- Email: [email protected]
Lactic acid separation from fermentation broths
News and Views
L a c t i c acid separation from fermentation broths
Figure 1: Top: Fluid Systems 4" tapewrapped element. Bottom: Standard flbreglass reinforced plastic (FRP) element.
Laboratory scale a n d pilot plant nanofiltration a n d reverse osmosis experiments with fermentation broths were carried out b y researchers at the Netherlands Institute for Dairy Research (J. Membrane Sol., 92, pp 185-197). They h a d the foliowing aims: • to quantify lactic acid rejection a n d to determine whether a previously developed theoretical model could be u s e d to predict lactic acid rejection; a n d •
Further Informatlon from: Fluid Systems, 10054 Old Grove Road, San Diego, CA 92131, USA. Tel: +1 619 695 3840. Fax: +1 619 695 21 76.
New g e l a t i n filter for air s a m p l i n g A new gelatin disposable filter, the SM 17528-80-ACD, is now available from Sartorius Separation Technology for use with its MD8 air sampler. Customers who p u r c h a s e a sufficiently high volume of the new filters on an ongoing basis will be eligible for a free MD8 unit (worth approximately £2500). With gelatin m e m b r a n e filters, the MD8 constitutes a n airborne microorganism sampling system for accurate, reproducible a n d quantitative detection of airborne microorganisms in room air, whether conventionally ventilated or u n d e r laminar flow. It is particularly suitable for use in the pharmaceutical, food a n d processing industries a n d hospitals. The new filter is a n individually packed, ready-to-use, sterile unit consisting of a gelatin filter in a holder for the coliection of samples of airborne microbes for analysis. Made of cyrolite, a recyclable material, the holder of the new filter protects the filter during transport. Being disposable m a k e s it possible to maximize the advantages of the gelatin filter m e t h o d (i.e. it remains moist during sampling, the volume of air filtered can be measured, it is water soluble) b e c a u s e handling is greatly improved, s a y s the company.
Further Informatlon from: Sartorlus Separation Technology, Longmead Business Centre, Blenheim Road, Epson, Surrey, KT19 9QN, UK. Tel: 0372 728879. Fax: 0372 726171.
to quantify fouling of NF m e m b r a n e s a n d to determine the major fouling m e c h a n i s m .
Lactic acid is a major food preservative that can be produced either by chemical synthesis or fermentation. If the fermentation process is carried out without using pH adjustment, lactic acid c a n be removed u s i n g cellulose acetate RO m e m b r a n e s , b u t additional techniques are required to concentrate the dilute lactic acid stream obtained. In this application NF m e m b r a n e s show lower rejection for lactic acid t h a n RO m e m b r a n e s , so both systems were looked at here, along with experiments with broth that w a s ultrafiltered prior to investigation. For industrial applications a predictive model for the lactic acid rejection of NF a n d RO m e m b r a n e s which can be used for process development or optimization is necessary. This model should take into a c c o u n t fouling of the m e m b r a n e s . From lactic acid rejection experiments, it w a s found that the previously-developed rejection model, based on the extended Nernst-Planck equation, could be u s e d to quantify the rejection of RO a n d NF m e m b r a n e s . Especially at high fluxes the prediction of lactic acid rejection using p a r a m e t e r s determined with lactic a c i d / w a t e r mixtures was quite good. At Iow fluxes the predicted rejection of lactic acid was usually lower. Fouling of the spiral w o u n d NF40 m e m b r a n e could be quantified b y a model in which three different resistances - - m e m b r a n e resistance, initial fouling resistance a n d time-dependent fouling resistance w e r e taken into account. In the case of a UF-broth a colloidal fouling model could be u s e d to describe the tlme-dependent fouling, while for a b r o t h a gel layer model was used. It was s h o w n that during NF of a n ultrafiltered fermentation broth the initial fouling resistance, resulting from concentration polarization effects, was the p r e d o m i n a n t resistance. For a fermentation broth the tlme-dependent fouling becomes more important t h a n the initial fouling resistance. This was c a u s e d mainly b y protein fouling, so it was concluded that it is beneficial to remove the proteins b y UF prior to NF.
Further Information from: J.M.K. Timmer, Netherlands Instltute for Dalry Research, Kernhemseweg 2, 6718 ZB Ede, the Netherlands.
M e m b r a n e T e c h n o l o g y No. 51
5
L a c t i c acid separation from fermentation broths
Figure 1: Top: Fluid Systems 4" tapewrapped element. Bottom: Standard flbreglass reinforced plastic (FRP) element.
Laboratory scale a n d pilot plant nanofiltration a n d reverse osmosis experiments with fermentation broths were carried out b y researchers at the Netherlands Institute for Dairy Research (J. Membrane Sol., 92, pp 185-197). They h a d the foliowing aims: • to quantify lactic acid rejection a n d to determine whether a previously developed theoretical model could be u s e d to predict lactic acid rejection; a n d •
Further Informatlon from: Fluid Systems, 10054 Old Grove Road, San Diego, CA 92131, USA. Tel: +1 619 695 3840. Fax: +1 619 695 21 76.
New g e l a t i n filter for air s a m p l i n g A new gelatin disposable filter, the SM 17528-80-ACD, is now available from Sartorius Separation Technology for use with its MD8 air sampler. Customers who p u r c h a s e a sufficiently high volume of the new filters on an ongoing basis will be eligible for a free MD8 unit (worth approximately £2500). With gelatin m e m b r a n e filters, the MD8 constitutes a n airborne microorganism sampling system for accurate, reproducible a n d quantitative detection of airborne microorganisms in room air, whether conventionally ventilated or u n d e r laminar flow. It is particularly suitable for use in the pharmaceutical, food a n d processing industries a n d hospitals. The new filter is a n individually packed, ready-to-use, sterile unit consisting of a gelatin filter in a holder for the coliection of samples of airborne microbes for analysis. Made of cyrolite, a recyclable material, the holder of the new filter protects the filter during transport. Being disposable m a k e s it possible to maximize the advantages of the gelatin filter m e t h o d (i.e. it remains moist during sampling, the volume of air filtered can be measured, it is water soluble) b e c a u s e handling is greatly improved, s a y s the company.
Further Informatlon from: Sartorlus Separation Technology, Longmead Business Centre, Blenheim Road, Epson, Surrey, KT19 9QN, UK. Tel: 0372 728879. Fax: 0372 726171.
to quantify fouling of NF m e m b r a n e s a n d to determine the major fouling m e c h a n i s m .
Lactic acid is a major food preservative that can be produced either by chemical synthesis or fermentation. If the fermentation process is carried out without using pH adjustment, lactic acid c a n be removed u s i n g cellulose acetate RO m e m b r a n e s , b u t additional techniques are required to concentrate the dilute lactic acid stream obtained. In this application NF m e m b r a n e s show lower rejection for lactic acid t h a n RO m e m b r a n e s , so both systems were looked at here, along with experiments with broth that w a s ultrafiltered prior to investigation. For industrial applications a predictive model for the lactic acid rejection of NF a n d RO m e m b r a n e s which can be used for process development or optimization is necessary. This model should take into a c c o u n t fouling of the m e m b r a n e s . From lactic acid rejection experiments, it w a s found that the previously-developed rejection model, based on the extended Nernst-Planck equation, could be u s e d to quantify the rejection of RO a n d NF m e m b r a n e s . Especially at high fluxes the prediction of lactic acid rejection using p a r a m e t e r s determined with lactic a c i d / w a t e r mixtures was quite good. At Iow fluxes the predicted rejection of lactic acid was usually lower. Fouling of the spiral w o u n d NF40 m e m b r a n e could be quantified b y a model in which three different resistances - - m e m b r a n e resistance, initial fouling resistance a n d time-dependent fouling resistance w e r e taken into account. In the case of a UF-broth a colloidal fouling model could be u s e d to describe the tlme-dependent fouling, while for a b r o t h a gel layer model was used. It was s h o w n that during NF of a n ultrafiltered fermentation broth the initial fouling resistance, resulting from concentration polarization effects, was the p r e d o m i n a n t resistance. For a fermentation broth the tlme-dependent fouling becomes more important t h a n the initial fouling resistance. This was c a u s e d mainly b y protein fouling, so it was concluded that it is beneficial to remove the proteins b y UF prior to NF.
Further Information from: J.M.K. Timmer, Netherlands Instltute for Dalry Research, Kernhemseweg 2, 6718 ZB Ede, the Netherlands.
M e m b r a n e T e c h n o l o g y No. 51
5