Mycological survey of activated sludge in MBRs

Abstract

The objective of this research was to conduct a survey of fungi in activated sludge plants with membrane bioreactors (MBRs). Thirty-six samples of both aerobic and anoxic activated sludge were taken from two plants with MBRs treating domestic wastewater. Over a period of 8 months, two samples from each plant were taken per month. The samples were prepared for count and identification of fungi. The obtained data show that 61 species belonging to 30 genera were identified from activated sludge samples, under aerobic conditions (27 genera and 54 species) and anoxic conditions (21 genera and 39 species), by culturing at 30 °C for 15 days. In aerobic activated sludge samples, the prevalence of Geotrichum candidum was 100% followed by Fusarium (72.2%), yeast (61.1%), Aspergillus (50.0%), Penicillium (50.0%) and Trichoderma (41.6%), while in anoxic activated sludge, G. candidum (94.4%), Fusarium (91.6%), Aspergillus (77.7%), yeast (63.8%), Penicillium (50.0%) and Trichoderma (50.0%) species were the most prevalent. In addition, the other genera found included Chaetomum, Chrysosporium, Cladosporium, Doratomyces, Gibberella, Gliocladium, Gymnoascus, Mucor, Paecilomyces, Phialophora, Rhizopus, Scopulariopsis, Stachybotrys, Stemphylium and others. The results indicate that aerobic and anoxic activated sludge provides a suitable habitat for the growth and sporulation of different groups of fungi, both saprophytic and pathogenic.