FIELD OF INVENTION

The present disclosure relates generally to a method and apparatus for fermentation of sugar solution to produce alcohols such as ethanol and more particularly to a bioreactor for fermentation of sugar solution using encapsulated biocatalyst. The method includes agitation of encapsulated biocatalyst and sugar solution by means of gases produced during fermentation.

BACKGROUND OF INVENTION

The use of encapsulated biocatalyst for fermentation of sugar solution has been studied since 1980. It provides certain advantages over conventional methods of fermentation, for example, continues fermentation systems and easy recovery of biocatalyst. There are various methods known in the prior-art to produce encapsulated biocatalyst.

U.S. Patent number US 5070019 A titled “Immobilization of Yeast in Alginate Beads for Production of Alcoholic Beverages” discloses a method of production of immobilized yeast (encapsulated biocatalyst) by hardening the calcium alginate beads containing yeast in CaCl2 solution and thereafter washing the beads with water having some salt content and drying the beads at temperature maintained within the range of 10o C to 50o C.

U.S. Patent number US 5079011 A titled “Method using immobilized yeast to produce ethanol and alcoholic beverages” describes a method to immobilize the yeast through a substantially noncompressible carrier such as granular Diethylaminoethyl (DEAE) cellulose having anion exchange properties. Such immobilized yeast can then be utilized to ferment a sugar-containing substrate. It discloses method for continuous column fermentation that does not require on-site formation of the column material. Other objects are to develop a method that eliminates sources of contamination and also to develop a method of this type that can withstand pressure.

In conventional bioreactor, encapsulated biocatalyst tends to float over liquid sugar solution due to formation of various gases. The top layer of encapsulated biocatalyst loses contact with the sugar solution due to buoyancy and the fermentation surface area is reduced considerably. Therefore, either the encapsulated biocatalyst is agitated by means of mechanical stirring or the sugar solution is sprinkled over the encapsulated biocatalyst to achieve larger fermentation surface area. In view of limited physical strength of the encapsulated biocatalyst, they cannot be agitated by mechanical stirrers or impellers. A column of encapsulated biocatalyst totally packed over the sugar solution holds up the gases and that process ruptures the encapsulated biocatalyst. Another conventional method of increasing the fermentation surface area is by sprinkling the liquid sugar solution on the encapsulated biocatalyst. In the conventional method known in prior-art the sugar solution is recycled and sprinkled over the top layer of beads. The significant limitation of the conventional bioreactor employing sprinkling of sugar solution over top layer of encapsulated biocatalyst is the possibility of contamination or leakage during sprinkling. Such bioreactor is prone to introduction of bacteria of contaminants like bacteria, etc to enter and resultantly the final product of fermentation, that is, alcohol is degraded in quality. Due to various folds and crevices in the conventional bioreactor design, cleaning and sterilization is difficult.

There is a requirement of a novel method and bioreactor for fermentation of sugar solution using encapsulated biocatalyst without need of physical agitation or sprinkling to obtain higher yield of alcohol.

OBJECTIVE OF THE INVENTION

1. It is the primary objective of the present disclosure to provide a bioreactor comprising more than one section to hold encapsulated biocatalyst during fermentation of sugar solution using said encapsulated biocatalyst.

2. It is another objective of the present disclosure to increase the rate of fermentation by reducing the diffusion limitations of sugar solution through agitation of said encapsulated biocatalyst through gases produced during fermentation process.

3. It is another objective of the present disclosure to provide a bioreactor which prevents the introduction of bacteria or other contaminants during fermentation process to improve or maintain the quality of alcohol produced by fermentation process.

BRIEF DESCRIPTION OF THE DRAWING

The present invention is illustrated by way of example and not limitation in the figures and in which:

Figure shows a cross-sectional drawing of the system upon which the preferred embodiment may be implemented. Figure shows the cross-sectional view of a bioreactor (100) for fermentation. The said bioreactor (100) comprises an inlet (101) at the top of said bioreactor (100) for filling sugar solution. The Figure further shows seven perforated screens (103) to hold encapsulated biocatalyst. The said bioreactor (100) comprises equal number of inlets (106) to ingress said encapsulated biocatalyst in each of said perforated screens. Figure shows an outlet (102) at top of said bioreactor to release gases produced during fermentation. The sugar solution after fermentation is removed from an outlet (105) at the bottom of said bioreactor. An peristaltic pump system (104) removes and reintroduces the sugar solution into said bioreactor during the fermentation.

DESCRIPTION OF THE INVENTION

The present disclosure discloses a bioreactor containing more than one section. The said sections are perforated. The said more than one section may be fabricated using different methods. In one method of fabrication, said sections are fabricated as containers having a mesh bottom. The said containers are stacked vertically. In another method of fabrication, the said sections are fabricated as perforated screens. The said perforated screens are welded in vertical fashion. In each of said perforated sections, containers or perforated screens, encapsulated biocatalyst is filled.

In one of the preferred embodiment of the present disclosure the height of each of said section is 4-6 inches. The said encapsulated biocatalyst is filled in each of said sections upto 2-3 inches of the height of each of said sections. Thereafter, the said bioreactor is filled with sugar solution having higher concentration of sugar capable of fermentation. The said encapsulated biocatalyst is filled inside each of said sections. The said sections prevent the upside movement of encapsulate biocatalyst from one of said sections to the other thereby keeping said encapsulated biocatalyst completely immersed in said sugar solution. The said sugar solution capable of fermentation may be obtained from wort, fruit juice, sugar syrup, starch syrup, corn syrup, molasses or any material providing higher concentration of sugar solution. The gases such as carbon-di-oxide are released with the start of fermentation process. The said gases cause the said encapsulated biocatalyst filled in said sections to rise upwards. Each of said sections entraps or obstructs the upward movement of said encapsulated biocatalyst. Thereby, the said encapsulated biocatalyst are kept in the contact of the liquid sugar solution during complete fermentation process and the said gases move freely in upward direction inside said reactor. Such movement of said gases inside said reactor agitates the said encapsulated biocatalyst enhancing the process of diffusion of sugar solution into said encapsulated biocatalyst thereby increasing the rate of fermentation. The agitation of said encapsulated biocatalyst as disclosed in the present disclosure is controlled by release of said gases. The agitation increases in upward direction like more agitation on the top-most of said sections due to accumulation of said gases. The said sugar solution is recycled after 20-40 minutes of each fermentation cycle through a peristaltic pump system. The system disclosed in present disclosure ferments the said sugar solution around 1.5-2 times faster and the alcohol yield is atleast 5-10% higher than the known methods and bioreactors.

Preferred Embodiment:

In one of the preferred embodiments of the present disclosure 900 liters of 14% barley malt solution is used as said sugar solution. The said sugar solution is fermented in the said bioreactor (100). In one of the embodiments of the present disclosure, the said bioreactor (100) is cylindrical in shape. The capacity of said bioreactor (100) is 1200 litres with working volume capacity of 900 litres. The diameter of said bioreactor (100) is 3 feet and height is 4 feet. An inlet (101) and an outlet (102) are at top of said bioreactor. The said gases produced during fermentation are released through said outlet (102). The said bioreactor comprises seven layers of perforated sheets (103) of stainless steel 304 grade as said sections to place said encapsulated biocatalyst placed vertically as illustrated in Figure. The gap between two consecutive layers of said perforated sheets is 6 inches. The said encapsulated biocatalyst in form of beads is ingressed into said bioreactor from atleast one inlet (106) placed on curved surface of said bioreactor (100). The number of said inlets for ingressing said encapsulated biocatalyst into said bioreactor (100) is equal to number of said perforated sheets. The said encapsulated biocatalyst occupies 3 inches from the 6 inches gap between two consecutive said perforated sheets. The sugar solution is filled from said inlet (101). The said gases produced during fermentation, while rising from lower-most of said perforated sheet to top-most of said perforated sheet, keep agitating the said encapsulating biocatalyst at each of said perforated sheet placed above. The agitation reduces the constraints of diffusion of sugar solution in said encapsulated biocatalyst. The rising gases are released from the said outlet (102). The said sugar solution is egressed from the bottom of said bioreactor. The said egressed sugar solution is re-introduced into said bioreactor through a peristaltic pump system (104) after the interval of 30 minutes. After the completion of fermentation, the fermented sugar solution is removed from an outlet (105).

Claims:I/We claim:
1. A bioreactor for fermentation of sugar solution using encapsulated biocatalyst to obtain alcohol, the bioreactor comprising:
more than one section placed inside said bioreactor to hold said encapsulated biocatalyst;
more than one inlet on curved surface of said bioreactor to fill said encapsulated biocatalyst in each of said more than one section;
an inlet on top of said bioreactor to fill sugar solution;
an outlet on the top of said bioreactor to release gases produced during fermentation;
an peristaltic pump for removal and re-introduction of sugar solution into said bioreactor;
one outlet at the bottom of said bioreactor to remove said sugar solution after fermentation.
2. The bioreactor as claimed in claim 1, wherein said more than one section are containers with mesh or perforated screens.
3. The bioreactor as claimed in claim 1, wherein each of said more than one section have height ranging between 4 inches to 6 inches.
4. The bioreactor as claimed in claim 1, wherein total volume of said bioreactor is upto 100,000 litres.
5. A method for fermentation of sugar solution in a bioreactor to obtain alcohol, the method comprising:
feeding encapsulated biocatalyst in more than one section placed inside said bioreactor;
filling said bioreactor with sugar solution to initiate fermentation;
releasing the gases produced during fermentation from said bioreactor;
removing and reintroducing said sugar solution into said bioreactor;
removing said sugar solution after fermentation.
6. The method as claimed in claim 5, wherein said encapsulated biocatalyst is immobilized yeast obtained by encapsulation.
7. The method as claimed in claim 5, wherein gases release from an outlet at top of said bioreactor.
8. The method as claimed in claim 7, wherein a system controls the release of said gases from said bioreactor.
9. The method as claimed in claim 8, wherein said system may be computer controlled or physical.