Waste Management: NBSE Class 9 Environment

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Get summaries, questions, answers, solutions, notes, extras, PDF and guide of Chapter 13 Waste Management, NBSE Class 9 Environmental Education textbook, which is part of the syllabus of students studying under Nagaland Board. These solutions, however, should only be treated as references and can be modified/changed.

Summary

Waste management is about controlling and reducing waste and ensuring its safe disposal. Waste is anything we throw away. It can be solid, liquid, or gas. Managing waste is important because it affects the environment and health. People everywhere create waste. This problem is bigger in developing countries due to less technology and fewer people helping.

The goal of waste management is to understand what kind of waste is made and how much. It also aims to find out how waste impacts the environment and suggests ways to handle it. Waste is increasing because of more industries and cities. Proper disposal of waste is necessary for all countries. People need to realize that preventing waste is better than managing it. Reusing and recycling waste can solve many problems but these ideas are still not common.

Proper waste management helps keep people healthy and safe. It prevents diseases and reduces health risks. It stops soil, water, and air from getting dirty. Good waste management protects the environment. It saves natural resources and keeps ecosystems safe. Recycling and proper disposal reduce pollution. Waste management also helps the economy by creating jobs. Recycling and turning waste into energy can make money. Proper waste management ensures a clean future. It follows rules set by local, national, and international laws.

There are different ways to dispose of waste safely. Solid waste includes things like food garbage, construction debris, industrial chemicals, and agricultural waste. Solid waste can be managed by separating it into groups, dumping it in landfills, composting, or burning it. Composting involves letting waste break down naturally to make fertilizer. Burning waste reduces its size and volume. Liquid waste requires drainage systems and treatment before being released. Gaseous waste can be cleaned using scrubbers and electrostatic precipitators.

Reducing, reusing, and recycling are three key methods in waste management. Reducing means using fewer resources. Reusing means using items again for the same purpose. Recycling means turning waste into new products. Reducing waste at the source is the best way to manage it. Recycling conserves energy and reduces pollution. Many materials like steel, aluminum, plastic, paper, and glass can be recycled. Legal rules help manage waste properly. Important laws include the Environment Protection Act, Biomedical Waste Rules, and others.

India has special rules for handling plastics and vehicles. The Basel Convention controls the movement of hazardous waste between countries. India’s constitution encourages protecting the environment. Citizens have a duty to protect forests, lakes, rivers, and wildlife. Laws ensure people follow these duties. Understanding and following these laws is necessary for everyone.

Textbook solutions

Multiple Choice Questions (MCQs)

1. Major ingredient in borosilicate:

(a) Alkali
(b) Silica
(c) Borax
(d) Lead

Answer: (c) Borax

2. Method of reusing the things:

(a) Recycle
(b) Reduce
(c) Reuse

Answer: (c) Reuse

3. When the Environment Protection Act was passed?

(a) 1984
(b) 1989
(c) 1990
(d) 1986

Answer: (d) 1986

4. Which act provides protection and improvement of environment and other connected matters?

(a) Environment Protection Act 1986
(b) The National Environment Tribunal Act 1995
(c) The Wildlife (Protection) Act 1972
(d) None of these

Answer: (a) Environment Protection Act 1986

5. 3R’s of waste management are:

(a) Reproduce, Repair, Reuse
(b) Recycle, Repair, Reuse
(c) Reduce, Reuse, Recycle
(d) Recycle, Reuse, Reproduce

Answer: (c) Reduce, Reuse, Recycle

Very Short Answer Questions

1. What is waste management?

Answer : Waste management is described as the practice of control and reduction of the further generation of wastes and their safe disposal.

2. What is dumping of waste?

Answer : Dumping is an activity of depositing waste in an area. It is considered a common and cheapest method of disposing of waste on land because transport cost is the only major expenditure.

3. What is composting?

Answer : Composting is a method of solid waste disposal that requires time and patience. Through this process, waste is not only disposed of but also converted into fertilizer through natural decomposition.

4. What is incinerator?

Answer : An incinerator is a modern machine used in the process of incineration, which involves burning waste under controlled conditions to reduce it by 90% in weight and volume.

5. Name the major sources of liquid waste.

Answer : The major sources of liquid waste include domestic and industrial discharges, with estimates suggesting that an average person contributes 227 litres of sewage per day from activities like cooking, bathing, washing, and recreation.

6. What is recycling?

Answer : Recycling is a process designed to recover materials instead of throwing them away and making further use of those materials, often involving sorting and processing waste products to serve as new material for new products.

Short Answer Questions

1. What do you understand by waste segregation?

Answer : Waste segregation refers to the process of separating waste into different categories based on their nature. The separation is typically done into biodegradable and non-biodegradable wastes. Biodegradable wastes include materials that can be decomposed naturally, such as vegetable and fruit peels, while non-biodegradable wastes consist of materials that cannot be decomposed naturally, like plastics.

2. List different stages of liquid waste disposal.

Answer : Liquid waste disposal involves several stages. Initially, primary treatment occurs when wastewater enters the treatment plant, where solid material or debris is removed using screens or vertical bars. Following this, the wastewater passes through a grit chamber, which functions as a settling tank to separate inorganic and organic matter. The next stage involves sedimentation, where fine organic material settles down and is removed, sometimes aided by methods like coagulation and flocculation for quicker results. Floatation may also be used as an alternative to sedimentation, where air is forced into the wastewater to bring suspended particles to the surface for removal. Subsequently, digestion takes place in an anaerobic tank to convert organic sludge into methane, carbon dioxide, and humus-like material. Finally, dewatering occurs when the digested sludge is placed on sand beds to dry, either through percolation into the sand or evaporation, primarily being more efficient in warm weather.

3. Name the two common devices for gaseous waste disposal.

Answer : The two common devices for gaseous waste disposal are air scrubbers and electrostatic precipitators. Air scrubbers are anti-pollution devices visible as metal pipes used to trap particles from emissions of gaseous waste. Electrostatic precipitators are electric devices that remove suspended impurities like dust, mist, and fumes from the air. Both devices play crucial roles in minimizing air pollution and ensuring the safe disposal of gaseous waste.

4. Name four things that can be recycled

Answer : Four things that can be recycled include steel, aluminium, plastic, and paper. Steel scrap is melted in furnaces to be reused. Aluminium beverage containers are melted and recycled into ingots or sheets. Plastics undergo cleaning, shredding, and melting into pellets for recycling. Paper products like newsprint, office paper, wrapping paper, and cardboard are processed into pulp, filtered, and remade into new paper.

5. What do you mean by reuse of waste? Give example.

Answer : Reuse of waste refers to the practice of using a material again and again for its original purpose. It is another method of waste management where items are sterilized or repurposed instead of being discarded. For instance, cartridges and ribbons used in offices can be reused. Additionally, disposable items during picnics or journeys can be replaced with washable alternatives. Cloth napkins can also be used instead of paper napkins as part of this effort.

6. Name any two legal provisions for waste management.

Answer : Two legal provisions for waste management include the Environment Protection Act of 1986 and the Biomedical Waste (Management & Handling) Rules of 1998. The Environment Protection Act provides for the protection and improvement of the environment and other connected matters. The Biomedical Waste Rules aim to safeguard the public and healthcare workers from risks arising from biomedical waste, applying to individuals who generate, collect, store, transport, treat, or handle such waste in any form.

Long Answer Questions

1. Why do we need waste management?

Answer : Waste management is crucial for several reasons. It helps in preventing the spread of diseases and reduces health hazards, thereby ensuring public health and safety. Improper disposal of waste can contaminate soil, water, and air, leading to serious health issues. Effective waste management also reduces pollution, conserves natural resources, and protects ecosystems, contributing to environmental protection. Economically, waste management can create job opportunities and contribute to the economy through recycling and waste-to-energy processes that generate revenue and reduce costs associated with waste disposal. Furthermore, managing waste properly ensures a cleaner and healthier environment for future generations, promoting sustainability. Finally, proper waste management ensures compliance with local, national, and international regulations, helping avoid legal issues and penalties.

2. Briefly describe the different methods of solid waste disposal.

Answer : Solid waste disposal involves several methods, each suited to different types of waste. 

The first method is segregation, which refers to the separation of waste into different categories such as biodegradable and non-biodegradable. Biodegradable wastes include materials like vegetable and fruit peels that can be decomposed naturally, whereas non-biodegradable wastes include materials like plastic that cannot be decomposed naturally. 

Another method is dumping, which is the activity of depositing waste in an area. This method has evolved into what is now known as landfill, where solid waste should be spread in thin layers, each layer solidified by a bulldozer before the next is deposited. After every three meters, a layer of clean earth should be added and solidified. 

Composting is another method, requiring time and patience, where waste is not only disposed of but also turned into fertilizer through a natural process. The waste has to be segregated so that only compostable materials like paper, wood, and leaves are used. The waste is layered to allow air entry, with a little water added for easy decomposition. After a few days, the pile is covered to facilitate faster decomposition by heat and steam, and after about three weeks, it can be used as manure.

Incineration is another method where waste is burned to reduce its weight and volume by 90%. Modern incinerators are equipped with filters, precipitators, and wet scrubbers to control pollution. 

3. Explain the process of composting in detail.

Answer : Composting is described as a natural process that involves the decomposition of organic matter, which results in nutrient-rich compost used to enhance soil quality. In this process, various organic materials such as plant residues, animal manure, food scraps, and other biodegradable waste are gathered and placed in a designated area or container. 

These materials are categorized into two types: green materials, which are rich in nitrogen, and brown materials, which are rich in carbon. It is essential to maintain an appropriate balance between these two types to ensure efficient decomposition. The materials are then layered, ensuring proper aeration and moisture levels, because microorganisms like bacteria, fungi, and actinomycetes require oxygen and water to break down the organic matter effectively. 

Over time, with regular turning or mixing of the pile, the temperature within rises due to microbial activity, accelerating the breakdown process. Once the organic matter has decomposed sufficiently, it transforms into humus-like material known as compost, which can be applied to soil to improve its structure, fertility, and water retention capacity.

4. Give a brief description of liquid waste disposal.

Answer : Liquid waste disposal refers to the systematic management and treatment of wastewater originating from domestic, industrial, and commercial sources. This type of waste typically includes sewage, stormwater runoff, industrial effluents, and other forms of liquid byproducts. 

The process begins with the collection of liquid waste through a network of drains, sewers, and pipelines that transport the waste to treatment facilities. At these facilities, the liquid waste undergoes various stages of treatment, starting with preliminary processes such as screening and sedimentation to remove large solids and debris. Following this, primary treatment involves allowing the waste to settle in tanks where heavier particles sink to form sludge while lighter materials float to the surface for removal. Secondary treatment utilizes biological processes where microorganisms consume organic pollutants present in the wastewater.

 Advanced or tertiary treatment may also be employed to further purify the water by removing nutrients, pathogens, and any remaining contaminants. After thorough treatment, the resulting effluent is often discharged into natural water bodies or reused for purposes like irrigation, depending on the level of purity achieved. Proper disposal ensures environmental protection and human health safety by preventing pollution of water resources.

5. What is septic tank and what are its uses?

Answer : A septic tank is a method commonly used for treating domestic sewage. It involves the use of a concrete or metal tank equipped with a submerged outlet. In this system, solid waste settles at the bottom while floatable materials rise to the top. A liquid stream flows through the submerged outlet and percolates down into the soil. 

The floating matter and settled solids can remain in the tank for about a year or so, during which they decompose anaerobically. Septic tanks are primarily used for the treatment of domestic wastewater, allowing for the decomposition of organic matter and facilitating the safe disposal of effluents into the soil.

6. Explain the methods of gaseous waste disposal.

Answer : Gaseous waste, often in the form of smoke released from factory chimneys and vehicles, poses challenges in terms of safe disposal compared to solid or liquid wastes. Several methods have been developed to minimize the generation of gaseous waste and ensure its proper disposal. 

Two common devices utilized for gaseous waste disposal are air scrubbers and electrostatic precipitators. Air scrubbers function by trapping particles from emissions using metal pipes. Pollutants are removed from gas emissions by spraying scrubber liquid directly into the emissions, surrounding the dirty particles, which are then carried into a cylinder where they drop into a contaminated liquid reservoir as the gas cycles upward.

Electrostatic precipitators, on the other hand, are electric devices designed to remove suspended impurities like dust, mist, and fumes from the air. These precipitators work by passing gas through a passage containing discharged electrodes that ionize impurities, charging the suspended particles. Collector electrodes with opposite charges attract these particles, causing them to deposit on the electrode surface, which is periodically washed to remove impurities. Both air scrubbers and electrostatic precipitators play crucial roles in controlling pollution from sources such as cement kilns and steam boilers and are instrumental in recovering sodium compounds in soda and sulphate pulp mills.

7. Give a brief description of various legal provisions of waste management?

Answer : Some important legal provisions include the Environment Protection Act of 1986, which provides for the protection and improvement of the environment and other connected matters. The Biomedical Waste (Management & Handling) Rules of 1998 safeguard the public and healthcare workers from risks arising from biomedical waste. Penalties for these rules are the same as those under the Environment Protection Act of 1986. These rules apply to all persons who generate, collect, receive, store, transport, treat, dispose of, or handle biomedical waste in any form.

Agenda 21, a programme run by the United Nations (UN) related to sustainable development, was revealed at the United Nations Conference on Environment and Development (Earth Summit) held in Rio de Janeiro on June 14, 1992. It is a comprehensive plan of action to be taken globally, nationally, and locally by organizations of the UN, governments, and major groups in areas where humans impact the environment.

The Recycled Plastics Manufacture and Usage Rules of 1999 aim to regulate the manufacture and use of recycled plastics, carry bags, and containers. As per these rules, the thickness of carry bags made of virgin plastics or recycled plastics cannot be less than 20 microns. Carry bags and containers made of virgin plastic are to be in natural shade or white.

The Motor Vehicles Act of 1989 lays down responsibilities for vehicle drivers, including licensing, insurance, and maintenance. The Act empowers central and state governments to make rules as needed.

The Basel Convention, which came into force in 1992, relates to the control of transboundary movements of hazardous wastes and their disposal. It aims to protect human health and the environment against adverse effects of the generation, management, transboundary movements, and disposal of hazardous wastes.

Other significant acts include the Wildlife (Protection) Act of 1972, the Water (Prevention and Control of Pollution) Act of 1974, the Air (Prevention and Control of Pollution) Act of 1981, the Environment (Protection) Act of 1986, and the National Environment Tribunal Act of 1995. India has enacted more than 200 laws for the protection and improvement of the environment.

Extras

Additional questions and answers

1. Define waste management?

Answer : Waste management is the practice of control and reduction of the further generation of the wastes and their safe disposal. It is also the process in which we deal with the wastes.

Q. What are biodegradable wastes?

Answer : Biodegradable wastes include those materials that can be decomposed by natural means, like vegetable and fruit peels.

Q. What are non-biodegradable wastes?

Answer : Non-biodegradable wastes include those materials or wastes that cannot be decomposed by natural means, like plastic things.

Q. Give an example of non-biodegradable waste.

Answer : Plastic is an example of non-biodegradable waste.

Q. Name two common categories for segregating waste.

Answer : Two common categories for segregating waste are biodegradable and non-biodegradable.

Q. Define dumping.

Answer : Dumping is an activity of depositing waste in an area. An average city resident produces tons of waste every year. Cities, therefore, run out of space for waste disposal.

Q. What is a landfill?

Answer : A landfill is an improved method of dumping where solid waste should be spread in thin layers. Each layer should be solidified by a bulldozer before the next layer is deposited. After every three metres, a layer of clean earth should be added and solidified by a bulldozer. Sites of landfills should be selected so that flood water cannot reach there, and the underground water level should also be low.

Q. What is composting?

Answer : Composting is a method of solid waste disposal and it requires time and patience. The waste is not only disposed of but fertilizer is also made by a natural process.

Q. Define incineration.

Answer : Incineration is another method of solid waste disposal which involves its reduction in weight and volume. Modern machines used in this process are called incinerators. In the incinerator, the waste is burned and gets reduced by 90% in weight and volume.

Q. Name two devices used for gaseous waste disposal.

Answer : Two common devices for gaseous waste disposal are air scrubbers and electrostatic precipitators.

Q. What is an electrostatic precipitator?

Answer : An electrostatic precipitator is an electric device used to remove suspended impurities like dust, mist, fumes, etc., from the air. It works by passing the gas that needs to be purified through a passage containing a series of discharge electrodes. These electrodes ionize the impurities, charging the suspended particles. Collector electrodes with an opposite charge attract the ionized particles, causing them to deposit on the electrode surface. The collector electrodes are periodically washed to remove the impurities.

Q. What is an air scrubber?

Answer : An air scrubber is an anti-pollution device used to trap particles from the emissions of gaseous waste. It prevents pollutants from entering the atmosphere where they can transform into environmentally harmful compounds such as acid rain. In the air scrubber, pollutants are removed from gas emissions by spraying scrubber liquid directly into the emissions. The dirty particles are surrounded by the scrubber liquid and carried with the gas emissions into a cylinder, where the liquid-covered particles drop into a contaminated liquid reservoir.

Q. Define drainage.

Answer : Drainage is the process by which water or liquid waste is allowed to flow from one area to the site of disposal. It requires pipelines through which the waste can flow. Drains carry heavy waste from sources and dump it into lakes, rivers, and ponds, eventually reaching the sea. This method can be natural or artificial and is used for the removal of surface and sub-surface water from an area.

Q. What is a grit chamber?

Answer : A grit chamber is a settling tank used in the treatment of wastewater. It separates inorganic and organic matter. The inorganic matter, such as sand, silt, gravel, and cinders, is heavier and settles down, while the lighter organic solid matter remains suspended in the water and moves to the next stage of treatment. Modern grit chambers are spiral flow grit chambers with hopper bottoms and mechanical scraper arms.

Q. What is flotation in liquid waste treatment?

Answer : Flotation is an alternative to the sedimentation process in liquid waste treatment. In this process, air is forced into the wastewater under pressure, maintained at 1.75 to 3.5 kg per square cm. The wastewater becomes supersaturated with air and is discharged into an open tank. Rising bubbles bring up the suspended particles to the surface, where they are easily removed. More than 75 percent of the suspended particles are removed in this process.

Q. What is digestion in waste treatment?

Answer : Digestion is a microbiological process that converts organic sludge to methane, carbon dioxide, and humus-like material. This reaction occurs in a closed anaerobic tank (without oxygen), known as a digester. First, the solid matter is made soluble by enzymes, and then acid-producing bacteria are used for fermentation, reducing the matter to simple organic acids, which are converted into methane and carbon dioxide with the help of bacteria. The thickened sludge is heated in the digester, where it remains for 10 to 30 days and gets decomposed, reducing the matter by up to 60 percent.

Q. Define sedimentation.

Answer : Sedimentation is the process where fine organic material settles down in a chamber after the removal of grit at the second stage of wastewater treatment. Two methods used for quick sedimentation are coagulation and flocculation. In the coagulation method, chemicals like aluminum sulphate and ferric chloride are added to the water for quick sedimentation. In the flocculation method, the solid material is allowed to merge into one bigger particle. Both these methods help in removing more than 80 percent of solid matter.

Q. What is a septic tank?

Answer : A septic tank is a common method used to treat domestic sewage only. It is a concrete or metal tank with a submerged outlet. In this tank, the solid waste settles, and floatable material rises. A liquid stream flows through the submerged outlet and percolates down to the soil. The floating matter and settled solids can remain there for about a year or so and get decomposed anaerobically.

Q. Name the process used to chemically decompose solid waste by heat.

Answer : The process used to chemically decompose solid waste by heat is called pyrolysis or destructive distillation. It involves decomposing solid waste chemically by heat in an oxygen-reduced atmosphere.

Q. Define recycling.

Answer : Recycling is a process designed to recover materials instead of throwing them away and making further use of those materials. It involves sorting and processing of waste products, serving as a new material for new products. This method reclaims the original material and uses it for new products.

Q. Explain the objectives of waste management?

Answer : The objectives of waste management are:

• To assess the activities involved for the proposed and determine the type, nature, and estimated volumes of waste to be generated.
• To identify any potential environmental impacts from the generation of waste at the site.
• To recommend appropriate waste handling and disposal measures.
• To categorize waste material where practicable for disposal consideration, i.e., filling areas or landfills.

Q. List different forms of solid waste?

Answer : The different forms of solid waste include:

• Garbage of food
• Construction debris
• Trees
• Dead animals
• Industrial waste like chemicals
• Mining waste in the form of heaps
• Agricultural waste as manure and crop residues
• Solid material retained on sewage treatment
• Rubbish like paper, wood, glass, ceramics, cloth, etc.
• Ash

Q. Describe the method of waste segregation?

Answer : Waste segregation refers to the separation of waste into different categories based on their disposal techniques. The most popular segregation is into biodegradable and non-biodegradable wastes. Biodegradable wastes include materials that can be decomposed by natural means, such as vegetable and fruit peels. Non-biodegradable wastes include materials that cannot be decomposed by natural means, like plastic. In many countries, dustbins are categorized as biodegradable and non-biodegradable, and people’s participation is crucial to ensure proper disposal. Waste can also be segregated according to features like sharp-edged waste (e.g., blades, knives), inflammable waste (e.g., batteries, spray cans), recyclable waste (e.g., plastic, glass, paper), infectious waste (e.g., biomedical waste), and radioactive waste (e.g., radioactive substances).

Q. Explain the process of dumping solid waste?

Answer : Dumping is the activity of depositing waste in an area. An average city resident produces tons of waste every year, causing cities to run out of space for waste disposal. Several sites are located for quick dumping of waste where waste is thrown in the open. It is a common and cheapest method of disposing of waste on land because transport cost is the only major expenditure. Nowadays, this method is improved and is called landfill. For proper disposal in a landfill, the solid waste should be spread in thin layers, with each layer solidified by a bulldozer before the next layer is deposited. After every three meters, a layer of clean earth should be added and solidified by a bulldozer. Sites of landfills should be selected so that floodwater cannot reach there, and the underground water level should be low. In all landfills, gases are generated but are released by venting methods. When large amounts of methane collect, it can be disastrous.

Q. Describe the main steps in composting?

Answer : Composting is a method of solid waste disposal that requires time and patience, producing fertilizer through a natural process. The main steps in composting are: 

(i) Segregation: The waste must first be segregated so that only decomposable items like paper, wood, and leaves are selected. Materials like plastic and glass cannot be composted.
(ii) Layering: The waste is layered to allow air to enter easily, and a little water is added to the pile for easy decomposition.
(iii) Covering: After a few days, the pile or heap is covered so that heat and steam can decompose the matter faster. After about three weeks, it can be used as manure.

Q. What are the limitations of incineration?

Answer : The limitations of incineration are:

(i) Incinerators are very costly.
(ii) They pollute the air with smoke and ash.

Q. Outline the process involved in the drainage of liquid waste.

Answer : The process involved in the drainage of liquid waste is as follows:

(i) Drains carry heavy waste from the sources and dump all the waste into lakes, rivers, and ponds, from where it goes into the sea.
(ii) Drainage may be a natural or artificial method of removal of surface and sub-surface water from an area.
(iii) Through drainage, waste generated in vast areas can be carried to some distant place for treatment and neutralization before finally releasing it into any source of water.

Q. Briefly describe the primary treatment of wastewater.

Answer : The primary treatment of wastewater involves the following steps:

(i) When wastewater enters the treatment plant, it usually contains a lot of solid material or debris which can damage the pumps and other equipment of the machinery.
(ii) Screens or vertical bars are used to block the entry of this solid material, which is then removed and burned.
(iii) The wastewater then passes to the next stage of treatment.

Q. Explain the sedimentation process used in liquid waste disposal.

Answer : The sedimentation process used in liquid waste disposal involves the following:

(i) After the removal of grit at the second stage, the wastewater passes into the sedimentation tank.
(ii) Here, the fine organic material settles down and is removed.
(iii) Two methods used for quick sedimentation are coagulation and flocculation.
(iv) In the coagulation method, chemicals like aluminium sulphate and ferric chloride are added to the water for quick sedimentation.
(v) In the flocculation method, the solid material is allowed to merge into one bigger particle.
(vi) Both these methods help in removing more than 80 percent of solid matter.

Q. What happens in the digestion stage of waste treatment?

Answer : In the digestion stage of waste treatment, the following occurs:

(i) This is a microbiological process that converts the organic sludge to methane, carbon dioxide, and humus-like material.
(ii) The reaction occurs in a closed anaerobic tank (without oxygen), known as a digester.
(iii) First, the solid matter is made soluble by enzymes, and then acid-producing bacteria is poured for fermentation, reducing the matter to simple organic acids.
(iv) These acids are converted into methane and carbon dioxide with the help of bacteria.
(v) Thickened sludge is heated in the digester, where it remains for 10 to 30 days and gets decomposed.
(vi) The process of digestion reduces the matter up to 60 percent.

Q. What are the limitations of incineration?

Answer : The limitations of incineration are:

(i) Incinerators are very costly.
(ii) They pollute the air with smoke and ash.

Q. Outline the process involved in the drainage of liquid waste.

Answer : The process involved in the drainage of liquid waste is as follows:

(i) Drainage is the process by which water or liquid waste is allowed to flow from an area to the site of disposal.
(ii) It requires pipelines through which the waste can flow.
(iii) Drains carry heavy waste from the sources and dump it into lakes, rivers, and ponds, from where it eventually flows into the sea.
(iv) It may be a natural or artificial method of removal of surface and sub-surface water from an area.
(v) Through drainage, waste generated in vast areas can be carried to distant places for treatment and neutralization before being released into any water source.

Q. Briefly describe the primary treatment of wastewater.

Answer : The primary treatment of wastewater involves:

(i) When wastewater enters the treatment plant, it usually contains a lot of solid material or debris that can damage pumps and other equipment.
(ii) Screens or vertical bars are used to block the entry of this solid material, which is then removed and burned.
(iii) After this, the wastewater passes to the next stage of treatment.

Q. Explain the sedimentation process used in liquid waste disposal.

Answer : The sedimentation process used in liquid waste disposal involves:

(i) After the removal of grit at the second stage, the wastewater passes into the sedimentation tank.
(ii) Here, fine organic material settles down and is removed.
(iii) Two methods used for quick sedimentation are coagulation and flocculation.
(iv) In coagulation, chemicals like aluminium sulphate and ferric chloride are added to the water for quick sedimentation.
(v) In flocculation, solid material is allowed to merge into one bigger particle.
(vi) Both these methods help in removing more than 80% of solid matter.

Q. What happens in the digestion stage of waste treatment?

Answer : In the digestion stage of waste treatment:

(i) It is a microbiological process that converts organic sludge into methane, carbon dioxide, and humus-like material.
(ii) This reaction occurs in a closed anaerobic tank (without oxygen), known as a digester.
(iii) First, the solid matter is made soluble by enzymes, and then acid-producing bacteria are added for fermentation, reducing the matter to simple organic acids.
(iv) These acids are converted into methane and carbon dioxide with the help of bacteria.
(v) Thickened sludge is heated in the digester, where it remains for 10 to 30 days and gets decomposed.
(vi) The digestion process reduces the matter by up to 60%.

Q. What are the environmental consequences of gaseous wastes?

Answer : Excessive release of carbon dioxide, sulphur dioxide, and many other gases has resulted in acid rain and the greenhouse effect.

Q. How do air scrubbers help control pollution?

Answer : Air scrubbers are anti-pollution devices that trap particles from the emissions of gaseous waste. In the air scrubber, pollutants are removed from gas emissions by spraying scrubber liquid directly into the emissions. The dirty particles are surrounded by the scrubber liquid, which is then carried with the gas emissions into the cylinder. As the gas cycles upward through the cylinder, the liquid-covered particles drop from the gas into the contaminated liquid reservoir. This prevents pollutants from entering the atmosphere where they can change into environmentally harmful compounds such as acid rain.

Q. How does an electrostatic precipitator work?

Answer : An electrostatic precipitator is an electric device used to remove suspended impurities like dust, mist, fume, etc., from the air. The gas to be purified is made to pass through a passage that has a series of discharged electrodes suspended in the passage centers, insulated electrically from the rest of the precipitator. High voltage current applied to the discharged electrodes ionizes the impurities, charging the suspended particles. The collector electrodes have a charge opposite to the ionized particles, causing the suspended particles to move toward the collector electrodes and deposit on their surface. The collector electrode is washed periodically to remove the impurities.

Q. What is Agenda 21?

Answer : Agenda 21 is a programme run by the United Nations (UN) related to sustainable development. It is a comprehensive plan of action to be taken globally, nationally, and locally by organizations of the UN, governments, and major groups in all areas where humans impact the environment. Agenda 21 was revealed at the United Nations Conference on Environment and Development (Earth Summit), held in Rio de Janeiro on June 14, 1992, where 178 governments voted to adopt this programme. The number 21 refers to an agenda for the 21st century.

Q. Explain the environmental importance of waste management.

Answer : Waste management is crucial for several reasons:

• Public Health and Safety: Proper waste management helps prevent the spread of diseases and reduces health hazards. Improper disposal can contaminate soil, water, and air, leading to serious health issues.
• Environmental Protection: Effective waste management reduces pollution, conserves natural resources, and protects ecosystems. Recycling and proper disposal methods help minimize the negative impact on the environment.
• Economic Benefits: Waste management can create job opportunities and contribute to the economy. Recycling and waste-to-energy processes can generate revenue and reduce the costs associated with waste disposal.
• Sustainability: Managing waste properly ensures a cleaner and healthier environment for future generations. It promotes sustainable practices and helps in the conservation of resources.
• Compliance and Regulation: Proper waste management ensures compliance with local, national, and international regulations, helping avoid legal issues and penalties.

Q. Describe how segregation improves waste disposal.

Answer : Segregation refers to the separation of waste into different categories based on their nature. The most popular segregation is biodegradable and non-biodegradable wastes. In many countries, dustbins are categorized as biodegradable and non-biodegradable, where people’s participation is very important. They should throw waste in the proper dustbin so that it becomes easy to handle them separately. Segregation also includes sorting waste according to features like sharp-edged waste, inflammable waste, recyclable waste, infectious waste, and radioactive waste. This process makes waste disposal more efficient by ensuring that each type of waste is handled appropriately, reducing environmental harm and improving recycling efforts.

Q. Explain the proper method for waste disposal in a landfill.

Answer : For proper disposal in a landfill, the solid waste should be spread in thin layers. Each layer should be solidified by a bulldozer before the next layer is deposited. After every three meters, a layer of clean earth should be added and solidified by a bulldozer. Sites of landfills should be selected so that floodwater cannot reach there, and the underground water level should also be low. In all landfills, gases are generated but are released by venting methods. When large amounts of methane collect, it can be disastrous, so proper measures must be taken to manage gas emissions.

Q. Discuss the environmental impacts of incineration?

Answer : Incineration, a method of solid waste disposal, involves burning waste to reduce its weight and volume by 90%. However, it has certain environmental impacts:
(i) Modern incinerators control pollution using filter bags, precipitators, and wet scrubbers, but they still release smoke and ash into the air, contributing to air pollution.
(ii) New compounds may be formed during the burning process, which could have harmful effects on the environment.

Q. Explain the grit removal process in liquid waste treatment?

Answer : The grit removal process in liquid waste treatment is as follows:

(i) Grit chambers are settling tanks where inorganic and organic matter is separated.
(ii) Inorganic matter, such as sand, silt, gravel, and cinders (with particle sizes of 0.2 mm or more), is heavy and allowed to settle down.
(iii) Organic solid matter, being lighter, remains suspended in water and passes on to the next stage.
(iv) Modern grit chambers are spiral flow grit chambers with hopper bottoms and mechanical scrapper arms.
(v) After removal, the solid inorganic matter is treated as solid waste and taken to a landfill for disposal.

Q. Describe sedimentation methods used in wastewater treatment?

Answer : Sedimentation methods used in wastewater treatment involve the following steps:

(i) After grit removal, wastewater passes into a sedimentation tank where fine organic material settles down and is removed.
(ii) Two methods are used for quick sedimentation: coagulation and flocculation.
(iii) In the coagulation method, chemicals like aluminium sulphate and ferric chloride are added to the water to facilitate quick sedimentation.
(iv) In the flocculation method, solid material is allowed to merge into larger particles.
(v) Both methods help remove more than 80% of solid matter from the wastewater.

Q. Explain flotation as an alternative to sedimentation.

Answer : Flotation is an alternative to the sedimentation process in which air is forced into the wastewater. The pressure is maintained at 1.75 to 3.5 kg per sq cm. The wastewater then becomes supersaturated with air and is discharged into an open tank. The rising bubbles thus formed bring up the suspended particles to the surface where they are removed easily. More than 75 per cent of the suspended particles are removed in this process.

Q. What is the septic tank method of liquid waste disposal?

Answer : The septic tank method is a common method in which a tank is used to treat domestic sewage only. It is a concrete or metal tank with a submerged outlet. In this tank, the solid waste settles and floatable material rises. A liquid stream flows through the submerged outlet and percolates down to the soil. The floating matter and settled solids can remain there for about a year or so and get decomposed anaerobically.

Q. Explain the procedure of composting in detail.

Answer : Composting is a method of solid waste disposal and it requires time and patience. The waste is not only disposed but fertilizer is also made by a natural process.

(i) The waste, first of all, has to be segregated so that only those things are selected that can be decomposed like paper, wood, leaves, etc.
(ii) Things like plastic and glass cannot be composted so they are not used in composting.
(iii) The waste is layered in such a way that air can enter easily. A little water is added to the pile for easy decomposition.
(iv) After a few days the pile or heap is covered so that heat and steam can decompose the matter faster. After about three weeks it can be used as manure.

Q. Discuss the economic benefits of waste management.

Answer : Waste management can create job opportunities and contribute to the economy. Recycling and waste-to-energy processes can generate revenue and reduce the costs associated with waste disposal.

Q. Discuss the need for effective waste management?

Answer : The need for effective waste management is crucial for several reasons:

• Public Health and Safety: Proper waste management helps prevent the spread of diseases and reduces health hazards. Improper disposal can contaminate soil, water, and air, leading to serious health issues.
• Environmental Protection: Effective waste management reduces pollution, conserves natural resources, and protects ecosystems. Recycling and proper disposal methods help minimize the negative impact on the environment.
• Economic Benefits: Waste management can create job opportunities and contribute to the economy. Recycling and waste-to-energy processes can generate revenue and reduce the costs associated with waste disposal.
• Sustainability: Managing waste properly ensures a cleaner and healthier environment for future generations. It promotes sustainable practices and helps in the conservation of resources.
• Compliance and Regulation: Proper waste management ensures compliance with local, national, and international regulations, helping avoid legal issues and penalties.

Q. Explain liquid waste disposal methods, highlighting different treatment stages.

Answer : Liquid waste disposal involves several stages for proper treatment and safe disposal. The major sources of liquid waste include domestic and industrial discharges. The treatment stages are as follows:

• Primary Treatment : This is the initial stage of wastewater treatment. When wastewater enters the treatment plant, it usually contains a lot of solid material or debris which can damage the pumps and other equipment of the machinery. Screens or vertical bars are used to block the entry of this solid material which is then removed and burned. The wastewater then passes to the next stage.
• Grit Chamber : This chamber acts as a settling tank where inorganic and organic matter is separated. The inorganic matter consists of smaller solid materials such as sand, silt, gravel, and cinders, with particle sizes of 0.2 mm or more. This material is heavy and allowed to settle down. The organic solid matter, being lighter, remains suspended in water and is allowed to pass on to the next stage. Modern grit chambers are spiral flow grit chambers with hopper bottoms and mechanical scrapper arms. After the removal of solid inorganic matter, it is treated as solid waste and taken to landfill for disposal.
• Sedimentation : After the removal of grit at the second stage, the wastewater passes into the sedimentation tank. Here, the fine organic material settles down and is removed. Two methods used for quick sedimentation are coagulation and flocculation. In the coagulation method, chemicals like aluminium sulphate and ferric chloride are added to the water for quick sedimentation. In the flocculation method, the solid material is allowed to merge into one bigger particle. Both these methods help in removing more than 80% of solid matter.
• Floatation : It is an alternative to the sedimentation process where air is forced into the wastewater. The pressure is maintained at 1.75 to 3.5 kg per sq cm. The wastewater becomes supersaturated with air and is discharged into an open tank. The rising bubbles bring up the suspended particles to the surface, where they are easily removed. More than 75% of the suspended particles are removed in this process.
• Digestion : This is a microbiological process that converts the organic sludge to methane, carbon dioxide, and humus-like material. The reaction occurs in a closed anaerobic tank (without oxygen) known as a digester. First, the solid matter is made soluble by enzymes, and then acid-producing bacteria is poured for fermentation, reducing the matter to simple organic acids. These are converted into methane and carbon dioxide with the help of bacteria. Thickened sludge is heated in the digester for 10 to 30 days, reducing the matter by up to 60%.
• Drying : After the digestion of sludge, it is placed on sand beds for drying. Some water percolates into the sand, while some evaporates. This activity is known as dewatering and is more efficient in warm weather. Once dried, the sludge is used as a soil conditioner and sometimes as a fertilizer because it contains 2% nitrogen and 1% phosphorus.

Answer: Liquid waste disposal involves several stages for proper treatment and safe disposal. The major sources of liquid waste include domestic and industrial discharges. The treatment stages are as follows:

Primary Treatment: This is the initial stage of wastewater treatment. Wastewater usually contains solid material or debris that can damage equipment. Screens or vertical bars block this material, which is then removed and burned.
Grit Chamber: This chamber separates inorganic matter like sand, silt, gravel, and cinders (0.2 mm or more) by allowing it to settle. Lighter organic matter remains suspended. Modern grit chambers use spiral flow with hopper bottoms and mechanical scrapper arms. The removed grit is treated as solid waste and taken to landfill.
Sedimentation: After grit removal, fine organic material settles in a sedimentation tank. Coagulation (using chemicals like aluminium sulphate or ferric chloride) and flocculation (merging particles into bigger ones) help remove over 80% of solid matter.
Floatation: An alternative to sedimentation, air is forced into the wastewater at 1.75 to 3.5 kg per sq cm. Rising bubbles carry suspended particles to the surface, where over 75% are removed.
Digestion: A microbiological process converting sludge into methane, carbon dioxide, and humus-like material in an anaerobic digester. Enzymes and bacteria break down the matter over 10 to 30 days, reducing it by up to 60%.
Drying: After digestion, sludge is dried on sand beds (dewatering). Once dried, it can be used as a soil conditioner or fertiliser, containing 2% nitrogen and 1% phosphorus.

Q. Why is the reuse of materials crucial in waste management?

Answer : The reuse of materials is crucial in waste management as it is a practice of using a material again and again for its original purpose, which reduces the amount of waste generated. Reusing a thing is another method of waste management that helps minimize the volume of waste at the source. Many things can be sterilized and used again, such as office items like cartridges and ribbons. On a picnic or journey, disposable items can be replaced with washable items, reducing the amount of waste to be generated. Similarly, cloth napkins can be used instead of paper napkins.

53. Discuss the objectives and key features of the Environment Protection Act, 1986.

Answer : The objectives and key features of the Environment Protection Act, 1986 are: 

(i) This Act provides for the protection and improvement of the environment and other connected matters.
(ii) It takes appropriate steps for the protection and improvement of the human environment.
(iii) The Act lays down procedures to set standards for the emission of environmental pollutants.
(iv) It explains the prohibition and restrictions on the location and operation of industries in different areas.
(v) The Act lays down the procedure for taking samples, serving notice, submitting samples for analysis, and laboratory reports.

Additional MCQs

1. What is waste management?

A. Control reduction
B. Only disposal
C. Only recycling
D. Hazardous handling

Answer: A. Control reduction

Q. One objective of waste management is to:

A. Assess activities
B. Increase waste
C. Mix wastes
D. Ignore impacts

Answer: A. Assess activities

Q. Waste management deals with:

A. Generation, disposal
B. Only recycling
C. Only incineration
D. Only dumping

Answer: A. Generation, disposal

Q. The 3R’s of waste management are:

A. Reduce, Reuse, Recycle
B. Repair, Reuse, Recycle
C. Reuse, Recycle, Reproduce
D. Reduce, Repair, Reuse

Answer: A. Reduce, Reuse, Recycle

Q. Which method separates waste into different categories?

A. Segregation
B. Dumping
C. Composting
D. Incineration

Answer: A. Segregation

Q. Depositing waste in an open area is known as:

A. Incineration
B. Dumping
C. Composting
D. Segregation

Answer: B. Dumping

Q. Which disposal method produces fertilizer?

A. Incineration
B. Dumping
C. Composting
D. Segregation

Answer: C. Composting

Q. Burning waste to reduce its volume is called:

A. Composting
B. Dumping
C. Incineration
D. Segregation

Answer: C. Incineration

Q. Incineration reduces waste by approximately:

A. 50%
B. 90%
C. 70%
D. 30%

Answer: B. 90%

Q. Modern incinerators control pollution using:

A. Filter bags
B. Extra flames
C. Additional water
D. Extra air

Answer: A. Filter bags

Q. Allowing wastewater to flow via pipelines is known as:

A. Drainage
B. Digestion
C. Drying
D. Floatation

Answer: A. Drainage

Q. Which stage uses screens to remove large solids?

A. Primary treatment
B. Sedimentation
C. Grit chamber
D. Digestion

Answer: A. Primary treatment

Q. The grit chamber removes which matter from wastewater?

A. Organics
B. Inorganics
C. Foams
D. Chemicals

Answer: B. Inorganics

Q. Forcing air into wastewater to remove particles is called:

A. Floatation
B. Sedimentation
C. Digestion
D. Drying

Answer: A. Floatation

Q. Converting organic sludge to gas occurs in:

A. Digestion
B. Sedimentation
C. Primary stage
D. Floatation

Answer: A. Digestion

Q. During digestion, sludge typically remains for:

A. 1–5 days
B. 10–30 days
C. 40–50 days
D. 60–90 days

Answer: B. 10–30 days

Q. Removing water from sludge on sand beds is known as:

A. Digestion
B. Drying
C. Sedimentation
D. Floatation

Answer: B. Drying

Q. A septic tank is used mainly for treating:

A. Industrial sewage
B. Domestic sewage
C. Chemical waste
D. Gaseous waste

Answer: B. Domestic sewage

Q. Tall smokestacks in waste disposal primarily serve to:

A. Neutralise
B. Dilute
C. Condense
D. Capture

Answer: B. Dilute

Q. Trapping pollutants by spraying liquid into emissions uses an:

A. Electrostatic precipitator
B. Air scrubber
C. Incinerator
D. Grit chamber

Answer: B. Air scrubber

Q. Electrostatic precipitators remove:

A. Solid chunks
B. Liquid droplets
C. Suspended impurities
D. Biological agents

Answer: C. Suspended impurities

Q. In an electrostatic precipitator, high voltage ionises:

A. Water
B. Impurities
C. Dustbins
D. Filters

Answer: B. Impurities

Q. The collector electrode in an ESP collects:

A. Clean air
B. Ionised particles
C. Excess water
D. Uncharged waste

Answer: B. Ionised particles

Q. ‘Reduce’ means using:

A. Fewer resources
B. Reused items
C. Burnt waste
D. Mixed waste

Answer: A. Fewer resources

Q. ‘Reuse’ involves:

A. Discarding items
B. Using items again
C. Burning items
D. Breaking items

Answer: B. Using items again

Q. ‘Recycle’ converts waste into:

A. New products
B. More waste
C. Energy only
D. Water only

Answer: A. New products

Q. Scrap steel is recycled using the:

A. BOF
B. EAF
C. Grit method
D. Incinerator

Answer: A. BOF

Q. Aluminium beverage cans are recycled by:

A. Crushing, baling
B. Direct melting
C. Shredding only
D. Filtering

Answer: A. Crushing, baling

Q. Recycling plastics involves:

A. Shredding flakes
B. Direct melting
C. Crushing powder
D. Incinerating

Answer: A. Shredding flakes

Q. Recycled paper is produced by:

A. Pulping waste
B. Melting paper
C. Drying sheets
D. Incinerating

Answer: A. Pulping waste

Q. Scrap glass is known as:

A. Cullets
B. Residues
C. Debris
D. Fragments

Answer: A. Cullets

Q. The Environment Protection Act was enacted in:

A. 1986
B. 1972
C. 1992
D. 1999

Answer: A. 1986

Q. Biomedical Waste Rules were introduced in:

A. 1998
B. 1989
C. 1992
D. 1974

Answer: A. 1998

Q. Agenda 21 was adopted on:

A. June 14, 1992
B. December 3, 1984
C. January 1, 1990
D. July 4, 1996

Answer: A. June 14, 1992

Q. The Recycled Plastics Rules came into force in:

A. 1999
B. 1986
C. 1992
D. 2000

Answer: A. 1999

Q. The Motor Vehicles Act was passed in:

A. 1989
B. 1986
C. 1972
D. 1995

Answer: A. 1989

Q. The Basel Convention came into force in:

A. 1992
B. 1989
C. 1998
D. 1974

Answer: A. 1992

Q. Article 48A of the Constitution directs the state to:

A. Protect environment
B. Increase industry
C. Reduce recycling
D. Enhance waste

Answer: A. Protect environment

Q. Article 51A(g) mandates citizens to:

A. Protect nature
B. Ignore waste
C. Burn waste
D. Dump waste

Answer: A. Protect nature

Q. The National Council for Environmental Policy was set up in:

A. 1972
B. 1985
C. 1992
D. 1999

Answer: A. 1972

Q. The Ministry of Environment and Forests was established in:

A. 1985
B. 1972
C. 1992
D. 1999

Answer: A. 1985

Q. The Central Pollution Control Board is responsible for:

A. Pollution control
B. Waste incineration
C. Recycling only
D. Waste mixing

Answer: A. Pollution control

Q. State Pollution Control Boards handle:

A. Local pollution
B. Waste recycling
C. Energy saving
D. Only law enforcement

Answer: A. Local pollution

Q. Segregation means:

A. Keeping items separate
B. Mixing wastes
C. Burning wastes
D. Dumping wastes

Answer: A. Keeping items separate

Q. Biodegradable matter is:

A. Microbe decomposable
B. Indestructible
C. Recyclable only
D. Incinerable only

Answer: A. Microbe decomposable

Q. A dump is defined as:

A. Uncontrolled disposal site
B. Recycling plant
C. Compost facility
D. Treatment tank

Answer: A. Uncontrolled disposal site

Q. Composting is the process of:

A. Natural decomposition
B. Rapid burning
C. Manual sorting
D. Safe storage

Answer: A. Natural decomposition

Q. Incineration involves:

A. Controlled burning
B. Reusing items
C. Sorting wastes
D. Water treatment

Answer: A. Controlled burning

Q. Recycling means:

A. Recovering materials
B. Dumping wastes
C. Burning wastes
D. Compressing wastes

Answer: A. Recovering materials

Q. The Bhopal disaster occurred on:

A. December 3, 1984
B. June 14, 1992
C. January 1, 1990
D. July 4, 1985

Answer: A. December 3, 1984

Q. The Bhopal disaster claimed over:

A. 2000 lives
B. 500 lives
C. 100 lives
D. 10000 lives

Answer: A. 2000 lives

Q. The Bhopal incident released:

A. Lethal gas
B. Solid waste
C. Radioactivity
D. Chemical sludge

Answer: A. Lethal gas

Q. The company involved in the Bhopal disaster was:

A. Union Carbide
B. Dow Chemical
C. BASF
D. DuPont

Answer: A. Union Carbide

Q. Post-Bhopal lawsuits amounted to about:

A. $200 billion
B. $50 million
C. $1 billion
D. $500 million

Answer: A. $200 billion

Q. In landfill disposal, waste is spread in thin layers and solidified by a:

A. Bulldozer
B. Shredder
C. Conveyor
D. Compactor

Answer: A. Bulldozer

Q. In a landfill, after every three metres, a layer of clean earth is:

A. Added
B. Removed
C. Ignited
D. Compressed

Answer: A. Added

Q. Gases in landfills are released by:

A. Venting
B. Filtering
C. Incineration
D. Digestion

Answer: A. Venting

Q. Pyrolysis is the process to:

A. Decompose by heat
B. Segregate wastes
C. Filter water
D. Incinerate fully

Answer: A. Decompose by heat

Q. In composting, the waste pile is covered to:

A. Retain heat
B. Expose air
C. Reduce water
D. Block sun

Answer: A. Retain heat

Q. Sedimentation removes over what percent of solids?

A. 80%
B. 50%
C. 60%
D. 40%

Answer: A. 80%

Q. During floatation, the pressure is maintained at:

A. 1.75–3.5 kg/sq cm
B. 0.5–1 kg/sq cm
C. 5–7 kg/sq cm
D. 10 kg/sq cm

Answer: A. 1.75–3.5 kg/sq cm

Q. The digestion process reduces sludge by approximately:

A. 60%
B. 30%
C. 90%
D. 10%

Answer: A. 60%

Q. After the grit chamber, wastewater enters the:

A. Sedimentation tank
B. Digester
C. Drying bed
D. Septic tank

Answer: A. Sedimentation tank

Q. Grit accumulation in wastewater may range from:

A. 0.08–0.23 cu m
B. 1–2 cu m
C. 0.5–1 cu m
D. 0.01–0.05 cu m

Answer: A. 0.08–0.23 cu m

Q. Sedimentation uses chemicals like aluminium sulphate in the:

A. Coagulation method
B. Grit removal
C. Primary stage
D. Digestion process

Answer: A. Coagulation method

Q. In floatation, suspended particles are removed by:

A. Air bubbles
B. Chemicals
C. Filters
D. Sedimentation

Answer: A. Air bubbles

Q. The anaerobic tank used in digestion is called a:

A. Digester
B. Grit chamber
C. Septic tank
D. Settling tank

Answer: A. Digester

Q. Recycled plastics rules require carry bags to be at least:

A. 20 microns
B. 10 microns
C. 30 microns
D. 40 microns

Answer: A. 20 microns

Q. Virgin plastic carry bags must be in:

A. Natural shade/white
B. Bright colours
C. Transparent
D. Black only

Answer: A. Natural shade/white

70. Saving energy in waste management reduces pressure on:

A. Power resources
B. Landfills
C. Water supply
D. Transport systems

Answer: A. Power resources