Lakhan Lal, M.Tech student

ENE17014

Coal use and water pollution

Submitted to:

Prof. Rupam Kataki

Deptt. of Energy, Tezpur

University

Introduction

India’s energy sector is dominated by coal.It

contributes about 59% of total electricity

generation.

Cement Industry requires coal in substantial

amount.

It is also used for syn gas production.

Dankuni coal complex is producing syngas which

is piped to the industrial users in Calcutta.

It is also used for production of coke which is a

popular reducing agent used in metallurgical

industries.

How coal use creates water pollution

Coal Ash(all coal ash contains concentrated

amounts of toxic elements, including arsenic,

lead, and mercury.)

Coal Mining(contaminate water in various ways)

Water use in steam generation by coal fired

power plant(put excessive stress on existing

water resources in drought prone areas)

Coal Mining

Coal mining pollutes near by water bodies and

rivers by contaminating them with highly acidic

water having heavy metals like arsenic, copper

and lead.

The process is known as acid mine drainage. It

happens when certain substances (typically iron

sulfide, FeS2, or fool’s gold) is oxidized after

being exposed to air and water. Runoff can

change the pH of nearby streams.

Mountain top removal mining process is a serious

threat to water body.

The U.S. Environmental Protection Agency estimates that mountaintop removal “valley fills”are responsible for burying more than 2,000 miles of vital Appalachian headwater streams, and poisoning many more. As a result, water downstream of mountaintop removal mines has significantly higher levels of sulfate and selenium, and increases in electrical conductivity, a measure of heavy metals. These changes in water quality can directly kill aquatic species, or disrupt their life cycles so severely that populations dwindle, or even disappear .

Source- Ecological Impacts of Mountaintop Removal, Applachian Voice

Finally, after coal is mined, it is typically washed

with water and chemicals to remove impurities

before it’s burned. The resulting coal slurry must

then be stored, often with coal ash or in

improvised ponds that can leak, spill, or fail. In

2000, the bottom of a Kentucky coal slurry

impoundment gave way, contaminating more than

a hundred miles of rivers and streamswith more

than 300,000,000 gallons of thick black sludge—

30 times larger than the Exxon-Valdez oil spill.

Coal Ash

When coal is burned it leaves behind a grey powder-like substance known as coal ash. Although the exact chemical composition depends on the type of coal burned, all coal ash contains concentrated amounts of toxic elements, including arsenic, lead, and mercury.

Ash can be reused in some way (often in concrete); the rest is stored in landfills, abandoned mines, and hazardous, highly toxic ponds.

Most coal ash is stored in unlined ponds or pits. Over time, heavy metals in the ash can escape into nearby waterways and contaminate drinking water.

Exposure to coal ash is linked with a heightened risk for cancer as well as heart damage, reproductive problems, neurological disorders, and other serious health conditions.

Coal Burning Burning coal emits large quantities of pollutants,

including sulfur dioxide, carbon dioxide, nitrous oxides,

and mercury. Sulfur dioxide and nitrous oxides can mix

with rain or snow to form acid rain. This mixture

increases the acidity of lakes and streams and can

harm or kill plants and animals.

Pollution control equipment on power plants, called

“scrubbers," can reduce the emissions of sulfur dioxide

to the atmosphere by using a mixture of limestone and

water to absorb pollutants. This process produces

close to 200,000 tons of sludge waste per year for a

typical power plant.

Source-Union of Concerned Scientists. 2012. UCS EW3 Energy-Water Database

V.1.3.www.ucsusa.org/ew3database.

Water Use All coal plants rely on water. They function by heating

water to create steam, which then turns turbines, generating electricity.

“Once-through” coal plants pump the water directly from a water source, heat it up, then discharge it back. The waste water is typically hotter (by up to 20-25° F) than the water that receives it, creating "thermal pollution" that can decrease fertility and increase heart rates in fish.

These and other energy-water collisions may worsen as the climate heats up. For example: droughts can restrict the amount of water available to coal plants, forcing them to shut down. And hot weather can make water supplies too warm for cooling, forcing power plants to reduce their electricity production when it’s needed most (hot days are also peak electricity usage days).

Water pollution due to coal in

India The Water (Prevention and Control of Pollution)

Act 1974 (amended in 1988) is applicable to coal industries.

It consider impacts on water due to:-

a) Residues of explosives induce heavy metal contamination into the surface water bodies through run-offs & ground water.

b)Water spraying to reduce the fugitive emissions gets contaminated and finds its way to surface water bodies and ground water.

c)Water being used for domestic activities at mining sites is contaminated.

Source- Central pollution control board’s report on pollution due to coal

The implementation of environmental laws in

mining industry is governed by the conditions

imposed in environmental clearance issued by

Ministry of Environment and Forests and consent

to establish/operate issued by State Pollution

Control Board.

In coal mining major environmental impacts on

surroundings are erosion & sedimentation, habitat

modification, surface & ground water 24

contamination and drawdown of ground water.

Drawdown is lowering of ground water table by

continuous pumping of ground water to prevent

ground water seepage in open cast mining.

Possible events and the expected consequences

from various mining operations are as below:-

Event Consequences

Change in land use, land –

cover and land form

1.Disturbance in natural

watersheds & drainage

pattern of the region

2.Disturbance in wind

direction, flow and

temperature

3.Ultimately disturbance in

rivers/stream flow, agriculture

patterns etc.

4. Floods and loss of bio-

diversity

Waste products including

uranium, thorium and other

radioactive and heavy metal

contaminations

Air/water/soil/food grain

contamination or direct

exposure to flora/fauna

Event Consequences

Acid rain Contamination in

surface/ground water, soil,

agriculture

Acid mine drainage Contamination in

surface/ground water, soil and

agriculture

Disturbing recharge area Interference with groundwater

and water table level, surface

water

Disturbances in the drainage

and water-sheds of surface

water bodies

Causing change in flows and

discharges of rivers and

streams

Beneficiation of coal 1. Contamination of surface/

ground water, soil, agriculture

2. Air pollution health impact

and visibility hindrance.

Study of CPCB on coal mines

related water pollution

The project “Impact of coal mine discharge on

surrounding with special reference to heavy

metals” was formulated by CPCB to conduct the

study in central zone.

Field observation recorded by CPCB :

There were no measuring devices installed in

coal mines for measurement of waste water

generated and discharged.

The SPCB has recommended for zero discharge

from all coal mines but in most of mines zero

discharge in not complied.

The treatment provided to waste water by coal

companies are need based only, wherever waste

water is to be used for domestic purpose in

townships, it being treated for proper settling followed

by pressure filtration.

In many mines it was found that RCC tanks were

provided for settling with low retention time. The

waste water being pumped in that tanks are having

sufficient pressure for creating turbulence in settling

tanks.

Treatment plants of many mines were found very old

or over aged and nor fit for it operation especially in

underground mines.

In underground mines the left mined pits are being

used as storage pit and claimed as settling pit. This

water is pumped to ground level in RCC tanks and

over flow is allowed for discharge.

There were no sludge collection and with drawl system in settling tanks. The fine coal particles flowing in waste water was found deposited in agricultural fields using this water for irrigation.

The waste water discharged by mines finds its way in perennial drain and ultimately joins the rivers of that area. The heavier coal particles get settled in way either in RCC tanks or in carrying drain, 31 but very fine coal particles in suspension decreases the sunlight permeability in River water.

In case of open cast mines the waste water generated is collected in open pits and pumped in to drains as and when required.

The improper stacking and slope of top soil and overburden increases the possibility of contamination of ground water during rainy season.

Most of the coal mines have not provided catch drain and catch pits for run-off collection from top soil and over burden stacking.

Garland drain for management of rain water was found either not constructed and if constructed not maintained properly.

Huge deposition of fine coal particles were observed in and around the coal mines on road as well as on tree. This may be due to open transportation of coal in the area. These fine coal particles find its ways to drain and finally to River in rainy season.

Outcomes of CPCB study

The impact of coal mine discharge on

surroundings could not be ruled out.

The mine waste water used for irrigation has

given an impact of fine coal particle deposition in

agricultural fields.

The fine coal particles coming in mine discharge

are increasing turbidity of River water flowing very

near to mine area as in case of River Kelo and

River Rehar in Raigarh area of Chhattisgarh.

The fluoride present in ground water is going to

Rivers through effluent of coal mines.

Increasing the dependency of villagers on coal

mine discharge water by reducing ground water

table in the area.

Increasing metal concentration in River water

especially in non-monsoon period.

Decreasing plantation growth in the area by

emitting fine particles during its transportation.

Recommendation

Strict compliance of zero discharge condition.

Complete treatment of industrial wastewater to

confirm the prescribed standard and its in house

use.

The treated water quality norms shall be stringent

up to portable water norms.

Providing water meters to measure quantity of

waste water generation and discharge

Construction of Catch drains, siltation ponds, Garland drains and settling ponds.

Providing artificial recharge measures, rain water harvesting system and meeting water requirement of nearby villages by permanent water supply system.

All internal roads shall be black topped and good housekeeping shall be maintained.

Coal shall be transported in duly covered conveying system/vehicles to control fugitive emission during transportation.

The coal mines shall develop thick green belt around the leased mine area.

Top soil and overburden stacking shall strictly follow the norms of its height and slope.

Conclusion

Coal mining as well as its consumption directly

causes water pollution.

Coal proudces water pollution during mining

stages as well as its burning and after burning

stage.

Coal mining industries specially Indian industries

are not following zero emission standard as

prescribed by MoEF.

Ground scale Implementation as well as time to

time monitoring is necessary for controlling

pollution from coal industry.