Since the raw material of the fermentation is only food waste, it is inevitable to stain with some bones and papers when collecting. The collected raw materials are put into raw material pretreatment tank for carry on crushing processing, and adjust the concentration  and PH value of raw materials as well. Through pretreatment, raw material is pumped to raw material pool by rotor pump, by cutting pump, rotor pump, conveying raw material to primary fermentation tank.

1st fermentation tank adopts CSTR method (completely mixed anaerobic reactor Continuous Stirred Tank Reactor, CSTR) fermentation. On top of this kind of fermentation tank has top stirring or inner mixing machine, and inside of tank have heating coil, by stirring and heating, the methane bacteria and raw material fully contacts with each other, while maintaining the optimum reaction temperature of methane bacteria, so as to greatly improve the utilization efficiency of raw material and save the reaction time. This advantage makes the CSTR biogas fermentation process has been widely used in the biogas project.

Raw material in fermentation tank maintains medium temperature fermentation, control the temperature at 36 ± 2 ℃, meet the reaction time, namely the hydraulic residence time, deliver fermented raw materials to the secondary fermentation tank through rotor pump of feeding system.

The top of secondary fermentation tank is a two-film flexible gas cabinet, which is used to store biogas comes from primary fermentation tank. The bottom of tank is a round storage tank, which is used to accept residue slurry delivers from primary fermentation tank. This part of the residue slurry can also produce about 10% biogas, and will be collected into gas cabinet on the top of tank. Such structure is not only save the floor space of double-film gas cabinet and improve land utilization rate of equipment, but also take advantage of potency of biogas slurry and biogas slurry storage roles of secondary fermentation tank.

Biogas stored in the gas cabinet at the top of secondary fermentation tank is delivery to desulfurization system through roots blower, so as to remove hydrogen sulfide of biogas (H2S). Hydrogen sulfide is a corrosive gas, if not remove, it will bring the corrosion of the pipe, causing a series of problems, so need timely remove hydrogen sulfide. Hydrogen sulfide in the gas is removed, through the preliminary dewatering device, to remove saturated steam in the biogas. Then the biogas can be used to generate electricity.