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- Arkell, Anders, et al.
(författare)
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Back-pulsing as an energy-saving method in the microfiltration of milk
- 2014
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946. ; 35:1, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- Extended shelf-life milk can be produced by a combination of microfiltration and pasteurisation. However, due to the need for high cross-flow velocity during microfiltration, the energy consumption is high. One way of decreasing the energy demand during microfiltration is to use back-pulsing for fouling control. Microfiltration was performed in constant flux mode on skim milk to measure the fouling rate. Different frequencies and durations of back-pulsing were investigated to determine the optimal conditions. The most promising conditions were used to evaluate the degree to which the cross-flow velocity could be decreased without significantly affecting the performance of the membrane. It was found that short pulses (0.2 s) at a frequency of 1 min-1 were most efficient, and the membrane performance was only slightly affected by reducing the cross-flow velocity from 5.8 m s-1 to 4.5 m s-1 with back-pulsing. This corresponds to a reduction in the energy requirement of 50%.
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- Arkell, Anders, et al.
(författare)
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Evaluation of membrane performance and cost estimates during recovery of sodium hydroxide in a hemicellulose extraction process by nanofiltration
- 2013
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Ingår i: Separation and Purification Technology. - : Elsevier BV. - 1873-3794 .- 1383-5866. ; 118, s. 387-393
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Tidskriftsartikel (refereegranskat)abstract
- The recovery the alkaline solvent from of a residual stream after the extraction of hemicelluloses in wheat bran was investigated. The solution was withdrawn from an ultrafiltration (UF) process in which hemicelluloses were recovered. The UF permeate, containing mainly NaOH, lignin and mono- and oligosaccharides, was treated by nanofiltration (NF). Seven NF membranes were tested in a parametric study, and the two membranes showing the best performance were further evaluated in a concentration study. The mean flux of a Koch SelRO MPF 36 and a Microdyn-Nadir NP010 membrane was about 200 l/m2 h during concentration to a volume reduction of 0.75. The retention of NaOH was <20%, while the retention of lignin and sugars was about 70% and >95%, respectively. Cost estimates for a NaOH recovery process indicated that an NF plant would have a pay-back time of less than 2 months if the plant was run continuously, and 7 months if it was used 25% of the time.
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- Arkell, Anders, et al.
(författare)
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Extraction of Lignin from Kraft Black Liquor by Membrane Filtration
- 2014
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Ingår i: [Host publication title missing]. ; , s. 219-220
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Lignin from black liquor in the kraft pulping process is a potential raw material for production of renewable chemicals and fuels. However, an efficient extraction method for the lignin from the black liquor is needed. Therefore, two new processes have been designed, which both utilize membrane filtration for the isolation of lignin from the kraft black liquor. The first one includes precipitation and filtration for the production of a solid lignin, while the second involves a base-catalysed reaction and organic-solvent extraction for the production of a precursor for liquid fuels.
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- Arkell, Anders, et al.
(författare)
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Increasing flux by back-pulsing in the microfiltration of milk
- 2015
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946. ; 41, s. 23-25
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Tidskriftsartikel (refereegranskat)abstract
- Milk with extended shelf-life can be produced by microfiltration (MF) and pasteurisation in a cascade arrangement. In a previous study, we have shown that back-pulsing can be used to reduce the energy requirement in the MF of defatted milk. In this study, the influence of back-pulsing on MF was investigated at higher milk fluxes than in a prior study. The MF experiments were performed in constant-flux mode. The operational time until a certain pressure build-up was used as a measure of the performance. Fluxes between 350 and 500 L m−2 h−1 were investigated, with and without back-pulsing (frequencies ranging from 6 to 0.2 min−1). It was shown that the fouling rate was strongly dependent on the permeate flux; higher flux leading to a higher fouling rate. Improved MF performance was found using back-pulsing at a flux of 350 L m−2 h−1, while at higher fluxes, back-pulsing impaired the performance.
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