The UASB reactor wastewater is introduced to the bottom of the reactor as evenly as possible, and the sewage flows up through the sludge bed containing granular or flocculent sludge. Anaerobic reaction occurs in the process of contact between wastewater and sludge particles. Biogas produced under anaerobic conditions (mainly methane and carbon dioxide) causes internal circulation, which is beneficial for the formation and maintenance of granular sludge. Some of the gases formed in the sludge layer attached to the sludge particles, and the attached and unattached gases rose towards the top of the reactor.
The sludge rising to the surface hits the bottom of the three-phase reactor gas emitter, causing the sludge flocs attached to the bubbles to be degassed. After the bubble is released, the sludge particles will settle to the surface of the sludge bed, and the attached and unattached gases will be collected to the gas collection chamber of the three-phase separator on the top of the reactor.