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Q.
The waste water from Industries may contain toxic heavy metals having density of more than
Environmental Issues
Solution:
Unlike domestic sewage, waste water from industries
like petroleum, paper manufacturing, metal extraction and
processing, chemical manufacturing, etc. often contain
toxic substances, notably heavy metals (defined as
elements with density $> 5g/cm^3)$; such as mercury,
cadmium, copper, lead etc.) and a variety of organic
compounds.