Systems, articles, and methods related to foam fractionation of fluids

A method for treating a solution comprising one or more per- and/or polyfluoroalkyl substance (PFAS) molecules, comprising:

• exposing an aqueous solution comprising one or more PFAS molecules and a surfactant to bubbles such that at least some of the PFAS molecules are associated with at least some of the bubbles, thereby forming PFAS-associated bubbles;
• and
• separating at least some of the PFAS-associated bubbles from a remainder of the aqueous solution, thereby forming:
• a foamate comprising the at least some of the PFAS-associated bubbles, wherein the foamate comprises the one or more PFAS molecules at a concentration that is greater than that of the aqueous solution by a factor of greater than or equal to 50, and
• a liquid output comprising at least a portion of the remainder of the aqueous solution, the liquid output having a concentration of PFAS molecules that is less than that of the aqueous solution.

A foam fractionation system, comprising:

• a vessel comprising:
• a vessel body portion comprising an interior volume configured to process an input liquid solution;
• and
• an elongated portion in fluid communication with the interior volume;
• and
• a bubbler configured to:
• receive a gas input, and
• inject bubbles into the interior volume;
• wherein:
• at least 80% of the total volume of the bubbles is made up of bubbles having a largest cross-sectional dimension of greater than or equal to 1 micron and less than or equal to 200 microns;
• and
• the elongated portion has:
• a flowpath length along a long axis along a direction of fluid flow from the interior volume;
• and
• an average cross-sectional area along the long axis;
• wherein a ratio of the flowpath length divided by the average cross-sectional area is greater than or equal to 1 cm/cm2.

A foam fractionation system, comprising:

• a vessel comprising:
• a vessel body portion comprising an interior volume configured to process an input liquid solution;
• and
• an elongated portion in fluid communication with the interior volume;
• and
• a bubbler configured to:
• receive a gas input, and
• inject bubbles into the interior volume;
• wherein:
• at least 80% of the total volume of the bubbles is made up of bubbles having a largest cross-sectional dimension of greater than or equal to 1 micron and less than or equal to 200 microns;
• the elongated portion has an average cross-sectional area perpendicular to a direction of fluid flow from the interior volume;
• and
• a ratio of the volume of the interior volume divided by the average cross-sectional area of the elongated portion is greater than or equal to 2000 cm.

A foam fractionation system, comprising:

• a vessel comprising:
• a vessel body portion comprising an interior volume configured to process an input liquid solution;
• and
• an elongated portion in fluid communication with the interior volume;
• and
• a bubbler configured to:
• receive a gas input, and
• inject bubbles into the interior volume;
• wherein:
• at least 80% of the total volume of the bubbles is made up of bubbles having a largest cross-sectional dimension of greater than or equal to 1 micron and less than or equal to 200 microns;
• and
• the vessel body portion comprises a main body portion and a taper portion, wherein the main body portion is connected to the elongated portion via the taper portion.