Respond to this post, answer in essay style format, expanding on the points: The review by Srivastava et al. (2025) touches on many subjects we've previously discussed and focuses on the process of dark fermentation for pilot-scale biohydrogen production utilizing organic waste as the primary substrate. In this process, biodegradable waste materials such as food scraps, agricultural residues, and common refuse are processed via anaerobic fermentation in bioreactors under controlled conditions. Microorganisms convert organic material into hydrogen gas and other byproducts. The process operates in continuous-stirred-tank reactors under ideal conditions and involves parameters such as hydraulic retention time, pH, and organic loading rate. Pretreatment of the substrate is used to optimize and improve hydrogen yields. As for profitability, first is the cost and availability of the substrate. Using low-cost or negative-cost waste material can significantly reduce operational costs, but constant availability would need to be maintained for stability. Another major driver is conversion efficiency. Higher hydrogen yields directly increase revenue potential, while unutilized material adds waste disposal costs. Energy consumption also plays a crucial role. Heating, mixing, and gas separation require more input, especially during pretreatment. As well, effective gas handling and purification are essential to ensure that the hydrogen produced meets quality standards