Performance and microbial characteristics of a novel pilot-scale tubing biological contact oxidation reactor for rural drinking water

Abstract

Drinking water treatment under rural conditions often require compactness and portability. To address this, the present study developed a pilot-scale helical tubular biological contact oxidation (BCO) reactor filled with annular porous biofilm carriers (fillers). To determine the drinking water treatment efficiency and microbial characteristics, the system was investigated for 212 days at (24.1 ± 3.4) °C under different flow rates (1.86 L · h−1, 3.72 L · h−1, and 7.2 L · h−1) to treat simulated rural drinking water. The results show that (62.7 ± 9.3) % of ammonium (NH4+-N) and (19.5 ± 5.4) % of UV254 absorbance were removed by the BCO reactor after entering the stable operation period. It is shown that shorter hydraulic retention time (HRT) weakened the removals of tryptophan-like substances and fulvic acid according to the three-dimension fluorescence excitation emission matrix spectroscopy, with the removal ratios decreased from 90% to 0% when the HRT declined from 16.8 h to 4.2 h. Despite operating at regular room temperature ((24.1 ± 3.4) °C), the drinking water BCO reactor underwent a long start-up period (5.5 months) to reach a steady state in terms of biofilm concentration and pollutant removal performance. Genus Xanthobacter and Methylobacterium might significantly contribute to the removal of NOM in the BCO reactor, while genus Pedomicrobium and Bradyrhizobium were speculated to be responsible for nitrogen conversion. The present study provides new insights into the application of BCO reactors for ammonium and NOM removal from rural drinking water.