A buoyant material trap having a treatment tank with a base wall and a vertically-extending sidewall, a feed pipe to introduce fluid at a first location in the tank, and an exit pipe to remove at least a portion of the fluid from a second location in the tank. One or more wall structures form a circuitous passage between the first location and the second location. The wall structures are open at the top and substantially prevent fluid from passing below the passage, but allow buoyant material to rise above the passage. The walls may extend to the bottom of the tank to prevent fluid from passing beneath them, and may be removably installed in the tank to facilitate cleaning. An overflow chamber may be provided to receive buoyant material. The sidewall may have a spout and be adapted to empty the tank by tilting.