Application This method is suitable for wastewater with a chemical oxygen demand (COD) ranging from 10 to 5000 mg/L and chloride ion (Cl⁻) concentrations below 2 g/L. Based on actual user requirements, it can also be applied to wastewater with chloride ion (Cl⁻) concentrations below 20 g/L. Technical Parameters Method Basis National Standard HJ 828-2017 "Water Quality — Determination of Chemical Oxygen Demand — Potassium Dichromate Method" Measurement Range 10–5000 mg/L