Microflore hétérotrophe impliquée dans le procédé simultané de biolixiviation des métaux et de digestion des boues d'épuration

Abstract

Until now, some microbiological studies have made it possible to highlight the role and identification of certain chimiolithotroph microorganisms directly involved in the simultaneous sewage sludge digestion and metal leaching (SSDML process). Moreover, some other studies have established the performance of the SSDML process for the destruction of pathogens. However, until now no study has been carried out to define the equilibrium of the heterotrophic microbial populations during the sludge acidification occurring during the operation of the SSDML process. Hence, the SSDML process was studied in batch and continuous mode employing different types of sludges (Communauté Urbaine de Québec (CUQ)-East primary sludge, Beauceville secondary sludge, and mixture of primary and secondary Valcartier sludge). The equilibrium of heterotrophic microbial populations was investigated along with sludge acidification and solids degradation. The results obtained during the SSDML process on different sludges showed a decrease followed by the destruction of a majority of heterotrophic bacterial species found in fresh sludges. The isolation and characterization of different microbial species showed that only two types of microorganisms persisted: the yeast Blastoschizomyces capitatus and an unidentified fungus.Key words: sewage sludge, simultanous bioleaching and digestion, heterotrophic bacteria, Blastoschizomyces capitatus, fungi.