Prevention of Waste or By-products

The first principle gives priority to preventing waste from being created in the first place, rather than treating or cleaning it up after a chemical process has already generated it. The illustrating concept is zero waste technology (ZWT): in an ideal chemical synthesis under ZWT, the waste product generated should be zero, or at least minimised, and wherever some waste is unavoidable, the aim is to use the waste product of one system as a raw material for a different system, so nothing is simply discarded. Two concrete examples are given. First, the bottom ash produced by a thermal power station -- ordinarily a waste product -- can be used as a raw material in the cement and brick industries rather than being dumped. Second, the effluent water that comes out of cleansing machinery parts in an industrial plant can be reused as coolant water in a thermal power station instead of being released as wastewater. Both ex …