Application: The GT-CAR recovery process combines GTC’s liquid-liquid extraction technology with distillation to recover and concentrate carboxylic acids from wastewater. Using 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 have sufficient purity to be sold as glacial grade or recycled back to the process. The biological oxygen demand (BOD) of the resulting wastewater stream is greatly reduced. The process is economical for any aqueous stream generated in the production of dimethyl terephthalate (DMT), acetic acid, pulp/paper, furfural and other processes.
Process description: Acid-containing aqueous stream is fed to an extraction column, which operates using a proprietary, phosphine oxidebased solvent, highly 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 wastewater stream, containing acid levels on the order of < 2,000 ppm, exits he system to the plant’s wastewater treatment area. Advantages: • Up to 98% of the acids can be recovered • Acid concentrations as low as 0.5%+ can be economically recovered • Low capital investment results in typical ROI up to 40% • Modular systems approach enables minimal disruption of plant operation and shorter project schedule • Use of high-boiling solvent yields high-acetic recovery and substantial energy savings • Solvent is easily separated from water, giving a solvent-free (< 20 ppm) wastewater exit stream • Acetic acid product purity allows for recycle or resale • High acid recovery provides environmental benefits, unloading the biological treatment system Licensor: GTC Technology.