Petroleum Research Center, Kuwait Institute for Scientific Research, P.O. Box 24885, Safat, 13109, Kuwait.
Department of Environmental Sciences, Central University of Jammu, Samba, 181143, (J&K), India; Department of Environmental Science, Babasaheb Bhimrao Ambedkar University, Lucknow, UP, India.
J Environ Manage. 2021 Feb 15;280:111789. doi: 10.1016/j.jenvman.2020.111789. Epub 2020 Dec 25.
Petroleum refining operations such as hydroprocessing and fluid catalytic cracking (FCC) generate huge quantities of spent catalysts containing toxic and valuable metals (Ni, V, Mo, Co, W, Al, etc.), the management of which is a serious environmental issue. Besides environmental concerns, the different metals present in the spent catalysts are also a valuable commodity to modern industries. Therefore, these spent catalysts also provide an opportunity to use it as a source of value to the refiners. In recent years, a biotechnological based leaching process 'bioleaching' has emerged as a promising eco-friendly technique for the extraction of metals from these refinery spent catalysts. Among various bioleaching agents such as archean, bacterial, or fungi, the process mediated by the fungi (Aspergillus niger, Penicillium simplicissimum, and many others) is gaining attention owing to the high metal extraction ability of the various fungal produced metabolites (organic acids) under moderately acidic conditions. Furthermore, the ability of these fungi to withstand wide process conditions (pH, spent catalyst concentration, substrate types, etc.), high metal toxicity and use of low-cost organic substrate make them an ideal candidate for bioleaching. In this review article, we shed light on the role and mechanisms of fungi involved in extracting different metals from spent hydroprocessing and FCC catalysts. Key process parameters that affect the efficiency of fungal based bioleaching are discussed. The techno-economic challenges associated with the process are elaborated, and the needed future research directions to promote its commercial applications are highlighted. Based on our analysis, it can be argued that the fungi bioleaching has potential, however, some challenges (slower kinetics, and health and safety) should be addressed before the process can be scaled up for the commercial application.
炼油操作，如加氢处理和流化催化裂化（FCC），会产生大量含有有毒和有价值金属（如镍、钒、钼、钴、钨、铝等）的废催化剂，这些金属的管理是一个严重的环境问题。除了环境问题外，废催化剂中存在的不同金属也是现代工业的宝贵商品。因此，这些废催化剂也为炼油商提供了一个将其作为有价值资源利用的机会。近年来，一种基于生物技术的浸出工艺“生物浸出”作为一种从这些炼油厂废催化剂中提取金属的有前途的环保技术已经出现。在各种生物浸出剂中，如古菌、细菌或真菌，由真菌（黑曲霉、简单青霉等）介导的过程由于真菌产生的各种代谢物（有机酸）在适度酸性条件下具有较高的金属提取能力而受到关注。此外，这些真菌能够承受广泛的工艺条件（pH 值、废催化剂浓度、底物类型等）、高金属毒性和使用低成本有机底物，使它们成为生物浸出的理想候选物。在这篇综述文章中，我们探讨了真菌在从废加氢处理和 FCC 催化剂中提取不同金属方面的作用和机制。讨论了影响真菌基生物浸出效率的关键工艺参数。详细阐述了与该工艺相关的技术经济挑战，并强调了未来促进其商业应用所需的研究方向。根据我们的分析，可以认为真菌生物浸出具有潜力，然而，在该工艺能够扩大规模用于商业应用之前，应该解决一些挑战（较慢的动力学和健康与安全）。
