Process optimization and filtration performance of an anaerobic dynamic membrane bioreactor treating textile wastewaters

The study aimed at investigating the performance of anaerobic dynamic MBR (AnDMBR) for the treatment of synthetic textile wastewater. A laboratory scale anaerobic bioreactor was operated to test nylon mesh support materials with different pore sizes (20 μm, 53 μm and 100 μm). The performances of the AnDMBR were evaluated with a stimulated wastewater containing 1,000 mg.L−1 COD and 100 mg.L−1 dye (Remazol Brilliant Violet 5R). To develop an effective dynamic cake layer on the support material, different operational strategies, i.e. high flux, continuous and intermittently biogas recycle were studied for process optimization and increase the filtration performances. Initially, the bioreactor was operated under continuous biogas recycle. Under this operation strategy, the cake layer was not formed, then intermittent biogas recycle was applied to improve the development of dynamic layer. Effluent SS decreased below 20 mg-SS.L−1 for all the tested different pore sized supports after the development of the cake layer. Almost complete color (>99%) and high COD removal efficiencies (95–97%) were observed. For all the three supports, the bioreactor was operated at fluxes of 5–15 L.(m2.h)−1 (LMH), which was quite high compared to conventional AnMBRs equipped with micro/ultra-filtration membranes. In order to better understand the formation and its structure, detailed cake layer characterization analyses were conducted with scanning electron microscopy (SEM), SEM coupled Energy Dispersive X-ray Spectroscopy (EDS) and inductively coupled plasma-optical emission spectrometer (ICP). Provided the formation of the cake layer, the comparable flux and removal performances with AnMBRs for all three tested support materials were possible. •High COD and color removal were obtained in the AnDMBR.•Low effluent SS values were obtained under steady-state conditions in all supports.•AnDMBR was stably operated with 20 μm support material in average 8.05 ± 3 LMH flux.•SEM images showed that the membrane surface was completely covered with cake layer.•High concentrations of Ca, P, Fe, Mg, Al and Si were observed in the cake layer.