STM 423 – Waste Treatment and Utilization OSUNTECHCOLLEGE 20212022 SECOND Semester Examination

ANSWERS

Question 1a:
Five (5) definitions of waste:

1. Waste is any material that is discarded after primary use or is no longer useful.

2. Waste refers to any substance or object that is disposed of, intended to be disposed of, or required to be disposed of by law.

3. Waste is an unwanted or unusable material that results from human activities or industrial processes.

4. Waste includes any by-product or leftover material from manufacturing, consumption, or service activities that has no further use.

5. Waste is any discarded, surplus, obsolete, or broken material that requires disposal or recycling.

Question 1b(i):
Five (5) sources of waste:

1. Household waste (e.g., food scraps, plastics, paper)

2. Industrial waste (e.g., chemicals, metals, manufacturing residues)

3. Agricultural waste (e.g., crop residues, animal manure)

4. Medical waste (e.g., expired medicines, syringes, used bandages)

5. Commercial waste (e.g., packaging materials, office paper, electronic waste)

Question 1b(ii):
Two (2) examples of waste from any two sources:

• Household waste: Plastic bottles, food waste

• Industrial waste: Metal scraps, chemical residues

Question 2a:
Brief discussion of types of waste:
i) Solid Waste: Solid materials discarded from homes, industries, and commercial areas, including plastics, paper, and metals.
ii) Liquid Waste: Waste in liquid form, such as sewage, industrial effluents, and wastewater from households.
iii) Gaseous Waste: Waste in the form of gases released into the air from industries, vehicles, and combustion, including carbon dioxide and methane.

Question 2b:
Examples of each waste type:

Question 3a:
Four (4) classes of waste and brief discussion of two:

1. Organic Waste – Biodegradable materials like food scraps and garden waste.

2. Inorganic Waste – Non-biodegradable materials such as plastics and metals.

3. Hazardous Waste – Dangerous substances like chemicals, batteries, and medical waste.

4. E-waste – Discarded electrical and electronic devices.

Brief discussion:

• Organic Waste: Easily decomposes and can be composted for agricultural use.

• Hazardous Waste: Requires special handling and disposal due to potential health and environmental risks.

Question 3b:
Difference between biodegradable and non-biodegradable waste:

• Biodegradable waste: Can be broken down by natural processes (e.g., food waste, paper).

• Non-biodegradable waste: Cannot decompose easily and remains in the environment for a long time (e.g., plastics, metals).

Question 3c:
Three (3) Rs in waste management:

1. Reduce – Minimizing waste production by consuming less.

2. Reuse – Using items multiple times before disposal.

3. Recycle – Processing used materials into new products.

Question 4a:
Two (2) ways of treating wastewater:

1. Physical treatment (e.g., sedimentation, filtration)

2. Biological treatment (e.g., activated sludge process, trickling filters)

Question 4b:
Brief description of biological methods of wastewater treatment:
i) Activated Sludge: Uses microorganisms to break down organic pollutants in aerated tanks.
ii) Aerated Lagoon: Wastewater is treated in a pond where oxygen is supplied to support microbial degradation.
iii) Waste Stabilization Pond: Large shallow ponds where sunlight, bacteria, and algae treat wastewater naturally.
iv) Trickling Filters: A bed of stones or plastic media is used to allow bacteria to break down organic waste in sewage.

Question 4c:
Two (2) advantages of activated sludge:

1. Efficient removal of organic matter from wastewater.

2. Reduces environmental pollution by breaking down harmful contaminants.