Potential for anaerobic treatment of wastewater from pet bottle washing in a fluidized bed reactor

Abstract

This study evaluated the potential of anaerobic treatment of wastewater from washing polyterephthalate ethylene (PET) bottles sent to recycling (WWPR) in a fluidized bed reactor. The reactor had a total volume of 2.16 L and was fed with the WWPR diluted in a nutritional medium operated with a hydraulic retention time (HRT) of 24 h and maintained at a temperature of 33 ± 2 °C. Coarse sand was used as a support material for the immobilization of biomass in the reactor. The potential of the anaerobic system was evaluated as a result of the progressive increase in chemical oxygen demand (COD) and anionic surfactants, both from the WWPR. The biomass was subjected to an immobilization and adaptation process over 10 days, and after this period, concentrations of anionic surfactants were added. The maximum COD load removed was 2.6 ± 0.43 kg/m³d, which represented a removal of 64 ± 8%. The maximum surfactant removal was 0.063 ± 0.001 kg/m³d for an initial concentration of 15 mg/L. The fluidized bed reactor was stable and robust in relation to the applied load of organic matter; however, surfactant removal was inhibited at initial concentrations above 30 mg/L.