Determine the points of contact between the treated wood and the aluminum. Often, it is the fasteners or connectors that creates the contact point.
Use plastic or polymer washers to separate the materials from the fasteners, if it is determined that it is the fasteners that are creating the contact points. These rubber-like washers, which are available at many home improvement stores, insulate the two materials against making contact.
If the contact points occur along the entire length of a treated wood member, you should remove that piece of structure and install a non-treated wood member instead. This will prevent galvanic action and eliminate the risk of corrosion. Alternately, a rubber or plastic mat or sheet can be installed between the treated wood and aluminum to eliminate contact points.