Conversion of slaughterhouse and poultry farm animal fats and wastes to biodiesel: Parametric sensitivity and fuel quality assessment

Over recent past, animal fat wastes have drawn significant attention for the production of biodiesel all around the globe. The present article provides a comprehensive review on the production of biodiesel from various slaughterhouse animal fats (SHAFs) waste resources viz. beef tallow, pork lard, mutton fat, lamb meat, fleshing oil as well as poultry fats (PFs) and wastes viz. chicken fat, duck tallow and feather meal. Methods of physical-pretreatment of SHAFs and PFs for recovering usable fat and subsequent chemical pre-treatment for reduction of free fatty acids have been enumerated. Biodiesel synthesis processes through both single and two-step trans/esterification employing homogeneous and heterogeneous catalytic routes have been critically assessed. Advantages of reusability of heterogeneous catalysts over their homogeneous counterparts have been elucidated. Besides, parametric effects viz. catalyst concentration, temperature, pressure and alcohol to fat ratios on biodiesel yield along with optimal process conditions have been meticulously presented. Relative merits and demerits of enzymatic and supercritical conversion processes have been highlighted. Current advancements in process intensification technologies have been assessed and comparative appraisals of biodiesel properties produced from various SHAFs and PFs have also been decisively summarized.