Each year, large quantities of waste cooking oils are produced worldwide which are currently reused mainly for biodiesel production. Since lipids have a very high potential for biomethanation, the production of biogas is a possible alternative for the recycling of edible used oils. The digestion of fats is hindered mainly by their hydrophobicity, which implies a biphasic system with problems of floating and foaming of the oily materials, and by the accumulation of long-chain fatty acids, which are toxic to microbial consortia. The objectives of this review were to highlight the recycling potential of waste cooking oil to biogas production and to facilitate the application of the technology by identifying solutions to overcome biological and engineering limits to its diffusion. Particular attention was paid to the microbial populations involved, to the process factors whose control is important to improve the digestion of fats such as lipid concentration, pH, temperature, and agitation, and to technological solutions whose application also aims to improve digestion, such as pretreatment of raw materials and co-digestion of fats with other feedstocks. The state of the art in reactor designs suitable for lipid digestion was also examined.

中文翻译：

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将废食用油转化为沼气的观点和局限性。

每年，世界范围内都会生产大量的废食用油，这些废油目前主要用于生产生物柴油。由于脂质具有很高的生物甲烷化潜力，因此沼气的生产是可回收食用废油的可能替代方法。脂肪的消化主要受其疏水性（这意味着存在油性材料的漂浮和起泡问题）的两相系统以及长链脂肪酸（对微生物菌群有毒）的积累的阻碍。这次审查的目的是强调废烹饪油在沼气生产中的再循环潜力，并通过确定解决方案来克服其扩散的生物学和工程学限制，促进该技术的应用。特别注意涉及的微生物种群，其控制对改善脂肪消化（例如脂质浓度，pH，温度和搅动）很重要的工艺因素，以及其应用还旨在改善消化的技术解决方案（例如原料预处理和脂肪共消化）与其他原料。还检查了适合脂质消化的反应器设计中的技术水平。