Experimental studies on the removal of natural and artificial 2-MIB in the surface water of Lake Biwa were conducted using a biological filter pilot plant with porous granular ceramic media. Microbiological and biochemical studies on the mechanism of bio-degradation of 2-MIB were also conducted.From the results of a series of the pilot plant study, the removal efficiencies of 2-MIB under the filtration rate of 180 and 120m·d-1 were 70% and 80%, respectively. Performances of water treatment by the biological filter pilot plant were almost the same as those by the commercial slow sand filter, when the filtration rate of the biological filter was decreased to 12m·d-1. 2-MIB removal efficiency by the biological filter pilot plant after 48 hours' pause of filtration recovered in about 12 hours.In addition, two different types of bacteria belonging to the genera Pseudomonas and Enterobacter were isolated from the backwashed water of the pilot plant. Also, four degradation products of 2-MIB such as 2-methylcamphene, 2-methylenebornane, camphor and 4,7,7-trimethyl-2-oxabicyclo [2.2.1] heptan-3-one were detected.