In the first half of 2019–20, India produced 129.09 million tonnes more fly ash than it did in the first half of 2018–19 (93.26 million tonnes vs. 120.9 million tonnes). The particulates (fine particles of burned fuel) and flue gases that are ejected out of coal-fired boilers together make up fly ash, also known as flue ash, coal ash, or pulverized fuel ash. Fly ash is typically collected by electrostatic precipitators or other particle filtration equipment in modern coal-fired power plants before the flue gasses reach the chimneys. Ash that stays at the bottom is referred to as bottom ash. This article will explain to you about Fly Ash which will be helpful in preparing the Environment Syllabus for the UPSC Civil Service exam.

What exactly is a Fly Ash?

• Every time a solid material is burned, ash is created. One such residue that rises into the atmosphere with the gasses is fly ash.
• Fly ash is a very fine particle that disperses widely in the atmosphere.
• The majority (90%) of India's installed thermal power generation capacity is derived from coal, with the remainder coming from diesel, wind, gas, and steam.
• Generally speaking, fly ash is finer than lime and portland cement.
• Fly ash is made up of silt-sized, often spherical particles with sizes between 10 and 100 microns.

Fly Ash - Composition

• SiO2, Al2O3, Fe2O3, and possibly CaO are thought to be the primary components in fly ash.
• While floating in exhaust fumes, fly ash material solidifies.
• Fly ash contains a variety of minerals as well. They are quartz, mullite, and the iron oxide minerals hematite, magnetite, and/or maghemite.
• The American Society for Testing and Materials has two classes for fly ash: Class F and Class C.
• The amounts of calcium, aluminium, and iron in each of them makes a difference.
• The burned coal's chemical composition plays a significant role in determining the fly ash's chemical composition.

Fly Ash - Environmental Effects

• Groundwater Contamination: The majority of the elements in coal, a component of fly ash, including arsenic, barium, boron, selenium, and mercury, are harmful to both humans and animals.
• Therefore, fly ash produced after coal combustion has the potential to contaminate groundwater.
• Ecological Impact: The impact of fly ash on the environment depends on the nature of the thermal power plant discharge and the type of enterprise involved.
• This is a result of the varied chemical composition of coal depending on the local geology.
• Therefore, the plants and animals in the vicinity will be impacted by the fly ash that will be dumped on the topsoil.

Fly Ash - Exposure Concerns

• Fly ash includes considerable amounts of trace amounts of heavy metals and other chemicals that are known to be harmful to human health.
• Arsenic, beryllium, cadmium, barium, chromium, copper, lead, mercury, molybdenum, nickel, radium, selenium, thorium, uranium, vanadium, and zinc are traces of coal that have the potential to be harmful.
• Exposure risks to the environment and human health are posed by hazardous compounds, crystalline silica, and lime.
• Silicosis: Fly ash includes crystalline silica, which when inhaled is known to induce lung conditions, most notably silicosis.
• Human Carcinogen: The US National Toxicology Program and IARC both categorize crystalline silica as a recognised human carcinogen.
• Lung Damage: Fly ash has a pH between 10 and 12, making it a medium to strong base as calcium hydroxide [Ca(OH)2] is produced when lime (CaO) and water (H2O) combine. If present in large enough amounts, this can also harm the lungs.
• Radiation: Fly ash has 100 times more radiation than nuclear waste stored in a dry cask or water for a given amount of electricity produced.

Safety Measures

• When handling or working with fly ash, a number of safety measures are advised by the material safety data sheets.
• These include avoiding stirring the fly ash in order to reduce the amount that becomes airborne as well as donning safety eyewear, respirators, and disposable clothing.
• "The existence of high pollutant levels in certain CCR (coal combustion residue) leachates may raise human health and ecological issues," the National Academy of Sciences stated in 2007.

Why is Fly Ash a Pollutant?

• The low-grade coal used in thermal power generation carries 30-45% ash content.
• The high-grade imported coal has a low ash content of 10-15%.
• Since most of the coal used in thermal plants is low-grade, it generates a large quantity of ash which requires a large area as a landfill or pond for disposal.
• The ponds where fly ash is usually dumped are poorly managed.
• Fly ash becomes dry as temperature increases and gets airborne.
• Thus, it becomes one of the major sources of air and water pollution.
• Apart from causing various diseases, it also leads to a reduction in the recharging of groundwater.
• Thus the air in areas around coal-fired power plants in polluted with fly ash.

Fly Ash - Applications

• Construction of Embankments: Even though it is uncommon, fly ash is used to build embankments.
• Fly ash has particles the size of clay and has a high homogeneity coefficient.
• Fly ash embankments have the following engineering features: compaction characteristics, shear strength, compressibility, permeability, and frost susceptibility.
• Soil Stabilization: The process of stabilising soil involves permanently changing the physical and chemical characteristics of the soil.
• Fly ash's granular nature can improve a soil's ability to contract and expand, enabling the construction of subgrade pavements and foundations
• Creation of Asphalt Concrete: Asphalt concrete is a composite material made of a mineral aggregate and an asphalt binder that is frequently used to pave roads.
• In asphalt concrete mixes, fly ash is frequently used as a mineral filler to fill voids and create contact points between bigger aggregate particles.
• Waste Treatment and Stabilization: Because of its ability to absorb water and alkalinity, fly ash can be combined with other alkaline materials to convert sewage sludge into organic fertilizer or biofuel.
• As a Catalyst: In a high-temperature process called pyrolysis, which is used in wastewater treatment, fly ash appears to work effectively as a catalyst for turning polyethylene into a material akin to crude oil when treated with sodium hydroxide.

Fly Ash - Policy Measures of MoEF

• India's Ministry of Environment, Forests, and Climate Change first announced the use of fly ash in a gazette notification in 1999.
• It set a deadline for all thermal power plants to comply by ensuring 100 % utilization.
• The compliance deadline was extended to 2014 by subsequent amendments made in 2003 and 2009.
• Only 60% of the produced fly ash was being used as of 2015, according to the Central Electricity Authority in New Delhi.
• Due to this, a revised deadline of December 31, 2017 was established in the most recent notification, issued in 2015.
• Out of the roughly 55.7 % fly ash used, the majority of it (42.3 %/) is used to make cement, while only about 0.74 % is added to concrete.
• In all construction projects, road embankment works, and low lying land filling projects within a 100 km radius of a thermal power station, the Ministry of Environment and Forests has mandated the use of fly ash-based products.
• Usage of fly ash in mine filling operations within a 50-kilometer range of thermal power plants was also mandated.

Fly Ash Management and Utilization Mission

• The Fly Ash Management and Utilization Mission will examine how 1,670 million tonnes of residual (accumulated) fly ash can be used in the least hazardous way and how the power plants can implement all necessary safety measures, in addition to keeping an eye on the disposal of annual stock of unutilized fly ash.
• Aim: Its aim is to "coordinate and monitor concerns connected to the treatment and disposal of fly ash and associated difficulties."
• Head & Nodal Agency: The mission will be jointly led by the secretary of the union Ministry of Environment, Forests, and Climate Change (MoEF&CC) and of coal and power, with the chief secretaries of the respective states where the mission is being carried out on board.
• Provisions: The 'forcing, monitoring, audit and reporting' of the progress of fly ash utilization and implementation by coal thermal power plants and user agencies has been provided for in the revised fly ash notification of December 2021.
• The Notification places responsibility for ensuring that its mandates are carried out effectively on the CPCB and the State Pollution Control Boards (SPCB) / Pollution Control Committees (PCC).
• The Mission does, however, give the chief secretaries of the states additional authority over fly ash control in addition to these statutory authorities.
• The Notification requires each thermal power plant to provide on its online portal once a month of data on ash generation and use.

Fly Ash - Related Initiatives

• National Thermal Power Corporation: National Thermal Power Corporation Limited (NTPC) issued an Expression of interest (EOI) call earlier in 2021 for the sale of fly ash.
• Additionally, NTPC has worked with cement producers all throughout the nation to supply fly ash.
• Pradhan Mantri Awas Yojana: The Pradhan Mantri Awas Yojana (Urban) has placed a strong emphasis on cutting-edge, ecologically friendly building techniques, like the utilization of fly ash bricks.
• State Governments: Even the state governments have released their plans for using fly ash, with Maharashtra being the first to do so.
• “ASHTRACK”: The government has introduced a mobile application called "ASHTRACK" and an online portal for tracking fly ash production and use.
• Goods and Services Tax: Fly ash and related products now only incur a 5 percent Goods and Services Tax (GST).

Conclusion

In order to help accomplish the goal of % use of fly ash, researchers in India are working on activated pozzolanic cement such as geopolymer and fly ash as an additive for concrete. The issue of increasing the amount of fly ash used in concrete has the most potential, without a doubt. In 2016, India manufactured 280 million tonnes of cement. There is a heck of a lot of room for fly ash incorporation in both the growing share of PPC and low to moderate strength concrete, as the housing sector consumes 67 percent of the cement.

FAQs

MCQs

1. What is fly ash?

A) A type of air pollution
B) A by-product of coal combustion
C) A chemical fertilizer
D) A type of industrial waste generated from plastic processing

2. Which of the following is a potential use of fly ash?

A) In the production of synthetic fuel
B) As a soil amendment for agricultural crops
C) As a partial substitute for cement in concrete
D) As a refrigerant in air conditioning systems

3. Which environmental hazard is most commonly associated with fly ash?

A) Soil erosion
B) Groundwater contamination with toxic elements
C) Increased air pollution
D) Ozone layer depletion

4. What is the main objective of the Fly Ash Notification (1999) in India?

A) To regulate the mining of coal
B) To promote the recycling of fly ash for various industrial uses
C) To prevent power plants from using coal
D) To encourage the import of coal from foreign countries

5. Which of the following is a regulation related to fly ash management in India?

A) Environment Protection Act, 1986
B) Coal Conservation Act, 1977
C) Plastic Waste Management Rules, 2016
D) Water Pollution Control Act, 1974

GS Mains Questions and Model Answers

Q1: Discuss the environmental impact of fly ash and the steps being taken to mitigate its adverse effects.

Answer: Fly ash is a significant environmental concern due to its potential for air, soil, and water pollution. It contains harmful heavy metals like arsenic, mercury, and cadmium, which can contaminate groundwater and soil, posing health risks. Airborne fly ash can also affect respiratory health. To mitigate these effects, India has implemented the Fly Ash Notification, promoting the recycling of fly ash in cement and brick production. Additionally, the National Green Tribunal (NGT) has set guidelines for the safe disposal and management of fly ash, encouraging power plants to adopt cleaner technologies and proper ash handling systems.

Q2: How can fly ash be effectively utilized to reduce its environmental impact and benefit industries?

Answer: Fly ash can be effectively utilized in several industries to reduce its environmental impact. In construction, it can replace a portion of cement in concrete production, improving its strength and durability while reducing the overall carbon footprint. It can also be used in the production of eco-friendly bricks, contributing to sustainable building practices. Moreover, fly ash can stabilize soil in road construction projects. By recycling fly ash into these beneficial products, the need for landfills and hazardous waste disposal is reduced, leading to a more sustainable and circular economy.

Q3: Evaluate the role of government regulations in managing the disposal and utilization of fly ash in India.

Answer: Government regulations play a crucial role in managing the disposal and utilization of fly ash in India. The Fly Ash Notification (1999) mandates that power plants located within 100 km of certain areas must use fly ash in cement and brick manufacturing. This regulation encourages the recycling of fly ash, reducing its environmental impact while providing valuable materials for industries. The Environment Protection Act, 1986, and the National Green Tribunal’s guidelines further promote responsible fly ash management by ensuring safe disposal practices and encouraging the use of advanced technologies. These measures help mitigate pollution and promote the sustainable use of fly ash in India.

Previous Year Questions on Fly Ash

1. UPSC CSE Prelims 2021:

Question: Fly ash is a by-product of which of the following?

A) Petroleum refining
B) Coal combustion in power plants
C) Cement manufacturing
D) Textile industry processing

Answer: (B)

Explanation: Fly ash is a by-product produced by the combustion of coal in thermal power plants.

2. UPSC CSE Mains 2020 (GS Paper 3):

Question: Discuss the potential benefits and challenges of recycling fly ash in construction and manufacturing.

Answer: Recycling fly ash in construction helps reduce waste and provides an eco-friendly alternative to traditional materials like cement. It improves the durability and strength of concrete, reduces the carbon footprint, and aids in soil stabilization. However, challenges include ensuring that fly ash is free from hazardous elements like heavy metals and managing its collection and transportation efficiently. Proper regulation and monitoring are essential to ensure that the use of fly ash does not pose environmental or health risks.