Effects of seasonal temperature variation on nitrification, anammox process, and bacteria involved in a pilot-scale constructed wetland.

Effects of seasonal temperature (especially low temperature) variation on nitrogen removal process and bacteria involved in an experimental domestic wastewater treatment wetland were investigated in this study. Three different functional groups of bacteria, namely anammox bacteria, ammonia-oxidizing bacteria (AOB), and Nitrospira sp., were involved. Anammox process was seriously inhibited with mean temperature lower than 15 °C. However, obvious adaptation of anammox bacteria also appeared after a long time operation under low temperatures. Contrary to anammox bacteria, AOB were more abundant in winter than in summer. Nitrospira sp. was the least prevalent and showed the lowest level of variation. Distinct nitrate accumulation observed under winter temperatures was likely due to inhibition of anammox process, comparative advantage of Nitrospira sp. in winter, and the presence of cold-tolerant AOB species.