What are wastes?
Substances or objects which are disposed of or are intended to be disposed of or are required to be disposed of by the provisions of the law.
Disposal Means- Any operation which may lead to resource recovery, recycling, reclamation, direct reuse or alternative uses.
Classifications of wastes according to their origin and type:
- Municipal solid waste: Wastes which are collected from the household, construction sites, market place, packaging materials, trade refuses etc collected by the municipality.
- Industrial wastes: Solid or liquid wastes which are generated by manufacturing and processing units of various industries like paper, metal, leather, glass and ceramic, jute, chemical, petroleum, sanitary products etc.
- e-waste: Electronic wastes generated from modern-day gadgets or discarded electrical and electronic devices. The discarded materials may include CRTs, wires, circuits, mobiles, TVs, laptops and computers.
- Construction waste: Wastes generated during construction, renovation and demolition activities. These are also known as C&D wastes.
- Agricultural waste: Wastes generated from the farming activities. These wastes are biodegradable.
- Food processing waste: The wastes generated in food processing units- fruit and vegetable peels and pulps.
- Biomedical waste: Solid or liquid wastes which are generated in hospitals or any health care centers during diagnosis, treatment or research activities in medical sciences.
- Nuclear waste-: Radioactive materials in nuclear power plants.
Classification according to the physical state and nature of the wastes:
- Solid Wastes: Wastes in the solid forms may include plastics, bottles and jars, cans, papers, scrap metals and other trash.
- Liquid Wastes: Wastes in the liquid forms may include domestic washings, chemicals, oils, wastewater from ponds, manufacturing industries and other sources.
- Bio-Degradable: Can be degraded like paper, wood, fruits and other agricultural wastes.
- Non- Biodegradable: Can not be degraded like plastics, bottles, old machines, cans, Styrofoam containers etc.
- Hazardous wastes: Substances which are unsafe to use commercially, industrially, agriculturally or economically and have any of the following properties-inflammability, corrosive, toxic, carcinogenic.
- Non-hazardous: Substances which are safe to use commercially, industrially, agriculturally or economically which are non-toxic or non-carcinogenic.
What is a Landfill?
There are two ways to bury trash:
- Dump – An open hole in the ground where trash is buried in unorganized way. Age- Old method of dumping trashes which doesn’t have a scientific thought, often pollutes the atmosphere with toxic gases, rodents, flies and microorganisms.
- Landfill – This is a carefully designed structure built into or on top of the ground in which trash is isolated from the surrounding environment (groundwater, air, rain). This isolation is accomplished with a bottom liner and daily covering of soil. A sanitary landfill uses a clay liner to isolate the trash from the environment. A municipal solid waste (MSW) landfill uses a synthetic (plastic) liner to isolate the trash from the environment
The purpose of a landfill is to bury the trash in such a way that it will be isolated from groundwater, will be kept dry and will not be in contact with air. Under these conditions, trash will not decompose much. A landfill is not like a compost pile, where the purpose is to bury trash in such a way that it will decompose quickly.
Modern landfills are well-engineered and managed facilities for the disposal of solid waste. Landfills are located, designed, operated and monitored to ensure compliance with federal regulations. They are also designed to protect the environment from contaminants, which may be present in the waste stream. Landfills cannot be built in environmentally-sensitive areas, and they are placed using on-site environmental monitoring systems. These monitoring systems check for any sign of groundwater contamination and for landfill gas, as well as provide additional safeguards.
How a place is identified to make a landfill ?
- The area of land should be large enough to hold large quantities of trash.
- The bottom area of the land or the pit should be water-tight in the sense that no water should seep into the ground or groundwater.
- The flow of water in the area should be diagnosed so as to prevent rainwater runoff.
- The impact of landfills on the nearby land should be assessed.
- The historical and archaeological value of the area of the landfill need to be assessed.
Structure of a Landfill:
A scientifically designed landfill must have the following components.
- Bottom liner system–
Bottom liner system is a system that ensures that no rubbish seeps to the ground so as to reduce pollution. These liners are made of material made of polyvinyl chloride which is durable and seepage resistant.
- Water drainage system–
In this system, the dryness of the landfills is maintained so that water does not penetrate into the nearby rivers or lakes.
- Leachate collection system–
In this system, Leachate is collected which otherwise will seep to the ground.
- Methane collection system–
In this methane collection system, gas and other useful gases from the landfills are collected and sold as per the requirement.
The following video describes how a landfill should be constructed.
Types of landfills :
- Municipal Solid Waste Landfills (MSWLFs) – Specifically designed to receive household waste, as well as other types of nonhazardous wastes.
- Bioreactor Landfills – A type of MSWLF that operates to rapidly transform and degrade organic waste.
- Industrial Waste Landfill – Designed to collect commercial and institutional waste (i.e. industrial waste), which is often a significant portion of solid waste, even in small cities and suburbs.
- Construction and Demolition (C&D) Debris Landfill – A type of industrial waste landfill designed exclusively for construction and demolition materials, which consists of the debris generated during the construction, renovation and demolition of buildings, roads and bridges. C&D materials often contain bulky, heavy materials, such as concrete, wood, metals, glass and salvaged building components.
- Hazardous Waste Landfills – Facilities used specifically for the disposal of hazardous waste. These landfills are not used for the disposal of solid waste.
Effects of landfills :
One of the major threats landfills pose is the emission of methane gas due to accumulation of waste. Methane is the leading cause of fires at landfills, resulting in garbage burning which causes severe air pollution. Landfills also pose tremendous health hazards as they are the storehouse of virus and bacteria, causing cardiovascular and lung diseases. A scientific landfill is constructed as a sustainable space for waste disposal and treatment of municipal solid waste. The technology deployed in constructing a scientific landfill is simple and a scientific landfill ensures complete control over gas developed in the landfill and leachate (water that has infiltrated through a solid and leached out) as well as limited access of vectors such as rodents and flies to the waste. A scientific landfill is termed so because of its scientific design during construction. One of the biggest problems of ordinary landfills is the seeping of solid waste into underlying soil and water, contaminating both. Scientific landfills eliminate the risk of waste seeping underground as it is constructed layer by layer to prevent seepage. The presence of these layers ensures that leachate is collected before it seeps underground.