Learning Objectives:

• Define fermentation as a metabolic process in which microorganisms (such as yeast or bacteria) convert organic compounds into energy, gases, and other products.
• Describe the historical significance and various traditional uses of fermentation in food and beverage production.
• Understand the different types of microorganisms used in fermentation and their roles in the process.

Fermentation is a metabolic process that converts organic substances, typically sugars or carbohydrates, into alcohol, gases, or organic acids using microorganisms such as bacteria, yeasts, or fungi.

1. Alcoholic Fermentation: In alcoholic fermentation, yeast or other microorganisms convert sugars into ethanol and carbon dioxide. This process is used in the production of alcoholic beverages and bioethanol.
2. Lactic Acid Fermentation: Lactic acid fermentation involves the conversion of sugars into lactic acid. It is utilized in the production of yogurt, sauerkraut, and pickles.
3. Acetic Acid Fermentation: Acetic acid fermentation is responsible for the production of vinegar from alcohol. Acetic acid bacteria convert ethanol into acetic acid.

Solved Example: 9126-01

Which of the following is the process of converting sugar into alcohol?

A. Oxidation

B. Pasteurisation

C. Bleaching

D. Fermentation

Correct Answer: D

Solved Example: 9126-02

Fermentation is a process in which:

A. Organic compound is slowly decomposed into simple substances in presence of O$_2$

B. Organic compound is slowly decomposed into simple substances in absence of O$_2$

C. Simple substances are polymerized into complex substances

D. All of the above

Correct Answer: B

Biological treatment systems are environmentally sustainable processes that use microorganisms to degrade organic pollutants, nutrients, and contaminants in wastewater and other environmental media.

1. Municipal Wastewater Treatment: Biological treatment is extensively used to treat domestic sewage and wastewater before release into the environment or return to the water supply.
2. Industrial Wastewater Treatment: Various industries employ biological treatment to remove organic and inorganic contaminants from their wastewater streams, including food processing, petrochemical, and pharmaceuticals.
3. Biogas Production: Anaerobic treatment processes like anaerobic digestion produce biogas, which can be used for energy production.

Solved Example: 9125-01

The activated sludge process is an:

A. Aerobic attached growth system

B. Anaerobic attached growth system

C. Anaerobic suspended growth system

D. Aerobic suspended system

Correct Answer: D

Solved Example: 9125-02

Which of the following statements is true for trickling filter sludge?

A. It is more difficult to dewater than activated sludge

B. It is bulky

C. It has a comparatively low concentration of sludge solids

D. It has a comparatively low sludge volume index

Correct Answer: D

Solved Example: 9125-03

What will be the Sludge Volume Index (SVI) if 100 ml of sludge collected in 30 mins on drying weighs 800 mg?

A. 125

B. 8

C. 0.008

D. 0.125

Correct Answer: A

Solved Example: 9125-04

Identify the waste water treatment unit which use both aerobic and anaerobic mechanism for the removal of organic matter?

A. Activated sludge process

B. Stabilization ponds

C. Trickling filter

D. Oxidation ditch

Correct Answer: B

In the presence of oxygen, cells undergo aerobic respiration, which is highly efficient and yields a significant amount of ATP. In the absence of oxygen, cells may resort to anaerobic respiration or fermentation, which is less efficient and produces lactic acid or ethanol.

Solved Example: 9123-01

Aerobic attached growth process is classified under:

A. Activated sludge process

B. Chemical clarification

C. Preliminary treatment

D. Biological treatment

Correct Answer: D

Anaerobic processes are a type of biological treatment that occurs in the absence of oxygen (anaerobic conditions). They are used for the degradation of organic matter, wastewater treatment, and biogas production. Anaerobic processes are characterized by the absence of oxygen, and they rely on a diverse group of microorganisms to convert organic matter into methane (CH4) and carbon dioxide (CO$_2$).

Solved Example: 9124-01

Which of the following is a product of anaerobic respiration in our muscles?

A. Water

B. Alcohol

C. Glucose

D. Lactic acid

Correct Answer: D

Nutrient removal is a critical process in wastewater treatment and environmental engineering. It involves the removal of excess nutrients, such as nitrogen and phosphorus, from wastewater to prevent water pollution and ecological imbalances.

Biological nutrient removal (BNR) is a common method used in wastewater treatment plants. It involves the use of microorganisms to remove nitrogen and phosphorus from wastewater. The BNR process includes denitrification and phosphorus removal stages, where specific microorganisms convert nitrogen compounds to nitrogen gas and precipitate phosphorus.

Nitrogen Removal: The removal of nitrogen is crucial to prevent nitrogen pollution and its harmful effects, such as algal blooms and oxygen depletion. Nitrogen can be removed through nitrification and denitrification processes, which convert ammonia (NH$_3$) into nitrate (NO$_3^-$) and then to nitrogen gas (N$_2$).

Phosphorus Removal: Excess phosphorus can lead to eutrophication, which disrupts aquatic ecosystems. Phosphorus removal aims to reduce phosphorus concentrations in wastewater. Chemical precipitation and biological processes are common methods for removing phosphorus from wastewater.

Solved Example: 9127-01

Antinutrients are also termed as:

A. Metabolic byproduct

B. Synthetic toxicants

C. Natural toxicant

D. Primary metabolites

Correct Answer: C