In situ Identification of Filamentous Bacteria from Activated Sludge Wastewater Treatment Plants in Ghana

Abstract

Filamentous bacteria are important in the activated sludge process as they contribute to proper solids-liquid separation in the secondary clarifier by providing a skeletal matrix for the formation of compact flocs. Morphological and molecular techniques were applied over a one-year period to comprehensively identify filamentous bacteria in municipal and industrial wastewater treatment plants (WWTPs) in Ghana. Several morphologically distinguishable filamentous microorganisms were observed and in most cases, microscopic characteristics of these organisms were in close agreement with those described in published keys. The presence of Haliscomenobacter hydrossis, Thiothrix nivea, Sphaerotilus natans, Nostocoida limicola II, Eikelboom Type 1851 and members of the Eikelboom Type 021N group II was subsequently confirmed based on hybridization with their respective oligonucleotide probes. Filaments were not unique to each plant, with higher filament diversity in industrial compared to municipal plants. Additionally, the results revealed that although geographic differences have no significant effect on filament morphology, they likely play a limiting role in the occurrence of specific filaments.