A gas-liquid rotating coalescer includes first and second sets of one or more detent surfaces on a rotary drive member and a driven annular rotating coalescing filter element which engagingly interact in interlocking mating keyed relation to effect rotation of the coalescing filter element by the rotary drive member. The apparatus comprises air injection modules, which serve to float a substrate, and can be independently attached to or detached from the substrate transferring apparatus. Widths of the plurality of holes are in the range of 0. The second axis incorporates a radiation source and beam shaping optics. The pH of the pre-reaction solution is preferably greater than 0 and not greater than 2. The insert may include a driving head, either solid or having a central hollow and may include a frangible neck to dissociate the head from the insert.