Method for lactide and lactic acid recovery at polylactide (pla) production steps

A Polylactide (PLA) preparation method with improved overall yield, of the method comprising:

• providing together or separately, various a plurality of gas streams containing lactide, lactic acid, and water;
• sending each of the plurality of gas streams onto an assembly of packed columns comprising at least one column, in which the gas stream will be condensed;
• bringing the gas stream, in the assembly of packed columns, in contact with a wetting fluid at a temperature of 1° C. to 30° C., this fluid comprising water, lactic acid and dissolved lactide;
• recovering the fluid leaving the assembly of packed columns at a temperature of 15° C. to 70° C., this fluid inter alia containing lactide in solid form of 0.1% to 20% by weight relative to a total weight of lactates contained in solution;
• optionally, filtering and extracting at least partially the precipitated lactide contained in this fluid;
• heating this aqueous solution, from which solid lactide may have been partially removed, via at least one exchanger, to bring the temperature to a value comprised between 50° C. and 95° C.;
• sending this acid aqueous solution into a feed tank under agitation and continuously fed with a stream of lactic acid, this feed tank being positioned upstream of the present treatment circuit and being held at a temperature of 50° C. to 95° C.;
• and
• in this feed tank, converting the lactide contained in the aqueous solution to lactic acid and/or lactic acid oligomer by performing hydrolysis.