Industrial Waste Management Questions and Answers – Methods Practiced in Chemical Industries

This set of Industrial Waste Management Multiple Choice Questions & Answers (MCQs) focuses on “Methods Practiced in Chemical Industries”.

1. Which of the following inorganic pollutants are NOT released from effluents of chemical industries?
a) Metals
b) Acids
c) Bases
d) Minerals
View Answer

Answer: d
Explanation: Production of chemicals does not deal with soils and clays in any form or manner, even raw materials. Therefore, minerals like soil and clay are not present in the effluents from chemical industries.

2. Which of the following organic pollutants are present in effluents from chemical industries?
a) Detergents
b) Proteins
c) Phenols
d) Oils
View Answer

Answer: c
Explanation: Effluents from chemical industries may contain phenol. Phenol may be used as a raw material (production of explosives), or it may form as a by-product during effluent treatment, depending on the process.

3. Rubber manufacture produces which of the following gaseous waste?
a) Sulphur dioxide
b) Particulate matter
c) Nitrogen dioxide
d) Nitric oxide
View Answer

Answer: b
Explanation: Rubber manufacture causes the release of particulate matter (ex: talc). Talc is used between two layers of rubber to prevent them from sticking. The other examples are gaseous effluents.

4. How are phenols removed from effluents of chemical industries?
a) By solvent extraction
b) By absorption towers
c) By reverse osmosis
d) By filtration
View Answer

Answer: a
Explanation: Phenols are removed from effluents by liquid-liquid extraction, i.e., solvent extraction. It is an efficient and cost-effective process and takes preference over other methods (adsorption).

5. What is an efficient way to remove colour and odour from wastewater?
a) Solvent extraction with benzene
b) Adsorption on carbon
c) Sedimentation with alum
d) Reverse osmosis under high pressure
View Answer

Answer: b
Explanation: Adsorption is an efficient method used to remove colour and odour from wastewater. The adsorbent used for this process most commonly is activated carbon, which is cheap and effective.

6. How are trace metals recovered from wastewater?
a) By flocculation of the metals
b) By absorption of the metals
c) By ion exchanging the metals
d) By sedimentation of the metals
View Answer

Answer: c
Explanation: Trace metals like cadmium, copper, lead, et cetera, are recovered by method of ion exchange. If not removed, animals end up consuming heavy metals, causing their accumulation in the food chain.

7. How are suspended solids removed from effluents?
a) Adsorption
b) Coagulation
c) Sedimentation
d) Biological treatment
View Answer

Answer: b
Explanation: Coagulation is the method used to remove suspended solids. Coagulants like alum are used for this process since they are cheap. The suspended particles clump together and then settle. They are later collected.

8. Which of the following factors determines the use of wastewater treatment methods?
a) The wastewater characteristics
b) The wastewater appearance
c) The standards set by policy-makers
d) The cost of operation
View Answer

Answer: a
Explanation: The properties and contents of the wastewater determine the choice of treatment method. Expenses are a factor only when two or more of the operations have similar results, for example, choosing between two unit-operations that remove particulate matter.

9. Talc dust is removed by using which of the following equipment?
a) Sedimentation
b) Spray filters
c) Wet scrubber
d) Cyclone separator
View Answer

Answer: d
Explanation: An efficient unit operation used to remove talc dust is cyclone separator. In this process, heavier particles separate from lighter particles on account of centrifugal force. Sedimentation is used for the removal of solids from liquid effluents.

10. Which of the following is a solvent suitable for the collection of sulphur dioxide?
a) Sodium Hydroxide
b) Sodium carbonate
c) Aluminium hydroxide
d) Magnesium hydroxide
View Answer

Answer: a
Explanation: An easy way to remove gaseous sulphur dioxide is by absorption with the help of a base. Sodium hydroxide is a base which is efficient and readily available. The choice of other absorption media is process-dependent.

11. Which contaminant is removed by catalytic oxidation during formaldehyde manufacture?
a) Vapours
b) Fumes
c) Carbon dioxide
d) Formaldehyde
View Answer

Answer: d
Explanation: Formaldehyde has a low boiling point and vaporises at low temperatures. Therefore, it is present in the waste gases. Catalytic oxidation is used to recover it, where the oxidation occurs at high temperatures.

12. Slime is an example of solid waste released due to the manufacture of chemicals.
a) True
b) False
View Answer

Answer: a
Explanation: Chemical manufacture releases solid waste like insoluble salts, metal tailings and slime. Such materials are recovered during primary wastewater treatment. They cannot be broken down further, and hence, are disposed of in landfills or are incinerated.

13. How is chromium recovered from wastewater?
a) Dialysis
b) Precipitation
c) Adsorption
d) Solvent extraction
View Answer

Answer: b
Explanation: Chemical precipitation is used for the recovery of chromium from effluents. For this purpose, barium salts that are soluble in water are used widely. An example of such a salt is barium sulphate.

14. How is chromic acid recovered from effluents of cooling towers?
a) Biological treatment
b) Dialysis
c) Ion-exchange
d) Reverse osmosis
View Answer

Answer: c
Explanation: Ion exchange is used to recover chromic acid. In this process, the target metal ions get exchanged with metal ion from salts added for the recovery. Usually, the materials used for the ion-exchange are resins.

15. How are cyanides removed from plating wastes?
a) Reverse osmosis
b) Adsorption
c) Ion exchange
d) Chemical oxidation
View Answer

Answer: d
Explanation: Chemical oxidation is used for the removal of cyanides. Examples of oxidising agents used for this process are chlorine and ozone. Alkaline conditions are maintained for this process to prevent the formation of hydrogen cyanide.

Sanfoundry Global Education & Learning Series – Industrial Waste Management.

To practice all areas of Industrial Waste Management, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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