Abstract: A liquid treatment apparatus imparts a distinctive flavor and scent to beverages and other liquids. In one embodiment, a wooden wave insert body undulates and crosses a center line, while the wood grain runs substantially parallel to the center line and does not undulate materially. In another embodiment, a wooden plug passes through and is affixed to the wall of a beverage container, and imparts a distinctive flavor and scent through an aging process that includes controlled oxidation. The wooden plug includes a hollow bolt having a bolt opening exposed to ambient air, a closed bolt head distal to the bolt opening, and a bolt fluid exchange passage between the bolt opening and the closed bolt head. The bolt passes through the wooden block between the bolt head and container wall. The bolt fluid exchange passage couples ambient air to the wooden block interior.