The potential of Whole Effluent Assessment

To date effluent discharges have largely been assessed and regulated on the basis of physical and chemical properties, such as chemical oxygen demand (COD), biological oxygen demand (BOD), suspended solids, pH and concentrations of specific hazardous substances.

These properties provide a sound basis for controlling effluents containing relatively few well-characterized contaminants with well-defined and understood toxicological properties. However it is sometimes difficult to assess the environmental significance of complex and variable effluents on the basis of their composition and physico-chemical properties alone.