Polishing Filter

The limitations in removing oil from water are dictated by physics. The smaller the suspended oil droplet, the longer oil takes to separate out. In addition, the smaller the oil droplet, the bigger its surface tension, thereby it becomes more difficult for oil drops to join, i.e. to coalesce. Therefore, the oily water separator when processing bilge water will reach a boundary condition beyond which coalescence is no longer possible. This limit depends on the viscosity and density of the oil, as well as agitation of the bilge. Separation to the legal ppm limit is possible under favorable condition. On board ships, that is rarely the case.  The PFM filter uses absorption media to remove hydrocarbons from the effluent. The media absorbs emulsified and residual oils, which the separator is unable to remove.