Characterize the process — obtain the full process flow diagram, chemical inventory, and water balance for every unit operation (machining, cleaning, plating/coating, cooling, etc.).
Estimate/measure waste generation rates (see below) to size the treatment train.
Identify applicable discharge standard — direct discharge permit limits, or a sewer-use bylaw if discharging to a municipal system, sets the required removal efficiency.
Screen for pollution prevention first — process water reuse, counter-current rinsing, and dry material handling reduce both flow and load before any treatment is designed.
Select and size the treatment train from the characterized waste (equalization, physical-chemical or biological treatment, sludge handling) and confirm it meets the discharge standard with an appropriate safety factor.
Plan for monitoring, O&M and permitting from day one of operation, including a startup/commissioning sampling program to confirm the design assumptions.
Getting the information needed for waste generation rates is the critical first step, since a new facility has no operating history:
Engineering mass/water balance from the process design — use the equipment vendor's specified water consumption per unit produced and expected production rate to project flow and, from the chemical inventory, expected pollutant mass loads.
Data from comparable existing facilities — benchmark against a similar plant of known size (this or another operator's facility, or published industry-sector effluent guidelines) and scale by production capacity.
Published industry-sector unit-loading factors (e.g. Nemerow & Dasgupta's typical-industry tables, or EPA/Environment Canada effluent guideline development documents) when no directly comparable plant data exists.
Pilot-scale testing of the actual process wastewater, once available, to confirm and refine the design basis before full-scale construction, if the process is novel enough that none of the above are reliable.
