[Atrazine wastewater treatment in a SPG membrane-aerated genetically engineered microorganism biofilm reactor].

Membrane-aerated biofilm reactor(MABR) represent a novel membrane-biological wastewater treatment technology. In addition,bioaugmented treatment using genetically engineered microorganism(GEM) biofilm in MABR is proposed to improve refractory pollutant removal. In the present study,a SPG membrane aerated-biofilm reactor(SPG-MABR) with GEM biofilm formed on the SPG membrane surface was applied to treat atrazine wastewater. The influences of air pressure,biofilm biomass and liquid velocity on the performance of the SPG-MABR were investigated. The variation of GEM biofilm during the SPG-MABR operation was observed.The results indicated that the increased air pressure could promote atrazine and COD removal as well as re-oxygenation by increasing oxygen permeability coefficient. A higher biofilm biomass could also enhance atrazine and COD removal,but simultaneously reduce the re-oxygenation rate because biofilm thickness and oxygen transfer resistance increased. When liquid velocity in the SPG-MABR was decreased under laminar flow condition,atrazine and COD removal was improved due to the facilitated contaminant diffusion from wastewater to biofilm. The atrazine removal efficiency reached to 98. 6% in the SPG-MABR after 5d treatment at air pressure of 300 kPa,biofilm biomass of 25 g·m- 2and liquid velocity of 0. 05 m·s- 1. The microbial polymorphism of GEM biofilm was observed during the SPG-MABR operation. The surface of GEM biofilm was gradually covered by other microbial cells and the distribution of GEM cells reduced,but inside the GEM biofilm,the GEM cells were still dominant.