Operation Performance of a Bioaugmented Membrane-aerated Biofilm Reactor Treating Atrazine Wastewater

Abstract

A hydrophobic SPG (shirasu porous glass) membrane-aerated biofilm reactor (MABR) with genetically engineered microorganism (GEM) biofilm formed on the SPG membrane surface was applied to treat atrazine wastewater. The contaminant removal performance and its influencing factors were investigated during the stable operation of this MABR. The results indicated that the oxygen supply capacity could be increased in the SPG membrane aeration when the membrane pore size and the aeration pressure increased, which could improve the performance of COD and atrazine removals. The maximum oxygen supply capacity of hydrophobic SPG membrane with pore size of 1.5 μm was estimated to be about 22.4 g·(m2·d)-1 at aeration pressure of 70 kPa. When aeration pressure was 70 kPa and hydraulic retention time (HRT) was 1.5 h, the average COD removal efficiency was 80.1% and the average organic loading rate removed was 1.86 kg·(m3·d)-1in the MABR with 1.5 μm hydrophobic SPG membrane. Under the same operating conditions, the average atrazine removal efficiency was 62.5% and the average atrazine loading rate removed was 0.18 kg·(m3·d)-1. The COD and atrazine removal efficiencies decreased significantly at further shortened HRT and increased influent organic loading rate. DO concentration showed more significant influence on atrazine removal. The simplex genetically engineered microorganism biofilm turned into complex microbial community gradually during MABR operation, but the GEM cells could still reside in the biofilm well. Therefore, the efficient atrazine removal by GEM bioaugmentation could be maintained.