TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Apparatus: The heating stage comprises a steam heat exchanger.The steam stripping stage comprises at least one counter current heat exchangers, which serve to heat the oil blend before steam stripping.The ratio controller stage comprises a modulating control valve apparatus in which appropriate proportions of waste oil is blended with a feed of virgin oil.The apparatus comprises a feedstock flow rate controller unit to control the relative proportions of virgin and waste oils blended to produce the target reduced free fatty acid content; a unit for blending the first and second virgin oils to form the virgin oil feedstock.The controller unit comprises a data processor operating in a feedback loop with valve unit in at least one of the feed stocks, thus permitting adjustment of the relative volumetric flow rates of feed stocks required to achieve the desired proportions of waste oil to virgin oil in the oil blend; and comprises unit adapted to control the relative proportions of first and second virgin oils which are pre-blended to produce the virgin oil feedstock.The data processor further includes a feedback loop with valve unit in at least one of the first and second virgin oil sources, through which the relative flow rates of the respective virgin oils adjusted to give a desired pre-blend free fatty acid content.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The process is conducted in the absence of a preliminary esterification process conducted on the waste oil to remove free fatty acids before blending.The process further involves cleaning the oil blend to remove impurities after the blending step and before the stripping step.The cleaning step is adapted to remove fine particulate debris, un-reacted phosphoric acid from virgin oil degumming stage and residual hydratable gums that present in the oil blend.The cleaning step involves mixing the oil with hot water.The cleaning step further involves centrifuging the oil and hot water mixture to wash the oil blend and remove impurities.The wash water from the centrifuge is passed to an effluent treatment stage.Before the stripping step, and after any cleaning step, the blended oil is heated in a heating stage to 85-95degrees C; and the oil blend is dried to remove air and moisture from the oil blend.The stripping step is steam stripping conducted in steam stripping stage in which free fatty acids contained in the oil are distilled from the oil by a steam flow.The free fatty acids are condensed and collected for later use.The stripped oil blend flows away from the stripping stage through the counter current heat exchanger, as a result of which heat from the stripped oil blend is transferred to the pre-stripped oil blend. The proportion of waste and virgin oils is maintained at a pre-determined target ratio by a ratio controller stage.Preferred Components: The waste natural oil is a used cooking oil.At least one of the waste and virgin oils is a vegetable oil.The virgin oil is degummed oil provided from a virgin oil degumming stage; or the virgin natural oil is a pre-blended combination of at least two types of virgin natural oil so as to produce the relatively low free fatty acid content virgin oil.The combination of at least two virgin natural oils comprises at least one virgin oil having a relatively high free fatty acid content and at least one diluting virgin oil having a lower fatty acid content which ensures that the pre-blend free fatty acid content is less than that of the high fatty acid content virgin oil before blending.The target reduced free fatty acid content of the oil blend is 0.5-1.5 wt%.The virgin oil feedstock comprises a first virgin oil source and a second virgin oil source.The first virgin oil source has a higher free fatty acid content than the second. EXAMPLE - No suitable example given.