Integrated oxidation process and biological treatment for highly concentrated petrochemical effluents: A review

Biological treatments are the most widely used method in petrochemical complexes to treat wastewaters. However, they are not always effective, especially when refractory nature of certain organic contaminants is introduced into the system. A more promising method, therefore, is the one in which the biological treatment is integrated with the chemical methods where the primary contaminants are first converted into biodegradable compounds before being entered in biological treatment. This paper reviews the application of four oxidation processes that treat petrochemical waste, namely: photo catalytic oxidation (PCO), Fenton/photo-Fenton, wet air oxidation (WAO), and catalytic wet air oxidation (CWAO), and proposes a new configuration for the treatment of petrochemical wastewaters. This configuration is established based on adding one oxidation process at the effluent of each processing unit before all the effluents are mixed into a single wastewater influent stream for the biological treatment. As the reviewed processes have different capabilities in the degradation of organic compounds and operate under diverse conditions, the selection of the oxidation process best matched to each processing unit will depend on the characteristics of the unit effluent such as organic concentration, toxicity of the effluent to biomass, temperature, and pressure, which will be thoroughly discussed in the paper.