Hemicellulose isolation from thermomechanical pulp mill process water using UF: Optimisation and economics
Lipnizki, Frank LU
; Persson, Tobias
LU
and Jönsson, Ann-Sofi
LU
(2008)
International Congress on Membrane and Membrane Processes 2008
- Abstract
- Every year, 100,000 tons of dissolved hemicelluloses are discharge unused with wastewater from thermomechanical pulp mills around the world. Isolation of these hemicelluloses from the wastewater would not only reduce the treatment costs for the pulp mills but would also provide an excellent raw material for high value applications such as oxygen barriers in food packaging. The isolation of the hemicelluloses can be combined with polishing of the waste-water by using different filtration processes. The initial step in this combination is either a drum filter or a microfiltration treatment to remove solid residues from the wastewater followed by ultrafiltration to concentrate the hemicelluloses. The permeate from the ultra-filtration can... (More)
- Every year, 100,000 tons of dissolved hemicelluloses are discharge unused with wastewater from thermomechanical pulp mills around the world. Isolation of these hemicelluloses from the wastewater would not only reduce the treatment costs for the pulp mills but would also provide an excellent raw material for high value applications such as oxygen barriers in food packaging. The isolation of the hemicelluloses can be combined with polishing of the waste-water by using different filtration processes. The initial step in this combination is either a drum filter or a microfiltration treatment to remove solid residues from the wastewater followed by ultrafiltration to concentrate the hemicelluloses. The permeate from the ultra-filtration can then be further polished by reverse osmosis before recycling. The focus of this paper is on the optimisation of the ultrafiltration step concentrating on the membrane selection and its impact on the process economics. The membrane selection includes the newly developed commercial UFX5 pHt membrane (Alfa Laval, Denmark) based on hydrophilised polyethersulfone. The feed studied in this paper is process water from the thermomechanical pulp mill Stora Enso Kvarnsveden (Sweden). The temperature of this process stream is 75°C. To reduce the need for cooling and preserve the energy, temperature tolerance is an important membrane selection parameter. Further, since the process water contains resin and lignin, which tend to foul membranes, the hydrophilicity of the membrane is another important selection parameter. Based on this, five membranes with molecular weight cut-offs (MWCOs) between 1 – 10 kD were pre-selected: (1) a hydrophilised fluoro polymer membrane ETNA01PP, MWCO: 1 kD, (2) a hydrophilised fluoro polymer membrane ETNA10PP, MWCO: 10 kD, (3) a hydro¬philised polyethersulfone membrane UFX5 pHt, MWCO: 5 kD (all Alfa Laval, Denmark), (4) a regenerated cellulose membrane UC005, MWCO: 5 kD, and (5) a polyethersulfone membrane UP005, MWCO: 5 kD (all Microdyn-Nadir, Germany). The ETNA01PP, ETNA10PP, and UC005 are limited to a temperature of 60/55°C and to a pH range of 1 to 11, whereas the UP005 and UFX5 pHt can be operated up to 75°C and in a pH range from 1 to 14/13. In the initial study, a small flat test module was used to study the pure water fluxes and the fouling behaviour of the membranes related to octanoic acid, a fouling substance which represents a significant number of small hydrophobic substances. Based on this, ETNA01PP, ETNA10PP, and UFX5 pHt were selected for further experiments in 2.5” spiral wound modules using process water from Kvarnsveden pulp mill. In these experiments, among others the flux decline with increasing concentration of hemicelluloses at different transmembrane pressures and cross-flow velocities as well as the retention of hemicelluloses under these conditions were studied. The experimental results of ETNA10PP, ETNA01PP and UFX5 pHt were then used as basis for the development of a full-scale system to treat a feed stream of 100 m3/h with an initial feed temperature of 60/75ºC. Both investment and operating costs were analysed as well as the impact of retention and operating conditions on the ultrafiltration process. It was revealed that operating temperature and membrane selection/retention had an impact on both the investment and operating costs. In conclusion, the results show that ultrafiltration is an attractive process unit in the hemicelluloses isolation process. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/4e47f447-93a4-4b40-8dd4-9ba06ce832cf
- author
- Lipnizki, Frank
LU
; Persson, Tobias
LU
and Jönsson, Ann-Sofi
LU
- organization
- publishing date
- 2008
- type
- Contribution to conference
- publication status
- published
- subject
- keywords
- Membrane separation, Pulp and paper industry, Hemicellulose
- conference name
- International Congress on Membrane and Membrane Processes 2008
- conference location
- Honolulu, United States
- conference dates
- 2008-07-12 - 2008-07-18
- language
- English
- LU publication?
- yes
- id
- 4e47f447-93a4-4b40-8dd4-9ba06ce832cf
- date added to LUP
- 2018-10-18 08:18:17
- date last changed
- 2019-03-08 02:29:54
@misc{4e47f447-93a4-4b40-8dd4-9ba06ce832cf,
abstract = {{Every year, 100,000 tons of dissolved hemicelluloses are discharge unused with wastewater from thermomechanical pulp mills around the world. Isolation of these hemicelluloses from the wastewater would not only reduce the treatment costs for the pulp mills but would also provide an excellent raw material for high value applications such as oxygen barriers in food packaging. The isolation of the hemicelluloses can be combined with polishing of the waste-water by using different filtration processes. The initial step in this combination is either a drum filter or a microfiltration treatment to remove solid residues from the wastewater followed by ultrafiltration to concentrate the hemicelluloses. The permeate from the ultra-filtration can then be further polished by reverse osmosis before recycling. The focus of this paper is on the optimisation of the ultrafiltration step concentrating on the membrane selection and its impact on the process economics. The membrane selection includes the newly developed commercial UFX5 pHt membrane (Alfa Laval, Denmark) based on hydrophilised polyethersulfone. The feed studied in this paper is process water from the thermomechanical pulp mill Stora Enso Kvarnsveden (Sweden). The temperature of this process stream is 75°C. To reduce the need for cooling and preserve the energy, temperature tolerance is an important membrane selection parameter. Further, since the process water contains resin and lignin, which tend to foul membranes, the hydrophilicity of the membrane is another important selection parameter. Based on this, five membranes with molecular weight cut-offs (MWCOs) between 1 – 10 kD were pre-selected: (1) a hydrophilised fluoro polymer membrane ETNA01PP, MWCO: 1 kD, (2) a hydrophilised fluoro polymer membrane ETNA10PP, MWCO: 10 kD, (3) a hydro¬philised polyethersulfone membrane UFX5 pHt, MWCO: 5 kD (all Alfa Laval, Denmark), (4) a regenerated cellulose membrane UC005, MWCO: 5 kD, and (5) a polyethersulfone membrane UP005, MWCO: 5 kD (all Microdyn-Nadir, Germany). The ETNA01PP, ETNA10PP, and UC005 are limited to a temperature of 60/55°C and to a pH range of 1 to 11, whereas the UP005 and UFX5 pHt can be operated up to 75°C and in a pH range from 1 to 14/13. In the initial study, a small flat test module was used to study the pure water fluxes and the fouling behaviour of the membranes related to octanoic acid, a fouling substance which represents a significant number of small hydrophobic substances. Based on this, ETNA01PP, ETNA10PP, and UFX5 pHt were selected for further experiments in 2.5” spiral wound modules using process water from Kvarnsveden pulp mill. In these experiments, among others the flux decline with increasing concentration of hemicelluloses at different transmembrane pressures and cross-flow velocities as well as the retention of hemicelluloses under these conditions were studied. The experimental results of ETNA10PP, ETNA01PP and UFX5 pHt were then used as basis for the development of a full-scale system to treat a feed stream of 100 m3/h with an initial feed temperature of 60/75ºC. Both investment and operating costs were analysed as well as the impact of retention and operating conditions on the ultrafiltration process. It was revealed that operating temperature and membrane selection/retention had an impact on both the investment and operating costs. In conclusion, the results show that ultrafiltration is an attractive process unit in the hemicelluloses isolation process.}},
author = {{Lipnizki, Frank and Persson, Tobias and Jönsson, Ann-Sofi}},
keywords = {{Membrane separation; Pulp and paper industry; Hemicellulose}},
language = {{eng}},
title = {{Hemicellulose isolation from thermomechanical pulp mill process water using UF: Optimisation and economics}},
year = {{2008}},
}