Long-term monitoring of a full-scale MBR plant in a coastal resort: impact of high seasonal load variations on sludge characteristics and filtration capability

A full scale MBR plant has been monitored for nearly two years with intense analyses campaigns during the summers of 2005 and 2006. This paper presents the results of seasonal variations on the process and filtration performances and on the sludge characteristics (filterability, Soluble Material Products). During both summers 2005 and 2006, the transmembrane pressure (TMP) experienced a slight increase in the range 0.18 - 0.23 bar. The detailed analysis of the filtration performances showed the significant role of the process aeration as it changes the hydrodynamic conditions around the membrane. Despite a low F/M ratio (between 0.015 and 0.050 kgBOD5.kgMLVSS-1.d-1), the seasonal load clearly impacted on the sludge filterability but without affecting the fouling rate which also didn't seem to be influenced by the SMP concentrations.