Evaluating the performance and membrane fouling of a submerged membrane bioreactor (MBR) treating plywood industry wastewater

This study evaluates the performance of a membrane bioreactor (MBR) for treating wastewater from the laminated plywood industry. To this end, a pilot-scale MBR was operated for 60 days with a hydraulic retention time (HRT) of 20 h and a solid retention time (SRT) of 20 days. The reactor's performance was assessed based on the removal of chemical oxygen demand (COD), phenol, turbidity, and apparent color. Furthermore, we monitored the solids content, dissolved oxygen concentration, and pH of the mixed liquor, as well as the progression of the transmembrane pressure (TMP). The wastewater exhibited a COD/BOD ratio of 5.5, suggesting low biodegradability, usually when this ratio is higher than 4.0. Nevertheless, it was observed that the MBR's performance was stable and satisfactory, with average removal efficiencies of 98% for COD, 70% for phenol, 99% for turbidity, and 93% for true color. The evolution of TMP indicated gradual membrane fouling; however, the operational limit of 0.6 bar was not reached during the study period. In conclusion, the utilization of MBR presents a promising approach to mitigate the environmental impacts associated with wastewater from the laminated plywood industry.