chapter - 1 introduction - Meghalaya State Pollution Control Board

Hills Cement Co. Limited.
particles and encourages growth of an active culture of aerobic
organisms. Main features of aerobic treatment are to clarify effluent by
absorbing majority of colloidal and suspended solids on the surface of
sludge particles and oxidize organic matter.
Over flow from aeration tank shall flow by gravity to secondary clarifier
(Tube settler). A part of the sludge from secondary clarifier is recirculated
to aeration tank to maintain desired quantity of mixed liquor
suspended solids (MLSS) and excess sludge is sent to sludge drying
beds. The dried sludge is composted and used as manure for green
belt. The clarified and treated wastewater from secondary clarifier is
collected into a storage tank and passed through pressure sand filter
and used for green belt. The treated sewage shall have the following
characteristics.
pH : 6.5 to 8.5
Total Suspended Solids : < 50 mg/L
Biochemical Oxygen Demand : < 30 mg/L
COD : < 100 mg/l
Oil & Grease : < 10 mg/L
Solid Waste Disposal
Solid wastes from Thermal Power Plants generally consist of fly ash
and solid waste from faecal sewage. The following measures will be
taken to reduce/re-use the solid wastes:
• Bottom ash, almost in dry form will be sieved for re-cycling as bed
material in the AFBC Boiler.
• Fly ash, collected in various hoppers of he dust collection Systems
provided in the path of the flue gas, will be pneumatically transported
to the silos from where the same will be taken out to ash dump area by
totally enclosed dumpers.
• Normally, the dry ash will be utilized for secondary use, land filling,
road construction, cement making, etc.
• Green belt around ash disposal area will be developed.
The municipal solid waste generated from the plant and the colony
will be segregated and separated as combustible and noncombustibles
wastes. The combustible wastes will be used as fuel
in the kiln. This will solve the problem of solid waste disposal and
will also reduce the fuel requirement for the kiln. The kiln will act as
an incinerator in this case. The non-combustible wastes will be land
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