Cheese whey treatment and valorisation process with continuous ethanolic fermentation

Abstract: The invention deals with a process used for Cheese whey treatment and valorisation. The plant where this process is applied includes three main components - an ultrafiltration unit, a bioreactor and a destillation unit. Final products of this process are a whey protein concentrate and ethanol. Ultrafiltration and distillation units are similar to the ones being used in other cheese whey treatment plants. The innovative characteristics of this process lie on the design of the bioreactor and its operation mode and on the microorganism being used. The bioreactor, with a total volume of 1000 litters at the installed scale, is a concentric tube internal loop air-lift bioreactor with a degassing zone at the top; the mode of operation is continuous; the lactose fermenting used yeast strain has the ability to form flocs. By using a flocculating yeast strain and operating the bioreactor continuously a higher productivity in lactose conversion to ethanol may be achieved with a simultaneous reduction in the volume of residual solids. This process allows for a 90% reduction in the pollution caused by cheese whey disposal. The innovative character of this invention lies on the use a continuously operating bioreactor with a new design. The integration of the fermentation unit in the overall cheese whey treatment and valorisation process forces the extension of the request for protection of the patent to the entire process.

Description: Field of the Invention This invention describes a process for a cheese whey treatment and valorisation plant that incorporates a continuously operating concentric internal tube airlift bioreactor with a sedimentation zone at the top. A lactose fermenting yeast with the ability to form flocs is used. In this process a high protein concentration effluent for further processing and food grade ethanol are obtained, with a reduction in the cheese whey pollutant charge. Background of the Invention Patrice Vienne et al . (Enzyme Microb. Technol., (1985), 7(6), 287-94, and Biotechnology and Bioengineering Symposium, 1983, vol. 13, pages 421-35) refer to methods for recycling whey, using stirred tank systems. In one of the alternatives, under operating conditions, the used strains ( Kluyveromyces fragilis 665 and Kluyveromyces lactis NCYC 571), have not the ability to flocculate and the biomass retention is obtained by using an ultrafiltration device. In other alternative, where a flocculating strain is applied (only for the case of Kluyveromyces lactis NCYC 571) an exterior sedimentation unit and a peristaltic pump for biomass recycling are used. In both articles is referred to that the whey permeate is supplemented with yeast extract. Kolodkin A. M., el al . (RU 2036231) refer to a process for obtaining ethanol from milk whey. It is a batch process, with no protein removal from cheese whey prior to fermentation and a mixed culture of two lactose fermenting yeast strains is used. Young-Sup Shim. et al (Journal of Food Science and Technology, vol. 30, No. 1, 1998, pages 161-167) also refer to a batch process for obtaining ethanol from cheese whey. This process uses a mixed culture of a bacteria and a yeast. Michel Henry et al . (EP-A-0 199 634) describe a method and device for producing ethanol by alchoolic fermentation. A non-airlift bioreactor is used in said process and complementary devices are used to retain the flocculated biomass. Summary of the Invention The main objective of this invention is the implementation of a process that, when compared with existing plants, allows for the obtention of a higher productivity in the alcoholic fermentation with decreased operating costs. The biorector used in the fermentation process is the main innovative characteristic of this invention, since all the others operations involved are similar to already existing processes. The proposed unit for cheese whey valorisation is implemented at pilot plant scale. It includes the following processes: after being stored in a retention tank, cheese whey is fed to a 40000 MWCO organic membranes ultrafiltration unit where two fractions are obtained - the permeate and the retentate. Whenever necessary, cheese whey is pasteurised. The protein rich fraction - retentate - is stored in a tank for further processing. The deproteinized cheese whey is fed continuously to the bioreactor where fermentation occurs. The outlet flow of the biorector, with a 2.5% (w/v) ethanol content is stored in a retention tank for distillation in a batch distillation unit. The solid residues of the distillation process as well as the biomass purged from the bioreactor are treated in an existing solid wastes treatment plant. Brief Description of the Figure In fig. 1, the bioreactor used in the conversion of lactose from deproteinized cheese whey to ethanol is presented. Dimensions are also indicated. Detailed Description of the Invention The bioreactor has a total volume of 1000 litres and is composed of two main zones: a central body formed by two concentric tubes and a decantation zone (2). The bioreactor is a concentric tube airlift bioreactor, wherein the air used to promote biomass circulation is injected at the bottom of the interior tube (3), after adequate sterilisation. Air is fed through a perforated disc (diameter - 130 mm) with 4 mm holes. This process is a continuous fermentation process that allows for the obtention of 12 g ethanol l -1 h -1 productivities Inside and outside tube diameters are, respectively, 180 and 392 mm, in order to assure an adequate biomass circulation for high cell densities. Thus, the diameter ratio between internal and external tubes is 2.18. The decantation zone is an enlarged decantation zone at the top of the bioreactor, forming a 60° angle with the main body of the bioreactor In the top part (2) degassing of the liquid phase and biomass decantation occur. Biomass is recirculated to the central body of the bioreactor. In this way, biomass accumulation is improved and the biomass in the outflow is minimised. When an excessive biomass accumulation occurs, purges are done. Biomass retention is improved by the use of a retention device - baffle - installed in the decantation zone near the effluent outlet of the bioreactor. Temperature and pH control systems are also installed. A lactose fermenting yeast - Kluyveromyces marxianus ATCC 10022 - with the ability to form flocs in the continuously operating bioreactor is used. This yeast property allows for the obtention of high biomass concentrations in the bioreactor and its sedimentation ability is used at the top of the bioreactor. The conjugation of these two factors - use of a flocculating yeast strain and an innovative bioreactor design - makes possible to continuously ferment lactose to ethanol with higher productivities that the conventional batch processes.

Claims: Cheese whey treatment and valorisation process, characterised by the use of a bioreactor composed of two main zones: a central body formed by two concentric tubes; and a decantation zone, wherein the conversion of lactose to ethanol is done using a flocculating lactose fermenting yeast - Kluyveromyces marxianus ATCC 10022. Cheese whey treatment and valorisation process according to claim 1, characterized by the use of a continuous fermentation process. Cheese whey treatment and valorization process according to claim 1 or 2, characterized by the decantation zone is an enlarged decantation zone at the top, forming a 60° angle with the main body of the bioreactor. Cheese whey treatment and valorisation process according to any one of claims 1 to 3, characterised by the bioreactor is a concentric tube airlift bioreactor, wherein the air is injected in the bottom of the internal tube being 2.18 the diameter ratio between internal and external tubes. Cheese whey treatment and valorisation process according to any one of claims 1 to 4, characterised by sedimentation of said yeast is used at the top of the bioreactor. Cheese whey treatment and valorization process according to any one of claims 1 to 5, characterised by the placement of a baffle in the decantation zone near the effluent outlet of the bioreactor.

Inventors: COUTO TEIXEIRA JOSE ANTONIO, MAGALHAES GOMES MOTA MANUEL JO, COUTO TEIXEIRA, JOSE ANTONIO, MAGALHAES GOMES MOTA, MANUEL JOSE
Applicants: QUINTA DOS INGLESES AGRO IND L, QUINTA DOS INGLESES, AGRO-INDUSTRIA, LDA.
Application year: 1998
Main classification: C12P7
IPC codes: C12P7