Solid Waste Management | Civil Engineering Optional Notes for UPSC PDF Download

What is Solid Waste Management?

One of the control measures to prevent the negative impacts of solid waste is proper management of solid wastes. Waste can be defined as substances that are disposed of or are disposed of according to the provisions of law. Depending on the physical states of wastes, there are two types of wastes – solid and liquid wastes.Solid wastes

• Solid wastes are any disposed materials that have resulted from industries, commercial uses, mining, agricultural and household or community activities.
• In order to classify waste as non-liquid/solid, it must have 20% of its content as solid and must not liberate any liquids while transporting it.

The collection, treatment, and disposal of this solid waste in a proper manner is called solid waste management.

Liquid waste

• Liquid waste is defined as wastewater, fats, oils or grease (FOG), or sludges and hazardous household liquids that are harmful or potentially harmful to humans or the environment.

In this article, let us learn in detail about solid waste management. Read on to know more.

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Types of Solid Waste

Hazardous Waste
Wastes that are hazardous can be classified based on their impact on the environment and human health. These include substances from industries and hospitals that are toxic. The Resource Conservation and Recovery Act has identified four main characteristics of hazardous waste: reactivity, ignitability, corrosivity, and toxicity.

• Reactivity: Unstable substances that can cause explosions and release toxic fumes when in contact with water.
• Ignitability: Substances that can easily catch fire and burn vigorously.
• Corrosivity: Substances with pH levels below 2 or above 12.5 that can corrode metal surfaces.
• Toxicity: Substances that are harmful or lethal to humans.

Examples of hazardous wastes include pesticides, insecticides, paints, cleaners, batteries, kerosene, chlorine bleach, prescription drugs, mothballs, fire extinguishers, toilet cleaners, medical waste, and radioactive waste.

Non-Hazardous Waste

Waste that does not harm people's health or the environment directly and whose disposal is less stringent is called non-hazardous waste. This waste can be divided into two kinds:

• Municipal solid waste: This is commonly known as the garbage or trash that we collect at a domestic level from homes, schools, commercial level, and clinics. This includes everyday items like paper, newspaper, food waste, glass, furniture, clothing, plastics, etc. The high level of urbanization today has increased the level of municipal solid waste that is generated these days. Items like construction waste, automobile bodies, combustion ash, industrial wastes, and municipal sludges are not included in municipal solid waste even if these wastes are disposed of in municipal landfills or incinerators.

Municipal solid waste In simpler terms, non-hazardous waste refers to waste that does not directly harm people or the environment and is easier to dispose of. It can be divided into two main types. One type is municipal solid waste, which includes everyday items like paper, food waste, and plastics that we throw away at home, school, or work. Despite its name, municipal solid waste doesn't include construction waste or industrial byproducts, even if they end up in the same disposal sites. The amount of municipal solid waste has increased due to urbanization.

Solid Waste Characteristics

• Non-municipal solid waste: Agricultural waste, construction waste, automobile bodies, combustion ash, mining wastes, industrial wastes, and municipal sludges are the main components of the non-municipal solid waste.

Non-municipal solid waste
If you are reading the Solid Waste Management article, also read about Quality of Water here.
In order to have a better understanding of solid waste, we can analyze its characteristics in two parameters –

Physical Characteristics

• Density: It is defined as the mass per unit volume. The densities of solid wastes vary with location, duration of time in storage, the season of the year, etc. If a certain amount of waste needs to be disposed of in a landfill, it needs to be compacted or reduced to an optimum density. Any normal compaction can reduce the volume of wastes by 75%, thereby increasing the density manifold. So, 100 kg/m3 becomes 400 kg/m3 in density after compaction. Note: the compaction ratio is not more than 1.5:1. Changes in density can occur due to disposal, scavenging, wetting, drying, handling, etc.

• Density is the measure of mass per unit volume. The density of solid wastes can vary based on factors like location, storage time, and season. To dispose of waste in a landfill efficiently, it should be compacted to an ideal density. Regular compaction can decrease waste volume by 75%, significantly increasing density. For instance, 100 kg/m3 can become 400 kg/m3 post-compaction. Changes in density may result from disposal methods, scavenging activities, moisture content alterations, and handling procedures.

• Moisture is the ratio of the water weight to the total weight of the waste. The moisture content in solid waste is not more than 20%. The formula for moisture content is (Wet weight - dry weight) / Wet weight x 100.

• The size of waste varies from particle size, small size, medium, large to huge. Size can be calculated by various formulas such as Size = length of the waste component in mm, or Size = (Length in mm width in mm) / 2, or Size = (Length in mm width in mm height in mm) / 3.

• Solid wastes can have different optical properties. They can be opaque like bricks, woods, batteries, etc., translucent like tissues, butter paper, frosted glass, or transparent like glass and plastic sheets.

Solid Waste Properties

• Magnetic Property: Solid wastes with metallic contents that have magnetic properties and can easily be separated by magnetic separators like batteries, iron rods, etc.

• Combustibility: A solid waste which has ignitability as one of its properties is combustible in nature. For example, wastes like paper, leaves, matchbox, etc. Solid wastes that are non-combustible include glass, ceramic, metal, dust, and ash.

Combustibility

• Contents: The chemical content of most dry solid wastes includes carbon, hydrogen, nitrogen, sulphur, and oxygen. Metals may also be present in some solid waste.

Contents

• Volatility: Represents the part of waste that turns into vapor when burned. In the case of typical municipal solid waste, the volatility rate falls within 40% to 60%.
• Volatility: Describes the segment of waste that transforms into vapor during combustion. For regular municipal solid waste, the volatility rate varies from 40% to 60%.

Volatility

• Lipids, carbohydrates, proteins, natural fibers, and plastics contribute to the composition of solid wastes, altering the chemical composition based on their varying percentages.
• Explore more on Sewage and its types in this linked article.

Sources of Solid Waste

• There exist numerous origins of solid wastes, with the primary ones being:
• Household
• Commercial
• Institutional
• Construction & demolition
• Municipal Services
• Treatment plant sites
• Industrial
• Agricultural
• Biomedical

Methods of Solid Waste Management & Treatment of Solid Waste

There are various methods of solid waste management. The most recognized ones include:

• Landfill: A common method where waste is buried underground in designated areas.
• Incineration: The process of burning waste at high temperatures to reduce its volume and convert it into energy.
• Recycling: The practice of processing waste materials to create new products, reducing the need for raw materials.
• Composting: The natural decomposition of organic waste to create nutrient-rich soil for gardening.
• Waste-to-Energy: Converting non-recyclable waste into energy through various processes like thermal treatment.
• Solid Waste Collection: Collection refers to how solid wastes are gathered for disposal. It should be done regularly without overloading storage systems. Municipalities collect waste daily and transport it to disposal sites.
• Separation: This involves manually sorting solid waste before disposal, like separating dry from wet waste or biodegradable from non-biodegradable waste.
• Sanitary Landfill: The most common waste disposal method. Trash is taken to landfills, layered with soil and materials to prevent water seepage and contamination.
• Incineration: This method burns waste at high temperatures, reducing volume but emitting pollutants. Recycling incinerators turn heat energy into power.
• Recycling: Converting waste into new products like plastics, glass, metal, paper, and e-waste. Segregated waste is reprocessed for reuse.
• Composting: The biological decomposition of biodegradable waste using microorganisms, producing organic matter for eco-friendly manure.
• Pyrolysis: A process decomposing waste at high heat, creating ash, carbon, and liquid residue. Effective but may produce toxic residue.

Importance of Solid Waste Management

• Solid waste management is crucial in modern society.
• It involves handling waste in accordance with the law to prevent environmental pollution and littering.
• Environmental hygiene and public health are major reasons for the necessity of solid waste management.
• Another objective is to reduce and eliminate waste for improved quality of life and economic development.

Seven Principles of Solid Waste Management

• Reduce
• Reuse
• Recycle
• Recover
• Redesign
• Remanufacture
• Residual management
• Rethink: Before purchasing anything, consider if it is truly needed. Avoid buying plastic water bottles to protect the environment; opt for reusable glass or steel bottles instead.
• Refuse: Say no to excess packaging and plastic bags. Bring your own reusable bags for shopping to reduce harm to nature.
• Reduce: Minimize household waste by buying only necessary items. Reuse plastic bags, glass jars, and containers. Convert biodegradable waste into compost for plants and avoid unnecessary solid waste.
• Reuse: Recycle items like plastic, glass, and paper for new purposes. Donate or repurpose old clothes to extend their use.
• Repurpose: Modify items creatively for reuse, such as using old tires as swings or repainting shoes for a fresh look.
• Repair: Fix broken items instead of discarding them to reduce waste generation, like repairing electronics or furniture.
• Rot: Compost biodegradable waste to create eco-friendly organic matter for agricultural use.

Effects of Poor Solid Waste Management

• Littered environment: If there is no proper waste disposal system, solid wastes will be thrown in heaps in roads, leading to increased pollution of air, water, and land. Surroundings become littered, causing health risks.
• Affect on human health: Improper waste disposal can pollute air, water, and land, resulting in health issues like bronchitis, asthma, and even cancer.
• Emission of toxic gases: Poor waste management can release toxic fumes, posing serious health risks.
• Affect on land and marine creatures: Pollution from waste can harm animals on land and marine life due to ingestion of harmful substances like plastic and chemicals.