New techniques and means for their utilization are described for substantially improving gas to liquid transfer including aeration of hydroelectric project tailwaters and treatment of sewage sludge and sewage treatment effluent or other wastewaters. Liquid flow is directed over an infuser device to separate the liquid into a plurality of free-falling curtains disposed to impinge upon a collection pool therebeneath wherein a substantial number of gas bubbles entrained by any particular curtain are acted upon by successive impingements of downstream curtains to effect turbulent interaction, shearing, and reentrainment of such bubbles and substantially increase the residence time thereof in the resulting recombined flow.