HSBTE Environmental Studies & Disaster Management, Subject Code 220016, July 2023 Examination, 1st Semester.

HSBTE July 2023 Examination. Time : 3 Hrs. M.M.: 60

1st Sem. Subject: Environmental Studies & Disaster Management, Subject Code 220016

SECTION-A

Note: Multiple choice questions. All questions are compulsory (6x1=6)

Q.1 Solar energy, wind energy, and tidal energy are_______sources of energy.

a) Renewable b) Non-conventional c) Both (a) & (b) d) Non-renewable

Ans: c) Both (a) & (b)

Note: Solar energy, wind energy, and tidal energy are both renewable and non-conventional sources of energy. They are renewable because they are derived from natural processes that are continuously replenished. They are non-conventional because they are not traditional sources of energy like fossil fuels.

Q.2 Deforestation leads to ________.

a) Global warming b) Air Pollution c) Soil erosion d) All of the above

Ans: d) All of the above

Note: Deforestation leads to a variety of environmental problems, such as global warming, air pollution, and soil erosion. When trees are removed, the ecosystem loses its ability to absorb carbon dioxide. This leads to an increase in greenhouse gases and contributes to global warming.

The absence of trees also reduces the natural filtration of air pollutants. This results in increased air pollution.

Additionally, trees play a crucial role in preventing soil erosion by stabilizing the soil with their root systems, and deforestation can lead to increased erosion.

Q.3 Example of a natural disaster is:

a) Industrial pollution b) Earthquake c) Road accident d) Nuclear disaster

Ans: b) Earthquake

• Note: Natural disasters are events that result from natural processes of the Earth. This causes significant damage and loss of life. Among the options provided, the example of a natural disaster is: b) Earthquake

• Earthquakes are natural disasters caused by the sudden release of energy in the Earth's crust. This leads to seismic waves that can result in shaking of the ground. This causes widespread damage.

• The other options (a) Industrial pollution, (c) Road accidents, and (d) Nuclear disasters are not natural disasters; they are typically associated with human activities or technological incidents.

Q.4 BOD stands for:

a) Biochemical oxygen demand b) Biological ozone depletion

c) Biochemical Ozone demand d) None of the above

Ans: a) Biochemical oxygen demand.

Q.5 Noise levels can range from

a) 35 to 60 dB     b) 120 to 240 dB     c) 0 to More than 120 dB     d) None of the above

Ans: c) 0 to More than 120 dB.

Q.6 Which of the following methods cannot be used for waste disposal?

a) Dumping b) Gasification c) Incineration d) Open sea disposal

Ans: d) Open sea disposal

SECTION-B

Note: Objective/ Completion type questions. All questions are compulsory. (6x1=6)

Q.7 Ozone layer in the stratosphere is destroyed by _______.Ans: ozone-depleting substances (ODS)

Ans: The ozone layer in the stratosphere is mainly destroyed by human-made chemicals known as ozone-depleting substances (ODS). The most significant contributors to ozone layer depletion are chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and other similar compounds. These substances release chlorine and bromine atoms when they break down in the stratosphere. This leads to the breakdown of ozone molecules in the ozone layer. The resulting reduction in ozone concentration is commonly referred to as ozone layer depletion.

Q.8 Scarcity or shortage of ______ is the most important cause of draught.    Ans: rainfall.

Note: Drought is a natural disaster characterized by an extended period of deficient rainfall. It leads to water shortages, crop failure, and various other impacts on ecosystems and human activities. Other factors, such as high temperatures, soil conditions, and water management practices, can contribute to drought severity.

Q.9 What is a biological disaster?

A biological disaster is an event that results in a significant disruption of the normal functioning of a community or society due to the impact of biological agents. These agents can include infectious diseases, pathogens, or biological toxins that affect humans, animals, and plants.

Note: Biological disasters can have widespread and severe consequences for public health, agriculture, ecosystems, and the overall well-being of a population.

Examples of biological disasters include:

• 1. Pandemic: Widespread outbreaks of infectious diseases that affect a large geographical area It may affect multiple countries or continents.

• 2. Epidemic: Localized outbreaks of infectious diseases that affect a specific community or region.

• 3. Epidemics: Localized outbreaks of infectious diseases that affect a specific community or region.

• 4. Bioterrorism: Deliberate release of biological agents to harm or terrorize a population.

• 5. Outbreaks of Vector-Born Disease: Increased incidence of diseases transmitted by vectors such as mosquitoes, ticks, or other organisms.

• 6. Crop or Livestock Diseases: Outbreaks of diseases that affect crops or livestock. This leads to significant economic losses and food supply disruptions.

Q.10 _____ is the most abundant greenhouse gas.

Ans: Water vapor (H₂O) is the most abundant greenhouse gas in the Earth's atmosphere.

Note: Water vapor (H₂O) concentrations in the atmosphere are highly variable and depend on factors such as temperature and local weather conditions. Other important greenhouse gases are carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and various synthetic gases like chlorofluorocarbons (CFCs)

Q.11 What is stress?

Ans: In environmental science, "stress" is used to describe the impact of environmental factors on living organisms or ecosystems. It refers to any external factor or condition that disrupts the normal functioning or balance of an organism or ecosystem. Environmental stressors can be natural or anthropogenic (caused by human activities). It affects organisms at various levels, from individuals to entire populations or ecosystems. Examples of environmental stressors are pollution, climate change, Habitat destruction, etc.

Q.12 E-waste means_____.

Ans: E-waste or electronic waste is discarded electrical or electronic devices. These devices include a wide range of items, such as computers, smartphones, tablets, televisions, refrigerators, and other electronic gadgets that have reached the end of their useful life or are no longer wanted by their users

SECTION-C

Note: Short answer type questions. Attempt any eight

questions out of ten questions. (8x4=32)

Q.13 Explain the advantages of landfilling.

Ans: Landfills are a common method of waste disposal. The following are some advantages of landfills

• 1. Cost-Effective: Landfills are cost-effective in the short term compared to some alternative waste disposal methods. Constructing and maintaining a landfill may be less expensive than other waste management technologies.

• 2. Volume Reduction: Landfills help to reduce the volume of waste through compaction. Waste decomposes. it can result in a reduction in the overall volume of the landfill.

• 3. Energy Production: Landfills are designed to capture the methane gas produced by decomposing organic waste. Methane is utilized as a source of energy for electricity generation or other applications. It is a form of renewable energy.

• 4. Land Reclamation: A landfill reaches its capacity and is closed. The land is used for other purposes such as parks or green spaces. This process is known as landfill reclamation.

Q.14 What are the harmful effects of acid rain?

Ans: Acid rain (rain, snow, sleet, or hail) contains acidic components, such as sulfuric acid (H₂SO₄) and nitric acid (HNO₃). Atmospheric deposition of sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) emitted from human activities for these acids. Acid rain can have harmful effects on the environment, ecosystems, and human-made structures. Some of the harmful effects are:

• 1. Soil Degradation: Acid rain filters essential nutrients, such as calcium and magnesium, from the soil. This process disrupts soil chemistry. This makes it more difficult for plants to obtain the nutrients. It can also release aluminum from the soil, which is toxic to plants.

• 2. Water Pollution: Acid rain leads to the acidification of water bodies, such as lakes, rivers, and streams. This acidification harms aquatic life, like fish and other organisms. Some species of fish and aquatic insects are unable to survive in acidic conditions.

• 3. Damage to Vegetation: Direct contact with acid rain can damage the leaves, needles, and stems of plants and trees. This can weaken the plants and make them more susceptible to diseases, harsh weather conditions, and other environmental stresses.

• 4. Impact on Aquatic Ecosystem: Acidification of water bodies disrupts the reproductive and developmental processes of aquatic organisms. It also affects the availability of food sources for fish and other aquatic species.

• 5. Corrosion of Building and Infrastructure: Acid rain accelerates the corrosion of buildings, monuments, and infrastructure made of limestone, marble, concrete, and metals. Over time, this leads to structural damage and the deterioration of cultural heritage sites.

• 6. Human Heath Concerns: The direct health impacts of acid rain on humans are limited. The component of acid rain (sulfur dioxide and nitrogen oxides) contributes to the formation of fine particulate matter and ground-level ozone. These pollutants have respiratory and cardiovascular health effects.

Q.15 What is a nuclear disaster?

Ans: A nuclear disaster refers to the release of radioactive materials from a nuclear facility. This leads to severe environmental, health, and socio-economic consequences. Nuclear disasters result from accidents, malfunctions, or intentional acts. They pose serious risks due to the ionizing radiation emitted by radioactive substances. The following are some of the most well-known nuclear disasters include:

• 1. Chernobyl Disaster (1986): The Chernobyl nuclear power plant in Ukraine experienced a catastrophic explosion and meltdown during a reactor test. The release of radioactive materials affected a large area, leading to long-term health problems and environmental impacts.

• 2. Fukushima Daiichi (2011): The Fukushima Daiichi nuclear power plant in Japan experienced a series of releases of radioactive materials due to earthquake and tsunami. It resulted in the evacuation of nearby residents and raised concerns about the safety of nuclear power plants in earthquake-prone regions.

• 3. Three Mile Island Accident (1979): The Three Mile Island nuclear power plant in the United States experienced a partial meltdown of one of its reactors. The incident led to increased public concerns about the safety of nuclear power.

Nuclear disaster consequences

• 1. Human Health Impacts: Exposure to ionizing radiation leads to acute and long-term health effects. This includes radiation sickness, an increased risk of cancer, and genetic mutations.

• 2. Environmental Contamination: Radioactive materials released during a nuclear disaster contaminate air, water, soil, and food. It damages to ecosystems and wildlife.

• 3. Evacuation and Displacement: Residents in the affected areas may need to be evacuated. This leads to the displacement of communities.

• 4. Economics and Social Disruptions: Nuclear disasters have significant economic and social impacts. This includes the loss of agricultural land, disruption of local economies, and long-term stigma associated with the affected region.

Q.16 Define any two:

i) Trauma ii) Stress iii) Rumour iv) Panic

Trauma: “Trauma is a disturbing experience that leaves a lasting impact on an individual's physical or psychological well-being”.

Traumatic events can be physical, such as accidents or injuries, or psychological, such as abuse, violence, or witnessing distressing events. The effects of trauma can be noticeable in emotional, cognitive, and behavioral changes. This leads to long-term consequences if not appropriately addressed.

Stress: In environmental science, "stress" is used to describe the impact of environmental factors on living organisms or ecosystems. "Stress is any external factor or condition that disrupts the normal functioning or balance of an organism or ecosystem".

Environmental stressors can be natural or anthropogenic (caused by human activities). It affects organisms at various levels, from individuals to entire populations or ecosystems. Examples of environmental stressors are pollution, climate change, Habitat destruction, etc.

Rumor: “A rumor is a piece of information or a story that is circulated without verification or confirmation”.

Rumor spreads quickly among people. Rumors can be true, false, or somewhere in between true and false. They can influence perceptions, attitudes, and behaviors. Rumors have social, political, or cultural consequences.

Panic: “Panic is a sudden and intense feeling of fear or anxiety that leads to uncontrolled behavior”.

Panic results in a loss of rational thinking, increased heart rate, rapid breathing, and a heightened state of arousal.

Q17 Write a short note on rainwater harvesting.

Ans: Rainwater harvesting is the collection, storage, and utilization of rainwater for domestic, agricultural, and industrial purposes. This practice conserves water. It also controls issues related to water scarcity in regions facing irregular rainfall patterns and limited access to freshwater sources.

Components of rainwater Harvesting

• 1. Catchment Area: The surface upon which rain falls and is collected. This can be the roof of a house or any other surface that allows for efficient water runoff.

• 2. Conveyance System: Gutters are used to channel rainwater from the catchment area to the storage system.

• 3. Filter: Screens or filters are installed to remove debris, leaves, and other impurities from the collected rainwater.

• 4. Storage Tank: Rainwater is stored in tanks for later use. These storage systems can be above-ground or underground. It depends on available space and local conditions.

• 5. Distribution System: Piping and outlets are used to distribute the harvested rainwater to different areas for various purposes.

Advantages of Rainwater Harvesting

• 1. Water Conservation: Rainwater harvesting reduces dependence on conventional water sources. It helps to conserve precious freshwater resources.

• 2. Cost-Effective: Rainwater harvesting systems are economical to maintain and operate.

• 3. Groundwater Recharge: Harvesting rainwater helps to maintain groundwater levels.

• 4. Reduced Flooding: Rainwater harvesting captures rainwater. This reduces the risk of flooding.

• 5. Agriculture: Farmers use harvested rainwater for irrigation.

Q.18 Write any four causes of water pollution.

Ans: Water pollution is caused by the entry of contaminants into water bodies. This poses risks to human health and the environment. The following are four common causes of water pollution:

• 1. Industrial Discharge: Many industries release pollutants into water bodies like rivers, lakes, or oceans. These pollutants include heavy metals, chemicals, and toxins. They contaminate the water and harm aquatic ecosystems. These releases from factories and industrial facilities are contributors to water pollution.

• 2. Agricultural Runoff: Agricultural activities, such as the use of fertilizers, pesticides, and herbicides, contribute to water pollution. These chemicals are washed off into nearby rivers and streams, leading to nutrient pollution and the introduction of harmful substances into aquatic environments. This runoff can cause oxygen depletion and harm to aquatic life.

• 3. Urban Runoff: Urban areas generate pollution. This pollution carries pollutants like oil, grease, heavy metals, and debris. These all enter drains and reach into water bodies. They degrade the water quality and negatively impact aquatic ecosystems.

• 4. Improper Disposal of Wastes: Improper disposal of solid and hazardous wastes causes of water pollution. Dumping of garbage, plastics, and other waste materials into water bodies contaminates the water. This poses a threat to aquatic life. Improper disposal of hazardous waste, such as chemicals and pharmaceuticals has long-term effects on water quality and ecosystem health.

Q.19 How can noise pollution be minimized?

Ans: Individual, community, and regulatory bodies adopt various strategies to minimize noise pollution. The following are some effective measures to reduce and lessen noise pollution:

• 1. Use of Noise Barriers: Physical barriers like walls, fences, or soundproofing materials are used to block or absorb noise.

• 2. Urban Planning and Zoning: Implement urban planning and zoning regulations. This separates noisy activities (industries, highways) from residential and quiet areas..

• 3. Noise Reduction in Transportation: Encourage the use of silent modes of transportation such as electric vehicles. The maintenance of vehicles and design roads with noise-reducing surfaces reduce noise emissions.

• 4. Public Transport and Traffic Management: Promote the use of public transportation to reduce the number of individual vehicles on the road.

• 5. Enforcement of Noise Regulation: Enforce existing noise regulations and establish new ones where needed. Set limits on noise levels for different types of activities.

• 6. Limiting Construction Noise: The regulatory body fixes construction hours to limit noisy activities during sensitive times, such as evenings and weekends. Encourage the use of quieter construction equipment and methods also reduce noise pollution.

• 7. Noise Efficient Building Design: Design buildings with features such as double-pane windows, insulation, and acoustic panels. Landscaping with plants and trees also act as natural sound barriers.

• 8. Community Education and Awareness: Raise awareness in communities about the impact of noise pollution. Educate individuals on practices that reduce noise levels. This may include promoting the use of headphones and reducing loud music.

Q.20 Write a note on sustainable development.

Ans: Sustainable development is an approach to growth and progress that meets the needs of the present without compromising the ability of future generations to meet their own needs. It involves a harmonious combination of economic, social, and environmental considerations. It aims to create a balanced and equitable society that preserves natural resources and ecosystems.

Principles of Sustainable Development

• 1. Environmental Stewardship: Sustainable development recognizes the limited nature of the Earth's resources. Sustainable development emphasizes responsible management and conservation of natural ecosystems. It minimizes environmental impact and promotes practices that maintain biodiversity and ecological balance.

• 2. Economic Prosperity: Sustainable development aims for economic growth that benefits all members of society. It encourages the development of businesses and industries that contribute to social well-being and minimize negative environmental and social impacts.

• 3. Social Equity and Inclusivity: Sustainable development promotes social justice. It ensures the benefits of development are shared equally among all members of society. It addresses issues of poverty, inequality, and access to basic human rights such as education, healthcare, and employment.

• 4. Lomg Term Vision: Sustainable development considers the long-term consequences of present actions. Decision-making considers the needs of future generations.

• 5. Community Engagement: Sustainable development involves communities in the decision-making process. It respects local knowledge and promotes a sense of ownership and responsibility.

• 6. Resource Efficiency: Sustainable development promotes the efficient use of resources, minimizing waste and reducing the environmental footprint of human activities. This includes adopting technologies and practices that enhance resource productivity and minimize negative impacts.

Q.21 What are the effects of air pollution on human health?

Ans: Air pollution affects various organ systems of the human body. It has both short-term and long-term health issues. The specific health effects depend on the type and concentration of pollutants in the air and individual susceptibility. The following are some of the common effects of air pollution on human health:

• 1. Respiratory Problems:

  • Aggravation of Respiratory Conditions: Air pollution can worsen pre-existing respiratory conditions such as asthma, chronic bronchitis, and chronic obstructive pulmonary disease (COPD).

  • Increased Respiratory Infections: Exposure to pollutants weaken the immune system. It makes individuals more susceptible to respiratory infections.

• 2. Cardiovascular Effects:

  • Heart Attacks and Strokes: Long-term exposure to air pollution is associated with an increased risk of cardiovascular diseases, including heart attacks and strokes..

• 3. Cancer Risk-like Lung Cancer: Inhalation of certain air pollutants, such as benzene, formaldehyde, and polycyclic aromatic hydrocarbons (PAHs), is linked to an increased risk of lung cancer.

• 4. Developmental Issues such as Birth Defects and Low Birth Weight: Exposure to air pollution during pregnancy is associated with an elevated risk of birth defects and low birth weight.

• 5. Reduced Lung Function:

  • Impaired Lung Development in Children: Children exposed to air pollution may experience reduced lung function and impaired lung development, which can have long-term consequences.

• 6. Neurological Effects:

  • Cognitive Decline: Long-term exposure to air pollution is linked to cognitive decline and an increased risk of neurodegenerative diseases such as Alzheimer's and Parkinson's.

• 7. Allergies and Respiratory Symptoms: Air pollution can worsen allergy symptoms and contribute to the development of allergic reactions.

• 8. Systemic Inflammation:

  • Inflammatory Responses: Exposure to pollutants can trigger systemic inflammation in the body, contributing to various health issues, including chronic diseases.

• 9. Increased Mortality:

  • Premature Death: Long-term exposure to high levels of air pollution is associated with an increased risk of premature death, particularly due to cardiovascular and respiratory diseases.

Q.22 Write an explanatory note on natural disasters.

Ans: Natural disasters are the result of natural processes of the Earth. These events can cause significant harm to the environment, human populations, and property. Natural disasters are started by geological, meteorological, hydrological, or climatological factors.

Types of Natural Disasters:

• 1. Earthquakes: Causes: Sudden movement of tectonic plates beneath the Earth's surface. Effects: Ground shaking, surface rupture, and potential for tsunamis.

• 2. Hurricanes/Cyclones/Typhoons: Causes: The formation and intensification of tropical storms. Effects: Strong winds, heavy rainfall, storm surges, and flooding.

• 3. Floods: Causes: Heavy rainfall, storm surges, dam failure, or rapid snowmelt. Effects: Inundation of land, destruction of infrastructure, and displacement of communities.

• 4. Tornadoes: Causes: Violent atmospheric conditions, often associated with severe thunderstorms. Effects: Intense rotating winds, destruction of structures along a narrow path.

• 5. Volcanic Eruptions: Causes: Movement of magma from the Earth's interior to the surface. Effects: Lava flows, ash clouds, pyroclastic flows, and potential for atmospheric impacts.

• 6. Wildfires: Causes: Dry conditions, high temperatures, and ignition sources such as lightning or human activities. Effects: Uncontrolled fires, destruction of vegetation, and threats to human and animal life.

• 7. Droughts: Causes: Prolonged periods of below-average rainfall. Effects: Water scarcity, crop failure, and economic hardships.

• 8. Landslides: Causes: Heavy rainfall, earthquakes, volcanic activity, or human activities destabilizing slopes. Effects: Rapid downhill movement of soil and rock, damaging infrastructure and threatening lives.

Impacts of Natural Disasters

• 1. Loss of Lives: Natural disasters can result in the tragic loss of human lives, especially in densely populated areas.

• 2. Infrastructure Damage: Homes, buildings, roads, bridges, and other critical infrastructure can be severely damaged or destroyed.

• 3. Displacement of Communities: People are forced to evacuate their homes, leading to temporary or long-term displacement.

• 4. Economic Consequences: Natural disasters have devastating economic impacts, affecting industries, agriculture, and local economies.

• 5. Environmental Degradation: Disasters contribute to environmental damage, such as deforestation, soil erosion, and pollution.

• 6. Humanitarian Crises: Access to clean water, food, healthcare, and shelter may be compromised, leading to humanitarian challenges

• 7. Mitigation and Preparedness: Efforts to mitigate the impact of natural disasters involve proactive measures, including:

SECTION-D

Note: Long answer type questions. Attempt any two questions out of three questions. (2x8=16)

Q.23 What are the advantages and disadvantages of renewable or non-conventional sources of energy?

Ans: Advantages of Renewable or Non-Conventional Sources of Energy:

• 1. Environmentally Friendly: Renewable energy sources are solar, wind, and hydropower. They generate electricity with significantly lower greenhouse gas emissions compared to fossil fuels. They contribute to controlling climate change and reducing air pollution.

• 2. Sustainability: Renewable sources are sustainable and inexhaustible. They harness energy from natural processes that are continuously replenished, such as sunlight, wind, and water flow.

• 3. Reduced Dependence on Fossil Fuels: Dependence on renewable energy decreases dependence on fossil fuel resources. This reduces their price fluctuations and supply disruptions.

• 4. Local Job Creation: The renewable energy sector creates jobs in manufacturing, installation, maintenance, and research, contributing to economic growth and local employment.

• 5. Energy Security: Renewable sources enhance energy security by providing a decentralized and distributed energy generation model. It reduces reliance on centralized power plants and vulnerable supply chains.

• 6. Grid Stability: It reduces transmission losses, and enhances the flexibility of the energy grid.

• 7. Low Operating Costs: Once installed, many renewable energy systems have low operating and maintenance costs. Solar panels and wind turbines, for example, have minimal fuel or ongoing fuel costs.

• 8. Technological Advancements: Ongoing advancements in technology are reducing the costs of renewable energy systems. It makes them increasingly competitive with traditional energy sources.

Disadvantages of Renewable or Non-Conventional Sources of Energy

• 1. Fluctuations in power generation: Many renewable sources, such as solar and wind, are dependent on weather conditions. Energy storage solutions are required to address fluctuations in power generation.

• 2. Land Use Concerns: Large-scale renewable energy systems, such as solar farms and wind turbines, require large land area.

• 3. High Initial Costs: The installation costs are relatively high. Although, ongoing costs are lower.

• 4. Resource Availability: Renewable resources are location-dependent. For example, regions with low solar exposure are not suitable for solar system to generate energy.

• 5. Environmental Impact: Hydropower projects can alter ecosystems and affect aquatic life.

• 6. Energy Storage Challenges: Renewable energy requires an effective energy storage system. Current technologies (e.g., batteries) have limitations in terms of cost, efficiency, and environmental impact.

• 7. Transition Challenges: Canging from traditional energy sources to renewables may face challenges related to existing infrastructure, policy frameworks, and vested interests in the fossil fuel industry.

• 8. Aesthetic Concerns: Some people find the appearance of renewable energy infrastructure unappealing. This leads to resistance from local communities

Q.24 Explain the various steps involved in water treatment.

Ans: Water treatment process: Sewage and industrial wastes are properly treated to make them harmless for human beings and environment. Objectives of water treatment are

• 1. Production of water safe for the environment

• 2. Production of water safe for human beings

• 3. Production of water appealing to human beings,

• 4. Production of a water treatment facility is economical and easy to operate.

Sewage treatment: Sewage pollutes the water body. It can be made harmless by its proper treatment. Sewage water treatment consists of three steps: Primary treatment, secondary treatment, and tertiary treatment.

• 1. Primary treatment: It is a physical process to separate suspended pollutants from sewage discharge. It consists of sedimentation, floating, fragmentation, and filtration. Sediment collected after primary treatment is called primary sludge. The rest portion is called effluent. Primary sludge is used to generate biogas.

• 2. Secondary treatment: Effluent contains a high concentration of organic matter and other dissolved matter. Secondary treatment helps to remove them. Secondary treatment is also called biological treatment. Microbial flora is used to decompose organic matter. It is carried out in the following two ways:

  • · Anaerobic secondary treatment: Sludge is stored in a large tank called a sludge digestor or bioreactor. Anaerobic microbes decompose the macromolecules such as proteins, lipids, polysaccharides, etc. At the end of decomposition, it releases methane gas and water.

  • · Aerobic secondary treatment: It consists of two methods: the trickling filter method and the activated sludge method.

  • Tricking filter method: Effluent is passed through a bed of small stones. Bed of small stones have microbial flora. It consumes organic matter present in effluent. At the bottom of the small stone bed, effluents are collected. It is further cleaned by chlorination. Chlorination kills microbes present in effluent obtained after secondary treatment.

    • o Activated sludge method: Effluent after primary treatment is aerated in a large tank containing microbial flora mostly algae and bacteria. Algae produces oxygen for bacteria and bacteria decompose organic matter present in effluent. Then effluent is chlorinated to kill microbes.

• 3. Tertiary treatment: Chlorinated effluent has a large concentration of salts. They are precipitated by using alum, ferric chloride, and lime. It removes 90% of solids and 90% of phosphates and nitrates. Then water is released for irrigation.

Q.25 Briefly explain any four manmade disasters.

Ans Manmade disasters are events caused by human actions, negligence, or intentional activities. It results in significant harm to people, property, and the environment. The following are four types of manmade disasters:

• 1. Industrial Accidents:

• Industrial accidents involve the release of hazardous materials or the failure of industrial processes. This leads to immediate harm or long-term environmental damage.

• Examples are Chemical spills, industrial explosions, nuclear power plant accidents (e.g., Chernobyl, Fukushima), and incidents at manufacturing facilities.

• 2. Technological Accidents:

• Technological accidents are failures in technological systems, such as transportation or communication. This results in negative consequences.

• Examples are Plane crashes, train derailments, power grid failures, and telecommunications breakdowns.

• 3. Environmental Pollution:

• Environmental pollution disasters involve the release of pollutants into the air, water, or soil, causing harm to ecosystems, human health, and wildlife.

• Examples are air pollution from industrial emissions, water pollution from oil spills, water pollution from industrial discharges, soil contamination from hazardous waste disposal, and plastic pollution.

• 4. Structural Failures:

• Structural failures occur when buildings, bridges, dams, or other infrastructure components collapse or malfunction due to design flaws, poor construction, or lack of maintenance.

• Examples are Building collapses, dam failures, bridge collapses, and infrastructure failures during natural disasters (e.g., earthquake-induced building damage).

Dr Pramila Singh