Chapter 12 Waste Products Introductions
The throwaway products that are generated due to our day-to-day activity and are not required for any other activity are called waste products.
Examples: Plastic or glass bottles, cans, plastic/jute/paper carry bags, banana peels,
Classification Of Waste Products
The waste products may be classified on the basis of their
- Source,
- Chemical nature,
- Physical properties,
- Degradational ability etc.
Read And Learn More: WBBSE Notes For Class 6 School Science
Chapter 12 Waste Products On the Basis of the Source
On the basis of source, waste materials can be classified into 7 different types as detailed below:
1. Municipal waste:
This includes trash or garbage from households, schools, offices, marketplaces, restaurants and other public places.
They include everyday items like food debris, used plastic bags, soda & soft drink cans and plastic water bottles, broken furniture, grass clippings, product packaging, broken home appliances and clothing.
2. Medical/Clinical waste:
Medical/clinical waste normally refers to waste produced by healthcare facilities, such as hospitals, clinics, surgical theatres, veterinary hospitals and laboratories.
They tend to be classified as hazardous waste rather than general waste. Items in this group include surgical items, pharmaceuticals, blood, body parts, wound dressing materials, needles and syringes.
3. Agricultural waste:
Typically, this is waste generated by agricultural activities. These vegetable peels, old blades, rotten food items, old electronic items etc.
These include horticulture, fruit growing, seed growing, livestock breeding, markets, gardens and seedling nurseries.
Waste items in this group include empty pesticide containers, old silage wrap, out-of-date medicines and wormers, used tyres, surplus milk, cocoa pods and corn husks.
4. End-of-life Automobiles:
When cars stop working, where do they end up? Many people just leave them to rust in the fields, but there is a better way to deal with them.
In many cities, these vehicles are sent to the plant, where all the removable parts are taken out for recycling.
The rest is flattened up and shredded into pieces for recycling. The last bits that cannot be used again are sent to a landfill.
5. Industrial waste:
Since the industrial revolution, the rise in the number of industries manufacturing glass, leather, textile, food, electronics, plastic and metal products has significantly contributed to waste production.
Take a look at the things in your home, every item was manufactured and one day it will be of no use, and waste will be produced as a result.
6. Construction/demolition waste:
Construction waste is that resulting from the construction of roads and buildings. Sometimes old buildings and structures are pulled down (demolished) to make space for new ones.
This is particularly common in old cities, that are undergoing modernization. This is called demolition waste.
Waste items include concrete debris, wood, earth, huge package boxes and plastics from the building materials etc.
7. Electronic or e-waste:
This is waste from electronic and electrical devices. Think of DVD and music players, TV, telephones, computers, vacuum cleaners and all the other electrical stuff in your home.
These are also called e-waste, e-scrap, or waste electrical and electronic equipment (WEEE). Some e-waste (like TV) contains lead, mercury, cadmium, and brominated flame retardants.
These are TIS harmful to humans and the environment. It is therefore important that the right authorities ensure the proper disposal of such waste.
Chapter 12 Waste Products On the Basis of Chemical Nature
On this basis, waste materials can be classified as inorganic and organic.
1. Inorganic waste:
It includes the different inorganic salts and processed compounds that are produced as by-products in less industrial processes like salts of heavy metals including copper, iron, chromium, etc.
2. Organic waste:
These are complex organic compounds generated from rubber, nylon, elo paint, etc. Organic wastes also contain complex hydrocarbons.
Chapter 12 Waste Products On the Basis of Physical Nature
On this basis, the waste material can be classified as solid waste, liquid waste and gaseous waste.
1. Solid waste:
Solid wastes include metallic and non-metallic waste including plastic, glass, and paper, which are disposed of in a landfill or maybe incinerated at high temperatures.
2. Liquid waste:
They include water-soluble compounds, or simply organic solvents. If these are added to a water body, it causes water pollution and reduces the oxygen level of the water body.
3. Gaseous wastes:
These are oxides of carbon, sulphur, nitrogen, several toxic hydrocarbons, aerosols, methane and green. house gases like CFC (chlorofluorocarbon).
These are largely emitted from factories, chemical plants, vehicles etc.
Chapter 12 Waste Products On the Basis of Degradational Ability
On this basis, the waste products can be classified as non-biodegradable and biodegradable.
1. Non-biodegradable waste:
This waste product cannot be recycled by the normal microbial degradational process, it includes plastic, heavy metals etc.
2. Biodegradable waste:
These materials. include household products which may be vegetables or cooked food materials that are easily degraded by microbes. It also includes agricultural waste.
Chapter 12 Waste Products Waste Management
It is the collection, transport and disposal of garbage, sewage and other waste products.
Waste management encompasses the management of all processes and resources for proper handling of waste materials, maintenance of waste, and transportation by trucks and dumping facilities in compliance with health codes and environmental regulations.
The four principles (4R process) of waste reduction are Reduce, Reuse, Recycle, and Refuse.
1. Reduce:
Those waste products which increase garbage in our environment should be reduced on day to day basis, for example, plastic bags, thermal, plastic bottles etc.
2. Reuse:
Reusing the waste materials instead of discarding them, for example, vegetable peels, rechargeable batteries, etc.
3. Recycle:
This involves making new useful products from waste products, for example, plastic toys, old iron, glass materials, papers, aluminium, etc.
4. Refuse:
People should learn to refuse to accept such materials which would eventually produce non-biodegradable
Chapter 12 Waste Products Waste Recycling Processes
Recycling is processing used materials (waste) into new, useful products. This is done to reduce the use of raw materials that would have been used.
Recycling also uses less energy and great way of controlling air, water and land pollution.
Effective recycling starts with the household (or the place where the waste is created). In many serious countries, the authorities help households with bin bags with labels on them.
Households then sort out the waste themselves and place them in the right bags for collection. This makes the work less difficult.
Waste items that are usually recycled include:
1. Paper waste:
Paper waste items include books, newspapers, magazines, cardboard boxes and envelopes.
Recycling of Paper Waste:
1. Collection, transportation and storage:
The biggest task for paper recycling companies probably includes the collection, transporting and sorting of waste paper.
This is because we always add paper to other waste items and get them contaminated with food, plastic and metals.
Sometimes collected paper is sent back to the landfills because they are too contaminated to use.
Waste paper should be kept in separate grades at home or in the office, for example, newspapers and corrugated boxes should not be mixed.
All paper recovered is sent to the recycling centre, where it is packed, graded, put into bales and sent to the paper mill. At the mill, all the paper is stored in a warehouse until it is needed.
2. Repulping and Screening:
From the storage shelves, they are moved into a big paper grinding machine called a vat (pulper).
Here the paper is chopped into tiny pieces, mixed with water and chemicals and heated up to break it down into organic plant material called fibre.
After that, it is screened to remove contaminants such as bits of plastic and globes of glue.
3. Deinking:
This involves ‘washing’ the pulp with chemicals to remove printing ink and glue residue.
Sometimes, a process called floatation is applied to further remove got stubborn stains and sticky substances.
Floatation involves the use of chemicals not and air to create bubbles, which absorb the art stickies in the pulp.
4. Refining, Bleaching and Colour Stripping:
Refining involves beating the recycled pulp to make them ideal for paper-making.
After refining, additional chemicals are added to the bay to remove any dyes from the paper. It is then bleached to whiten and brighten it up.
5. Papermaking:
At this stage, the pulp is ready to be used for manufacturing paper. Sometimes new pulp (virgin pulp) is added to give it extra strength and smoothness.
Water is added to the pulp and sprayed onto a large metal screen in continuous mode. The water is drained on the screen and the fibres begin to bond with each other.
As it moves through the paper-making machines, press rollers squeeze out more water, heat them dry and coat them up. They are then finished into rolls.
2. Plastic waste:
Items include plastic bags, water bottles, rubber bags and plastic wrappers. They cannot be degraded so bio-plastic may be used, which is degraded by bacterial enzymes. The reuse of plastic is highly recommended.
3. Glass waste:
All glass products like broken bottles, beer and wine bottles can be recycled.
1. Recycling of Glass:
Recycling glass starts in your home. There is a reason why many 916 local councils provide different containers for green, brown, plain glass and even glass hot from broken windows.
The reason is that they are all made very differently and mixing them can create huge problems at the recycling centre.
2. Collection:
Many cities have collection spots. Trucks may also pick them up from your home, or you may be required to drop them off at a point in your town.
In all cases, try to do what the authorities have suggested. So, be sure you know the various glass types that are collected from your home.
They are washed and separated into the required grades for collection.
3. Cleaning and Crushing:
The glass is transported to the processing plant, where contaminants such as metal caps and plastic sleeves are removed.
Different grades are treated separately. Clean glass is then crushed into small pieces called cullet. Cullet is in high demand from glass manufacturers.
It melts at a lower temperature and it is cheaper than raw glass materials.
4. Ready for use:
The cullet is then transported to glass-making factories. Here, it is mixed with sand, soda ash and limestone.
It is heated at a very high temperature and melted into liquid glass. This liquid is then poured into moulds that give glass its shape.
Glass is used for many things, depending on what grade they were recycled from. A few items made of recycled glass include fibre-glass, countertops, bottles and jars.
4. Aluminium waste:
Cans from soda drinks, tomatoes, fruit cans and all other cans can be recycled.
When these are collected, they are sent to the recycling unit, where all the waste from each type is combined, crushed, melted and processed into new materials.
1. Aluminium recycling:
In recent times, there has been a massive improvement in recycling aluminium cans. Those cans, hoil-placed end-to-end, could make 171 circles around the earth.
Every minute, an average of 105,800 aluminium cans are recycled. It is clear that can recycling is very important in the present life.
2. Collection:
People may use special cans. recycling containers (bins) that are clearly marked. This helps people to know what to place in them.
Can include soda, fruit and vegetable cans. Trucks come for these at pick-up spots at the recycling centres. Cans may also be metallic or steel, but usually, common people do not know the difference.
3. Preparation:
At the collection centre, a huge magnet is rolled over them as they move on the conveyor belt to pull out all the metal and steel cans.
Only the aluminium cans are washed, crushed, and condensed into 30 pounds. briquettes for other companies for further processing. The rest is also sorted and sent to their appropriate recycling centres.
4. Melting:
The crushed cans are loaded into a burning furnace, where all printing and designs on the cans are removed, melted and blended with new (virgin) aluminium.
The molten (liquid) aluminium is poured into moulds and made into bars called ingots.
5. Sheets:
The ingots are then fed into powerful rollers, which flatten them into. thin sheets of aluminium. These thin sheets are rolled into coils and sold or sent to can-making factories.
They use aluminium coils to prepare cans and containers for other food and drink manufacturers.
It is estimated that cans collected at collection points take up to 60 days to reappear in the shops again as new cans containing your favourite soda, juice or food.
Chapter 12 Waste Products Importance and Benefits of Waste Recycling
1. Recycling helps to protect the bar environment:
Had recycling not been done, these waste materials would have otherwise been burned or ended up in the landfill. Thus pollution of the air, land, water and soil is reduced through recycling.
2. Recycling conserves natural resources:
Recycling more waste means that we do not depend too much on raw (natural) resources, which are already massively depleted. This enormously preserves natural earthly resources.
3. Recycling saves energy:
It takes more energy to produce items with raw materials than from recycled used. materials. This means that recycling is more energy efficient and so, the prices of products can come down through this.
4. Recycling metals reduces the cost of processing from ores.
5. Recycling plastic can straight away reduce the menace of plastic pollution, protecting the microbes from getting killed due to the mulching effect.
6. The waste products generated from a particular industry can be used by other industries developing along with it, thus developing the economy of the country.
