Treatment of pyrolysis wastewater using heterogeneous advanced oxidation processes



In this study, treatment of a real wastewater sample produced in a thermal pyrolysis plant for plastic waste disposal was performed using a practical design of multiphase falling film reactor. The reduction in the level of chemical oxygen demand (COD) as well as color removal of this type of wastewater was evaluated by means of three different heterogeneous advanced oxidation processes (TiO2/UVA/O2, TiO2/O3, and TiO2/UVA/O3). In addition, the effect of acidification of this type of wastewater as well as the influence of the content of phosphate anions existing in the wastewater for biological treatment purposes on several treatment aspects were investigated and discussed in detail. The COD level of pyrolysis wastewater was decreased by about 32 and 38% after 1 h of treatment using the catalytic ozonation and photocatalytic ozonation approaches, respectively, while the decrease in the COD of this wastewater was negligible during the photocatalytic oxidation. The wastewater color was completely removed after 40 min of treatment using both ozone-based oxidation systems, while the photocatalytic oxidation led to a slight decrease in color extinction by about 10% after 1 h of treatment. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 178–183, 2014