Characterization and removal of phenol from wastewater generated at a condensate crude oil refinery

Phenols are present in discharge effluents of many heavy industries such as refineries. Emirates National Oil Company (ENOC) processes condensate oil and produces wastewater that is treated at the Refinery Wastewater Treatment Plant (ENOC-RWTP). Characterization of phenol level at ENOC-RWTP and assessment of the effectiveness of employed pollution control technologies in reducing phenol level at the treatment plant have been conducted in this study. It was found that the main sources of phenol in the received waste streams at ENOC-RWTP are the tank water drain (average 11.8 mg/l), the desalter effluent (average 1.4 mg/l) and the neutralized spent caustic (average 234 mg/l). However, there are large fluctuations from the average phenol level within each waste stream. Also, the level of phenol and its derivatives (substituted phenols) in these streams vary significantly with phenol, m-p-cresols, o-cresol, tri and tetra-chlorophenols and to a lesser extent 4-chloro- 3-cresol are common among these streams. The study further showed that the most effective process employed in the reduction of phenols within the plant is the sequencing batch reactors. The study further showed that the relationships between phenol level in the discharged treated effluent and levels of COD, BOD ₅ and sulfides are weak but statistically significant.