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Q.
Limit of $BOD$ prescribed by Central Pollution Control Board for the discharge of industrial and municipal waste waters into natural surface waters is
Environmental Issues
Solution:
Strength of sewage of degree of water pollution is measured in terms of $BOD$ (Biological oxygen demand) value. $BOD$ may be defined as, 'number of milligrams of $O _{2}$ required for decomposition of one litre of waste or water by decomposing micro-organisms (bacteria)'. According to central pollution control board, limit of BOD prescribed is $<30\, ppm$ $( mg / d )$ for $3$ days at $27^{\circ} C$.