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Handling and Management of Hazardous Wastes: NBSE Class 11
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.
If you notice any errors in the notes, please mention them in the comments
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%
Q. What percentage of solid waste in Nagaland is hazardous waste?
A. 0.02%
B. 0.04%
C. 0.06%
D. 0.08%
Answer: C. 0.06%
Q. How much estimated infectious waste is generated daily by healthcare facilities in Nagaland?
A. 450 kg/day
B. 550 kg/day
C. 650 kg/day
D. 750 kg/day
Answer: C. 650 kg/day
Q. What is the first priority in hazardous waste management?
A. Recycling waste
B. Reducing waste quantity
C. Treating waste
D. Incinerating waste
Answer: B. Reducing waste quantity
Q. What is the most common method of recycling performed in Kohima?
A. Recycling by factories
B. Organized recycling programs
C. Ragpickers sorting waste
D. Government-sponsored recycling
Answer: C. Ragpickers sorting waste
Q. What are the four R’s mentioned in the waste management process?
A. Reduce, Reuse, Refine, Recycle
B. Refuse, Reuse, Recycle, Reduce
C. Refine, Recycle, Reuse, Reduce
D. Recycle, Reduce, Refuse, Refine
Answer: B. Refuse, Reuse, Recycle, Reduce
Q. What is the estimated percentage of materials that could be sorted and recycled?
A. 30%
B. 40%
C. 50%
D. 60%
Answer: D. 60%
Q. Approximately how much solid waste is generated in India’s urban areas each year?
A. 20 million tonnes
B. 25 million tonnes
C. 30 million tonnes
D. 35 million tonnes
Answer: C. 30 million tonnes
Q. What is the annual volume of liquid waste generated in India’s urban areas?
A. 3200 million cubic metres
B. 3800 million cubic metres
C. 4400 million cubic metres
D. 5000 million cubic metres
Answer: C. 4400 million cubic metres
Q. Which treatment process is primarily used for the separation of liquids and solids in waste management?
A. Biological treatment
B. Chemical treatment
C. Physical treatment
D. Incineration
Answer: C. Physical treatment
Q. What process is used in composting to decompose organic matter?
A. Chemical reaction
B. Physical sedimentation
C. Microbial biodegradation
D. Thermal oxidation
Answer: C. Microbial biodegradation
Q. What is the typical temperature range in the combustion chamber of an incinerator?
A. 1800 to 2200°F
B. 2400 to 2800°F
C. 2800 to 3200°F
D. 3200 to 3600°F
Answer: C. 2800 to 3200°F
Q. Which type of landfill method is most suitable where groundwater is near the surface?
A. Trench method
B. Area method
C. Ramp method
D. Deep well injection
Answer: B. Area method
Q. What is the main advantage of the trench method in landfilling?
A. Availability of cover material
B. Proximity to waste sources
C. Suitability for shallow water tables
D. Lower operational costs
Answer: A. Availability of cover material
Q. What is a significant drawback of incineration as a waste disposal method?
A. High operational costs
B. High water usage
C. Slow process time
D. Requirement of large areas
Answer: A. High operational costs
Q. What type of waste disposal is typically done in open dumps in India?
A. Controlled landfilling
B. Insanitary open dumps
C. Deep well injection
D. Recycling
Answer: B. Insanitary open dumps
Q. What is a major environmental issue caused by landfill sites?
A. Increased air pollution
B. Production of landfill gases
C. High water consumption
D. Depletion of topsoil
Answer: B. Production of landfill gases
Q. What is the primary use of electrostatic precipitators in power plants?
A. Removing large particles
B. Removing very small particles
C. Cooling gases
D. Increasing pressure
Answer: B. Removing very small particles
Q. What is the collection efficiency of electrostatic precipitators?
A. Up to 80%
B. Up to 90%
C. Up to 95%
D. Up to 99.99%
Answer: D. Up to 99.99%
Q. Which pollutants are typically trapped by wet scrubbers?
A. CO2 and O2
B. SO2 and NH3
C. N2 and H2
D. CO and H2O
Answer: B. SO₂ and NH₃
Q. What method uses fabric bags to collect particulate pollutants?
A. Electrostatic precipitation
B. Wet scrubbing
C. Fabric filtration
D. Ionization
Answer: C. Fabric filtration
Q. What happens to particles when they pass through the electrodes in an electrostatic precipitator?
A. They dissolve
B. They get collected
C. They evaporate
D. They combust
Answer: B. They get collected
Q. In which industries are wet scrubbers commonly used?
A. Textile and agriculture
B. Chemical, mining, and metallurgical
C. Food processing and packaging
D. Automotive and aviation
Answer: B. Chemical, mining, and metallurgical
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.
Q. What percentage of industrial waste is made up of hazardous waste chemicals?
Answer: Hazardous waste chemicals make up to 15 per cent of the total industrial wastes. Their extremely dangerous nature requires that they should be properly and carefully disposed off.
Q. What is the percentage of hazardous waste in Nagaland’s solid waste?
Answer: In the state of Nagaland, hazardous wastes comprise 0.06% of the total volume of solid waste generated. Despite being a small percentage, their proper disposal is crucial due to their potential hazard to public health and the environment.
Q. What is the estimated infectious waste generation in healthcare facilities in Nagaland?
Answer: The estimated infectious waste generation in healthcare facilities in Nagaland is about 650 kg/day. Proper management is crucial to eliminate public health hazards associated with medical waste.
Q. What are the activities involved in the management of hazardous wastes?
Answer: The activities involved in the management of hazardous wastes include: (i) Reduction in the quantity of waste (ii) Recycling and reuse of waste (iii) Treatment of wastes (iv) Disposal of wastes and landfilling
Q. What is the first priority of hazardous waste management?
Answer: The first priority of hazardous waste management is to reduce the quantity of wastes. This can be done by the process of modification, waste concentration, and waste segregation.
Q. What are the four R’s in the context of recycling and reuse of hazardous wastes?
Answer: The four R’s in the context of recycling and reuse of hazardous wastes are Refuse, Reuse, Recycle, and Reduce.
Q. What is the best example of recycling waste in industrial processes?
Answer: The use of waste organic solvents is the best example of recycling waste in industrial processes.
Q. What is the estimated percentage of materials that could be sorted and recycled?
Answer: It has been estimated that 60% of the materials that we throw away could be sorted and recycled.
Q. How are recyclable wastes typically managed in Nagaland?
Answer: In Nagaland, 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.
Q. What are the different categories of treatment technologies for hazardous waste?
Answer: The treatment technologies for hazardous waste can be divided into the following categories: (i) Physical treatment (ii) Chemical treatment (iii) Biological treatment (iv) Solidification (v) Incineration
Q. What does physical treatment of hazardous waste involve?
Answer: Physical treatment of hazardous waste involves processes like lagooning, prolonged storage in tanks, sludge drying in beds, and separation of particulate impurities through methods such as screening, sedimentation, centrifugation, floatation, filtration, evaporation, and stripping.
Q. What does chemical treatment of hazardous waste aim to achieve, and what processes are involved?
Answer: Chemical treatment of hazardous waste aims to achieve the complete breakdown of hazardous wastes. This is based on different types of chemical processes like oxidation-reduction reactions, neutralisation, and precipitation.
Q. How is composting?
Answer: Composting is defined as the decomposition of heterogeneous organic matter by a mixed microbial population in a moist, warm, and aerobic environment. The purpose of composting is to produce compost, which is used as manure to condition infertile fields.
Q. What are the benefits of composting?
Answer: The benefits of composting include: (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.
Q. What is incineration?
Answer: Incineration is the process of destroying waste materials by burning them. It is used in waste management to detoxify hazardous wastes and to reduce the volume of solid wastes from their raw collected states to more manageable levels.
Q. What are the benefits and drawbacks of incineration?
Answer: Benefits of incineration: (i) This technique is clean. (ii) Less polluting. (iii) Less harmful.
Drawbacks of incineration: (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.
Q. What is the importance of landfill disposal in hazardous waste management?
Answer: Landfill disposal is an important method of disposal of hazardous wastes. It involves proper collection, transport, dumping, and storage systems, with the aim to confine the refuse to the smallest practical volume and to cover it with a layer of earth to minimise public health hazards.
Q. What are the three methods of landfilling?
Answer: The three methods of landfilling mentioned in the text are: (i) The trench method (ii) The area method (iii) The ramp method
Q. What factors must be considered for site selection in landfilling?
Answer: Factors that must be considered for site selection in landfilling include: (i) Land requirement and its cost (ii) Accessibility (iii) Cover Material (iv) Climate (v) Topography
Q. What are the steps involved in the treatment of effluents before discharge?
Answer: The steps involved in the treatment of effluents before discharge include:
- Primary treatment: Removal of sludge and solid content of the sewage.
- Secondary treatment: Aeration of the clear effluent produced from primary treatment.
- Tertiary treatment: Passing the primary and secondary treated liquid phase through clean quartz tubes exposed to intense ultraviolet light.
Q. What methods are mentioned in the text for the disposal of untreated sewage in India?
Answer: The methods mentioned in the text for the disposal of untreated sewage in India include:
- Disposal along with city refuse.
- Disposal in riverbeds and on banks.
- Open-pit burning.
Q. What is the function of an electrostatic precipitator in waste management?
Answer: An electrostatic precipitator is used in waste management to remove very small particles from gases, particularly in power plants. It works by using two electrodes to electrically charge particulate matter, which then precipitates on the electrode, thereby removing it from the air.
Q. What is a wet scrubber, and how is it used in controlling air pollution?
Answer: A wet scrubber is used in controlling air pollution by trapping emissions of SO₂, NH₃, and metal fumes in chemical, mining, and metallurgical industries. It works by using sprays or other methods to capture and neutralise pollutants from flue gases.
Q. How does the fabric filter method work in air pollution control?
Answer: The fabric filter method works in air pollution control by passing polluted gases containing particulate dust through porous fabric bags. The fabric bags collect the dust, which can then be periodically shaken out of the bags, similar to the function of a common vacuum cleaner.
Q. What is hazardous waste? Why is it important to manage it properly?
Answer: Hazardous waste is defined as a type of waste that poses a potential hazard to human health or the environment when improperly treated, stored, transported, or disposed of. This type of waste includes substances that can cause significant harm if not managed properly. For instance, medical waste is a form of hazardous waste that can lead to serious health hazards. In Nagaland, the management of medical waste has not yet received adequate attention, with an estimated infectious waste generation of about 650 kg/day in healthcare facilities. This highlights the pressing need to improve and implement systematic methods for managing medical wastes, including storage, segregation, transfer, treatment, and disposal, to eliminate public health hazards.
Q. What are the key activities involved in the management of hazardous wastes?
Answer: The management of hazardous wastes involves several key activities aimed at reducing their impact on human health and the environment. These activities include the reduction in the quantity of waste, recycling and reuse of waste, treatment of wastes, and disposal of wastes through methods like landfilling. The priorities in hazardous waste management follow a hierarchy: total elimination or minimisation of waste generation, reprocessing for recycling, recovery, incineration or treatment, and finally, residual disposal. This systematic approach ensures that hazardous wastes are managed in a way that minimises their harmful effects and promotes environmental sustainability.
Q. What are the priorities in hazardous waste management?
Answer: The priorities in hazardous waste management focus on reducing the environmental and health risks associated with hazardous wastes. The first priority is the total elimination or minimisation of waste generation. This can be achieved through modification, waste concentration, and waste segregation processes. The next priority is the reprocessing of waste for recycling and reuse, which helps in reducing the volume of waste that needs disposal. Following this, the recovery of valuable materials from waste is emphasised. Incineration or treatment of wastes comes next, particularly for those wastes that cannot be recycled or reused. Finally, the residual disposal of hazardous wastes is carried out in a manner that ensures safety and minimal environmental impact.
Q. What are the methods of landfilling? How do they contribute to hazardous waste disposal?
Answer: Landfilling is an important method of hazardous waste disposal that involves the proper collection, transport, dumping, and storage of wastes. There are three primary methods of landfilling: the trench method, the area method, and the ramp method. The trench method is advantageous as it provides cover material through excavation, suitable for areas with deep water tables. The area method is used where groundwater is near the surface, often in flat or rolling terrains, including canyons and ravines. The ramp method combines elements of both the trench and area methods. Landfilling, particularly when done in a controlled and sanitary manner, is essential for safely disposing of hazardous wastes without posing a threat to public health or safety.
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.
