Frank Brothers Solutions for ICSE Class 9 Biology Chapter 23 Safe Disposal Of Wastes

PAGE NO: 212

Question 1:
Answer: The important steps in waste management are:
1. Dematerialization of production by reducing the amount of raw materials use and energy used in production.
2. Recycling wastes back into the production process.
3. Recovery of some ingredients and / or treatment of wastes.
4. Dispersal, dumping or storage.
Effective waste management helps us move towards a "zero waste" society by reusing materials. This systematic approach prevents environmental pollution and conserves natural resources.
Teacher's Tip: Think of the "3 Rs" (Reduce, Reuse, Recycle) plus "D" for Disposal to remember these four steps easily.
Exam Tip: List the steps in the exact order shown to demonstrate a logical flow from production to final disposal.

Question 2:
Answer: Following are the measures adopted to prevent the spread of disease from sewage water:
Sewage water must be disposed off in a suitable manner to prevent large scale outbreak of diseases and toxicity to living organisms.
They should not be allowed to collect in the open.
Sewage should be treated in sewage treatment plants wherein the pathogens are destroyed.
Proper sewage disposal is a vital part of public health infrastructure. It ensures that contaminated water does not reach our drinking sources or residential areas.
Teacher's Tip: Imagine sewage like a "germ highway" - we need to block its path so it doesn't reach us.
Exam Tip: Use the word "pathogens" instead of "germs" to give your answer a more scientific and professional tone.

Question 3:
Answer: Two advantages of garbage incineration are:
1. Incineration reduces the weight and volume of the waste by as much as 95%.
2. It helps in the treatment of clinical wastes and toxic pathogens.
3. It is designed in such a way that it can be also used to produce electricity. (Write any two)
Incineration is an efficient way to handle large amounts of waste in crowded cities where land for dumping is scarce. It turns bulky trash into small amounts of ash while generating useful power.
Teacher's Tip: Remember that "Incineration" means "burning at very high heat" - it’s like a giant high-tech fireplace for trash.
Exam Tip: Mentioning the specific percentage "95%" helps show you have studied the textbook details carefully.

Question 4:
Answer: Composting is an effective way of disposing of wet garbage from households and biomass wastes from gardens.
The processes involves in composting are:
Vegetable peels, fruit peels, food-scraps, twigs, dry leaves, grass clippings can be dumped into a pit or a big bin.
Then soil is spread over this pile.
Earthworms can be introduced into the compost pit to decompose the organic matter which enrich the compost. This method is called vermi-composting.
The soil microbes break down the organic matter.
The compost obtained is rich organic manure for the plants in the garden.
Composting turns kitchen scraps into "black gold" for plants by recycling nutrients back into the earth. It is a natural process that reduces the amount of waste sent to landfills.
Teacher's Tip: Think of earthworms as "nature's tiny recyclers" that work day and night for free!
Exam Tip: Clearly define "vermi-composting" as the use of earthworms to gain extra marks for technical vocabulary.

Question 5:
Answer: Sewage water is treated in three steps:
1. Primary treatment - In this, the coarse and fine suspended , solids are removed by sedimentation, coagulation and precipitation.
2. Secondary treatment - It is essentially a biological treatment process which involves the removal of colloidal and dissolved organic substances and some toxic chemicals.
3. Tertiary treatment - Here, excess nutrients are removed to allow the reuse of that water.
These three stages ensure that wastewater becomes safe enough to be returned to nature without causing harm. The process moves from physical filtering to biological cleaning and finally to advanced chemical purification.
Teacher's Tip: Remember "P-S-T" - Physical (Primary), Small microbes (Secondary), and Total cleaning (Tertiary).
Exam Tip: For full marks, mention that secondary treatment is "biological" and primary involves "sedimentation."

Question 6:
Answer: An electrostatic precipitator removes particulates of less than 50mm size. The particulates are electrically charged and then attracted to oppositely charged plates for collection. The vibration of these plates removes the particulate matter to the bottom and the pollutant free air then escape to join the atmosphere.
Diagrammatic view of the working of electrostatic precipatator
This device acts like a giant magnet for smoke and dust particles inside factory chimneys. It significantly reduces air pollution by catching tiny bits of soot before they can float away into our air.
Teacher's Tip: Use the phrase "Opposites Attract" to remember how charged particles are pulled toward the collection plates.
Exam Tip: If asked to explain this, mentioning that it targets particles "less than 50mm" shows you know the technical specifications.

Question 7:
Answer: Segregation is the separation of wet and dry wastes in order to dispose them safely. Household wastes consist of organic biodegradable matter as well as non biodegradable matter. They should be segregated from each other using separate bins. Wherever possible, the non-biodegradable matter is recycled and used. The organic biodegradable matter i.e. wet waste must be separated from other dry wastes. They are collected by municipal workers and transported to a landfill.
Separating trash at the source makes it much easier to recycle plastics and metals while composting food waste. It prevents clean dry materials from getting ruined by messy wet waste.
Teacher's Tip: Remember the two-bin rule - Green for "Green" (organic) stuff and Blue for "Dry" (recyclable) stuff.
Exam Tip: Use the terms "biodegradable" and "non-biodegradable" to accurately categorize the two types of waste.

Question 8:
Answer: Two uses of incineration are:
1. Incineration reduces the weight and volume of the waste by as much as 95%.
2. It helps to destroy pathogens and toxins using high temperature, thereby playing role in the treatment of clinical wastes and certain hazardous wastes.
Incineration is particularly useful for medical waste like bandages and needles because the high heat kills all harmful bacteria instantly. This prevents the spread of infections that could occur if such waste was simply buried.
Teacher's Tip: Think of incineration as a "Super-Sterilizer" that uses fire to make hazardous waste safe.
Exam Tip: Mentioning "clinical wastes" is important because incineration is the preferred method for medical disposal.

Question 9:
Answer: Most liquid wastes contain both dissolved and suspended matters. Treatment of such effluent involves the removal of contaminants and is done to prevent any adverse effects on receiving water or allow its reuse. Three steps are usually followed in the treatment of effluents:
Sewage water is treated in three steps:
1. Primary treatment - In this, the coarse and fine suspended solids are removed by sedimentation, coagulation and precipitation.
2. Secondary treatment - It is essentially a biological treatment process which involves removal of colloidal and dissolved organic substances and some toxic chemicals.
3. Tertiary treatment - Here, excess nutrients are removed to allow the reuse of that water.
Industrial and municipal liquids must go through this thorough cleaning process to protect our rivers and oceans. Each step removes a different layer of pollution until only clean water remains.
Teacher's Tip: The word "Effluent" is just a fancy scientific name for liquid waste or sewage flowing out of a pipe.
Exam Tip: Be sure to distinguish between "dissolved" and "suspended" matter as both are targeted during treatment.

Question 10:
Answer: The two ecofriendly ways of treating kitchen wastes are:
1. Composting
2. Segregation of wet and dry waste.
These methods are considered "eco-friendly" because they use natural processes and enable recycling. They help reduce the carbon footprint of a household by minimizing the trash that goes to huge city dumps.
Teacher's Tip: "Eco-friendly" means a method that is a friend to the "Ecology" or nature.
Exam Tip: If asked for "two ways," always provide these specific two as they are the most fundamental textbook answers.

Question 11:
Answer: Two benefits of composting are:
1. It is an eco-friendly method of disposing wet garbage from households and biomass wastes from gardens.
2. The compost obtained acts as rich organic manure for the garden plants.
Composting essentially turns trash into treasure by creating free fertilizer for your home garden. It also keeps moisture in the soil, which helps plants grow stronger during dry weather.
Teacher's Tip: Think of compost as "Vitamins for Plants" that you make right in your backyard.
Exam Tip: Emphasize that it is both a disposal method and a production method (manure) to show its double benefit.

Question 12:
Answer: (i) (a) microorganisms
(ii) (d) garbage and sewage sludge
(iii) (c) both (a) and (b)
(iv) (b) secondary treatment
These answers identify the key biological and physical components used in modern waste cleaning technology. For example, secondary treatment relies heavily on microorganisms to eat up organic pollution.
Teacher's Tip: In biology, remember that "microorganisms" are the main workers during any biological treatment phase.
Exam Tip: In multiple choice questions, read all options (a, b, and c) carefully before choosing "both (a) and (b)."