Weighted multiparameter compliance efficiency method for effluent assessment

Developing, validating and implementing effective numerical indicators are crucial tasks in both broad and specific environmental management practices. This work aims to describe a method for generating numerical indicators for effluent assessment based on flow and weighting factors for each chemical species present in the discharge stream. The premises are: (1) optimal effluent has no detectable pollutants; (2) strict legal parameters should have a greater weighting factor than less strict ones; (3) the weighting factor should be derived directly from the regulation that the effluent must comply to; (4) a tendency to lower volumetric discharges is more efficient than constant volumetric discharges. By these premises, a method was developed and applied to five sets of effluent data and regulations for different purposes. First, it was used to compare one French, one American and two Brazilian discharge regulations. Then, it was used to verify the relationship between flow and compliance efficiency. Finally, it was used to compare different effluent streams that must comply with the same regulation. The advantages of the method are: (a) it allows a periodic assessment of a given effluent for its instantaneous compliance efficiency; (b) it enables a comparative assessment of the same effluent with respect to different regulations; (c) it is possible to compare different composition effluents for the compliance of the same regulation. Using the efficiency indicator presented in this study will enable environmental managers and researchers to objective compare effluent polluters and treatment technologies.