Environmental Engineering in CE
Scale formation in boiler is controlled by

Keeping the pH value of feed water just below 7
Eliminating H₂S in feed water
Reduction in hardness, silica & alumina in feed water
Preheating of feed water

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Environmental Engineering in CE
Coal mines drainage waste water (acidic in nature) results from the earth's water percolating through the voids created in coal bed during mining. This polluted water which either drains out naturally to water courses or are removed before starting the mining is

None of these
Diluted with fresh water to reduce its acidity
Neutralised by alkali treatment
Left as such without any treatment

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