Even more efficient than counter-current pre-filtration process is the Oehmi process which guarantees savings up to 40% (Transfeld & Scheinder, 1996). This process requires two bleachers and two sets of filters; the spent bleaching clay of the second filtration is mixed back into the degummed oil in a specific manner and subsequently filtered. For palm oil, bleaching
earth consumption has been quantified with conventional single stage and counter- current processes. A bleaching earth consumption of 1% can be reduced to 0.8% with a conventional pre-filtration and up to 0.6% with the full counter-current system. Continuous bleaching units are often operating by means of the wet bleaching concept instead of conventional dry bleaching.