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Medium Preparation for the Cultivation of Microorganisms under Strictly Anaerobic/Anoxic Conditions
Published on: August 15, 2019
Acidogenic fermentation of lactose.
W S Kisaalita1, K L Pinder, K V Lo
1Department of Chemical Engineering, University of British Columbia, Vancouver, B. C. V6T 1W5.
Biotechnology and Bioengineering
|July 1, 1987
Summary
Two-phase fermentation of cheese whey effectively manages high biochemical oxygen demand (BOD) effluent. Optimizing the acidogenic stage at pH 6.0-6.5 maximizes desired products like acetate and butyrate while minimizing gas production.
Area of Science:
- Biotechnology
- Environmental Science
- Chemical Engineering
Background:
- Cheese whey is a high biochemical oxygen demand (BOD) effluent from dairy manufacturing.
- Disposal of whey requires significant effluent treatment to reduce BOD before discharge.
- Anaerobic fermentation is proposed as an effective waste management strategy for whey, particularly for small cheese plants.
Purpose of the Study:
- To investigate the feasibility of anaerobic fermentation for cheese whey valorization.
- To identify optimal conditions for the acidogenic stage of a two-phase fermentation process.
- To control fermentation products, specifically maximizing acetate and butyrate while minimizing gas (CO2 and H2) production.
Main Methods:
- Studied the acidogenic fermentation of lactose (whey's primary component) across a pH range of 4.0 to 6.5.
- Analyzed the impact of pH on the types and quantities of fermentation products (gases, ethanol, acetate, butyrate).
- Investigated the effect of transient low pH exposure on subsequent fermentation characteristics.
Main Results:
- Single-stage fermentation of whey leads to low pH and process inhibition.
- Two-phase fermentation mitigates process stalling.
- pH significantly influences acidogenic fermentation products: below pH 4.5, gas production occurs with ethanol, acetate, and butyrate; above pH 4.5, gas production ceases, favoring acetate over ethanol and butyrate.
- A transient pH drop below 4.5 can induce gas formation at subsequent higher pH levels.
Conclusions:
- Two-phase anaerobic fermentation is a viable method for treating cheese whey.
- The optimal pH range for the acidogenic stage to produce acetate and butyrate without gas is 6.0–6.5.
- Controlling pH during fermentation is crucial for directing metabolic pathways and product yields.
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