Coke removal from petrochemical oily wastewater using γ-Al2O3 based ceramic microfiltration membrane

Abstract

Destruction of coalescer filters by coke particles is an important concern faced with polyolefin units of petrochemical plants. A lot of fund and time is wasted for reclogging/substituting the coalescer filters. In the current work, γ-Al2O3 based ceramic microfiltration membrane was utilized to remove coke particles from petrochemical wastewaters before introducing to the coalescers. Perfect elimination of coke particles from oily wastewaters was achieved. Influence of temperature and some operating conditions such as filtration time and reusability was examined. Analysis results showed that the extent of volatile organic compounds (VOC) was not noticeably changed after the process; however, suspended solids were effectively retained by the ceramic membrane. The results indicated that most of the light organic compounds (e.g. gasoline) passed through the membrane but the troubling coke particles did not. By increasing temperature, the flux was increased due to viscosity reduction as well as solvents diffusivity enhancement. Microfiltration was performed at constant trans-membrane pressure of 15bar, cross-flow velocity of 2m/s and various temperatures (20–80°C). Moreover, reusability of the membranes was examined using HCl, NaOH and SDS as eluting agents. Normal flux recovery was obtained utilizing NaOH whereas HCl did not suggest an acceptable flux recovery.