AWWA MTC64620

A series of studies are currently being undertaken to develop a model that can be used to accurately predict the evolution of the trans-membrane pressure over time in a full-scale submerged membrane system. These studies investigate the effects of the hydrodynamic conditions and the configuration of submerged hollow fiber membrane systems on membrane fouling. The results from one of these studies indicated that the increase in the trans-membrane pressure during one filtration cycle, could be modeled using a relatively simple exponential relationship that was a function of reversible and irreversible fouling coefficients. The present study was undertaken to determine if this exponential relationship could be used to accurately describe the evolution of the trans-membrane pressure in a submerged membrane system during successive filtration cycles. The fraction of the total fouling that was initially defined as reversible (i.e. defined by a reversible fouling coefficient) could consolidate and produce irreversible fouling over time. The extent of consolidation appeared to be directly related to the duration of a filtration cycle (i.e. time between maintenance cleaning cycles). For relatively short filtration cycles, the extent of consolidation was negligible. Therefore, when a membrane system was operated with relatively short filtration cycles, the evolution in the transmembrane pressure over time could be modeled using a relatively simple exponential relationship that is a function of three parameters: the pseudo-steady-state permeate flux (JSS), an irreversible fouling coefficient (KI) and a reversible fouling constant (kr). Additional studies are currently being conducted to investigate the effects of different raw water sources on the parameters (i.e. JSS, KI, and kr) that describe the evolution in the trans-membrane pressure over time in submerged membrane systems. Includes 12 references, tables, figures.