Microbiology: Anaerobic Digestion Stages

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Questions and Answers

What is the primary role of methanogenic archaea in biogas production?

Convert organic acids and alcohols into acetic acid
Produce methane and carbon dioxide from acetic acid (correct)
Further break down simpler compounds into organic acids
Break down complex organic compounds

What is the result of the acidogenesis stage in biogas production?

Production of acetic acid, hydrogen, and carbon dioxide
Production of organic acids, alcohols, and intermediate products (correct)
Production of methane and carbon dioxide
Breakdown of complex organic compounds into simpler ones

What is the role of environmental microbiology in biogas production?

To break down complex organic compounds
To convert organic acids into acetic acid
To optimize and troubleshoot biogas production
To identify and characterize microbial consortia (correct)

What is the primary component of biogas?

Methane (C) Signup and view all the answers

What is the importance of understanding microbial communities in landfills?

To predict and control landfill gas emissions (A) Signup and view all the answers

What is the role of microorganisms in wastewater treatment?

To perform successive trains of unit operations and processes (A) Signup and view all the answers

What can be a result of excessive growth or excessive solids accumulation in RBC systems?

Media clogging (A) Signup and view all the answers

What is the outcome of the hydrolysis stage in biogas production?

Breakdown of complex organic compounds into simpler ones (C) Signup and view all the answers

What is the role of acetogenic bacteria in biogas production?

To convert organic acids and alcohols into acetic acid (C) Signup and view all the answers

Why may RBC systems have higher capital and maintenance costs?

Due to the need for complex rotating equipment (C) Signup and view all the answers

What is the most common suspended growth process used for municipal wastewater treatment?

Activated sludge process (A) Signup and view all the answers

What is the function of aeration in the activated sludge process?

To introduce oxygen into the wastewater (A) Signup and view all the answers

What is the mixture of wastewater and activated sludge known as?

Mixed liquor (B) Signup and view all the answers

What do microorganisms in the activated sludge consume as their food source?

Organic pollutants in the wastewater (A) Signup and view all the answers

What occurs in the settling tank or clarifier?

Settling of the biomass to the bottom (D) Signup and view all the answers

What is the role of microorganisms in the activated sludge?

To consume organic pollutants as their food source (C) Signup and view all the answers

What role do microbes play in wastewater treatment?

Removing organic matter, nutrients, and heavy metals (B) Signup and view all the answers

What is the primary function of biofilm in trickling filters?

To degrade organic matter and some nutrients (B) Signup and view all the answers

What is the primary advantage of trickling filters in terms of design?

Simple design and ease of operation and maintenance (D) Signup and view all the answers

What is a limitation of trickling filters in terms of nutrient removal?

Limited removal of nutrients such as nitrogen and phosphorus (A) Signup and view all the answers

What is a characteristic of fixed film systems?

Provide a large surface area for microorganism growth (C) Signup and view all the answers

What is an advantage of trickling filters in terms of energy efficiency?

Rely on gravity for wastewater flow, reducing energy needs (C) Signup and view all the answers

What type of system utilizes a biofilm to treat wastewater?

Fixed film system (D) Signup and view all the answers

What is an economic advantage of trickling filters?

Low construction and operational costs (B) Signup and view all the answers

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Study Notes

Biogas Production

Hydrolytic bacteria break down complex organic compounds into simpler compounds like sugars, fatty acids, and amino acids.
Acidogenic bacteria further break down these simpler compounds into organic acids, alcohols, and other intermediate products.
Acetogenic bacteria convert organic acids and alcohols into acetic acid, hydrogen, and carbon dioxide.
Methanogenic archaea convert acetic acid, hydrogen, and carbon dioxide into methane (CH4) and carbon dioxide, which is the key step in biogas production.

Solid Waste Management

Microorganisms play a crucial role in the degradation of waste within landfills.
Understanding microbial communities and their metabolic activities helps in managing landfill bioreactors, predicting and controlling landfill gas emissions, and stabilizing landfilled waste.

Water and Wastewater Treatment

Suspended Film Systems

Activated sludge process is the most common suspended growth process used for municipal wastewater treatment.
Wastewater is mixed with a microbial culture called activated sludge in a treatment tank or basin known as an aeration tank.
The process involves aeration, mixed liquor, biological oxidation, and settling.

Fixed Film Systems

Trickling filters are a type of wastewater treatment technology that utilize a biofilm attached to a solid medium to treat organic matter and pollutants present in wastewater.
A fixed film system consists of a bed or tank filled with a medium, such as rocks or synthetic materials, that provide a large surface area for the growth of microorganisms.
Microorganisms in biofilm degrade organic matter and some nutrients from wastewater.

Advantages and Disadvantages of Trickling Filters

Advantages: simple design, energy efficiency, and cost-effectiveness.
Disadvantages: limited nutrient removal, less efficient in removing nutrients such as nitrogen and phosphorus.