Environmental Biotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Aerobic Treatment of Solid Wastes – Composting – 2”.
1. Which of the following has a helical ridge?
a) Vertical reactor
b) Rotating drum
c) Horizontal reactor
d) Recycling
Answer: b
Clarification: Rotating drum has helical ridges on the inside which transports the waste in a helical manner with forced aeration and the mixing starts intensively which is then followed by self-heating, whereas, in vertical reactor, waste flows vertically, waste is loaded in a horizontal reactor with a wheel loader, and recycling is used to recycle the wastes and not produce compost.
2. Which of the following has a vertical flow of waste in a reactor system?
a) Vertical reactor
b) Rotating drum
c) Horizontal reactor
d) Windrow composting
Answer: a
Clarification: In vertical reactor, the waste flows vertically with mass flow in a vertical direction, rotating drum with helical ridges can transport the waste in a helical manner, whereas, windrow composting is a type of non-reactor system used for composting systems where the waste material is in direct contact with atmosphere, and waste is loaded into a horizontal reactor composting system with a wheel loader.
3. Non-reactor system is a classification of the composting systems.
a) True
b) False
Answer: a
Clarification: Non-reactor system and reactor system are two classification of the composting systems used for composting of the domestic waste and the urban waste that is industrial waste, hospital waste etc. Today, these two types of reactor systems are used to process the wastes generated in daily basis by composting method.
4. Which of the following is not a type of reactor system used for microbial composting?
a) Rotating drum
b) Horizontal reactor
c) Vertical reactor
d) Field composting
Answer: d
Clarification: Field composting and windrow composting is a type of non-reactor system of classification of the composting systems, whereas, rotating drum, horizontal reactor, vertical reactor is the three major type of reactor system used for microbial composting.
5. Which of the following methods is the simplest way of microbial composting?
a) Field composting
b) Vertical reactor
c) Horizontal reactor
d) Windrow composting
Answer: a
Clarification: Field composting and windrow composting, both the types are non-reactor systems of the composting systems and field composting is the simplest way of microbial composting which takes place in a very thin layer above the soil surface, whereas horizontal reactor, vertical reactor are major types of reactor system for microbial composting.
6. Reactor composting leads to forced exchange of gases.
a) True
b) False
Answer: a
Clarification: Reactor composting is often carried out in a closed vessel or reactor which has outlets and inlets for exchange of gases, hence, forced exchange of gases takes place. Reactor composting is classified into several types such as, vertical reactor, rotating drum, horizontal reactor on basis of material flow pattern.
7. Which of the following methods doesn’t use thermal disinfection method?
a) Field composting
b) Windrow composting
c) Vertical reactor
d) Horizontal reactor
Answer: a
Clarification: Field composting doesn’t use thermal disinfection method as it lacks self-heating mechanism due to its exposure to a larger surface area and the waste having sanitation problem cannot be used for composting in this method, whereas, windrow composting is a type of non-reactor system of the composting systems and horizontal reactor, vertical reactor are major types of reactor system for microbial composting.
8. Which non-reactor system serves as a direct contact between the waste and the atmosphere?
a) Windrow composting
b) Vertical reactor
c) Rotating drum
d) Horizontal reactor
Answer: a
Clarification: Windrow composting can influence the atmosphere by emitting a lot of gases like the greenhouse gases and odor but rotating drum, horizontal reactor and vertical reactor system are three major types of reactor system used for microbial composting.
9. Which of the following methods are not the result of windrow composting when the wastes are distributed?
a) Homogenization
b) Landfill sealing
c) Reintroducing free air space
d) Increased evaporation
Answer: b
Clarification: Reintroducing free air space, increased evaporation and homogenization to kill pathogenic microbes leads to high quality compost which is ensured by windrow composting when the wastes are distributed, whereas, landfill sealing is an environmental monitoring method used for measuring the landfill process efficacy in a long term basis.