Ecotoxicological evaluation to follow a 3 years in situ-experiment of a submerged mbr for oncological hospital effluent treatment
Résumé
In the hospitals and pharmaceutical industry effluents, as well as in wastewater-treatment plants and in wastewaters, several pollutants with various effects were able to be identified, genotoxics (hydrocarbons), endocrine disruptors (personal care products) or plastics (Bisphenol A) The antitumor molecules, although in lesser quantity represent an increasing danger. Considerable contents of these metabolites can be found in rivers. In this context, their removal seems to be a security measure. MBR appears to be good candidates: based on previous lab experiments the aims of the PANACEA project, are split into 3 interdependent objectives: 1) the evaluation of the occurrence of molecules, used in the treatments of cancers, in the effluents of the corresponding services; 2) The measure and quantification of the toxic effects, (geno / cytotoxic and endocrine disruptors); 3) the development of an hybrid process constituted by a combination of biological and physical-chemical treatments (coupling of a membrane bioreactor with adsorption / oxidation processes or nanofiltration). After presentation of the sampling protocol, the obtaining of the physico-chemical parameters and the quantification of 125 pharmaceutical molecules, allowed "to describe" the variability of the hospital effluent. From the processing point of view, the MBR was operated with sludge residence time (SRT) equal to 40 days; the study consisted in estimating the effect of the hydraulic residence time (HRT), the other parameters staying equal. Two experimental campaigns were conducted for HRT = 24 and 48 hours. From a hydraulic point of view the filtration performances are satisfactory with the chosen operating conditions (no backflushing, sequenced filtration). The treatment performances (macroscopic quality parameters) remain corresponding to standards of discharge. The 125 molecules quantification revealed that the MBR removals are very variable, from a total elimination to a fictive "production", as if un-conjugations would occur. On the same samples, series of tests of ecotoxicity and endocrine disruptors measurements were applied. They highlight a removal of the global ecotoxicity, oestrogenic, androgenic activities and glucocorticoïde. More over these global effect analyses coupled with chemical quantifications allowed to appreciate at which level pharmaceuticals molecules are implied in the environmental impact of such effluent, and in which extend MBR may help to reduce it.