Systematic analysis of microfauna indicator values for treatment performance in a full-scale municipal wastewater treatment plant

The indicator values of microfauna functional groups and species for treatment performance were systematically evaluated based on the continuous monitoring of the entire microfauna communities including both protozoa and metazoa over a period of 14 months, in two parallel full-scale municipal wastewater treatment systems in a plant in Beijing, China. A total of 57 species of ciliates, 14 species (units) of amoebae, 14 species (units) of flagellates and 4 classes of small metazoa were identified, with Arcella hemisphaerica, Vorticella striata, Vorticella convallaria, Epistylis plicatilis and small flagellates (e.g. Bodo spp.) as the dominant protozoa, and rotifers as the dominant metazoa. The abundance of the sessile ciliates was correlated with the removals of BOD5 (Pearson's r = 0.410, p < 0.05) and CODCr (r = 0.397, p < 0.05) while the testate amoebae was significantly positively related to nitrification (r = 0.523, p < 0.01). At the same time, some other associations were also identified: the abundances of the large flagellates (r = 0.447, p < 0.01), the metazoa (r = 0.718, p < 0.01) and species Aspidisca sulcata (r = 0.337, p < 0.05) were positively related to nitrification; the abundance of Aspidisca costata was correlated to the TN (total nitrogen) removal (r = -0.374, p <0.05); the abundances of the sessile species Carchesium polypinum (r = 0.458, p < 0.01) and E. plicatilis (r = 0.377, p < 0.05) were correlated with the removal of suspended solids.