Should rules for calcutating removal rates of trace organic and inorganic compounds in wastewater plants be upgraded?
Nouvelles règles de calculs des rendements épuratoires adaptées aux micropolluants
Résumé
This paper introduces a new methodology for the assessment of the micropollutants removal rates by wastewater treatment plant. The proposed calculation rules take into account the analytical uncertainty of measured concentrations, identifying three cases for which a removal value is reliable, and two cases for which it is highly variables (uncertain) due to very low concentrations, or not quantified concentrations in effluent, or when the difference of concentrations between influent and effluent is below the analytical uncertainty. The influence of the proposed calculation rules on removal rates was presented. This is accompanied by a discussion on the requirements necessary to increase the quality of the data on micropollutants. Several guidelines are proposed to limit the impact of sources of other uncertainties, during sampling step (sampling strategy, cleaning and field blank), chemical analyses step (suspended solids and sludge) and data treatment step, according to the targeted objectives.