This set of Industrial Waste Management Multiple Choice Questions & Answers (MCQs) focuses on “Methods Practiced in Paper Industries”.
1. What is the deciding factor for choosing a particular combination of effluent treatment steps in the paper and pulp industry?
a) Based on the materials to be recovered
b) Based on the raw material
c) Based on the types of waste
d) Based on the paper grade desired
View Answer
Explanation: The steps of effluent treatment are chosen based on the paper grade obtained. Some industrial plants only deal with paper pulping (by various methods), while others may carry out pulping and bleaching.
2. Which of the following materials are NOT present in wastewater from paper-making?
a) Bleaches
b) Carbohydrates
c) Proteins
d) Salts of metals
View Answer
Explanation: Effluents from paper-making industries do not contain proteins. The industry has no use for proteins. The other options are examples of organic and inorganic materials generally found in effluents from paper manufacture.
3. Which of the following is an approximate BOD level of effluents from paper pulping?
a) 26000 mg/l
b) 15000 mg/l
c) 1000 mg/l
d) 500 mg/l
View Answer
Explanation: The range of BOD levels in the effluents released from the paper pulping industries is between 1500 mg/l and 25000 mg/l. Among the given options, only the option 15000 mg/l falls inside this range.
4. Which stage in the paper processing industry is responsible for most of the effluent generation?
a) Bleaching
b) Pulping
c) Refining
d) Debarking
View Answer
Explanation: The bleaching stage of the paper-making process is responsible for the bulk of effluent generation. It produces more than 60% of the total effluent by volume. Other stages produce less significant volume of effluents.
5. The paper and pulp manufacture releases which of the following air pollutants?
a) Carbon monoxide
b) Hydrogen sulphide
c) Fumes
d) Nitrogen dioxide
View Answer
Explanation: The pulping of wood requires sulphate salts for the pulping process. As a result, the gases containing sulphur are present in the exhaust gases from the paper and pulp manufacturing industry.
6. In the paper and pulp industry, how are fine fibres recovered?
a) Settling
b) Sedimentation
c) Flotation
d) Clarification
View Answer
Explanation: All the given options are used to treat wastewater in the paper and pulp industry. However, for the collection of fine fibres from effluents, flotation is used because of its efficiency.
7. Biological treatment is not used for effluents from paper and pulp industries.
a) True
b) False
View Answer
Explanation: Biological treatment is used for the treatment of effluents produced during paper manufacture. This is because organic matter like lignin, which is present in the effluents, has high BOD and needs to be separated before release.
8. Which of the following is the most commonly used secondary treatment process in the paper manufacture?
a) Trickling filters
b) Activated sludge process
c) Flotation
d) Aerobic ponds
View Answer
Explanation: Activated sludge process has a higher cost of operation than trickling filters. For this reason, the most common equipment used is the trickling filter. Flotation is a primary treatment method, while aerobic ponds are for tertiary treatment.
9. Which of the following tertiary treatment methods is NOT used for treating paper and pulp effluents?
a) Electrodialysis
b) Membrane filtration
c) Coagulation
d) Solvent extraction
View Answer
Explanation: Solvent extraction is used to recover liquids like phenols, which are not present in effluents from this industry. Salts and fibres, which are present, are removed using the other methods listed.
10. Chemical precipitation is used for the removal of which material from paper-making industries?
a) Phosphates
b) Nitrates
c) Oxides
d) Sulphates
View Answer
Explanation: During tertiary treatment, chemical precipitation removes phosphorus from the effluents. Nutrient surplus through phosphates released with effluents can cause algal bloom.
11. Kraft pulping produces which kind of particulate matter?
a) Fumes
b) Smoke
c) Coal dust
d) Chemical dust
View Answer
Explanation: The kraft pulping process produces chemical dust, which is particulate in nature. Smoke, fumes, and coal dust are primary gaseous effluents released from other industries. Electrostatic precipitators are the prime choice for the removal of such particulate matter.
12. Which of the following heavy metals is present in the effluents from paper and pulp manufacture?
a) Cadmium
b) Chromium
c) Mercury
d) Lead
View Answer
Explanation: Mercury may be present in the raw materials (sodium hydroxide). Another possibility is of accidental release during the processing. That is the reason why it may be present in the effluents.
13. How is lignin separated from black liquor?
a) By absorption
b) By neutralisation
c) By oxidation
d) By precipitation
View Answer
Explanation: Lignin is recovered from black liquor by precipitation with sulphuric acid. Once separated, ultrafiltration recovers lignin. This process is carried out at the advanced treatment stage.
14. What is the fate of sulphur dioxide in the paper and pulp industry?
a) It is burned
b) It is recovered
c) It is released
d) It is collected
View Answer
Explanation: Sulphur dioxide is burned in recovery boilers in modern pulping plants instead of releasing it to the atmosphere. Additionally, the same process is used to burn other odorous gases as well.
15. What is the primary use of waste paper?
a) Discarded in a landfill
b) Paper board manufacture
c) Incineration
d) It is not recycled
View Answer
Explanation: Waste paper is used for the manufacture of paper board. The waste paper first needs to be collected, sorted and deinked. Then a slurry is made with paper and water, after which heavy and lighter material is collected from the bottom and top of the tank, respectively.
Sanfoundry Global Education & Learning Series – Industrial Waste Management.
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