Effects of Phenol on Activity and Microfauna Community Structure of Activated Sludge

Abstract

In order to investigate the effects of phenol on activity and microfauna community structure of activated sludge, phenol with different concentrations were added into the wastewater for activated sludge culturing in a SBR reactor, then the activity parameters of TTC-ETS and INT-ETS of activated sludge were measured, and the dynamics of microfauna community was analyzed. The results indicated that TTC-ETS activity was more applicable to evaluate the effects of phenol on sludge activity than INT-ETS activity. The higher the concentration of phenol was, the more seriously the sludge activity was inhibited. When 50 mg·L-1 of phenol was added into the influent, the inhibition rate of sludge activity was (20.75±10.43)%, while it increased to (39.73±26.92)% with a great fluctuation at the phenol concentration of 100 mg·L-1. The inhibition rate of sludge activity fluctuated at about 40% in the later period of sludge culturing with 300 mg·L-1 of phenol. The inhibitory effects on microfauna community in activated sludge increased with increasing phenol concentration. Phenol had different effects on various groups of microfauna community, i.e., only one group (testate amoebae) was inhibited significantly at a low feeding concentration of phenol, many groups (sessile ciliates, testate amoebae, crawling ciliates, carnivorous ciliates) were inhibited at the phenol concentrations of 100 mg·L-1 and 300 mg·L-1, whereas a few groups (flagellates, nematodes, etc.) were promoted at the phenol concentration of 300 mg·L-1. There was a certain degree of relationship between sludge activity and microfauna under the influence of phenol, which means that Centropyxis aculeata, Plagiocampa mutabilis etc., may be bio-indicators for low sludge activity, and Epistylis lacustris, Bodo lens and Pleuromonas jaculans can be used as bio-indicators for high sludge activity in the activated sludge used to treat phenolic wastewater.