Reciprocating freeze concentration for urine-based fertilizer production

A method of generating a concentrated product from a feedstock, the method comprising:

• providing the feedstock to a first chamber of a reciprocating concentration system;
• transferring, with a heat transfer system of the reciprocating concentration system, heat from the first chamber to a second chamber of the reciprocating concentration system to melt a frozen portion of the feedstock in the second chamber and freeze the feedstock in the first chamber, the heat transfer system being in thermal communication with the first and second chambers;
• removing the concentrated product from the second chamber before the frozen portion of the feedstock in the second chamber melts, as the frozen portion of the feedstock in the second chamber melts, or both before and as the frozen portion of the feedstock in the second chamber melts;
• removing at least one dilute product from the second chamber as the frozen portion of the feedstock in the second chamber melts, after the frozen portion of the feedstock melts, or both as and after the frozen portion of the feedstock melts;
• removing heat from the reciprocating concentration system with a heat dump system in thermal communication with the reciprocating concentration system;
• and
• switching a heat transfer direction of the heat transfer system to reverse operation of the reciprocating concentration system in preparation for freezing additional feedstock provided to the second chamber.