Waste butter and margarine as feedstock for biodiesel production

Abstract

The resulting bio-waste from butter and margarine factories should be disposed of in an environmentally friendly manner. Currently the bio-waste is either flushed into the municipal sewerage system or moved to landfill sites. The bio-waste from butter and margarine factories provides a potential alternative feedstock for biodiesel production, being both non-edible and non-competitive with edible oils. A butter factory (Clover) near Frankfort, South Africa, has been identified as a source of bio-waste for biodiesel production. This facility produces 60 tons of fatty bio-waste per annum. In this study fatty acid methyl esters (FAME) were produced using cow's milk butter, margarine, as well as the actual butter factory's bio-waste as feedstock. Even though yields in excess of 90% were obtained, the biodiesel produced from the butter factory's bio-waste failed to meet the specifications for sulphur (18 wt ppm) and oxidation stability. Unless further purification methods are considered, the resulting biodiesel cannot meet the 10 wt ppm specification. The problem with regards to oxidation stability and sulphur content can be addressed by blending with ultra-low sulphur biodiesel. The oxidation stability can also be improved by the addition of a commercial antioxidant formulation