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Molasses Fermentation / Foaming Issues

04/07/2016 4:53 AM

We are a distillery based in Pakistan, producing industrial grade ethanol by fermentation of sugar cane molasses, in batch fermentation (pre fermentors and fermenters). The molasses being used is of 90 brix containing 48.5% total sugar (34.5% sucrose and 14% reducing sugars). Our concerns are: 1. Why yeast cells are not visible in Pre fermenters and fermenters although activity is very fast (highly unusual)? 2. What is the reason for excess foaming in Pre fermenters and fermenters ? Foam starts to over flow at low levels <50% of the fermenter. The foam is a bit creamy and the antifoam doesn't seem to make too much difference. 3. What is the reason for cluster formation of cells in Pre fermenters during continuous biomass development? Note: we are not using any enzyme/catalyst/antibiotic for speeding up the reaction. The only chemical being added to the fermentation are: NaFl @ 3.33 ppm of pre fermenters volume. Urea @ 125kg/setup of pre fermenter. ~110m3 volume. Anti foam. Constant feeding at low concentrations. Shock dose at overflowing foam level at high concentrations. Phosphoric acid. Only shock dose of 5 kg/day. 1500 N M³/hr Air is fed by roots blower and fed in pre- fermenter through sparger. We are using dust filter on suction of blower. We are not adding any micro/ macro nutrient/ microbial decontaminate. Temperature is fermentation is less than 32 ⁰C. Fermentation efficiency is approximately 88% and alcohol % age in wash varies 7.7 to 8.0% v/v. Recovery is 235 liters per ton of molasses. Any suggestions in this case would be very helpful.

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#1

Re: Molasses fermentation / foaming issues.

04/07/2016 5:44 AM

If you compare the operation now with the commissioning records, Mildred, whatever has changed will give you a clue.

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#4
In reply to #1

Re: Molasses fermentation / foaming issues.

04/07/2016 7:59 AM

We have been doing that.. In the beginning the cells went invisible, then the cell count dropped and after that the foaming started. We've been operating the system the same way and also we've experimented with phosphoric acid, sulphuric acid, lectrol, NaFl but upto no good.

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#2

Re: Molasses Fermentation / Foaming Issues

04/07/2016 7:16 AM

Can't answer them all, I have a few Ideas.

On 2. What is the reason for excess foaming in Pre fermenters and fermenters ?

This could be a reaction on the enzymes you're using and is basically degassing.

Was this always a problem, if not when did it start, you can then look at any process changes at that time.

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#3
In reply to #2

Re: Molasses Fermentation / Foaming Issues

04/07/2016 7:51 AM

" Note: we are not using any enzyme/catalyst/antibiotic for speeding up the reaction."

Or did I miss something?

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#9
In reply to #3

Re: Molasses Fermentation / Foaming Issues

04/07/2016 9:25 AM

No john, I'm the one that missed it.... guess it was a little hard to read.

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#5
In reply to #2

Re: Molasses Fermentation / Foaming Issues

04/07/2016 8:04 AM

this problem only started one month into operations during late February this season. "In the beginning the cells went invisible, then the cell count dropped and after that the foaming started. We've been operating the system the same way and also we've experimented with phosphoric acid, sulphuric acid, lectrol, NaFl but upto no good." The process has been similar from the last years apart from the trials we've had.

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#6
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Re: Molasses Fermentation / Foaming Issues

04/07/2016 8:27 AM

You say the temperature is less than 32°C, but has it changed since the start of operations?

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#7
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Re: Molasses Fermentation / Foaming Issues

04/07/2016 8:44 AM

Quite. See #1 above.

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#8
In reply to #6

Re: Molasses Fermentation / Foaming Issues

04/07/2016 8:56 AM

No it hasn't changed, the temperature is kept less than equal to 32.5C.

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#10
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Re: Molasses Fermentation / Foaming Issues

04/07/2016 9:30 AM

Something changed.

Process change, Contamination, ....?

There are food grade anti-foaming for foam control for fermentation, but this is only a Band-Aid, not the solution.

I understand it you end product is not food grade require.

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#11

Re: Molasses Fermentation / Foaming Issues

04/07/2016 11:22 AM

If the process, temperature, and ingredients have remained the same, either the equipment is contaminated, or wild yeast is being allowed to enter the fermenting process.

Wild yeast was the only source of fermentation for hundreds of years, and can really shellac a controlled fermentation if allowed to enter.

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#12

Re: Molasses Fermentation / Foaming Issues

04/07/2016 1:26 PM

Just for what it's worth:

Try to use some of the produced ethanol to spray with a air based gun onto the foam.

Do not exaggerate the amount of air.

The foam should reduce and oxygen will increase your cell count. Monitor the L.E.L level while experimenting with the dose.

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#13

Re: Molasses Fermentation / Foaming Issues

04/07/2016 11:42 PM

Throw some activated charcoal in? It might gather up what ails your batch and won't hurt ethanol production if it fails.

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#14

Re: Molasses Fermentation / Foaming Issues

04/08/2016 8:57 AM

Hello. You can contact Hycontrol in the UK. They have systems for foam prediction and control. www.hycontrol.com

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#15

Re: Molasses Fermentation / Foaming Issues

04/09/2016 12:31 AM

The obvious answer is that SOMETHING in the process has changed, as the first respondent, and many others have pointed out. Your job is to figure out WHAT.

  • The change could be as simple as a new air filter on the blower with just the slightest change in free area allowing slightly higher air flow than originally, unnoticeable leakage of air into the system or something else with the air supply.
  • Then there is the possibility of minuscule accumulation of material or microscopic corrosion that forms additional nucleation points for the CO2 generated in the fermentation process.
  • Finally, having worked in cane sugar refineries, I am aware there is the possibility of some factor in each batch of molasses that might affect how it reacts with the any yeast. I recall that we would test every load of raw sugar coming in, as no two could be refined with the same ease.

The manner in which you present the situation seems to indicate that though the fermentation is a batch process, production is not shut down except as required for maintenance. If there are regular shutdowns, this alone could be contributory. Startups were always a problem in the refineries where I worked.

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#16

Re: Molasses Fermentation / Foaming Issues

08/01/2016 11:19 AM

Dear Mr. a7430418,

We have a distillery in our sugar factory. I have discussed with our colleague and the details are as follows. Pl. go through the same and any further details are required, pl. post in this thread or post your requirement through the Personal Messaging system available in CR4. You can indicate your mail Id. through the Personal Messaging System, since mail Id. is not allowed in the CR4 threads.

If you feel that the details below are useful to you we will feel happy. Pl. post your views. The details are:

  1. Why yeast cells are not visible in pre Fermenters and fermenters although activity is very fast?

Reason: in log phase we can’t able to vision yeast. In log (Exponential phase) second stage final only we can visible. In pre fermenter we are giving 1:5%(M:W) ratio dilution. That’s why we can’t able to see and saccharomyces crevice (yeast) doubling time is 18 hours. If we put in incubator after 24 hours we can see. In fermenter in stationary phase we can able to see.

2.What is the reason for excess foaming in pre fermenters and fermenters?

Reason: we are using saccharomyces cervical (yeast) is anaerobic yeast. In pre fermenter we are giving pure oxygen is giving through spurges at that time yeast gets some unseal. That time facultative anaerobic condition it will adjust that time foaming will comes. During the metabolism process glucose will convert into alcohol and CO2. While producing CO2 foaming will come. CO2 has the nature of foaming (for example: Beer, Soda extra). Because of continuous homoziniztion (rotation) CO2 foaming comes.

3.What is the reason for cluster formation of cells in pre fermenters during continuous biomass development?

Reason: Fungal cell walls contain special proteins (pectin). It is the reason for cluster formation during sticky gum like elements to synthesize carbohydrates. That’s why cluster formation of cells during biomass development by colony counting technic we can able to see yeast colonies.

DHAYANANDHAN.S

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#17
In reply to #16

Re: Molasses Fermentation / Foaming Issues

08/01/2016 11:24 AM

You use saccharomyces cervical yeast?, really?, as in interesting.

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#19
In reply to #17

Re: Molasses Fermentation / Foaming Issues

08/03/2016 6:14 PM

Nice, that. Candida is such a pretty name.

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#20
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Re: Molasses Fermentation / Foaming Issues

08/03/2016 6:37 PM

A rose by any other name is sti..... Ok, that's a stretch.

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#21
In reply to #17

Re: Molasses Fermentation / Foaming Issues

08/04/2016 6:36 AM

Can you recommend a strain/brand of the yeast to try using for molasses based fermentation? WE Have Tried using red ethanol also with no change.

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#18

Re: Molasses Fermentation / Foaming Issues

08/03/2016 1:10 PM

Dear Mr.a7430418,

In continuation to my posting - vide Sl. No. 16, I am furnishing further details, on the issue putforth by you, which is given by another colleague whose total service is in distillery. He is not a CR4 member. However if you post your contact mail Id. through the personal messaging that may help and speed up for arriving at a decision/solution.

I give below his suggestions and quieres.

Message recd. 2-8-2016

The current inputs to fermentation, additional inputs to be added, viability of the yeast culture used, ratios and parameters to be maintained, water and molasses condition etc to be reviewed in depth.

The heavy foaming will not allow the normal filling of fermenters and may result in production cut and likely to affect the quality of alcohol.

The operating nature needs immediate attention and to be addressed forthwith.

Please convey the details to the concerned.

FURTHER SUGGESTIONS

v We are producing industrial grade ethanol by fermentation of sugar cane molasses, in batch fermentation (pre fermentors and fermenters.

The unit is having Pre -Fermenters & Fermenters for FERMENTATION PROCESS.

Capacity of Distillery per day –

RS/ENA/ETHANOL --

Plant Supplied by --

How long in operation --

PF , Fermenters closed type OR open ---

Capacity and Filling capacity of PF &Fermenters ---

Yeast cultured/dry yeast/ compressed yeast (supplier)–

What is the retention time in Pre-Fermenter-

Fermentation period --

The molasses being used is of 90 brix containing 48.5% total sugar (34.5% sucrose and 14% reducing sugars).

· As per the above result, molasses meets near Grade – I status with good TRS.

· What is the colour of molasses—brown/brownish black? Temperature of molasses received at fermenter –

·

· Molasses Fresh OR how many months old –

· Source of molasses – own OR received from other mills

· Water used for dilution of molasses-- River / bore well /recycled –

· Any pre treatment of water adopted for process–

· General raw water analysis –

· A note on method by which Pre-Fermenter filled – Transferred to Fermenters- Filling hours sequence – Time taken for completion of fermentation,-- Fermentation temperature –Residual sugar percentage –

· Total unfermentable sugar in molasses sample.

· Volatile acid in molasses—

· Volatile acid in PF, at start &at time of transfer to fermenter-

· Volatile acid at start and end of fermentation –

· Yeast cells view details in PF & Fermenters at start &at end–

· Nutrients addition /Usage of enzymes if any –

· Alcohol percentage in wash –

· Alcohol Recovery per ton of molasses –RS /ENA /ETHANOL

· Any Carbon- di -oxide collected –

· Any recycling of spent wash /evaporator condensate water in fermentation.

v Why yeast cells are not visible in Pre fermenters and fermenters although activity is very fast (highly unusual)?
2. What is the reason for excess foaming in Pre fermenters and fermenters ? Foam starts to over flow at low levels <50% of the fermenter. The foam is a bit creamy and the antifoam doesn't seem to make too much difference.

· The yeast cells are in the mass and an alcohol content of 7.7% to 8% has resulted. Suspected yeast cells may be variant (Wild yeast)

· High foaming with creamy in nature indicates possible contamination in fermentation by other microbes.

· It has to be reviewed in multi angle and examined at lab and process levels closely.

v What is the reason for cluster formation of cells in Pre fermenters during continuous biomass development? Note: we are not using any enzyme/catalyst/antibiotic for speeding up the reaction. The only chemical being added to the fermentation are: NaFl @ 3.33 ppm of pre-fermenters volume. Urea @ 125kg/setup of pre-fermenter. ~110m3 volume. Anti foam.

v Constant feeding at low concentrations. Shock dose at overflowing foam level at high concentrations. Phosphoric acid. Only shock dose of 5 kg/day. 1500 N M³/hr Air is fed by roots blower and fed in pre- fermenter through sparger. We are using dust filter on suction of blower. We are not adding any micro/ macro nutrient/ microbial decontaminate. Temperature is fermentation is less than 32 C. Fermentation efficiency is approximately 88% and alcohol % age in wash varies 7.7 to 8.0% v/v. Recovery is 235 liters per ton of molasses.

· The only chemical used is indicated as NaFI???

· Phosphoric Acid shock dose 5kg per day ….As single dose???

· Urea at PF 125 KG at start of PF as single dose???

· AIR FILTER HEPA TYPE ???

· Antifoam consumption per day ---

· How much fusel oil separation per day (Average per month)….Quality of alcohol –PP Time - Organoleptic

· Fermentation is at 32 ⁰C. What is the highest & lowest temp

On an over all observation

· The recovery of Alcohol stands at 235 Lts /ton of molasses.

· Fermentation is vigorous with more foaming of creamy type not controlled by anti foam.

· Fermentation temperature is in normal range but foaming is heavy.

· Normal yeast cells are not presented and chain like are present.

Base on the above informations,The fermentation seems to be contaminated and entire fermentation section --all input materials sources – lab follow up to be made.

The yield rate also seems to be lower to some extent. IN DEPTH STUDY — OBSERVATION-- REMEDICAL MEASURES ARE THE NEED OF THE HOUR TO OVERCOME THIS.

Pl. note that I am not a distillery person, since we have distillery, I consulted my colleagues

Out of curiosity, I discussed and posted the detail, as my colleagues are not CR4 members.

DHAYANANDHAN.S

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