LAUSR

Abstract In this study, the effects of NaCl and phenol on anammox performance at low temperature (20 °C) were tested. In Reactor 1, an increase in NaCl concentration from 2 to 10 g/L decreased anammox activity. When the temperature was elevated to 35 °C and NaCl lowered to 8 g/L, the activity was restored. When the temperature was again decreased to 20 °C, anammox activity decreased sharply. This suggested that low temperature after activity recovery at high temperature was not beneficial to the anammox operation. In Reactor 2, 6 g/L NaCl inhibited anammox activity, which then recovered gradually. In the presence of 8 g/L NaCl, glycine betaine was helpful for relieving inhibition of activity. However, when NaCl was increased to 10 g/L, glycine betaine was not beneficial. The effect of phenol was tested in Reactor 3. The results showed that anammox activity was only 22% of the seed sludge in the presence of 35 mg/L phenol. By discharging a certain amount of sludge and adding new sludge every day, the reactor was stabilized with higher activity in the presence of 20 mg/L phenol. Both NaCl and phenol increased the production of extracellular polymeric substances and decreased settling velocity.