Abstract
In this study, we determined the wastewater treatment characteristic and eukaryotic community structure in the retained sludge of a down-flow hanging sponge (DHS) applied for post-treatment of upflow anaerobic sludge blanket (UASB) reactor treating municipal sewage under different seasons. The change in the eukaryotic community structure was observed during the entire operational conditions. Under the condition of higher concentration of COD and NH4+, which is an upper part of DHS, Paramecium spp. and Colpidium spp. were predominanted by microscopic observations. On the other hand, under the condition lower concentration of COD and and NH4+, which is a bottom part of DHS, Arcella spp. and Centropyxis spp. were predominated. Additionally, single cell of predominant eukaryote, which was isolated by micromanipulator from the sludge, was used for 18S rRNA gene sequence analysis. As a result, predominant eukaryotic species could be identified as species level based on 18S rRNA gene sequence. Therefore, simultanious use of morphological observation and sequence identification of eukaryotic spiecies is efficient method for evaluation of eukaryotic communities of sludge.
