Get notes, summary, questions and answers, MCQs, extras, and PDFs of Chapter 13 “Handling and Management of Hazardous Wastes” which is part of NBSE Class 11 Environment Education. However, the notes should only be treated as references and changes should be made according to the needs of the students.
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Summary
The chapter on “Handling and Management of Hazardous Wastes” discusses the various aspects of hazardous waste, its management, and the treatment methods for different types of waste. Hazardous waste refers to waste materials that pose a potential risk to human health or the environment when improperly treated, stored, or disposed of. This includes medical waste, which is a significant health hazard, particularly in places like Nagaland, where waste management systems are underdeveloped.
The chapter highlights the importance of reducing the quantity of hazardous waste through methods like modification, concentration, and segregation. It also discusses the recycling and reuse of waste, emphasizing the four R’s: Refuse, Reuse, Recycle, and Reduce. Recycling involves treating waste before reusing it in manufacturing processes, and while it is not widely practiced in places like Kohima, some recycling occurs through informal means like rag pickers.
Different treatment methods for hazardous waste are outlined, including physical, chemical, and biological treatments. Physical treatments involve processes like sedimentation and filtration, while chemical treatments break down hazardous materials through reactions such as oxidation and neutralization. Biological treatment, particularly composting, is a method where organic waste is decomposed by microorganisms to produce compost, which improves soil fertility.
The chapter also covers incineration, a method that burns waste at high temperatures to reduce its volume and detoxify hazardous materials. However, incineration has drawbacks, such as the release of toxic substances like dioxins and mercury. Lastly, the chapter discusses landfilling, where waste is buried under the ground in a way that minimises environmental and health risks. Different landfilling methods are described, along with the factors that need to be considered when selecting a site for waste disposal.
Textbook solutions
Multiple-Choice Questions
1. Which is the most important method of disposal of hazardous wastes?
A. Burning
B. Recycling
C. Open disposal
D. Landfill disposal
Answer: D. Landfill disposal
2. Which of the following methods is used for trapping emission of SO₂, NH₃, and metal fumes in chemical, mining, and metallurgical industries?
A. Electrostatic precipitator
B. Wet scrubber
C. Fabric filters
D. All of these, together
Answer: B. Wet scrubber
3. Incineration of waste products means its
A. Burning
B. Washing
C. Cleaning
D. Freezing
Answer: A. Burning
4. Chemical removal of nitrates, phosphates, metal ions, etc. comes under
A. Primary treatment
B. Secondary treatment
C. Centrifugation
D. Tertiary treatment
Answer: D. Tertiary treatment
5. A natural degradation process in which biodegradable materials are decomposed by microbes and converted into manure is called
A. Composting
B. Sludge
C. Lagooning
D. Floatation
Answer: A. Composting
Short Answer Questions
1. What do you mean by hazardous wastes?
Answer: Hazardous waste is a type of waste which poses a potential hazard to human health or to the environment when improperly treated, stored, transported, or disposed of.
2. Define (i) Landfill, (ii) Incinerator.
Answer: (i) Landfill: It is a method of disposing of refuse on land without creating nuisance or hazards to public health or safety.
(ii) Incinerator: Incineration is the process of destroying waste materials by burning.
3. What is the meaning of composting?
Answer: Composting is a natural degradation process in which biodegradable materials are decomposed by microbes and converted into manure.
4. Bring out any one difference between burning and composting.
Answer: Burning involves the destruction of waste materials by fire, leading to their combustion, whereas composting involves the decomposition of organic materials by microbes to create manure.
5. What are the 4 R’s?
Answer: The 4 R’s are Refuse, Reuse, Recycle, and Reduce.
6. How is recyclable waste treated in the state of Nagaland?
Answer: In Nagaland, all recyclable wastes such as plastics, scrap metal, and bottles are generally segregated, either sold to rag pickers at the household level or scavenged at community bins or disposal sites. Recycling procedures are not currently applied in Kohima. The only recycling performed is carried out to some extent by ragpickers exposed to harsh, unprotected conditions.
7. Where are incinerator facilities available in the state of Nagaland?
Answer: Incinerator facilities are available in hospitals of Nagaland for treating bio-medical wastes.
8. Write a peculiar difference between physical, chemical, and biological treatment of wastes.
Answer:
- Physical treatment: This treatment is conducted by processes such as lagooning, prolonged storage in tanks, and sludge drying in beds.
- Chemical treatment: This treatment is based on different types of chemical processes like oxidation-reduction reaction, neutralisation, precipitation, etc.
- Biological treatment: This includes methods like composting, which involves the biodegradation of waste materials by microorganisms.
9. Why does an incineration technique much better than the other techniques?
Answer: Incineration is better because it is a clean technique, less polluting, and less harmful. However, it emits dioxins, mercury, and other toxic substances that can have adverse effects on humans and animals at low doses.
Long Answer Questions
1. Explain the process of incineration.
Answer: Incineration is the process of destroying waste materials by burning. In this method, high temperature in the range of 2800 to 3200°F is created in the combustion chamber of the incinerator with the use of an auxiliary fuel. The purpose of this high-temperature environment is the achievement of total combustion, wherein bulky items, metals, glass, and other difficult-to-reduce materials are combusted or melted. Thus, this process serves to reduce the volume of solid wastes from their raw collected states to more manageable levels.
2. What are the drawbacks of incineration?
Answer: The drawbacks of incineration are:
(i) When waste is burnt in an incinerator, Dioxin as well as Mercury and other toxic substances are emitted. (ii) Burning of extremely potent toxic substances produces adverse effects in humans and animals at extremely low doses.
3. Describe the methods of landfilling.
Answer: Methods of landfilling:
(i) The Trench Method: The main advantage of this method is that the cover material is readily available as a result of excavation. This method is used in an area where the water-table is quite deep.
(ii) The Area Method: The area method is used where the groundwater is near the surface. The topography of the area may preferably be flat or rolling terrain; though, canyons and ravines are also acceptable.
(iii) The Ramp Method: This technique is a combination of the above two methods.
4. Describe in brief about the treatment of sewage.
Answer: The treatment of sewage involves the following steps:
- Primary treatment: This treatment removes the sludge, the solid content of the sewage. Larger solids such as plastics and other objects wrongly discharged into sewers are removed when wastewater is passed through screens.
- Secondary treatment: This involves aeration of the clear effluent produced from primary treatment. Often microorganisms are used to break down and remove the remaining dissolved wastes and fine particles.
- Tertiary treatment: This term implies “Third Degree Treatment.” It may take the form of passing the primary and secondary treated liquid phase through clean quartz tubes exposed to intense ultraviolet light.
5. What are the advantages of composting?
Answer: The advantages of composting are: (i) Increase in the fertility of soil. (ii) Compost consists of NPK which is essential for plant growth. (iii) It consists of trace elements required by plants. (iv) Increases water absorption quality of soil. (v) Compost returns the nutrients back to the soil.
6. How is power generated in incineration?
Answer: Power is generated in incineration by burning waste materials at high temperatures in an incinerator. The heat produced during the combustion process is used to generate steam, which then drives turbines to produce electricity.
7. Describe in brief treatment of gaseous wastes.
Answer: The treatment of gaseous wastes involves the following mechanisms:
- Electrostatic Precipitator: These are widely used in power plants for removing very small particles. Two electrodes are used in this method. When particulate matter is passed through the electrodes, the particles get precipitated on the electrode.
- Wet Scrubber: Wet scrubbers are used for trapping emissions of SO₂, NH₃, and metal fumes in chemical, mining, and metallurgical industries. Scrubbers along with condensers and traps are used to contain and collect waste solvents, toxic vapours, or dust.
- Fabric Filters: Fabric bags are used to collect the particulate pollutants. The polluted gases containing particulate dust are passed through porous fabric bags, which collect the dust. The dust can be periodically shaken out of the bags.
Think and Answer
Explain how will you manage your household wastes by applying the 4 R’s.
Answer: I will manage my household wastes by applying the 4 R’s as follows:
- Refuse: I will avoid bringing unnecessary items into my home, such as single-use plastics or products with excessive packaging, to reduce the amount of waste generated.
- Reduce: I will focus on minimizing waste by purchasing items in bulk, using reusable containers, and choosing products with minimal packaging. This will help in reducing the overall quantity of waste.
- Reuse: I will find ways to reuse items whenever possible, such as using glass jars for storage, repurposing old clothing into cleaning rags, or repairing items instead of discarding them.
- Recycle: I will segregate recyclable materials such as paper, glass, metal, and certain plastics from the rest of the waste. These materials will be cleaned and stored separately for recycling through local recycling programs or facilities.
Extras MCQs
1. What percentage of the total industrial waste is made up of hazardous waste chemicals?
A. 10%
B. 15%
C. 20%
D. 25%
Answer: B. 15%
24. What is a key advantage of electrostatic precipitators?
A. Low cost
B. High energy consumption
C. Minimal pressure loss
D. Complex maintenance
Answer: C. Minimal pressure loss
Extra Questions and Answers
1. What does the term ‘hazardous’ denote?
Answer: The term ‘hazardous’ denotes the potential of a substance to pose a threat to life or material. It is a broader term that includes toxic wastes in its spectrum.
30. What role do electrostatic precipitators play in controlling air pollution?
Answer: Electrostatic precipitators play a crucial role in controlling air pollution, particularly in power generation and industrial processes. These devices are highly efficient dust collectors with proven collection efficiencies of up to 99.99%. They work by using two electrodes, where particulate matter in the polluted air becomes electrically charged as it passes through the electrodes and is then collected on the electrode surfaces. This method is particularly effective in removing very small particles from the air, thus reducing the amount of particulate pollution released into the atmosphere. The use of electrostatic precipitators has become a widely adopted technology in industries to meet environmental regulations and protect public health from the harmful effects of air pollution.
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