DD157971A3 - METHOD FOR CULTURING MICRO-ORGANISMS ON LIQUID HYDROCARBONS - Google Patents

Abstract

The present invention relates to a process for the cultivation of microorganisms on liquid hydrocarbons as carbon and energy source. The object of the invention is characterized in that a recirculation of the exhaust air of the fermentation takes place, wherein removed from the returned gas, the carbon dioxide content by known methods and the consumed oxygen content is supplemented. The advantage of the method is the saving of complex ancillary equipment for the purification of the fermentation exhaust air (for example by catalytic afterburning), which are necessary in the known methods to ensure environmental protection. At the same time, an intensification of the process is achieved.

Description

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title

Process for the cultivation of microorganisms on liquid hydrocarbons

, The invention relates to a process for the microbial aerobic conversion of liquid hydrocarbons into biomass or products »

It can be used in the microbiological industry.

At present, most aerobic processes are carried out in open fermentation systems.

• Common air used as an oxygen-containing gas * By intensive mixing and contact of the gas with the liquid fermentation medium of the necessary_ gas exchange and thus the supply of microorganisms is achieved with oxygen.

'To. The Säuerstoffübergang increase, in addition to the fermentation with pure oxygen and fermentation under elevated system pressure known (DE-OS 2,032,169).' On the other hand, processes with a closed gas cycle are known only for fermentations with gaseous carbon sources (FR 1 565 428, GB 1 150 4-01). The processes that work with liquid hydrocarbons have economic and procedural disadvantages,

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They consist in the fact that

- Not all reaction products are detected and recycled by the open fermentation systems »Thus, considerable quantities of COg leave the fermentation system without being used.

~ considerable losses of substrate occur due to the open fermentation systems, since at high-performance per- mentors with gassing intensities of up to 100 nr / t h, the hydrocarbons present in the exhaust air

3) substances can reach concentrations of 0.5 to 3 g / m and thus in a fermenter with a content of 1000 t and the specified fumigation intensity of 1000 m / t »h, the discharged hydrocarbon amount can be about 1 (So kg / h "

· »In addition to the economic burden of the loss of hydrocarbons and a considerable contamination of the environment with hydrocarbons and therefore an additional economic burden of nachzuschaltende cleaning equipment, such. B, incineration

D systems and tall chimneys, exists.

Object of the invention

The aim of the invention is to largely prevent hydrocarbon discharges and at the same time to partially or completely recover the CO _{2 produced} . "

Essence of invention. ,

The object of the invention is to supply the discharged with the exhaust hydrocarbons to the process again and separate the carbon dioxide formed from the exhaust air stream.

This object is achieved according to the invention by a fermentation system in which the gas mixture leaving the fermentation is freed from its CO.sub.o content, the oxygen consumed is supplemented and then

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the gas mixture is returned to the cultivation process «

The gas mixture is either entspännt and cooled · or a special gas scrubbing subjected to "gas scrubbers are known In them an absorbent is recycled (for _e B" Äthanolanixn, propanolamine. "Or carbonate solutions), and by a subsequent 'regeneration process the absorbed COo and the Absorbing absorbent »This avoids contamination of the environment and loss of hydrocarbons«

At the same time, the advantages of those methods can be used, which work with higher partial pressures when a gas mixture with higher oxygen content or pure ner'Sauerstoff be used "At the same time this means a reduction of the gas volumes used" The supply of oxygen consumed can, depending on the procedure over a controlled system based on the oxygen concentration measurement, the use of air enriched with air or oxygen or via a controlled system, the. based on the input volume or »pressure measurement with pure oxygen,«

Exemplary embodiments: Example Jj_

The yeasts of the genus Candida guilliermondii are grown on a paraffin-containing petroleum distillate in a closed per- mentation system. "The fermentation medium contains 20% of this distillate, the content of n-alkanes in the distillate is 20 μl.% is set in the Permentor at 33 ⁰ C and the pH kept constant at 4.2 "If the supply of nutrient solution and hydrocarbons separated, the metered amounts in a unit of time give a flow rate of ~ ¹ × h 0J2

The nutrient solution contains the essential nutrients and trace salts necessary for growth

 In one liter of water are bezocren for- 1

2-19

Potassium 35 mg - in KCl Nitrogen ~ 120 mg - added as WH ₁ OH Magnesium - 2 mg - contained in MgSO, χ 7 Phosphorus - 13 mg - as 75% H ₃ PO ₄

In addition, trace salts (iron, copper, manganese, zinc) are added.

The fermentation medium is aerated with air consisting of oxygen and nitrogen in the ratio of about 1: 5 (21 % O ₂ and 79% N ₂ )

 The fumigation intensity is 100 l / kgh.

The gases leaving the fermentation medium contain nitrogen, oxygen and carbon dioxide in a ratio of 83.0; 13.7; 3.6 % if the productivity is 5 g HTS / kgh and the oxygen consumption coefficient is 2.3 and the r O ₀ value is 1.65.

⁰⁰ CO

The amount of exhaust air is 95 »5 l / h and consists according to the composition of 13.0 1 oxygen, 79 1 nitrogen and 3.5 1 CO ₂

 The air leaving the fermentation system is washed with a potash solution in a countercurrent process in a column filled with Raschig rings or fitted with internals.

The withdrawn at the bottom of the column bicarbonate solution is stripped with air.

In this case, 40 to 60 % are regenerated and obtained a CO ₂ with a purity of 98 to 99 % .

The stripping process is carried out at about 50 to 60 ° C. Thereafter, the C0 ₂ ~ depleted air is returned to the fermentation process and replaced the oxygen used.

Example 2:

In a fermentation system, yeasts of the genus Candida guilliermondii are grown on a p? Araffin-containing hydrocarbon fraction

 The fermentation system is in turn a closed system, the breeding conditions are the same as in the

~ 5

, Example 1 indicated *

However, the medium is mixed with a gas mixture containing oxygen and small traces of C0 _? contains, fumigated, the fumigation intensity is 30 1 0 _? per kg / h. The acidity reduction at a productivity of 5 and the stoichiometric coefficients given in Example 1 is 8 l / h kg and the amount of C0 "formed is 3.5 l / h kg. , ,

Thereby, the leaving the Permentor gas having a composition of 86.3% oxygen and 13.7% COP The carbon dioxide is removed by scrubbing the gas with potash solution in a countercurrent process "In order to increase the solubility of the carbon dioxide is supplied to the.

Absorbent glycine added «This reduces the volume of the scrubber by about 30 % _a

, The absorption process is carried out at 30 ° C under atmospheric pressure 9

For COp recovery, the absorbent is stripped with steam *

As a result, the wash liquor is completely regenerated and contains a carbon dioxide with a purity of 99 % . * The COp-poor gas is fed back to the per- mentor and the oxygen consumed before it enters the perforated door.

Claims (1)

2 19 0 9 2 Erf indixngsanspruch. , Method for cultivating microorganisms on liquid hydrocarbons in the presence of a gas containing free oxygen, characterized in that the gas leaving the culturing process is freed of its carbon dioxide content, the oxygen consumed is replenished, and then the mixture is returned to the culturing process. 10. 2, method according to item 1, characterized in that the resulting in the removal of the carbon dioxide hydrocarbons either returned to the cultivation process or the. fermented petroleum distillate are added.