Advancing dairy wastewater treatment: Exploring two-stage fluidized bed anaerobic membrane bioreactor for enhanced performance, fouling, and microbial community analysis

This study aimed to assess the performance and fouling mitigation of a staged anaerobic fluidized bed membrane bioreactor (AnFMBR) treating simulated dairy wastewater while unravelling microbial community through genome sequencing analysis. The staged reactor featured a two-column configuration comprising granular activated carbon particles (1-2 mm diameter) as a fluidized medium and a caseless PVDF hollow fibre membrane (0.05 mu m pore size) in the second stage. The performance of AnFMBR was investigated for 94 days at three different organic loading rates (OLR) of 1, 2.5, and 5 kg COD/(m(3)<middle dot>d) at an ambient temperature of 30 +/- 5 degrees C. The COD removal efficiency of up to 89 % was attained with a decent methane yield of 0.27 L CH4/gCOD(rem) at an OLR of 1 kg COD/(m(3)<middle dot>d). Increased OLR negatively impacted membrane fouling. The reactor demonstrated effective operation at permeate flux of 0.59, 1.65, and 3.29 L/(m(2).h). Notably, lower flux exhibited reduced susceptibility to membrane fouling, requiring no cleaning interventions for 45 days. Syntrophic fatty acid bacteria (Firmicutes, Proteobacteria, etc.) and acetoclastic methanogens (Methanosarcina and Methanothrix) played a crucial role in anaerobic degradation. The findings contribute valuable insights to enhance the efficiency of anaerobic membrane bioreactors, providing sustainable solutions for dairy wastewater treatment and advancing knowledge in fouling mitigation strategies and microbial community abundance.