Fermentation is the decomposition of organic materials by microorganisms in the absence of oxygen. Biogas, which is mostly composed of methane and carbon dioxide, is one of the fermentation products. Multi-substrate fermentation can be carried out to boost output yield.

Fermentation methods are frequently used to stabilize liquid and solid waste. Biogas generation from agricultural wastes, animal dungs, municipal and industrial wastes has the potential to be a viable alternative energy source for many nations. A cubic meter of biogas may generate 2.1 kWh of electricity and 2.9 kWh of heat energy. Multiple benefits of biogas were discovered in the 1990s, as well as a wide range of biomass sources that may have been used to produce this resource. One of the techniques of usage is such production. Sugar wastewater, for example, is one of the wastes from the food sector that may be used in this way. Not only is biogas made up of methane(CH4) and CO2, but it also contains hydrogen(H2). Hydrogen is increasingly being referred to as the fuel of the future, and ways for producing it are the focus of extensive research. Sugar industry and cellulose manufacturing wastes, as well as other wastes with high carbohydrates concentrations, are one of the sources of bio-hydrogen, because to its high concentration with comparatively low nitrogen rate. It's also important thinking about the waste produced by watering plants. Plants reduce nitrogen levels, but wastes remain a major source of hydrogen. The creation of hydrogen from fermentation effluent is an intriguing solution. The process is a two-phase fermentation in which hydrogen is produced in the first phase and methane is produced in the second. Some algae, such as Laminaria japonica, can be used as a substrate, but food industry wastes can also be used, which is more useful from a recycling standpoint.