An investigation of restaurant waste oil characteristics for biodiesel production in Trinidad and Tobago

In this study, the effect of cooking conditions on waste oil characteristics and yield of methyl esters was investigated for biodiesel production in Trinidad and Tobago. Used cooking oil was collected from eleven restaurants that were subdivided into four categories according to the type of meals served: four Chinese restaurants, four Indian restaurants, two Fried-Chicken restaurants and one Pizzeria. The waste oils were characterised as to their acid value, free fatty acid levels, saponification, peroxide value, water concentrations and fatty acid composition. Waste oil from one restaurant from each category was then selected to undergo base catalysed transesterification. The waste oils collected from the Indian restaurants were used less intensely and had the most desirable properties with the lowest free fatty acid content while those of the Chinese restaurants produced the highest yields of methyl esters. Biodiesel produced from the waste oil of these two restaurants also met the ASTM standard for the properties tested. Waste oils from the Fried-Chicken restaurants and the Pizzeria demonstrated high degradation that was reflected in their high acid values and free fatty acid levels and correspondingly poor yields of methyl esters. Given the high proportion of these less suitable waste oil feedstocks in the local market, biodiesel production via base catalysed transesterification may not be suitable in the Trinidad and Tobago context.

► Restaurant type influences the characteristics of waste cooking oil.
► Indian and Chinese restaurant waste oil had low acid and FFA values
► Fried-Chicken and Pizzeria restaurant waste oils had high acid and FFA values.
► Restaurant type determines the success of base catalyzed transesterification.
► Only Chinese and Indian restaurant waste oils produced biodiesel by base catalysis.
► Biodiesel production by base catalysis is not suitable for Trinidad and Tobago.