Description
The aim of this European project (QLK5-99-1357) was to design environmentally-sound methods for pitch control during manufacture of selected paper pulps based on: i) previous balance of extractive-derived compounds during manufacturing of eucalypt Kraft pulp and spruce TMP pulp, and identification of compounds responsible for pitch deposition; ii) selected fungal strains removing extractives from both wood types; iii) new (native or engineered) enzymes being able to degrade target compounds in pulps or liquids; and iv) improved physicochemical methods to remove pitch or decrease depositability. To develop the above pitch control methods at a pilot scale including: i) fungal growth optimization and formulation of inocula to treat wood; ii) optimized protocols for production of the new enzymes developed; iii) combined enzymatic-physicochemical treatments; iv) pilot-scale pulping and bleaching including the above optimized treatments; v) analysis of advantages of the new processes in terms of extractive removal, pitch depositability, pulp and process parameters, and effluent toxicity; and vi) evaluation of their commercial interest for different raw materials, pulping processes and world markets.
The work included studies on wood extractive compounds to show how they are chemically-modified or degraded in the course of the pulp manufacturing processes, which of them survive pulping and bleaching, how colloidal pitch stability and depositability are modified, and what are the main compounds responsible for the formation of deposits as well as the main reactions and mechanisms involved. Then, biological treatments will be developed with the aim of reducing deposit formation and obtaining additional environmental or process improvements. Selected fungal strains were investigated and optimized inoculation and treatment conditions (for both eucalypt and spruce wood) defined at the laboratory scale (compared with CartapipTM). These studies included pulping/bleaching experiments for evaluation of cooking, refining and papermaking properties, the subsequent production of microbial inocula, and the treatment of wood at pilot-scale. The use of enzymes offers additional advantages for pitch control due to the possibility of including them at different stages of pulping and bleaching. Currently, ResinaseTM and other lipases are being commercialized for pitch control. However, they are of limited utility in many pulping processes because their action is limited to glycerides, which in many cases are not the main responsible for pitch deposition. In order to expand the potential of enzymatic treatments for pitch control, two alternatives are being explored based on: i) the search for new enzymes in fungi efficiently-degrading eucalypt and spruce extractive compounds (using simple target compounds, "synthetic pitch" and other substrates); and ii) enlarging the potential of the already-known industrial enzymes for pitch control by the use of tools provided by the genetic engineering. Finally, several improved physicochemical methods for the control of pitch deposition based on dissolved-air flotation and ultrafiltration technologies, and their complementarity with the biological ones are being investigated. The project includes academic groups with expertise in microbiology, biotechnology, engineering and chemistry, technical centers, and biotechnology and paper pulp-producing companies, from 5 EU countries.
The work included studies on wood extractive compounds to show how they are chemically-modified or degraded in the course of the pulp manufacturing processes, which of them survive pulping and bleaching, how colloidal pitch stability and depositability are modified, and what are the main compounds responsible for the formation of deposits as well as the main reactions and mechanisms involved. Then, biological treatments will be developed with the aim of reducing deposit formation and obtaining additional environmental or process improvements. Selected fungal strains were investigated and optimized inoculation and treatment conditions (for both eucalypt and spruce wood) defined at the laboratory scale (compared with CartapipTM). These studies included pulping/bleaching experiments for evaluation of cooking, refining and papermaking properties, the subsequent production of microbial inocula, and the treatment of wood at pilot-scale. The use of enzymes offers additional advantages for pitch control due to the possibility of including them at different stages of pulping and bleaching. Currently, ResinaseTM and other lipases are being commercialized for pitch control. However, they are of limited utility in many pulping processes because their action is limited to glycerides, which in many cases are not the main responsible for pitch deposition. In order to expand the potential of enzymatic treatments for pitch control, two alternatives are being explored based on: i) the search for new enzymes in fungi efficiently-degrading eucalypt and spruce extractive compounds (using simple target compounds, "synthetic pitch" and other substrates); and ii) enlarging the potential of the already-known industrial enzymes for pitch control by the use of tools provided by the genetic engineering. Finally, several improved physicochemical methods for the control of pitch deposition based on dissolved-air flotation and ultrafiltration technologies, and their complementarity with the biological ones are being investigated. The project includes academic groups with expertise in microbiology, biotechnology, engineering and chemistry, technical centers, and biotechnology and paper pulp-producing companies, from 5 EU countries.
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