Abstract
Acomparative study of construction and function of microfauna (protozoa and metazoa) communities in biological domestic wastewater treatment reactors with and without a microorganism activator (Saponin) was carried out. It was showed that the addition of Saponin did not change the construction of microfauna communities, but promoted the growth of microfauna, especially attached rotifer that was famous as useful metazoa in biological treatments. The variation of species of metazoa was smaller than that of protozoa. When water temperatures dropped in the range of 10-13°C, the growth of protozoa highly decreased, but the growth of metazoa increased, showed that metazoa was highly tolerant to low temperatures than protozoa. The biomass of a special group of microfauna with the habits of attached living and SS feeding in the reactor with Saponin was the highest in microfauna communities and remarkably higher than that in the reactor without Saponin. Moreover, rotifer Philodina sp. was the most prosperous in all species of that special group. Statistical analysis showed the close connection between biomass of attached microfauna with the habit of suspended particle feeding and effluent SS concentrations, indicating these microfauna played an important and useful role in the removal of suspended solids.
