*4.1. Wheat Straw and Corn Stover*

Wheat straw is a known agricultural residue containing cellulose of about 34–40% of the total organic carbon of the waste. Hemicellulose is 21–26% of the organic carbon, while lignin is 11–23% of the total organic carbon content. Due to hydrolysis, the formation of a hydrolysate rich in carbohydrates can be achieved [7]. Some studies have shown wheat straw as an alternative means of carbon source provisioning in MFCs to generate electricity. The hydrolysate is formed after converting the solid residue into a carbohydrate-rich liquid, which can be used as a substrate in MFC to obtain a maximum power density of up to 123 mW/m<sup>2</sup> when the initial concentration of the substrate was 1 g/L. However, the reported energy output seemed to be on the lower side. Overall, wheat straw showed a high efficiency as a substrate in MFC. However, corn stover, another agricultural residue containing 70% cellulose and hemicellulose, can undergo conversion processes through cellulosic enzymatic treatment or steam explosion into sugar hydrolysates containing a similar profile of sugar content to other agricultural residue hydrolysates obtained [6]. In another experimental setup, the substrate as a hydrolysate from "raw corn stover" employed in the production of electricity in an MFC, generated a considerable amount of low power output, unlike in control MFC whereby glucose was employed [8]. This means an improvement is required in producing a hydrolysate from wheat straw and corn stover that is suitable for use in MFC technology development.
