| COAL
WASHERIES
The coal washeries release very large amount of solid and liquid waste
causing serious environmental problems. The washeries reduce the ash content of
coal to 17.5 + 0.5%. The study was conducted at coal washeries of Bihar State
to evaluate the status of pollution control and to assess performance of treatment
plant. This process consumes clear water in the range of 0.2 to 0.25 m3/tonne
of raw coal input. The washeries are operated in the closed water circuit system
but still about 12-18% of raw water is discharged as effluent. Though, effluent
is treated in settling tank but sometimes overloading results into failure of
closed circuit system. The rejects (15 to 25% of input) are dumped near available
land without caring for stability of dump, as a result dumps near the river bank
cause erosion of coal particles during rainy season and accumulation of fine coal
particles on the bottom of river Damodar. The analyses of effluent quality of
different washeries indicate high suspended particles and oil & grease. Though
washeries have adequate settling tanks but diposal of solid waste required to
be accelerated. The reject dump management is required to minimise soil erosion.
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