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Jan 2, 20216 min read

Starting the year with learning the W of the World of Waste

Updated: Jan 3, 2021

Waste, an inevitable consequence of our way of life, is an issue of critical importance. Today, the term is discussed with much sophistication, where the humungous threat it is posing on earth is condemned and contemplated upon. In order to fix things right globally and to also come up with local solutions to the different problem associated with waste issues found around us, the most essential pre-requisite is having your basics clear. One should be aware of the nature of different kinds of waste, the environmental damage they cause on earth and the most efficient way they can be managed and disposed off. Here, MH Vatavaran's 'Project Zero Waste' associates, Nancy, Raveena and Aditi Choudhary present to you an elaborate discussion on the same, which will not only brush up your school memories but would also provide a recourse of fundamentals and interesting factoids you can always come back to.

Waste is nothing but unwanted or unusable materials which is the outcome of exhaustion of things which were once of some use to us. Waste is classified on the basis of different parameters, which can be recyclability or non-recyclability of waste, organic waste, E-waste, wet waste, dry waste, hazardous, non hazardous etc. However, all these kinds of waste can be broadly put under the the following categories-

Liquid waste

Liquid waste is the only kind of waste which is caused due to the other wastes (gaseous, solid, etc.). The contamination of liquid or water with the solid waste and the conversion and mixture of harmful gaseous substances into liquid is known as liquid waste. Liquid waste is originally produced by the solid and gaseous wastes when they are added to stream water or absorbed by groundwater.

Industrial wastewater

ü Generated by manufacturing processes

ü Result of discharge of waste in rivers and other water channels

Domestic wastewater

ü Water discharged from homes

ü Commercial complexes

ü Hotels

ü Educational institutions.

Effects on environment

● Alters water's chemical composition

● Seeps through soil into groundwater, contaminating soil, making it infertile.

● Impacts air quality, like foul smells are common with liquid waste pollution, particularly with sewage systems.

● Disrupts aquatic ecosystems and marine life.

Disposal of Liquid waste:

Composting

Liquid waste which is organic, can be turned into compost. After removing the water, the remaining organic waste can be turned into an organic fertilizer, which contains nutrients such as nitrogen, potassium and sodium. This organic fertilizer increases the productivity of fields and also decreases the harmful effects of pesticides.

Root zone

Used for liquid wastes such as bathroom and kitchen water where liquid waste first passes through a sedimentation tank and then filtered with different processes before it is released into the nature when it is pure enough. It is a complex, but very effective method.

Solidification

Before transporting liquid waste into landfills, it undergoes the process of solidification. It generally involves adding fly ash, sawdust or lime dust to liquid waste. Safer technology is to turn liquid waste into solid waste without increasing its volume. This method is an easier way of disposal.

Solid Waste

Solid waste is any garbage, sludge, and refuse found in residential, industrial and commercial locations. The culture and socioeconomic level of communities determines the solid waste composition. The major types of solid rubbish are Glass and Ceramics, Non-recyclable Plastic waste, Paper rubbish, Metals and Tins, Debris, Organic household waste, E-waste

Effects on environment:

● Exhaust from open burning in dump sites or incineration are major sources of air pollution.

●The growth of bacteria, flies, and rodents in dump sites cause potential harm to human lives.

● Emissions of methane or carbon dioxide, the greenhouse gases, damage the atmosphere and trap more sunlight, leading to rise in temperature.

● Uncontrolled leachate in dump sites causes the irreversible contamination of groundwater.

● Bad odor from waste attracts all kinds of mosquitoes, germs etc.

Disposal of Solid waste

Solid wastes sanitary landfills

In this method, layers are compressed with some mechanical equipment or machines and covered with a layer of soil and then leveled and compacted. A deep trench of 3 to 5m is excavated Buried waste should not come in contact with surface water or groundwater. For this, bottom and cap liners may be made of flexible plastic membranes, layers of clay soil, or a combination of both. Micro-organisms act on organic matter and degrade it. Facultative bacteria hydrolyze complex organic matter into simpler organic.

Salvaging

Salvaging is the process of controlled removal of waste for proper utilization like recovery, reuse and recycling. Waste materials collected by waste pickers can be the raw material for various industries. Materials such as metal, paper, glass, rags, types of plastic and so on can be salvaged for recycling and reuse, reclamation and recovery.

Incineration and Waste to Energy PIants

Incineration is the process in which substances undergo combustion at high temperature under controlled conditions. Heat given off during incineration can be recovered by using refractory-lined furnace coupled to a boiler. Boilers convert the heat into steam or hot water, which is used for production of energy. Incinerators that recycle heat energy in this way are called waste-to-energy plants. Non- recyclable waste such as plastic, packaging ceramics, mirrors, plastic cups and disposable cutlery, plastic cartons – unless specified, crisp packets, cling film etc. are used as fuel in Waste to energy plant.

Constructing roads out of plastic

Plastic waste items like plastic carry bags, disposable cutlery, plastic bottles, plastic cups, plastic packaging for potato chips, biscuits, chocolates, etc. can be used for road construction. Plastic is durable, chemical resistant, odorless, unbreakable and light weighted. Plastic wastes are first shredded into a particular size using a shredding machine. This shredded plastic is heated and then mixed with heated bitumen at 160-170 °C resulting in good binding with stone which can be used for making roads. For every kilo of stone, 50 grams of bitumen and 1/10th of plastic is used. This decreases the use of bitumen and it also reduces plastic waste. Similarly, plastron blocks are made from granite, ceramic and plastic waste which are used for flooring , a substitute to cement blocks and it is resistant to water penetration.

Hazardous Waste

Hazardous wastes are the most dangerous wastes taking the form of solids, liquids, sludges or contained gases. Primarily, they are generated through chemical production, manufacturing and other industrial activities. Due to inadequate storage, transportation, treatment or disposal operations of these wastes, they can be potentially harmful and disastrous. If these wastes are dumped in the vicinity of residential areas, they can cause irreparable damage among humans. This category of waste includes :

Toxic waste
Corrosive waste
Radio Active Waste

Ignitable Waste
Infectious Waste

Effects on environment:

Radioactive materials persist in the environment for thousands of years as it may not decay quickly.
Corrosive wastes cause chemical reaction which destroy solid material and living tissue upon contact,
Being chemically unstable, reactive wastes react violently with air or water which lead to explosions or formation of toxic vapors.
Burning at relatively low temperatures, ignitable wastes may cause an immediate fire hazard.
In addition to acute effects causing death or sudden illness, toxic wastes may have chronic effects, slowly causing irreparable and irreversible harm. Some are carcinogenic or mutagenic, thereby causing cancer in later stages of life after exposure to it or major biological changes in the offspring of exposed humans and wildlife, respectively.

Disposal of Hazardous waste

Hazardous waste treatment is done by chemical, thermal, biological, and physical methods.

• Chemical methods include oxidation, reduction, neutralization, ion exchange and precipitation.

• Thermal method is incineration with high temperature. It detoxifies certain organic wastes and can even destroy them. Special types of thermal equipment can be used for burning waste in solid, liquid, or sludge form.

• Biological treatment of certain organic wastes such as waste from petroleum industry can be done through various techniques. e.g. Landfarming(In this method, waste is mixed with surface soil on a suitable land. Microbes and some genetically modified bacterial species can be added that metabolize the waste along with nutrients).

• Physical treatment concentrates or reduces the volume of waste. It include evaporation, sedimentation, flotation, and filtration. Underground dumping (at deep level) and dumping in sea is done after treatment.

Epilogue

There is a wide variety in the kind of wastes generated as a result of evolution and urbanization of human civilization throughout the world. The availability of different kind of products which make our lives comfortable comes at the cost of different types of wastes in our surroundings with their own unique damaging potential. However, what is waste for one group of individuals can be useful for another group.

Figure depicting composition of total waste generated in Organization for Economic Co- Operation and Development Region (OECD) in the world.

The waste materials can be converted into products which can be reused through recycling by using the waste as a raw material for different items. This can reduce energy consumption, further pollution of water and landfills and the need for waste disposal. Recyclable waste such as scrap material is recycled through waste collectors and recycling companies. Steel is the most recycled material on the planet. Other highly recycled metals include aluminum, copper, silver, brass and gold. Paper items such as books, notebooks, cardboard, newsprint , magazines, manuals and booklets, assorted office papers etc. can be recycled in paper recycling plants.

However, not all kinds of products can be recycled. Paper coated with metals or plastic (mixed waste) is non-recyclable. Such type of shiny, glittery wrapping paper should be replaced with other alternative recyclable options. Waste which is non recyclable is used as fuel in waste to energy plants and yet this method has proved itself inefficient due to improper segregation of waste at source. To contribute efficiently towards waste management in our surroundings, it is important that we remain informed about different kinds of waste and their proper disposal methods.