A Theoretical and Experimental Investigation of Wastewater Treatment for a Polyethylene Terephthalate Production Unit

Abstract

In this research, mathematical modelling of an anaerobic hybrid bioreactor for effluent treatment of a PolyEthylene Terephthalate (PET) unit in a petrochemical complex was performed. The developed model included a combination of a biofilm model for describing the substrate kinetics; a fluidized bed model for determination of species profiles along the reactor length and a bioreactor model for particle distribution inside the reactor. The reactions performed in the bioreactor included; i) the polymers hydrolysis; ii) fermentation of the resulting monomers; iii) the volatile fatty acids fermentation to Acetate and Hydrogen and iv) the Methane formation as the final product. The reactor was divided into n-segments each being fully mixed and the changes of granule densities at each one caused by granules growth were neglected. On the other hand, the experimental data obtained from an industrial unit in which, the pH was controlled by adding NaHCO3 and NaOH while; a mixture of Urea, di-ammonium phosphate and molasses were utilized as substrates. The total flow rate inside the 2,200 m 3 bioreactor was set 180 m 3 /h with 0.7 m/h upflow velocity. The theoretical data determined from the developed model for the volatile fatty acids’ (VFAs) production while the corresponding experimental data obtained from the industrial unit. Moreover, the comparison between the bioreactor effluent’s COD determined through both the theoretical and experimental studies were presented. The current model reproduced the experimental data with mean error of 14 % which considering the complexity of the undertaken system was rather satisfying.