<P> Waste (or wastes) are unwanted or unusable materials . Waste is any substance which is discarded after primary use, or is worthless, defective and of no use . </P> <P> Examples include municipal solid waste (household trash / refuse), hazardous waste, wastewater (such as sewage, which contains bodily wastes (feces and urine) and surface runoff), radioactive waste, and others . </P>

When do we consider a given substance as waste
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