Hundred-thousands of PET bottles were produced every second using fossil fuel feedstock that released GHG and created plastic waste disposal problem. Recycled PET (rPET) from bottles is an emerging “sustainable solution” to reduce GHG and the waste. Current process of rPET required high water demand with added sulfuric acid and sodium hydroxide that generated wastewater of high total dissolved solid (TDS). In this presentation, we will present technical feasibility study of recovering chemical resources from actual rPET wastewater obtained from a commercial treatment facility at Taiwan. Performance of water reclamation and chemicals recovery from rPET wastewater was evaluated using two electrokinetic separation techniques, electrodialysis (ED) to generated reusable water and bipolar membrane electrodialysis (BMED) for chemical resources recovery. ED was able to effectively decrease the TDS of rPET wastewater from specific conductivity of ~6000 μS/cm to 550 μS/cm with the productivity of 7 gal/m2/h and energy consumption of 8 kWh/gal. The quality of treated water met standards of reclaimed water, &lt;500 ppm TDS and therefore could be reused in the rPET process. With the successfully generated reusable water, we implemented BMED to recover the valuable acid and basic in the wastewater to future reduce the GHG footprint for rPET process. In the three-compartments separations technique, BMED simultaneously generated good quality of reclaimed water and produced separately sulfuric acid and sodium hydroxide basic streams recovery from the rPET wastewater via an electrically water splitting reaction. Preliminary techno-economic analysis to rPET process was assessed from the performance data of reclaimed water productivity, the purity of recovered aid/base by-products, and the energy consumption. With the treatment results of actual rPET wastewater, a life-cycle analysis was conducted to assess its environmental impacts on rPET bottles process.

Water reclamation and chemicals recovery in a recycled PET-bottle process using bipolar membrane electrokinetic separation

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ACS Fall 2022

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