**4. Agricultural Residues**

Agricultural residues are considered one of the most prominent substrates in renewable energy production and carbon source content due to their availability as a cheap renewable energy feedstock.

Moreover, any microbial community cannot directly utilize the agricultural residues in MFC to produce electricity. To generate fermentable sugar hydrolysates easily, either acidic or enzymatic pre-treatments is required [6]. Some of the important agricultural residues that contribute to bioelectricity generation include wheat straw, corn stover, rice straw, cassava mill effluent, plant and flower waste, vegetable waste, etc.
