Paper Machine Systems Research Articles

Analysis of Operational Readiness and Reliability of the Paper Machine System after Implementation of Model of Influence

Analysis of Operational Readiness and Reliability of the Paper Machine System after Implementation of Model of Influence

The reliability optimizing of the paper machine system by using of method of technical diagnostic

The reliability optimizing of the paper machine system by using of method of technical diagnostic

Influence of Alkaline Treatment and Alkaline Peroxide Bleaching of Aspen Chemithermomechanical Pulp on Dissolved and Colloidal Substances

Dissolved and colloidal substances (DCS) will be released during mechanical pulping and following bleaching operations. The accumulation of DCS in paper machine systems can bring various negative impacts on papermaking operations. In present study, the influence of alkaline treatment and alkaline peroxide bleaching of aspen chemithermomechanical pulp on released DCS was evaluated based on general DCS properties, lignin content, and carbohydrate and organic extractives compositions. Results showed that both treatments could promote the DCS release by increasing the concentration and cationic demand of DCS samples. However, alkaline peroxide bleaching caused the decrease in turbidity and average particle size. The total amounts of dissolved lignin, carbohydrates, and organic extractives were also increased. The dissolved lignin-related substances and carbohydrates were the predominant components of DCS. In the extractives, alkaline peroxide bleaching mainly resulted in the release of some lignin-degraded substances and a slight degradation of unsaturated fatty acids and their esters.

DISSOLVED AND COLLOIDAL SUBSTANCES (DCS) AND THE CHARGE DEMAND OF PAPERMAKING PROCESS WATERS AND SUSPENSIONS: A REVIEW

Dissolved and colloidal substances (DCS) in the process waters of paper machine systems can interfere with the retention of fine particles, retard the drainage of water from the wet web, and generally hurt the intended functions of various polyelectrolytes that are added to the process. This review considers publications that have attempted to characterize the nature and effects of different DCS fractions, in addition to some of the ways that paper technologists have attempted to overcome related problems. The consequences of DCS in a paper machine system can be traced to their ability to form complexes with various polyelectrolytes. Such tendencies can be understood based on a relatively strong complexing ability of multivalent materials, depending on the macromolecular size and charge density. Continuing research is needed to more fully understand the different contributions to cationic demand in various paper machine systems and to find more efficient means of dealing with DCS.

Impact of disinfectant and nutrient concentration on growth and biofilm formation for a Pseudomonas strain and the mixed cultures from a fine papermachine system

Biofilm formation in papermaking processes could inflict financial loss by interrupting paper machine operation and pose a potential health hazard. A mixed microbial culture obtained from paper machine slime and a Pseudomonas strain (identified as Pseudomonas putida HB45) which is tolerant to the alkyl dimethyl benzyl ammonium chloride (quaternary ammonium chloride, QAC) were used to investigate the interplay between disinfectants and glucose on bacterial growth and biofilm formation. QAC and 2,2-dibromo-3-nitrilopropionamide (DBNPA) were found to be effective at concentration lower than isothiazolone in both standardized Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) tests. Crystal violet staining technique demonstrated that biofilm formation of P. putida HB45 and the mixed culture could be controlled by modest dosage of DBNPA and QAC; however, they could be barely eliminated due to high MBC to MIC ratios. In simulated papermaking processing water, glucose was shown to increase the average biofilm formation rates during stationary phase for both P. putida HB45 and the mixed culture under the presence of biocides. Complexity and population diversity of biofilm of the paper machine slime was observed by in-situ cryo-scanning electron microscopy. Confocal laser scanning microscopy (CSLM) was employed to show qualitative and partial quantitative biofilm formation under various circumstances. The results of this study could assist improving strategy for controlling biofilm formation in papermaking processes.

Flocculation and redispersion of cellulosic fiber suspensions: A review of effects of hydrodynamic shear and polyelectrolytes

Cellulosic fibers in aqueous suspensions are subject to flocculation effects that involve two contrasting scales of dimension. The net effect of flocculation determines how uniformly fibers can become formed into a sheet during the manufacture of paper. At a macroscopic level, the highly elongated shape of typical wood-derived fibers in agitated suspensions can give rise to frequent inter-fiber collisions and the formation of fiber flocs. At a submicroscopic scale, surfaces of suspended materials can become joined by macromolecular bridges. Although such bridges tend to reduce paper’s uniformity, polyelectrolyte flocculants are used in most paper machine systems to achieve relatively high retention efficiencies of fine particles as paper is being formed. By adjusting the papermaking equipment, judiciously selecting points of addition of chemicals, and by managing chemical dosages, papermakers employ a variety of strategies to achieve favorable combinations of retention and uniformity. This review considers scholarly work that has been directed towards a greater understanding of the underlying mechanisms.

Isolation and characterization of filamentous bacteria from paper mill slimes

The composition of filamentous bacteria in paper machine systems has received little scientific scrutiny, even though these organisms have been associated with many problems that affect machine efficiency and paper quality. The objective of the study was to isolate and characterize filamentous bacteria in paper mill slimes using conventional microbiological techniques, fatty acid methyl ester (FAME) analysis, and 16S rRNA gene sequencing. Filamentous or long, thread-like bacteria from different genera were observed. Pink or red-pigmented filamentous bacteria identified as Flectobacillus sp. were commonly isolated from pink slime deposits, but they were also obtained from deposits that did not appear pink or red. Two organisms had certain characteristics that were different from similar organisms previously described. One was a Gram-negative, filamentous bacterium with golden yellow colonies. This organism was esculin positive, and hydrolyzed starch but did not produce hydrogen sulfide. A BLAST search of GenBank database produced an identity of 92% with Cytophaga sp. or Flavobacterium columnare. A Gram-positive bacterium that produced very long or filamentous structures was also observed. On tryptic soy agar, this organism produced yellow colonies, but on plate count agar, the colonies were white. The plate count agar-grown cells were atypical with many of them having bulbs either in the middle or at the ends of the cell. In indole nitrite broth, the organism produced a very extensive filamentous structure. The FAME and 16S rRNA gene analyses of this organism showed that the organism was a Bacillus sp., but no spores were produced in any of the media studied, including a sporulating medium. Various spore-formers, identified as Bacillus psychrophilus and Paenibacillus sp., also had long continuous chains of cells. Two species of Chryseobacterium produced long filaments. Actinomycetes with branched mycelia and identified as Norcardiopsis alba and Streptomyces albidoflavus were isolated from wet lap pulp samples. These actinomycetes produced a very strong earthy odor both in culture and in field samples. Information, such as growth requirements and presence or absence of endospores, gained about these organisms will help in their control.

Diagnosis of Microbial Problems on Paper Machines

Numerous microbes are capable of growth in paper machine systems. They form vis ble deposits that result in sheet defects, holes or even breaks in the web. Microbes are also responsible for performance loss and spoilage of pulp and expensive functional chemicals. This spoilage can lead to strength loss in fibers. formation of odors that result in rejected products, viscosity loss in starch and a variety of other problems. Diagnosis of microbial problems in complicated by the fact that simple aerobic plating techniques on tryptone glucose extract agar or Petrifilms TM with a 48-hour incubation period do not allow recovery of all of the microbes causing the problems. Nor do the numbers of planktonic (free-swimming) cells correlate to the severity of deposition on surfaces. This paper will discuss the limitations of generally accepted plating techniques and propose more accurate diagnostic methods for solving microbial problems.

Comparison of Two Biocides - Carbamate and Glutaraldehyde - in the Control of Fouling in Pulp and Paper Industry

Formation of fouling deposits is a serious problem facing paper mills. Despite the search for alternative methods, chemical biocides still represent the chief countermeasure to control microbial growth and general fouling buid-up in pulp and paper mills. The purpose of this work was to determine the effect of two biocides (carbamate and glutaraldehyde) on both planktonic cells and fouling layers of a paper machine system. A flow system was used for the study of fouling accumulation in an industrial white water circuit. Both biocides proved to be more effective in reducing the microbial loading of the white water circuit than the deposit accumulated on the stainless steel surfaces. Carbamate, in contrast to glutaraldehyde, had the ability of promoting cell agglomeration since the microbial loading decreased much more when the white water, treated with carbamate, was filtered through a filter-linen. The retention of suspended cells in the cellulose fibres acquires major importance since it is obtained by using an already existing physical process (filtration), which strongly enhances the overall microbial reduction obtained with the addition of the carbamate, without increasing the economic costs. These results also suggest that the use of conventional retention agents in pulp and paper processes can be efficient in controlling unwanted microbial effects.