Coal use and water pollution
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Transcript of Coal use and water pollution
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.