The continual pollution of the water supply in China has resulted in shortage of sufficiently clean drinking water, which is essential to this nation's quality of life in the 21st century. In this paper, an innovative way of evaluating the removal of micro-pollutants from lake water was studied, using MBR and MBR-PAC (powdered activated carbon) hybrid processes. Chemical analyses showed that the quality of treated water has the potential to comply with the drinking water regulations of China. In this experiment, the accumulation of inert compounds in the bioreactor was measured, and the concentration of soluble organic pollutants in the mixed liquor was recorded. Based on this data, both Am (organics accumulation factor in the mixed liquor) and S-m (membrane separation/rejection coefficient) were proposed to describe the removal of organic pollutants during the MBR process. Each has a close relationship with the removal efficiency of organic pollutants (eta). As such, the p contribution by biological treatment (or combined with PAC adsorption) in the bioreactor was calculated through establishing a mass balance equation. The membrane fouling conditions were also investigated. The study resulted in the conclusion that the addition of PAC enhanced the microbial activity in the bioreactor, contributed to the increase of the eta and was also found to decrease the membrane fouling. (c) 2007 Elsevier B.V. All rights reserved.