Population increase and industrialization has resulted in high energy demand and consumptions, and presently, fossil fuels are the major source of staple energy, supplying 80% of the entire consumption. This has contributed immensely to the greenhouse gas emission and leading to global warming, and as a result of this, there is a tremendous urgency to investigate and improve fresh and renewable energy sources worldwide. One of such renewable energy sources is biogas that is generated by anaerobic fermentation that uses different wastes such as agricultural residues, animal manure, and other organic wastes. During anaerobic digestion, hydrolysis of substrates is regarded as the most crucial stage in the process of biogas generation. However, this process is not always efficient because of the domineering stableness of substrates to enzymatic or bacteria assaults, but substrates’ pretreatment before biogas production will enhance biogas production. The principal objective of pretreatments is to ease the accessibility of the enzymes to the lignin, cellulose, and hemicellulose which leads to degradation of the substrates. Hence, the use of pretreatment for catalysis of lignocellulose substrates is beneficial for the production of cost-efficient and eco-friendly process. In this review, we discussed different pretreatment technologies of hydrolysis and their restrictions. The review has shown that different pretreatments have varying effects on lignin, cellulose, and hemicellulose degradation and biogas yield of different substrate and the choice of pretreatment technique will devolve on the intending final products of the process.

中文翻译：

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不同预处理方法优化木质纤维素材料沼气产量：综述

人口增长和工业化导致能源需求和消耗较高，目前化石燃料是主要能源的主要来源，占总消费量的80%。这极大地增加了温室气体排放并导致全球变暖，因此，迫切需要研究和改善全球的新鲜和可再生能源。其中一种可再生能源是沼气，它是利用不同的废物（例如农业残留物、动物粪便和其他有机废物）通过厌氧发酵产生的。在厌氧消化过程中，底物的水解被认为是沼气产生过程中最关键的阶段。然而，由于底物对酶或细菌攻击的稳定性非常高，因此该过程并不总是有效，但在沼气生产前对底物进行预处理将提高沼气产量。预处理的主要目的是使酶更容易接触木质素、纤维素和半纤维素，从而导致底物降解。因此，使用预处理来催化木质纤维素底物有利于生产具有成本效益和环境友好的工艺。在这篇综述中，我们讨论了不同的水解预处理技术及其限制。综述表明，不同的预处理对木质素、纤维素和半纤维素的降解以及不同底物的沼气产量有不同的影响，预处理技术的选择将取决于工艺的预期最终产品。