond basic regulatory control. |
| APC | Air Pollution Control: The equipment and operating practices used to capture particulate matter, sulfur compounds, nitrogen oxides, and other mill air emissions. |
| APMP | Alkaline Peroxide Mechanical Pulping: A high-yield process that treats wood chips with alkali and hydrogen peroxide before or during refining to improve brightness and fiber development. |
| AQ | Anthraquinone: A pulping catalyst used in small quantities to accelerate delignification, protect carbohydrates, and potentially improve chemical-pulp yield. |
| ATEX | Atmosphères Explosibles: The European regulatory framework governing equipment and workplaces exposed to explosive atmospheres, including areas with combustible dust, gases, or vapors. |
| B | |
| BACT | Best Available Control Technology: A case-specific United States air-permitting requirement that establishes emission controls for certain new or modified major sources. |
| BAT | Best Available Techniques: The European regulatory concept used to set permit conditions and emission performance for industrial installations, including pulp mills. |
| BCTMP | Bleached Chemi-Thermomechanical Pulp: A high-yield pulp produced by chemical chip pretreatment, heated mechanical refining, and non-delignifying bleaching. It provides bulk and opacity for selected paper, board, and absorbent applications. |
| BDMT | Bone-Dry Metric Tonne: A mass unit representing one metric tonne of material on a zero-moisture basis, used for fiber, biomass, chemical, and yield calculations. |
| BEKP | Bleached Eucalyptus Kraft Pulp: A hardwood market-pulp grade valued for short fibers, formation, smoothness, opacity, and softness in paper and tissue furnishes. |
| BFB | Bubbling Fluidized Bed: A boiler combustion technology that suspends fuel in a fluidized bed, enabling efficient use of bark, sludge, and other variable mill biomass fuels. |
| BHKP | Bleached Hardwood Kraft Pulp: The general market category for bleached kraft pulp made from hardwood species and used where formation, surface quality, opacity, or softness is important. |
| BKP | Bleached Kraft Pulp: Chemical pulp that has undergone kraft cooking and bleaching to reduce residual lignin and achieve the required brightness, cleanliness, and stability. |
| BL | Black Liquor: The spent kraft cooking liquor containing dissolved lignin, degraded wood constituents, and inorganic chemicals. Concentrating and burning it recovers energy and pulping chemicals. |
| BLDS | Black Liquor Dry Solids: The dry non-water fraction of black liquor, used to track evaporator performance, recovery-boiler loading, combustion stability, and production efficiency. |
| BLRB | Black Liquor Recovery Boiler: The kraft-mill unit that burns concentrated black liquor to generate steam and recover inorganic chemicals as molten smelt. |
| BLRBAC | Black Liquor Recovery Boiler Advisory Committee: An industry organization that publishes operating and safety guidance intended to reduce recovery-boiler explosions and related incidents. |
| BOD | Biochemical Oxygen Demand: A measure of the oxygen consumed by microorganisms while degrading biodegradable material in wastewater. It is a core indicator of treatment load and effluent performance. |
| BREF | Best Available Techniques Reference Document: A European technical document describing applicable techniques, consumption levels, and associated emission performance for regulated industrial sectors. |
| BSKP | Bleached Softwood Kraft Pulp: Bleached kraft pulp made from long-fiber softwood species and used to provide tensile, tear, reinforcement, and runnability properties. |
| C | |
| CE | Causticizing Efficiency: The proportion of sodium hydroxide relative to sodium hydroxide plus sodium carbonate in white liquor. It indicates how effectively recausticizing converts carbonate back into active cooking chemical. |
| CED | Cupriethylenediamine: A cellulose solvent used in standardized viscosity testing to assess molecular-chain degradation and pulp suitability for demanding cellulose applications. |
| Cepi | Confederation of European Paper Industries: The European industry association representing pulp and paper producers on policy, climate, energy, circularity, trade, and technical regulation. |
| CFB | Circulating Fluidized Bed: A boiler technology that recirculates entrained bed material and supports efficient combustion of varied biomass and residual fuels with relatively uniform temperatures. |
| CHP | Combined Heat and Power: The simultaneous production of electricity and useful process steam, a central energy configuration at many integrated and market-pulp mills. |
| CI | Carbon Intensity: Greenhouse-gas emissions expressed per unit of pulp, energy, revenue, or another defined output. It supports benchmarking and decarbonization planning. |
| CIP | Clean-in-Place: Automated cleaning of enclosed process equipment without disassembly, used to control deposits, contamination, and lost availability. |
| CLP | Classification, Labelling and Packaging: The European Union regulation governing hazard classification, labeling, and packaging of chemical substances and mixtures handled or supplied by mills. |
| CMP | Chemi-Mechanical Pulp: High-yield pulp produced by chemically softening wood before mechanical refining, improving fiber separation while retaining most of the wood substance. |
| CNC | Cellulose Nanocrystals: Highly crystalline nanoscale cellulose particles generally produced by removing less-ordered regions of purified cellulose. They are used in advanced composites, coatings, rheology, and barrier applications. |
| CNCG | Concentrated Non-Condensable Gas: A low-volume, high-concentration stream of odorous and combustible kraft-process gases requiring controlled collection, transport, and destruction. |
| CNF | Cellulose Nanofibrils: Long, flexible nanoscale fibrils produced by intensive fibrillation of cellulose fibers, often after chemical or enzymatic pretreatment. |
| CO2e | Carbon Dioxide Equivalent: A common unit that converts different greenhouse gases into an equivalent climate impact using their respective warming potentials. |
| CoC | Chain of Custody: A traceability system documenting the movement and control of certified, controlled, or recycled fiber from source through production and sale. |
| COD | Chemical Oxygen Demand: A measure of the oxygen equivalent needed to chemically oxidize substances in wastewater. It provides a rapid indicator of total oxidizable effluent load. |
| CSF | Canadian Standard Freeness: A standardized drainage test used to characterize pulp dewatering behavior and monitor changes caused by refining, fiber type, and fines content. |
| CST | Crude Sulfate Turpentine: A volatile kraft-pulping coproduct recovered from softwood digester and evaporation gases and sold as a renewable chemical feedstock. |
| CTMP | Chemi-Thermomechanical Pulp: High-yield pulp made by combining chemical chip pretreatment, heat, pressure, and mechanical refining to tailor strength, bulk, and optical properties. |
| CTO | Crude Tall Oil: A kraft-pulping coproduct recovered by acidulating separated soap from black liquor. It is refined into fatty acids, rosin, fuels, and other biobased products. |
| CW | Controlled Wood: Material assessed to reduce the risk of sourcing from unacceptable origins when it is mixed with certified fiber under an approved forestry certification system. |
| D | |
| DAF | Dissolved Air Flotation: A clarification process that uses fine air bubbles to float suspended solids, fibers, oils, and biological material for removal from water or wastewater. |
| DCS | Distributed Control System: The plantwide automation architecture used to monitor and control digesters, washers, bleaching, chemical recovery, utilities, and effluent treatment. |
| DCS | Dissolved and Colloidal Substances: Wood-derived and process-derived materials dispersed in mill water that can contribute to deposits, foaming, chemical demand, and impaired dewatering. |
| DDS | Due Diligence System: The documented procedures used to collect sourcing information, assess legality or deforestation risk, mitigate identified risks, and support regulatory compliance. |
| DHA | Dust Hazard Analysis: A structured assessment of combustible-dust fire and explosion hazards in areas such as chip handling, drying, conveying, and biomass-fuel systems. |
| DIP | Deinked Pulp: Recycled pulp processed to remove printing inks, adhesives, fillers, and other contaminants before reuse as a papermaking fiber source. |
| DKP | Dissolving Kraft Pulp: High-purity cellulose pulp produced by a kraft-based process for conversion into regenerated cellulose, cellulose derivatives, and other specialty products. |
| DNCG | Dilute Non-Condensable Gas: A high-volume, low-concentration kraft-mill gas stream containing odorous sulfur compounds that is collected and routed to an appropriate destruction system. |
| DO | Dissolved Oxygen: The concentration of oxygen available in water, used to control aerobic wastewater treatment and assess receiving-water conditions. |
| DP | Degree of Polymerization: The average number of glucose units in cellulose chains, indicating molecular-chain length and influencing viscosity, strength, and conversion performance. |
| DP | Dissolving Pulp: Purified cellulose pulp with very high alpha-cellulose content and tightly controlled reactivity, viscosity, ash, and extractives for chemical conversion. |
| DS | Dry Solids: The non-water fraction of a process stream, especially black liquor, lime mud, sludge, or biomass. Solids concentration directly affects handling, energy use, and combustion. |
| DSP | Dissolving Sulfite Pulp: High-purity cellulose pulp produced through sulfite cooking and purification for rayon, acetate, ethers, and other cellulose derivatives. |
| DTPA | Diethylenetriaminepentaacetic Acid: A chelating agent used to bind transition metals that would otherwise decompose peroxide and reduce bleaching efficiency. |
| DWP | Dissolving Wood Pulp: A market term for high-purity cellulose pulp made from wood and intended primarily for chemical or regenerated-cellulose production rather than conventional papermaking. |
| E | |
| EA | Effective Alkali: The sodium hydroxide plus one-half of the sodium sulfide in kraft liquor, usually expressed as sodium oxide. It represents the alkali immediately effective in cooking reactions. |
| ECF | Elemental Chlorine-Free: A bleaching approach that avoids elemental chlorine while commonly using chlorine dioxide, oxygen, peroxide, or related agents to achieve target brightness and cleanliness. |
| EDTA | Ethylenediaminetetraacetic Acid: A chelating agent used to control metal ions that interfere with peroxide bleaching or contribute to scaling and process instability. |
| ELG | Effluent Limitations Guideline: A United States industry-specific wastewater standard used to establish discharge requirements for direct and indirect dischargers. |
| ELV | Emission Limit Value: A legally enforceable maximum concentration, mass, or rate for a pollutant released under an environmental permit. |
| EMCC | Extended Modified Continuous Cooking: An extended-delignification kraft process that distributes chemical addition and controls dissolved organic material to improve selectivity and reduce bleach-plant load. |
| EOP | Extraction Reinforced with Oxygen and Peroxide: An alkaline bleaching stage using oxygen and hydrogen peroxide to remove oxidized lignin and improve brightness after an initial delignification stage. |
| EPA | United States Environmental Protection Agency: The federal authority administering major air, water, waste, chemical, and greenhouse-gas requirements applicable to pulp mills. |
| EPCRA | Emergency Planning and Community Right-to-Know Act: A United States law requiring qualifying facilities to report hazardous chemical inventories and certain toxic releases to authorities and communities. |
| EPD | Environmental Product Declaration: A standardized, independently verified statement communicating life-cycle environmental impacts for a defined product and set of calculation rules. |
| ESP | Electrostatic Precipitator: Air-pollution-control equipment that electrically charges and captures particulate matter from recovery boilers, lime kilns, power boilers, and other sources. |
| EUDR | European Union Deforestation Regulation: A due-diligence and traceability regime requiring covered wood-derived products placed on or exported from the European Union market to meet deforestation-free and legality requirements. |
| EUTR | European Union Timber Regulation: The predecessor timber-legality framework that remains relevant to historical sourcing controls, records, and transition to newer European deforestation requirements. |
| F | |
| FLEGT | Forest Law Enforcement, Governance and Trade: A European initiative addressing illegal logging through governance reforms, trade measures, voluntary agreements, and timber-licensing systems. |
| FPAC | Forest Products Association of Canada: The Canadian trade association representing forest-products producers on sustainability, fiber supply, trade, climate, transportation, and regulatory policy. |
| FQA | Fiber Quality Analyzer: An optical instrument used to measure properties such as fiber length, width, curl, kink, and fines for furnish control and pulp-quality evaluation. |
| FSC | Forest Stewardship Council: An international certification organization establishing requirements for responsible forest management and traceable sourcing of forest-based materials. |
| FTIR | Fourier Transform Infrared Spectroscopy: An analytical technique used to identify chemical functional groups and characterize cellulose, lignin, extractives, deposits, and process contaminants. |
| G | |
| GHG | Greenhouse Gas: A gas that contributes to climate warming, measured in mill inventories to distinguish fossil, biogenic, direct, energy-related, and value-chain emissions. |
| GL | Green Liquor: The aqueous solution formed by dissolving recovery-boiler smelt, principally containing sodium carbonate and sodium sulfide before recausticizing. |
| GW | Groundwood: High-yield mechanical pulp produced by grinding logs or wood against an abrasive surface, retaining most lignin and wood constituents. |
| GWP | Global Warming Potential: A factor comparing the heat-trapping effect of a greenhouse gas with carbon dioxide over a specified time horizon. |
| H | |
| HAP | Hazardous Air Pollutant: A pollutant regulated under the United States Clean Air Act because of potential health or environmental effects, including certain mill organic and inorganic emissions. |
| HAZOP | Hazard and Operability Study: A structured team review that uses guidewords to identify process deviations, their causes, consequences, safeguards, and required actions. |
| HBL | Heavy Black Liquor: Black liquor concentrated to a high dry-solids level for storage and firing in the recovery boiler. |
| HC | High Consistency: A relatively high pulp-solids condition used in operations such as storage, bleaching, mixing, and refining. The applicable percentage depends on the process and equipment. |
| HexA | Hexenuronic Acid: A carbohydrate-derived group formed during alkaline pulping that contributes to measured kappa number, chemical demand, brightness reversion, and metal binding. |
| HHV | Higher Heating Value: Fuel energy content including the heat recoverable by condensing water vapor, used when evaluating black liquor, bark, sludge, and other fuels. |
| HRT | Hydraulic Retention Time: The average time liquid remains in a vessel or treatment system, affecting reaction completion, biological treatment, settling, and capacity. |
| HVLC | High-Volume, Low-Concentration: A category of dilute kraft-process gases requiring collection systems designed for large airflow while preventing condensation, leaks, and unsafe mixtures. |
| HWKP | Hardwood Kraft Pulp: Kraft pulp made from hardwood species, generally providing shorter fibers suited to formation, smoothness, opacity, and softness. |
| I | |
| ICFPA | International Council of Forest and Paper Associations: A global network of national and regional associations coordinating forest-sector positions on sustainability, climate, recycling, and policy. |
| ICP-OES | Inductively Coupled Plasma Optical Emission Spectrometry: A laboratory method used to quantify metals and inorganic elements in pulp, liquors, deposits, biomass, ash, and wastewater. |
| IED | Industrial Emissions Directive: The principal European Union framework regulating emissions and environmental performance at major industrial installations through integrated permits. |
| ISO | International Organization for Standardization: The international standards body whose methods cover pulp sampling, moisture, brightness, viscosity, alkali resistance, fiber properties, and management systems. |
| ITC | Isothermal Cooking: A continuous kraft-cooking approach designed to maintain more uniform conditions and extend delignification while limiting carbohydrate damage. |
| L | |
| LAER | Lowest Achievable Emission Rate: A stringent United States air-permitting standard applied to certain new or modified major sources in areas that do not meet air-quality standards. |
| LBKP | Leaf Bleached Kraft Pulp: A market term used particularly in Asian trade for bleached hardwood kraft pulp made from broadleaf species. |
| LC | Low Consistency: A dilute pulp suspension suitable for pumping, screening, cleaning, and certain refining operations where fibers must remain readily dispersed. |
| LCA | Life Cycle Assessment: A standardized method for evaluating environmental impacts across raw-material sourcing, production, transport, use, and end-of-life stages. |
| LCC | Lignin-Carbohydrate Complex: A covalently linked association between lignin and carbohydrates that affects delignification, bleaching, fractionation, and biomass conversion. |
| LCI | Life Cycle Inventory: The quantified inputs and outputs underlying a life-cycle study, including wood, chemicals, energy, water, products, emissions, and wastes. |
| LDAR | Leak Detection and Repair: A formal program for identifying and correcting fugitive releases from valves, pumps, connectors, and other regulated equipment components. |
| LEL | Lower Explosive Limit: The minimum concentration of a combustible gas or vapor in air that can propagate flame, important in turpentine, methanol, and odorous-gas systems. |
| LHV | Lower Heating Value: Fuel energy content excluding heat recoverable from condensing water vapor, often used in boiler efficiency and energy-balance calculations. |
| LOI | Loss on Ignition: The mass lost when a sample is heated under specified conditions, used to estimate combustible or volatile content in lime mud, ash, sludge, and deposits. |
| LVHC | Low-Volume, High-Concentration: A category of concentrated kraft-process gases that can be combustible and toxic and therefore requires tightly controlled collection and destruction. |
| M | |
| MACT | Maximum Achievable Control Technology: The United States emissions-control standard for major sources of hazardous air pollutants, with sector-specific requirements affecting pulp and chemical-recovery operations. |
| MBBR | Moving Bed Biofilm Reactor: A biological wastewater process that grows treatment organisms on mobile plastic carriers, increasing biomass capacity within a compact basin. |
| MBR | Membrane Bioreactor: A wastewater system combining biological treatment with membrane separation to retain biomass and produce a low-solids effluent. |
| MC | Medium Consistency: An intermediate pulp-solids range, commonly used for oxygen delignification, bleaching, pumping, and mixing where reduced water volume is advantageous. |
| MCC | Modified Continuous Cooking: A kraft-cooking configuration using distributed chemical addition and controlled liquor profiles to improve delignification selectivity and pulp strength. |
| MCC | Microcrystalline Cellulose: Purified, partially depolymerized cellulose produced from high-quality pulp and used in pharmaceutical, food, cosmetic, and industrial formulations. |
| MEE | Multiple-Effect Evaporator: A series of evaporation stages that reuse vapor energy to concentrate black liquor while limiting fresh-steam consumption. |
| MFC | Microfibrillated Cellulose: A fibrillated cellulose material containing micro- and nanoscale fiber structures used to modify strength, rheology, barrier performance, and stability. |
| MLSS | Mixed Liquor Suspended Solids: The concentration of suspended biomass and solids in an activated-sludge basin, used to manage biological-treatment inventory and capacity. |
| MOC | Management of Change: A formal process for reviewing technical, procedural, organizational, or chemical changes before implementation to control safety and operational risk. |
| MPC | Model Predictive Control: An advanced control method that uses a process model to anticipate interactions and optimize multiple operating constraints over time. |
| MVR | Mechanical Vapor Recompression: An energy-efficiency technology that compresses process vapor so it can be reused as a heating medium in evaporation or concentration duties. |
| N | |
| NBKP | Needle Bleached Kraft Pulp: A market term used particularly in Asian trade for bleached kraft pulp made from long-fiber softwood species. |
| NBSK | Northern Bleached Softwood Kraft: A benchmark market-pulp grade produced from northern softwood species and valued for long fibers and reinforcement strength. |
| NCASI | National Council for Air and Stream Improvement, Inc.: A research organization serving the forest-products industry on environmental measurement, emissions, wastewater, sustainability, and regulatory science. |
| NCG | Non-Condensable Gas: Process gas that remains after vapor condensation and may contain reduced sulfur compounds, methanol, turpentine, and other volatile substances requiring collection and treatment. |
| NESHAP | National Emission Standards for Hazardous Air Pollutants: United States federal standards controlling hazardous air emissions from specified source categories, including pulp and chemical-recovery operations. |
| NFC | Nanofibrillated Cellulose: Cellulose processed into long, flexible nanoscale fibrils for strength enhancement, rheology control, coatings, films, and composite materials. |
| NFPA | National Fire Protection Association: A standards organization whose codes address combustible dust, boilers, electrical classification, fire protection, and other mill hazards. |
| NIR | Near-Infrared Spectroscopy: A rapid analytical method used for online or laboratory measurement of moisture, wood composition, lignin, and selected pulp or liquor properties. |
| NOx | Nitrogen Oxides: Combustion-related air pollutants regulated from recovery boilers, lime kilns, power boilers, and other mill sources. |
| NPDES | National Pollutant Discharge Elimination System: The United States permitting program that establishes conditions and monitoring requirements for discharges to surface waters. |
| NPE | Non-Process Element: An inorganic element not required for the kraft chemical cycle that can accumulate and contribute to scaling, corrosion, plugging, dead-load, and recovery problems. |
| NSR | New Source Review: A United States air-permitting program applying to qualifying new facilities and major modifications before construction begins. |
| NSSC | Neutral Sulfite Semichemical: A pulping process using neutral sulfite liquor followed by mechanical refining, commonly applied to hardwoods where high yield and stiffness are desired. |
| O | |
| ODL | Oxygen Delignification: An alkaline oxygen treatment applied after cooking to remove residual lignin before bleaching, reducing downstream chemical demand and effluent load. |
| ODMT | Oven-Dry Metric Tonne: A mass unit normalized to zero moisture using a specified oven-drying method, supporting accurate fiber, yield, and material-balance calculations. |
| OSHA | Occupational Safety and Health Administration: The United States federal agency responsible for workplace safety standards affecting chemical handling, process safety, hazardous energy, exposure, and mill operations. |
| P | |
| PAA | Peracetic Acid: An oxidizing chemical used in selected pulp bleaching and microbial-control applications, often where low halogen use is desired. |
| PAPTAC | Pulp and Paper Technical Association of Canada: A Canadian technical association supporting professional knowledge exchange, testing methods, standards, and operating practices across pulp and paper manufacturing. |
| PEFC | Programme for the Endorsement of Forest Certification: An international system that endorses national forest-certification schemes and provides chain-of-custody requirements for forest-based materials. |
| PGW | Pressure Groundwood: Mechanical pulp produced by grinding wood under elevated pressure and temperature to improve fiber development relative to conventional groundwood. |
| PHA | Process Hazard Analysis: A systematic evaluation of process hazards, causes, consequences, safeguards, and recommendations for operations involving hazardous chemicals or energy. |
| PHK | Prehydrolysis Kraft: A dissolving-pulp process that removes much of the hemicellulose before kraft cooking, enabling production of high-purity and high-alpha cellulose pulp. |
| PM | Particulate Matter: Airborne solid or liquid particles emitted from combustion, chemical-recovery, material-handling, and other mill operations and controlled through permits and capture equipment. |
| PSAQ | Polysulfide-Anthraquinone: A modified alkaline-pulping approach combining polysulfide and anthraquinone to protect carbohydrates, support delignification, and increase pulp yield. |
| PSD | Prevention of Significant Deterioration: A United States air-permitting program governing qualifying construction or modification in areas meeting national ambient air-quality standards. |
| PSM | Process Safety Management: A regulatory and management framework for preventing catastrophic releases involving highly hazardous chemicals through integrated technical and organizational controls. |
| R | |
| R10 | Alkali Resistance at 10% Sodium Hydroxide: The percentage of pulp remaining insoluble after standardized treatment with a 10% sodium hydroxide solution, used to characterize dissolving-pulp composition and purity. |
| R18 | Alkali Resistance at 18% Sodium Hydroxide: The percentage of pulp remaining insoluble after standardized treatment with an 18% sodium hydroxide solution, commonly used as an indicator of alpha-cellulose-rich material. |
| RB | Recovery Boiler: The kraft-mill boiler that generates steam from black liquor while reducing inorganic chemicals to a recoverable smelt. |
| RCRA | Resource Conservation and Recovery Act: The principal United States law governing solid and hazardous waste generation, handling, storage, treatment, and disposal. |
| RDH | Rapid Displacement Heating: An energy-efficient batch kraft-cooking system that uses liquor displacement and heat recovery to control cooking profiles and reduce steam demand. |
| RE | Reduction Efficiency: The degree to which sodium sulfate is converted to sodium sulfide in a recovery boiler, indicating chemical-recovery performance. |
| REACH | Registration, Evaluation, Authorisation and Restriction of Chemicals: The European Union framework governing chemical information, risk management, market access, and restrictions for substances manufactured, imported, or used. |
| RGP | Refiner Groundwood Pulp: High-yield mechanical pulp produced by refining wood material rather than grinding logs against a stone surface. |
| RMP | Refiner Mechanical Pulp: Mechanical pulp produced by fiberizing wood chips or other wood material in disc refiners without the primary use of pressurized thermal treatment. |
| RMP | Risk Management Program: A United States regulatory program requiring covered facilities to assess accidental-release hazards, maintain prevention controls, and prepare emergency-response information. |
| RO | Reverse Osmosis: A pressure-driven membrane process that removes dissolved salts and low-molecular-weight contaminants for water reuse, polishing, or concentration. |
| S | |
| SAQ | Soda-Anthraquinone: An alkaline pulping process using sodium hydroxide and anthraquinone, often applied to nonwood fibers or where sulfur-free pulping is desired. |
| SBSK | Southern Bleached Softwood Kraft: A long-fiber market-pulp grade produced primarily from southern pine and used for reinforcement, absorbency, and strength. |
| SCMP | Sulfonated Chemi-Mechanical Pulp: High-yield pulp produced by sulfite-based chemical pretreatment followed by mechanical refining to improve fiber separation and strength. |
| SCR | Selective Catalytic Reduction: An air-emissions control process that uses a catalyst and reagent to convert nitrogen oxides into nitrogen and water. |
| SDS | Safety Data Sheet: The standardized document describing a chemical’s hazards, composition, handling, storage, exposure controls, emergency measures, and disposal considerations. |
| SDT | Smelt Dissolving Tank: The vessel in which molten recovery-boiler smelt is dissolved to form green liquor, requiring careful control of steam, noise, venting, and explosion hazards. |
| SEC | Specific Energy Consumption: Energy used per unit of pulp or another defined output, particularly important for benchmarking mechanical refining, pumping, evaporation, and overall mill efficiency. |
| SEM | Scanning Electron Microscopy: A high-resolution imaging method used to examine fiber surfaces, fibrillation, deposits, contaminants, coatings, and nanocellulose structures. |
| SFI | Sustainable Forestry Initiative: A North American certification system addressing responsible forest management, fiber sourcing, conservation, and chain-of-custody controls. |
| SGW | Stone Groundwood: Mechanical pulp produced by pressing logs against a rotating grindstone, delivering high yield, bulk, and opacity but relatively low permanence. |
| SIL | Safety Integrity Level: A defined performance level for a safety instrumented function, based on the risk reduction required from the protective system. |
| SIS | Safety Instrumented System: An independent system of sensors, logic solvers, and final elements designed to move a hazardous process to a safe state. |
| SNCR | Selective Non-Catalytic Reduction: A nitrogen-oxide control process that injects ammonia or urea into a suitable furnace temperature zone without using a catalyst. |
| SOG | Stripper Off-Gas: A concentrated gas stream from foul-condensate stripping that may contain methanol and reduced sulfur compounds and requires controlled destruction. |
| SOx | Sulfur Oxides: Sulfur-containing combustion gases regulated from boilers, lime kilns, and other sources because of their effects on air quality and acid deposition. |
| SP | Sulfite Pulp: Chemical pulp produced with sulfite or bisulfite cooking liquor, offering distinct brightness, bleachability, and cellulose characteristics compared with kraft pulp. |
| SPCC | Spill Prevention, Control, and Countermeasure: A United States planning requirement for qualifying facilities storing oil, including measures to prevent and respond to releases to navigable waters. |
| SR | Schopper-Riegler: A standardized pulp drainage measure widely used to monitor refining development and dewatering behavior, with higher values indicating slower drainage. |
| SRT | Solids Retention Time: The average time biological solids remain in a wastewater-treatment system, influencing biomass concentration, treatment stability, and sludge production. |
| SWKP | Softwood Kraft Pulp: Kraft pulp made from long-fiber coniferous species and used where tear, tensile strength, reinforcement, or absorbency is required. |
| T | |
| TA | Total Alkali: The combined sodium compounds counted under a specified liquor-analysis convention, used for chemical balances and control of the kraft recovery cycle. |
| TAPPI | Technical Association of the Pulp and Paper Industry: An international technical association that develops test methods, publishes technical information, and supports professional knowledge exchange. |
| TCF | Totally Chlorine-Free: A bleaching approach that avoids both elemental chlorine and chlorine-containing bleaching chemicals, relying on agents such as oxygen, peroxide, and ozone. |
| TDS | Total Dissolved Solids: The concentration of dissolved inorganic and organic substances in water, condensate, or effluent, relevant to reuse, scaling, salinity, and treatment performance. |
| TEMPO | 2,2,6,6-Tetramethylpiperidine-1-Oxyl: A stable radical catalyst used to selectively oxidize cellulose surfaces, facilitating energy-efficient fibrillation into nanocellulose. |
| TKN | Total Kjeldahl Nitrogen: A wastewater measure combining organic nitrogen and ammonia nitrogen, used for nutrient control, treatment design, and discharge monitoring. |
| TMP | Thermomechanical Pulp: High-yield pulp produced by steaming wood chips before pressurized refining, improving fiber separation compared with unheated mechanical pulping. |
| TN | Total Nitrogen: The combined nitrogen content in water or wastewater, used to evaluate nutrient loads, treatment requirements, and permit compliance. |
| TOC | Total Organic Carbon: A measure of carbon in organic compounds that supports rapid monitoring of water cleanliness, condensates, spills, and wastewater-treatment performance. |
| TP | Total Phosphorus: The combined phosphorus content in water or wastewater, managed because it affects biological treatment and can contribute to receiving-water eutrophication. |
| TRS | Total Reduced Sulfur: A group of odorous sulfur compounds generated in kraft operations and regulated in emissions from recovery, pulping, evaporation, and lime-kiln systems. |
| TSCA | Toxic Substances Control Act: The United States law governing chemical substance reporting, evaluation, restrictions, recordkeeping, and certain product or process uses. |
| TSS | Total Suspended Solids: The concentration of filterable suspended material in wastewater, used to monitor fiber losses, clarification, biological treatment, and discharge compliance. |
| TTA | Total Titratable Alkali: The total alkalinity measured by specified titration of kraft liquors, supporting control of cooking, recausticizing, and chemical-recovery balances. |
| U | |
| UASB | Upflow Anaerobic Sludge Blanket: A high-rate anaerobic reactor in which wastewater flows upward through granular biomass, reducing organic load and generating biogas. |
| UEL | Upper Explosive Limit: The maximum concentration of a combustible gas or vapor in air above which flame propagation cannot occur because the mixture is too fuel-rich. |
| UKP | Unbleached Kraft Pulp: Kraft pulp used without full bleaching, retaining more residual lignin and its natural brown color for applications prioritizing strength or lower processing intensity. |
| V | |
| VFA | Volatile Fatty Acids: Short-chain organic acids formed during anaerobic treatment; their concentration is monitored as an indicator of digester loading and process stability. |
| VOC | Volatile Organic Compound: An organic substance that readily enters the atmosphere and may be regulated from pulping, evaporators, tanks, wastewater systems, and byproduct handling. |
| W | |
| WBL | Weak Black Liquor: Dilute spent cooking liquor leaving pulp washing before evaporation, with concentration and carryover affecting recovery capacity and energy use. |
| WESP | Wet Electrostatic Precipitator: An emissions-control device that captures fine particulate matter, acid mist, and condensable material from saturated or near-saturated gas streams. |
| WFGD | Wet Flue-Gas Desulfurization: A scrubbing process that contacts flue gas with an alkaline liquid to remove sulfur dioxide and selected acid gases. |
| WL | White Liquor: The alkaline cooking liquor regenerated in the kraft recovery cycle, containing sodium hydroxide and sodium sulfide as its principal active chemicals. |
| WLC | White Liquor Clarifier: A recausticizing vessel that separates lime mud and suspended solids from regenerated white liquor before the liquor returns to pulping. |
| WQBEL | Water Quality-Based Effluent Limitation: A discharge limit derived from the need to protect receiving-water quality when technology-based requirements alone are insufficient. |
| WRV | Water Retention Value: A laboratory measure of the water retained by pulp after standardized centrifuging, indicating fiber swelling, refining response, and dewatering behavior. |
| WWTP | Wastewater Treatment Plant: The integrated physical, chemical, and biological system that removes fiber, solids, organic load, nutrients, and other pollutants from mill effluent. |
| X | |
| XRD | X-Ray Diffraction: An analytical technique used to study cellulose crystallinity and identify crystalline mineral phases in ash, scale, deposits, and process solids. |
| XRF | X-Ray Fluorescence: A rapid elemental-analysis technique used to quantify inorganic constituents in wood, pulp, liquors, lime, ash, smelt, and deposits. |
| Z | |
| ZLD | Zero Liquid Discharge: A water-management configuration designed to eliminate routine liquid-effluent discharge through extensive reuse, concentration, and solids recovery. |
| ZST | Zero-Span Tensile Strength: A pulp-testing measure obtained with essentially no free span between jaws, used as an indicator of intrinsic fiber strength. |