Wastewater Generation Standards (wastewater generation benchmarks)

Wastewater generation standards are benchmarks for the quantity of wastewater an industry should produce per unit of output, expressed as cubic metres per tonne of product (or per kilolitre for liquids). Unlike effluent discharge standards, which control the quality (concentration) of what is discharged, these control the volume — they push industries toward water efficiency by capping how much effluent a tonne of production may generate. They are notified by the CPCB for specific industries and used by SPCBs as consent benchmarks.

Examples from the standards illustrate the wide range: large paper mills are benchmarked around 175 m³ per tonne, viscose filament yarn at 500 m³ per tonne (the most water-intensive textile), caustic soda at 1 m³ per tonne (membrane cell) versus 4 m³ per tonne (mercury cell), tanneries at 28 m³ per tonne of hide, distilleries at 12 m³ per kilolitre of alcohol, integrated iron and steel at 16 m³ per tonne, and natural rubber processing at 4 m³ per tonne.

The logic is that controlling volume reduces pollution load and water stress simultaneously. Less water used means less effluent to treat, lower treatment cost, and less freshwater drawn from stressed sources. Two plants meeting the same concentration limits can have very different environmental footprints if one generates twice the effluent volume; the generation standard catches this.

For recyclers, the directly relevant benchmark is process water in wet operations — plastic washing lines are heavy water users, as are hydrometallurgical metal recovery and any pre-processing washing. The practical implication is that water efficiency is both an environmental and a cost lever: recirculating wash water, using counter-current rinsing, and moving toward closed-loop or zero-liquid-discharge systems cut both the water bill and the effluent treatment burden. SPCBs increasingly judge a plant on its specific water consumption, not just its discharge quality.