The produced water effluent from a refinery can be treated in multiple stages, using appropriate equipment for each stage.
Primary Separation with a Plate separator (CPI) to give an Oil removal efficiency down to 500 ppm .
Secondary Separation by Induced Gas Flotation (IGF) or IGF- Stage Tank to give Oil removal efficiency down to 100 ppm.
Tertiary Separation in a set of Walnut shell filters for Oil removal efficiency down to 5 ppm.
Final Separation with Membrane / Absolute cartridge filters to achieve total Oil removal efficiency.
Begg Cousland Envirotec and Infinity International Malaysia can design and supply over-ground CPI units, and can retrofit existing gravity separators with Plate Packs to coalesce and remove the free oil thereby increasing separator efficiency from 5,000 ppm to 500 ppm.
Begg Cousland Envirotec and Infinity International Malaysia can design and supply Nutshell filters for the tertiary separation stage. They can also be used for treating the oil well produced water. These filters are usually supplied as a set, with one or more filters being off-line for the cleaning cycle, while the remaining units are in operation until the pressure loss reaches a limit value and their cleaning cycle is triggered.
They are filled with ground pieces of nut shells, typically walnut, which form a media bed which is continuously under pressure. These pieces of nutshell adsorb the suspended solids and the free oil in the water, and when backwash cleaned, there is an efficient cleaning with a very low attrition rate of the media.