When we exposed the simulated seawater seaweed effluent or artificial seawater to the reactor, the numbers of V. parahaemolyticus and E. coli contained in them decreased within 2.5 min and reached the lower detection level within 10 min (Fig. 3). However, the decreases were slower than those without seaweed (Fig. 3). Various organic compounds and salts may inhibit the photo-catalytic TiO2 reaction.