Petrobrazi Refinery Used Water Treatment Plant, Case Study Romania

During a petrochemical refinery process, high volumes of used water containing organic and/or inorganic compounds are generated. The specific characteristics of refinery used water (wastewater) are directly related to the various manufacturing processes, as well as the refinery plant operation, and emanate from differing raw materials and final products, maintenance works, the shutdown of single plant sections, and process adaptations. Therefore, used water characteristics can vary greatly throughout the day, the week, and the year, both in terms of water quantity and quality (Berne and Cordonnier 1995). Refinery used water requires extensive pretreatment before it can be treated biologically. It is necessary to remove toxic compounds such as hydrogen sulfides, cyanides, or hydrocarbons (oils) because they would negatively influence a biological treatment process. Aerobic biological treatment is a state-of-the-art technology for refinery effluent treatment. Many aerobic bacteria are able to degrade hydrocarbons, phenols, and organic acids and to use such compounds as a substrate. Even toxic cyanide can be converted into nontoxic thiocyanate by a number of bacteria that include Escherichia coli or Bacterium subtilis. A prerequisite for successful biological degradation is that the bacterial community is adapted to the specific used water characteristics, in order that the concentrations of toxic compounds remain below the critical (toxic) values and shock loadings are avoided. Within the context of the aforementioned, this chapter presents a case study describing the design and operational experience of the Petrobrazi used water treatment plant operated by WABAG at the OMV/Petrom-owned refinery and petrochemical complex at Ploiesti, Romania.