Carboxylic Acid Recovery

GT-CAR® is GTC’s carboxylic acid recovery technology that combines liquid-liquid extraction technology with distillation to recover and concentrate carboxylic acids from wastewater. The use of a high boiling solvent enables the process to attain the lowest energy use of any commercially available process, with minimal capital costs. The recovered acids may be sold as high purity products or recycled back to the process. The biological oxygen demand of the resulting wastewater stream is greatly reduced.

GTC’s GT-CAR process is economical for any aqueous stream generated in the production of dimethyl terephthalate (DMT), purified terephthalic acid (PTA), pulp/paper, furfural, and other processes. Acids concentrations as low as 0.5-3.0% can be recovered economically.  High purity formic acid or acetic acid are typical products.

Process Description

In GTC’s carboxylic acid recovery process, an acid-containing aqueous stream is fed to an extraction column, which operates using a proprietary, high boiling solvent which is selective to carboxylic acids.  The acid-rich solvent stream is carried overhead from the extraction column for regeneration.  In the two-stage regeneration step, surplus water is removed (dehydration) and the acids are recovered by acid stripping.  The solvent is routed back to the extraction column for reuse.  Final processing of the concentrated acids is determined on a plant-by-plant basis.  The treated waste-water stream, containing acid levels on the order of < 2,000 ppm, exits the system to the plant’s wastewater treatment area.

Process Advantages

  • Up to 98% of the acids can be recovered
  • Acids concentrations as low as 0.5% can be economically recovered
  • Low capital investment results in typical ROI up to 40 %
  • Modular systems approach means minimal disruption of plant operation and shorter project schedule
  • Use of high-boiling solvent gives high acid recovery and substantial energy savings
  • Solvent is easily separated from water, giving a solvent-free (<20 ppm) wastewater exit stream
  • The carboxylic acid product purity allows for recycle or resale
  • High acid recovery provides environmental benefits, unloading biological treatment systems