Which of the following is a key characteristic of a good biogas raw material?
Analysis & Theory
High moisture content facilitates microbial digestion and improves biogas yield.
Which component of cow dung makes it suitable for biogas production?
Analysis & Theory
Cellulose and moisture support anaerobic digestion and methane production.
What is the approximate C:N ratio in cow dung?
Analysis & Theory
Cow dung has a C:N ratio around 20:1, suitable for anaerobic digestion.
Why are food wastes considered highly efficient for biogas production?
A
They are dry and non-reactive
B
They have low energy content
C
They are rich in volatile solids
Analysis & Theory
Food waste contains high levels of volatile solids that are easily biodegradable.
Which of the following raw materials has high lignin content and is less suitable for biogas production?
Analysis & Theory
Wood chips have high lignin which resists microbial degradation.
Which waste material can cause ammonia inhibition in a biogas digester if not mixed properly?
Analysis & Theory
Poultry manure has high nitrogen, which can lead to ammonia buildup and inhibit microbes.
The carbon to nitrogen ratio ideal for anaerobic digestion is around:
Analysis & Theory
A C:N ratio of around 30:1 provides optimal conditions for microbial activity.
Which raw material is commonly co-digested with cow dung to improve biogas yield?
Analysis & Theory
Kitchen waste is rich in biodegradable organic matter and increases biogas yield.
Why are lignocellulosic materials less suitable for biogas production?
C
They are hard to degrade
Analysis & Theory
Lignin in lignocellulosic materials resists microbial breakdown.
Which of the following is NOT a biodegradable material for biogas generation?
Analysis & Theory
Rubber is non-biodegradable and unsuitable for anaerobic digestion.
The term 'volatile solids' in biogas feedstock refers to:
B
Water-soluble compounds
C
Organic matter that can decompose
Analysis & Theory
Volatile solids represent the biodegradable fraction of the feedstock.
What is a benefit of using mixed organic waste over a single type of feedstock?
A
Reduces methane production
B
Improves microbial diversity and gas yield
C
Increases lignin content
Analysis & Theory
Mixed feedstock balances nutrients and enhances microbial performance.
Which raw material has the highest methane yield per unit mass?
Analysis & Theory
Food waste has high biodegradable content and yields the most methane.
Which of the following materials requires pretreatment before biogas generation?
Analysis & Theory
Rice husk contains silica and lignin, needing pretreatment for better digestion.
High sulfur content in raw materials can lead to the production of:
Analysis & Theory
Sulfur-containing materials can release hydrogen sulfide, which is corrosive and toxic.
Which of the following is a benefit of using slurry from animal waste as feedstock?
C
Easy availability and biodegradability
Analysis & Theory
Animal slurry is rich in nutrients and easy to digest anaerobically.
Which form of organic matter degrades the fastest in a biogas digester?
Analysis & Theory
Fatty acids are quickly metabolized by microbes for gas production.
What is the role of micronutrients like cobalt and nickel in biogas production?
B
Enhance methane production by supporting methanogens
C
Disinfect raw materials
Analysis & Theory
These micronutrients are essential for the enzymes involved in methanogenesis.
Which raw material can generate foul odors and attract pests if not managed properly?
Analysis & Theory
Improperly handled food waste can rot and attract insects or rodents.
What is the advantage of using pre-digested sludge as part of feedstock?
A
Inhibits gas production
B
Contains active microbes that boost digestion
Analysis & Theory
Pre-digested sludge introduces methanogens and improves startup performance of digesters.