Process modification / material substitution — replace a high-strength cleaning or process chemical with a lower-BOD/COD alternative at the source, reducing the load before it ever becomes wastewater.
Water reuse and recycling — countercurrent rinsing, cascading rinse water from a cleaner to a dirtier stage, and reusing final rinse water as an initial rinse cuts both flow and, because concentration is unchanged but volume drops, effectively concentrates the load into a smaller stream that is cheaper to treat.
Segregation of high-strength streams — keeping a concentrated stream (e.g. a batch dump) separate from dilute cooling/rinse water allows it to be treated or recovered (e.g. by-product recovery) at high concentration rather than diluting it into the whole plant flow.
By-product/material recovery — recovering a reusable or saleable material from the waste stream before it is discharged (e.g. solvent recovery, metal recovery from plating rinse) removes mass directly rather than merely diluting it.
Good housekeeping — dry clean-up (sweeping/scraping) before wash-down keeps solids and spilled material out of the wastewater entirely.
