Slime problems in the paper and board industry

 The latest trends in the paper industry have been towards manufacturing by a neutral or alkaline process, greater consumption of secondary fibres and the closing-up of the process water systems. Under these conditions of papermaking, the problems of deposits, corrosion and odours due to the microbiological activity increase considerably and therefore, runnability and production problems occur. To help our understanding of the current situation in the paper industry, this paper presents a review of the microorganism sources, the consequences of the microbiological activity upon the actual systems of manufacturing paper and board, and the current state of the different alternatives for its prevention and control, as well as the future trends to address environmental considerations. Received: 20 March 1996/Received revision: 23 May 1996/Accepted: 28 May 1996     

The control of microbiological problems in the paper industry

The aqueous environment of the paper or board machine is ideal for the growth of many types of organisms. These can have a major impact on mill profitability by causing production downtime, product rejects and operational difficulties. Treatment of these problems first requires accurate definition, followed by a good understanding of the system. In-depth analysis allows the deposition succession to be summised, which in turn will allow a correct choice of control strategy. This may require treatments to include both biocide and chemical deposit control. The benefits of biocides and combination programmes are discussed.     

Review of research on closed loop supply chain management in the process industry

Closed loop supply chain (CLSC) management is a major enabler for sustainability in value creating networks. This contribution aims to describe and analyze the main characteristics of CLSC planning in the process industry and the related publications, in order to determine the evolution and gaps of this current research over time and improve our understanding of this issue. We built up a database with the articles on CLSC in different sectors of the process industry and identified the most relevant journals within this field. Furthermore, we derive and identify the requirements for CLSC considerations in the process industry for verifying whether these requirements are met in the literature so far. In addition, we have explored the topic, the methodology and the techniques of analysis, as well as other relevant aspects of the research in this field. We mainly focus on general and specific quantitative approaches, observing what has been done and how, where and by whom it has been carried out. The result is an extensive review of the research work itself and their limitations having an influence on CLSC concepts for the process industry. We conclude with some suggestions to those who begin to research on this apparently disregarded topic.     

Plant fibers in the paper industry

For 20 centuries, vegetable fibers from various sources have been converted into thin sheets for use in trade, communications, law, and even for shelter. Cotton and linen rags were the first fibrous raw materials to acquire widespread status in paper making, and they are still needed for specialty products. Increasing demands for paper ultimately surpassed the availability of rags, so that other sources of fiber were sought. About the year 1800, numerous other materials of agricultural origin began to come into use somewhat temporarily. Although woods have become the prime source of paper making fibers during the last 100-125 years, annual plant fibers retain their importance. The technical feasibility of non-woody materials is substantiated by more than 300 paper mills throughout the world that use such raw materials. Both necessity and special properties account for their use. The potential for various nonwoody fibrous plants is being investigated intensively by the United States Department of Agriculture’s Agricultural Research Service, to discover new crops that might hare practical significance in the national agricultural program and in the commercial production of paper.     

Application of enzymes in the pulp and paper industry

The pulp and paper industry processes huge quantities of lignocellulosic biomass every year. The technology for pulp manufacture is highly diverse, and numerous opportunities exist for the application of microbial enzymes. Historically, enzymes have found some uses in the paper industry, but these have been mainly confined to areas such as modifications of raw starch. However, a wide range of applications in the pulp and paper industry have now been identified. The use of enzymes in the pulp and paper industry has grown rapidly since the mid 1980s. While many applications of enzymes in the pulp and paper industry are still in the research and development stage, several applications have found their way into the mills in an unprecedented short period of time. Currently the most important application of enzymes is in the prebleaching of kraft pulp. Xylanase enzymes have been found to be most effective for that purpose. Xylanase prebleaching technology is now in use at several mills worldwide. This technology has been successfully transferred to full industrial scale in just a few years. The enzymatic pitch control method using lipase was put into practice in a large-scale paper-making process as a routine operation in the early 1990s and was the first case in the world in which an enzyme was successfully applied in the actual paper-making process. Improvement of pulp drainage with enzymes is practiced routinely at mill scale. Enzymatic deinking has also been successfully applied during mill trials and can be expected to expand in application as increasing amounts of newsprint must be deinked and recycled. The University of Georgia has recently opened a pilot plant for deinking of recycled paper. Pulp bleaching with a laccase mediator system has reached pilot plant stage and is expected to be commercialized soon. Enzymatic debarking, enzymatic beating, and reduction of vessel picking with enzymes are still in the R&D stage but hold great promise for reducing energy. Other enzymatic applications, i.e., removal of shives and slime, retting of flax fibers, and selective removal of xylan, are also expected to have a profound impact on the future technology of the pulp and paper-making process.     

Biofilm problems in dental unit water systems and its practical control

Dental chair units (DCUs) contain integrated systems that provide the instruments and services for a wide range of dental procedures. DCUs use water to cool and irrigate DCU-supplied instruments and tooth surfaces during dental treatment. Water is supplied to these instruments by a network of interconnected narrow-bore (2–3 mm) plastic tubes called dental unit waterlines (DUWLs). Many studies over the last 40 years demonstrated that DUWL output water is often contaminated with high densities of micro-organisms, predominantly Gram-negative aerobic heterotropic environmental bacteria, including Legionella and Pseudomonas species. Untreated DUWLs host biofilms that permit micro-organisms to multiply and disperse through the water network and which are aerosolized by DCU instrument use, thus exposing patients and staff to these micro-organisms, to fragments of biofilm and bacterial endotoxins. This review concentrates on how practical developments and innovations in specific areas can contribute to effective DUWL biofilm control. These include the use of effective DUWL treatment agents, improvements to DCU supply water quality, DCU design changes, development of automated DUWL treatment procedures that are effective at controlling biofilm in the long-term and require minimal human intervention, are safe for patients and staff, and which do not cause deterioration of DCU components following prolonged use.     

Influence of waste water from the paper industry and UV-B radiation on the photosynthetic efficiency of Euglena gracilis

The green flagellate Euglena gracilis has been used as a model organism to elucidate the possible large-scale and short-term effects of waste substances from the pulp and paper industry on photosynthetic efficiency (PE). Different concentrations of waste substances before and after treatment in a cleaning system were studied. The uncleaned sample at concentrations up to 1:10 and the cleaned sample at concentrations up to 1:5 showed stimulating effects on the PE after 7 days of incubation compared to the control. The effects of waste substances on the PE of E. gracilis were also studied in combination with short-term studies (20 and 40 min) of ultraviolet-B radiation (UV-B, 280–320 nm). It was shown that increasing concentrations of the uncleaned sample had continuously stimulating effects on the PE and worked protectively against UV-B radiation. The cleaned sample exhibited no effects, or negative effects, on the PE of E. gracilis together with UV-B radiation compared to the experiments with only UV-B radiation. At the concentration 1:1 of the cleaned sample an increase in the PE was detected due to the high concentration of the coloured substances and a decrease in the UV-B penetration. PE revealed itself to be highly sensitive for detecting toxic effects on E. gracilis and is thus very promising for use in regular toxicity tests of waste water from pulp and paper industry. This revised version was published online in July 2006 with corrections to the Cover Date.     

Enzymatic treatment for preventing biofilm formation in the paper industry

Microbiological control programmes at industrial level should aim at reducing both the detrimental effects of microorganisms on the process and the environmental impact associated to the use of biocides as microbiological control products. To achieve this target, new efficient and environmentally friendly products are required. In this paper, 17 non-specific, commercial enzymatic mixtures were tested to assess their efficacy for biofilm prevention and control at laboratory and pilot plant scale. Pectin methylesterase, an enzyme found in the formulation of two of the mixtures tested, was identified as an active compound able to reduce biofilm formation by 71% compared to control tests.     

Use of laccase in pulp and paper industry

Laccase, through its versatile mode of action, has the potential to revolutionize the pulping and paper making industry. It not only plays a role in the delignification and brightening of the pulp but has also been described for the removal of the lipophilic extractives responsible for pitch deposition from both wood and nonwood paper pulps. Laccases are capable of improving physical, chemical, as well as mechanical properties of pulp either by forming reactive radicals with lignin or by functionalizing lignocellulosic fibers. Laccases can also target the colored and toxic compounds released as effluents from various industries and render them nontoxic through its polymerization and depolymerization reactions. This article reviews the use of both fungal and bacterial laccases in improving pulp properties and bioremediation of pulp and paper mill effluents.     

Mini-review: microbial problems in paper production

Paper mills are open systems, which provide favorable conditions for microbial growth. Microbial contamination can cause substantial economic losses, including the deterioration of raw materials, interference with production processes by breakdowns and lowering product quality, and eventually, problems in wastewater treatment. Damage is caused by acidification, attack on raw materials, the formation of odorous products, discoloration of pigments, and the formation of methane and hydrogen, thereby producing potentially explosive conditions. Population analyses have revealed that a wide variety of microorganisms are involved, but there appear to be no typical strains associated with paper mills. Current trends in process engineering, such as chlorine-free bleaching, processing at neutral pH, closed cycles, and the use of recycled paper also favor microbial growth and biofilm (slime) formation. A fundamental problem associated with slimes is the extensive matrix of extracellular polymeric substances, which is composed of a large variety of highly hydrated polysaccharides, proteins, nucleic acids, and lipids. No ‘silver bullet’ against biofouling can be expected, and effective countermeasures have to be based on holistic approaches.     

生物酶在造纸工业绿色制造中的应用

近年来随着生物技术的发展,生物酶制剂的生产水平不断提高,促进了酶制剂在生物制浆、生物漂白、废纸生物脱墨、酶法纸浆改善性能及树脂生物控制等方面的应用,体现了酶技术在减轻制浆造纸工业环境污染、改善纸浆抄造性能等方面的潜力。文中重点介绍在不同制浆造纸原料及工艺中酶的选用、复配和应用技术及原理,以及酶制剂的应用效率及其对制浆造纸中节能减排和绿色环保的意义。     

Research strategies in the pharmaceutical industry to cope with the problems of ageing

The present research strategies for ageing are focussed around three areas. The first area is the demographic study of the present-day populations and those in the future. The analysis of the evolution of the metropolitan French population from 1950 to 2050 indicates that the proportion of subjects aged greater than 60 years will pass from 16% to 35%. In addition, the level of dependence of these subjects will vary considerably from one to another. The second area is the integration of epidemiological data of the pathologies related to the aged subject. Numerous epidemiological studies of the aged show that the elderly population is in better health, better informed about the diseases that affect them and also financially more secure, which allows them to take better care of themselves. The epidemiological studies of certain dementias show, for example, that if we reduce the delay to when the disease appears by five years, then we reduce the prevalence by a factor of 2. The third area relates to the important new progress in the understanding of the biological mechanisms involved in cellular ageing. The recent progress in the area of cellular biology has started to decode the complex mechanisms underlying cellular ageing. The important understanding of the phenomena of apoptose with the development of relevant biological models of the natural ageing process have anticipated future treatments and, eventually, the prophylactic treatment of specific pathologies of the elderly patient.