Relation between the form of assembly of carbon fiber strands and the amount of attached microorganism was studied by using an artificial waterway set up at the side of the pond AZAMI. A variety of rectangular sail-type carbon samples were prepared by arranging a definite number of the strands (N) in parallel to each other in width of A cm and in length of B cm. These samples were placed on a setting frame with a length of L0, and then immersed in the circulating water pumped up continuously from the pond during the period of each four months in winter and summer. The amount of microorganism attached and proliferated in carbon fiber entanglement network was evaluated by weight increase(Winc). It was found that Winc depends on the relative length, B/L0 and the value of N/A, namely, compactness of the strand consisting of 12, 000 monofilaments. The former value was closely related to easy separation of the strand into monofilaments that gives rise to an increase in effective surface area of carbon fibers for initial attachment of microorganism, while the latter was a function of an effective volume of network in water for proliferation of microorganism. A suggestion obtained was, further, that aerobe microorganism was preferential species within the carbon fiber network perturbed by water flow which leads to an increase in the rate of exchange of water in the network and this probably be related to the high bending modulus of carbon fiber filament. A most preferable result for proliferation of microorganism was obtained at the condition of B/L0=1.4 and N/A=2.7, and the average distance between neighboring carbon monofilaments entrapped in the aggregates of microorganism reached to about 750μm corresponding to ca. 100-folds of the diameter of carbon monofilaments.
