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Microbial Life in Paper Machine: Prevention and Control

Microbial Life in Paper Machine: Prevention and Control. TAPPI Monograph: Microorganisms in Papermaking. Piyush K. Verma, Nishi K. Bhardwaj, R. Varadhan Avantha Centre for Industrial R & D, Yamuna Nagar (Haryana). IPPTA ZONAL SEMINAR ON

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Microbial Life in Paper Machine: Prevention and Control

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  1. Microbial Life in Paper Machine: Prevention and Control TAPPI Monograph: Microorganisms in Papermaking Piyush K. Verma, Nishi K. Bhardwaj, R. Varadhan Avantha Centre for Industrial R & D, Yamuna Nagar (Haryana) IPPTA ZONAL SEMINAR ON Best Maintenance Practices in Pulp and Paper Mill to Improve Profitability

  2. Why do microbes grow? • Variedoxygenlevels Nutrients SuitablepHrange • Surfaces Sunlight Temperature • Increased surface area • Increased filler levels • Water system closure • Recycled pulp • i.e. machines contain: • Ideal conditions for microbial growth IPPTA ZONAL SEMINAR ON Best Maintenance Practices in Pulp and Paper Mill to Improve Profitability

  3. Changes in Operational / Industry Practices • Water system closure • Noxious chemical cycle up • Nutrients cycle up • Stagnant chests • Neutral to alkaline conditions • Increased use of recycled pulps • Large chests constructed with long dwell times • Reduced biocide programs due to cost constraints IPPTA ZONAL SEMINAR ON Best Maintenance Practices in Pulp and Paper Mill to Improve Profitability

  4. Microbial Deposits Filamentous bacteria Algae Fungi Non Microbial Deposits • In addition to wood fibers, fibrils, fines and fillers, other materials also get deposited: • Strength additives • Uncooked starch granules • Mimic microbes Moulds/ Yeast Reference TAPPI Monograph: Microorganisms in Papermaking, Papercon, 2011.

  5. Comparison of Biological Activity Test Methods • Reference: Bajpai P (2012) Slime Control. In: Bajpai P (eds) Biotechnology for pulp and paper processing.

  6. pH Preference of Microbes? Reference TAPPI Monograph: Microorganisms in Papermaking, Papercon, 2011.

  7. Machine Surfaces • Headbox • Approach piping • Frame Fresh Water Filamentous bacteria, algae, protozoa, worms Broke Towers Heavily contaminated Back Water Entry (Check) Points for Microbes White Water System Recycled Fibres Paper Mill Additives

  8. Why do We Care About Microbes? • Reduced paper quality & strength • Odor problems/ Obnoxious odors • Rejected paper, Customer complaints • Machine downtime • Viscosity deterioration of coating batches • Brightness , shade issues • Screening / filtering issues • Corrosion (MIC) • Decreased profitability Deposit from foil pan Sheet defects Reference TAPPI Monograph: Microorganisms in Papermaking, Papercon, 2011.

  9. Mill Safety Issues Reference TAPPI Monograph: Microorganisms in Papermaking, Papercon, 2011.

  10. Biocorrosion • Microbiologically influenced corrosion • Direct • Biofilm formation • Indirect • Corrosive metabolic byproducts • Types of Microbes Involved in MIC • Metal depositors • Slime forming bacteria • Acid formers • Sulfate reducing bacteria (SRB)

  11. Slime Forming Bacteria • Typically aerobic • All produce an exopolymer • Contains water, polysaccharides & protein • Traps inorganic salts, fibers, fines, fillers & debris • Metal Depositors • Gallionella, Sphaerotius, Crenothrix, Leptothrix • All aerobic; oxidize either iron or manganese to oxides

  12. Acid Producers • Clostridium (anaerobic) • Thiobacillus (aerobic) • Sulfate Reducing Bacteria • All SRBs are anaerobic • Desulfovibrio most common genus • SRBs do not attack metal directly • Typically produce localized pitting corrosion

  13. Monitoring Biocorrosion • After it has occurred • Post mortem examination • In situ monitoring • Difficult • Side stream monitoring • Suspension of coupons in raw or process water • Biofouling sampling device

  14. Strategies to control microorganisms • Water quality • Housekeeping • Oxidants- short term kill • Biocides- short and long term kill • Thermal • Radiation (UV/ gamma) • Key Elements of Microbial Control Program • Engineering survey • Microbiological survey • Product selection • Implementation/ Follow up

  15. Product Selection • Oxidizing biocides (very fast kill; short duration) • May be stabilized (hydantoins, sulfamate) • Typically continuous dosing • Non oxidizing biocide (slower kill; Longer half life) • Typical intermittent dosing • Inhibits reproduction, doesn’t necessary kill • Non biocidal technology • Enzymes, biodispersants & adjuvants • Monitoring and Follow Up • Employ routine monitoring , Machine runnability, quality, defects etc.

  16. Oxidants and Biocides: Functions • Oxidants and Non Oxidizing Biocides: • Kill all aerobic bacteria • Maintain adequate level of oxidant and/or biocide • Oxidants: • Oxidize compounds • Oxidants: Oxidation of processing chemicals, e.g. polyacrylic acid and CMC, limits the levels that can be used.

  17. Oxidants • Hydrogen Peroxide • Short term MB control • Environmentally friendly • Microbial resistance (degradation to water and oxygen by catalase enzyme) • Hypochlorite & Chlorine • Affects viscosity • Chlorinated organic compounds • Effective at neutral to acid pH • Very corrosive

  18. Oxidants • Ozone • Excellent • Short term MB Control • Peracetic acid • Short term MB control • Environmentally friendly • Sodium Chlorite • Short term MB control • Neutral to acid pH • Chlorine dioxide • Does not chlorinate • Short term MB control

  19. Biocides (Non–oxidizing) • Mills that produce food contact paper and paperboard • Isothiazolin • Benzisothiazolin • Glutaraldehyde • Bromonitropropanediol • Sodium orthophenylphenate • Thione Reference TAPPI Monograph: Microorganisms in Papermaking, Papercon, 2011.

  20. Additional Non-oxidizing Biocides • Methylisothiazolin(MIT) • Tetrakishydroxymethylphosphonium sulfate (THPS) • Dodecylquanidine(DGH) • Oxazolidines • Dibromodicyanobutane (DBDCB) • Methylenebiosthiocyanate( MBT) • Hydantoins • HCHO • Bromohydroxyacetophenone( BHAP) • Adamantanes • HCHO Reference TAPPI Monograph: Microorganisms in Papermaking, Papercon, 2011.

  21. Microbial Tolerance or Resistance to Oxidants and Biocides • Biofilm • Tolerance • Resistance • Prevention of biofilm formation • Cleaning • Sterilization

  22. Areas of Concern for Paper Mill Microbial Control • Unloading raw materials • Adequate microbiological control in slurry prior to unloading • Uncontaminated hoses, lines, pumps, etc. • Each raw material should have its own unloading system • Biocide-biocide compatibility, Biocide-process chemical compatibility • Raw material storage/ screening facilities • Adequate MB control in raw material storage tank • Storage tank recirculation system, good mixing • Equipment to add oxidants and/or biocides into the intake side of the recirculation pump • Biocide-biocide compatibility, biocide-process chemical compatibility • Water quality (closed water system: water reuse)

  23. Coating • Adequate MB control for each coating ingredient • Coating biocide should be effective and compatible • Coating storage tank • Key area for intensive bacterial monitoring • Adequate MB control • Run tank (excess coating typically recycled back to run tank) • Adequate MB control • Crucial area for MB control • Recirculation line from coater to coater feed tank

  24. Boilouts-Chemical Cleaning Programs • Goals of Boilout • Remove Organic and inorganic build-up • Remove deposits • Clean the forming fabric • Housekeeping = Runnability • Boilout Benefits • Prevention of Premature Slime Accumulation • Prevention of Corrosion Pitting • Prevention of Scale Formation • Removal of Organic Deposits

  25. Biolout Components • Caustic (Sodium Hydroxide) • Acid (Sulfuric) • Organic Penetrants • Inorganic Dispersants • Forming Agents • Typical Boilout • Pre Boilout wash-up • pH of 12-12.5 • Temperature of 1300-14500F • Re-circulation, Neutralization

  26. New Technology Options Modes of action of microbicides, biodispersants, enzymes and biofilm inhibitors Reference TAPPI Monograph: Microorganisms in Papermaking, Papercon, 2011.

  27. New Technology Options • Enzymes & Biodispersants • 0.1-0.5% typical usage rates • Proprietary combinations of enzymes, dispersants and surfactants • Neutral pH Boilouts: Effective in removing MB, starch, cellulosic and protein containing deposits •  Alternative if high or low pH solutions are problematic • Use of dispersants and penetrants with standard temperature and time • Accelerates removal of general wet end deposits during neutral boilout procedures • Reduces boilout time, maintenance on machine can be completed during the boilout • Causes no problems in waste treatment facilities

  28. Reference TAPPI Monograph: Microorganisms in Papermaking, Papercon, 2011.

  29. Monthly average values of Total bacterial Count at the wire pit in a tissue mill using the enzymatic biocide. Red bars indicate base line values Bacterial counts at the wire pit in a tissue mill after the usage of enzymatic biocide • Reference: Juan C. Cotrino and Victor Ordonez (2011), TAPPI Papercon Conference

  30. Monthly average values of Total bacterial Count at the machine chest in an OCC recycling mill. Red bar indicate base line values Bacterial count at the machine chest of an OCC recycling mill after the usage of enzymatic biocide. • Reference: Juan C. Cotrino and Victor Ordonez (2011), TAPPI Papercon Conference

  31. Summary • Microbial colonization of machines increases downtime and decreases profitability. • Biofilms form deposits that lead to sheet defects. • Microbial spoilage of additives and fibers can alter pH, cause odors, and reduce sheet strength and quality. • Understanding the papermaking process and basic microbial physiology is essential in diagnosing and solving problems. • Monitor microbiological contaminants throughout the paper mill. • Define biocide treatment with lab studies and confirm with field testing. • Follow biocide manufacturers recommendations. • Follow up with routine monitoring.

  32. Summary • Effective house cleaning & biocide application are integral parts of successful integrated microbial control strategies. • Oxidants and biocides must be selected with both efficacy and compatibility in mind. • Oxidant and biocide application techniques must adhere to environment, safety, and health regulations. • Resistance development is a reality. Oxidant, biocide, and microbial testing application must be accurate, precise, and as “real time” as possible. • Oxidants and biocides must not only be effective, they must not interfere or compromise subsequent papermaking applications.

  33. Summary • Mechanical cleaning to remove deposits. • Caustic cleaning with water/ dispersant flush. • After repairs, system refilled with water plus dispersant and non-oxidizing biocide that are non-aggressive to metallurgy; repeated as needed. • Under “normal operations”, system treated with nonionic dispersant and biocide. • Successful boilouts depend on: Adequate time, Proper pH, (alkalinity), Correct temperature, Solution formulation, Proper wash-up after the boilout. • Work with machine crew to establish good practices: Safety, Set-up, Clean-up & Inspection.

  34. IPPTA ZONAL SEMINAR ON Best Maintenance Practices in Pulp and Paper Mill to Improve Profitability

  35. http://www.tappi.org/content/events/11papercon/documents/700.655%20pptA.pdfhttp://www.tappi.org/content/events/11papercon/documents/700.655%20pptA.pdf

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