Biomass separation centrifugal filtration

Biomass separation of insoluble from soluble material, with either phase being retained depending on the location of the product as intracellular or extracellular material. Examples of unit operations commonly used include centrifugation, filtration, and sedimentation. 

The final system, shown in Figure 30.4D, is the continuous system with a partial (PRF) or complete (RF) cell recycle. It is similar to the continuous system, but cells are returned to the fermentor by means of a biomass separation device. Cross-filtration units, centrifuges, and settling tanks have all been used for biomass separation.22 In the partial cell recycle fermentor, a steady state is achieved as in the continuous system. This process is typically used to increase the productivity of the system and is used commonly in wastewater treatment and ethanol production type applications. 

Recovery. Citric acid fermentation broth is generally separated from the biomass using filtration or centrifugation. The citric acid is usually... 

Off-line determination of biomass concentration by classical gravimetric methods requires cell separation, washing steps and drying to constant weight. The separation of cells can be made either by centrifugation or by filtration. 

Yeast separation and concentration. Extraction of ethanol from biomass requires several separation steps, traditionally by centrifuging, sedimentation and cake filtration. First, after the fermentation, the yeast is removed from the fermentation broth and may be recycled. Additionally, after ethanol is stripped from the fermentation broth by steam followed by the removal of solid fractions, the remaining material called the thin stillage can be clarified for reuse upstream as the process water. 

Traditionally, the cellular biomass is separated by centrifugation. Ammonium sulfate is then added to the supernatant to precipitate the protein product from the media. This is followed by further centrifugation and dialysis to remove the residual ammonium sulfate from the protein product. Cross-flow filtration (CFF) can replace all of these steps with a significant improvement in recovery and yield. Indeed, CFF appears to offer many advantages over conventional separation processes like centrifugation, vacuum filtration and precipitation/dialysis for this application. 

Recovery of cells can be accomplished using one of several alternative unit operations, such as centrifugation, membrane filtration, or settling. Subscripts are employed in the figure to identify the usual process variables at particular points in the diagram. We employ the recycle ratio (R) to represent the ratio of the volumetric flow rate of the suspension of cells leaving the separation device to the volumetric flow rate of the net product stream. The symbol t / represents the ratio of the concentration of biomass in the recycle stream to that in the effluent from the CSTBR. You may assume that the system is operating at steady state and that the feed is sterile. 

Downstream processing constitutes a key part of the entire PHA production process. After biosynthesis of the polyester and separation of the bacterial biomass (normally by well-established techniques like centrifugation, sedimentation, flocculation or filtration), the process required for PHA recovery from the microbial cell mass must be considered as an important cost factor, especially considering large scale production. Choosing the adequate method for separating PHAs from residual biomass is dependent on several factors the production strain, the required product purity that is determined by the final application of the biopolymer, the... 

A typical downstream process includes (1) removal of production microbes (biomass) and solids (e.g., gypsum) from the broth, (2) recovery of crude lactic acid, and (3) purification of lactic acid. The biomass and solid waste can be separated from the liquid streams by various means, such as filtration, centrifugation, and decantation. If calcium alkali is used to control the fermentation pH, it produces calcium lactate precipitates which must be dissolved by acids such as phosphoric or sulfuric acid to extract lactic acid back into solution. After sulfuric acid has been added, calcium sulfate (CaS0 -2H20, known as gypsum) is formed and must be removed from the liquid stream as a major solid waste. 

Not the least, catalytic/biocatalytic systems can be very simple separated and recycled by applying an external magnetic force, avoiding the complications associated with the use of rmit operations as catalyst filtration or centrifugation. Hence, several designs of the magnetical-separated com-posite/biocomposite have been developed and appHed for biomass conversion into platform molecule and further to value-added products. 

In the primary separation, the pretreated liquid containing the enzyme is separated from the biomass and other insolnble materials by filtration [7] or centrifugation [8]. The two technologies nse different driving forces (pressure and gravity in case of filtration and centrifngation, respectively), bnt both of them can be nsed for bacteria as well as fnngi. 

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