Method and device for preparing cell suspensions

Abstract

Method for preparing cell suspensions comprising the following successive steps: - Supplying at least one cell suspension and at least one process gas and mixing the cell suspension and process gas, - Bringing the mixture of cell suspension and process gas into a supercritical or subcritical state by increasing the pressure with a high-pressure pump to a pressure greater than 20 MPa and a defined temperature, - Sudden release of pressure below 20 MPa to disrupt the cells of the cell suspension, - Separating the mixture of process gas and cell suspension and separating at least one product, in particular by means of extraction and / or separation, characterized in that dewatering is provided between the step of disrupting the cells and the separation, and wherein the process takes place in a closed pressure system.

Description

The invention relates to a method and an apparatus for preparing cell suspensions comprising the following successive steps:supplying at least one cell suspension and at least one process gas and mixing the cell suspension and process gas,bringing the mixture of cell suspension and process gases into a supercritical or subcritical state by increasing the pressure by means of a high-pressure pump to a pressure greater than 20 MPa and a defined temperature,Abrupt release of the pressure below 20 MPa in order to disrupt the cells of the cell suspension.In addition to the use in the food industry, for example for stabilizing fruit juices, use for obtaining valuable materials from cells is conceivable, in particular from algae, microalgae, yeast cells and / or bacteria.From the prior art of DE 10 2008 036 723, a method is known in which the cell disruption is no longer effected mechanically but by means of physical decompression. Process gas is thereby enriched in the cells at an increased pressure and the cell membranes are then caused to burst by sudden pressure relief. Due to the rapid pressure reduction, the gas cannot be released fast enough across the cell membranes and expands in the cells, so that they do not withstand the load and burst and thus the cell content is released.A disadvantage of the previously known methods is that a comparatively large amount of liquid must be carried along in the further process stages.Furthermore, WO 2010 / 0153898 A1 discloses a method in which cell disruption and simultaneously extraction are carried out in countercurrent in a container.Finally, EP 2 486 122 B1 discloses a method for algal culture, wherein an emulsion is produced by mixing a medium with a gas stream containing CO 2- in a high shear device and subsequently an algal culture is hereby cultivated in a bioreactor.The invention therefore addresses the problem of making the process more economical.This object is achieved by a method according to claims 1, 2 or 4.According to one variant, it is provided that dewatering is provided between the step of separating the cells and separating the mixture of process gas and cell suspension and separating at least one product, in particular by means of separation and / or extraction. The dewatering of the process stream enables the stream to be carried further, which is then separated into the products to be obtained and the further streams which are either recycled and circulated or are obtained as secondary or waste products, to be reduced. Moreover, the liquid obtained by dehydration can also be further used for the preparation of the cell suspension.As the dewatering, any known method can be used. It is particularly preferred in this case if a PGSS method is used.Through an interposed dewatering, the material stream can be reduced by at least 50%, in particular by at least 60%, and further in particular by at least 70%, and further in particular by at least 80%, this being volume percentages. This has the advantage that subsequent process steps are smaller in size and can therefore be operated more cost-effectively and the concentration of the products is already improved.Alternatively, it can also be provided that the dewatering is provided after the step of separating the cells without a further separation stage being provided.According to the invention, it is provided that the method is designed such that the pressure increase by means of the high-pressure pump takes place once for the entire method and the pressure drops over the method steps, in particular up to the atmospheric pressure (low-pressure level). In this way, it can be achieved that the comparatively cost-intensive pressure build-up does not have to be carried out anew before each process stage, but only once for the entire process. Subsequent pressure increases then take place only via adiabatic temperature increases. By using a closed pressure system over the entire method or the entire device and a continuous pressure reduction in cascaded form or cascaded use of the pressure energy, the pressure energy is used efficiently. In particular, this pressure energy, which is applied before and for the step of cell digestion by decompression, is also available for the subsequent dewatering, so that in particular here methods requiring pressure energy can also be used. The pressure energy is provided via a high-pressure pump. The closed printing system also comprises all further process stages, including any secondary strands.Finally, the invention also comprises an independently inventive method in which the separation of the mixture of process gas and cell suspension and the separation of at least one product is embodied in multiple stages, in particular by means of extraction and / or separation, and the method is carried out in a closed pressure system.Preferably, material or energy streams can be added between the steps "cell disruption" and "dewatering" and / or "dewatering" and "separation" and also between the separation steps or thereafter. By means of these material or energy flows, wherein the energy is added in particular in the form of thermal energy, the energy and / or pressure level can be adjusted or raised and the necessary method parameters for the subsequent method steps can be set.In addition, a process gas is added before the cell digestion stage, which is mixed with the suspension. The process gas can be, in particular, argon, carbon dioxide or nitrogen. In addition, a defined process temperature is set before the cell disruption, which can be, for example, 5° C.The separation process can be a mechanical separation, such as in particular a filtration. However, at least one "pressurized liquid extraction" is particularly preferred.It can be provided that the separation, in particular the extraction in series and / or in parallel, is multistage. By means of a multistage arrangement, different products can be obtained and different separations can be carried out. For extraction, a solvent, such as, for example, ethanol, ethyl acetate and / or water, is added to the partially dewatered suspension and mixed with the latter under particular temperature and pressure conditions. A temperature of in particular at least 60° C., in particular at least 70° C. and further in particular at least 80° C. is preferred here. The solvents of the extraction steps can be evaporated and recovered, for example, and recycled.Subsequently, further process steps can be provided, such as in particular the separation of liquid and solid phase, wherein the liquid phase can be treated in further process and extraction stages for obtaining further products. For this purpose, a series of extractions and / or fractionations can be provided, which enables cascaded recovery of different substances (products).It is preferred in this case if an adiabatic temperature increase takes place before the dewatering. This can be effected, for example, by means of conduction and / or induction and / or electromagnetic radiation. The temperature increase can be effected, for example, to at least 60° C., in particular to at least 70° C. and further in particular to at least 80° C. Preferably, if the dewatering is to take place subsequently, a gas stream, for example carbon dioxide, is fed in. In this case, the gas phase can be supercritical. A separation of water saturated gas and solid is then achieved by reducing the pressure below the critical point of the gas supplied. The saturated gas can evaporate from the respective device unit and can be separated from the water at the low pressure level. The liquid is then likewise present at a low pressure level, wherein the gas can be circulated again by conditioning to a defined pressure and a defined temperature and is available for renewed dewatering.As an example, after an extraction from microalgae with a non-polar solvent, a second extraction with a polar solvent may take place. The extract obtained by means of extraction and subsequent separation contains, according to the chosen solvent, for example polar or non-polar lipids, such as carotenoids, glyco- and / or phospholipids or also other protein molecules.In addition to a cascaded separation with a plurality of separating stages, a multi-strand separation can also be provided in which the steps do not run in series but in parallel, i.e. the separating stages are arranged in parallel. In any case, however, it remains that this is a closed pressure system via the method or the device.The invention furthermore relates to a device for carrying out the method, as described above, comprising a feed for cell suspension and process gas, and a high-pressure pump for establishing a required pressure level upstream of a digestion unit, a digestion unit for the cell suspension, and downstream dewatering and downstream separation thereof, in particular extraction and / or mechanical separation for a digested cell mass.The process and the apparatus can produce end products, intermediates and / or byproducts which result from the solvents used for the extraction or the separation steps. This allows targeted utilization of the fractions. Process gases and solvents of the individual stages can be recovered and reused in the respective process steps.The invention is described below with reference to a drawing. The single figure shows a flow chart of a preferred example of the method.In the preferred embodiment, the presentation of a cell suspension, for example of microalgae, is marked with the reference sign 1. Reference numeral 2 designates a stage for subjecting the cell suspension to the maximum operating pressure and a first temperature level and for mixing the streams, at least one process gas having been added to the cell suspension. In this case, the reference sign 17 identifies the mixing in of the process gas, which is recovered at reference sign 14.After the streams have been mixed and subjected to an operating pressure which is preferably greater than 20 MPa at a temperature level of 5° C., the streams are maintained at the pressure, denoted by the reference numeral 18, until optimum diffusion of the gases into the cells is achieved. A step for disintegration of the microbial cells of the cell suspension (biomass) by lowering the pressure is identified by 3. The cells are thereby ruptured, so that the cell constituents which were previously enclosed in the cell membrane are now accessible.Thereafter, under 4 one or more substances are fed in liquid or gas phase and mixed as indicated at 19. In the stage identified by the reference numeral 5, the temperature level of the streams is increased adiabatically.Reference numeral 6 identifies any further supplies of auxiliary substances as required.Stage 7 identifies a dewatering step which takes place by means of supercritical gases. By lowering the pressure below the critical point of the supplied gas, for example CO 2, a separation of water-saturated gas and solid is achieved. Reference numeral 8 now designates a separation stage for separating gas saturated with steam, wherein the gas is separated via a low pressure receptacle for 9a gas or 9b liquid and the gas, namely the CO 2, is fed back to the circuit.The dewatered solid is passed on to the extraction stage 11 as a dewatered mass stream for extraction at an elevated temperature and pressure level, wherein 10 denotes a receiver vessel for the solvent required for extraction.The extraction stage is denoted by reference numeral 11 and has a lower pressure stage, with the dashed line and 15 providing a plurality of extraction and fractionation stages in shunt with the module 7.After extraction, in the separation stages 12 a, 12 band 12 c, constituents dissolved during extraction are separated from the solid stream, it being possible for any desired number of separation stages to be provided for fractionating the extract. In this case, the extracted substances are collected together with the process gas (e.g. nitrogen) in the containers 14 at ambient pressure level, just as in the collecting container 13.Reference numeral 16 designates a stage for the further processing, for example the drying and pelletization of the solid stream at the low-pressure level. In this case, dewatering in the stage denoted by 7 is particularly characteristic, as a result of which a lower mass flow is passed on into the extraction stage, and in particular that a pressure energy is introduced into the system by means of a high-pressure pump only once, namely in the region denoted by the reference symbol 2, and otherwise, independently of the number of subsequent process stages, including process stages arranged alongside, a closed pressure system is present, to which no further pressure energy has to be fed. In this way, a more cost-effective workup of the cell material is possible.

Claims

Method for preparing cell suspensions comprising the following successive steps: - supplying at least one cell suspension and at least one process gas and mixing cell suspension and process gas, - bringing the mixture of cell suspension and process gas into a supercritical or subcritical state by increasing the pressure by a high-pressure pump to a pressure greater than 20 MPa and a defined temperature, - suddenly releasing the pressure below 20 MPa in order to break up the cells of the cell suspension, - separating the mixture of process gas and cell suspension and separating at least one product, in particular by means of extraction and / or separation, characterized in that dewatering is provided between the step of breaking up the cells and the separation, and wherein the method takes place in a closed pressure system.Method for preparing cell suspensions comprising the following successive steps: - supplying at least one cell suspension and at least one process gas and mixing cell suspension and process gas, - bringing the mixture of cell suspension and process gas into a supercritical or subcritical state by increasing the pressure by means of a high-pressure pump to a pressure greater than 20 MPa and a defined temperature, - suddenly releasing the pressure below 20 MPa in order to break up the cells of the cell suspension, characterized in that after the step of breaking up the cells a dewatering is provided and wherein the method takes place in a closed pressure system.Method according to claim 1 or 2, characterised in that the increase in pressure by means of the high-pressure pump takes place once for the entire method and the pressure falls over the steps, in particular up to the atmospheric pressure.Method for preparing cell suspensions comprising the following successive steps: - supplying at least one cell suspension and at least one process gas and mixing cell suspension and process gas, - bringing the mixture of cell suspension and process gas into a supercritical or subcritical state by increasing the pressure by a high-pressure pump to a pressure greater than 20 MPa and a defined temperature, - suddenly releasing the pressure below 20 MPa in order to break up the cells of the cell suspension, - separating the mixture of process gas and cell suspension and separating at least one product, in particular by means of extraction and / or separation, characterized in that the separation is designed in multiple stages and the method takes place in a closed pressure system.Method according to one of the preceding claims, characterized in that material or energy streams are added between the steps of cell digestion and dewatering and / or dewatering and separation.Process according to one of the preceding claims, characterized in that the separation, in particular the extraction in series, is multistage.Method according to one of the preceding claims, characterized in that an adiabatic temperature increase takes place before the dewatering.Method according to one of the preceding claims, characterized in that further separating stages are provided connected in parallel, in particular are provided in multiple-strand parallel.Device for carrying out the method according to one of the preceding claims, comprising a feed (1) for cell suspension and process gas, and a high-pressure pump (2) for establishing a required pressure level in a digestion unit (3), a digestion unit (3) for the cell suspension and a downstream dewatering (7) and a separation (15), in particular extraction (11) and / or mechanical separation, of the digested cell mass, downstream of the latter, and wherein the device relates to a closed pressure system.

Images