The SBR (Sequential Batch Reactor) system is a discontinuous flow treatment system capable of incorporating the different treatment phases in a single basin; it does not develop in space like traditional activated sludge systems, in which the flow passes from one tank to the next, but is a time-oriented system that allows variations in the flow and volume of the tank in accordance with the different operating strategies.
Feeding: during this first phase the sewage is sent to the basin, where it mixes with the residual biomass from the previous cycle.
Ventilation: inside the basin there are activated sludge which provides for the biological degradation of pollutants. The oxygen necessary to keep the muddy mass alive and homogenize is delivered through the blowers and distributed on the bottom through special micro-bubble diffusers. It is during the aeration phase that the necessary oxygen is supplied for aerobic biological reactions to occur with the removal of BOD and the transformation of ammonia nitrogen into nitrates.
Sedimentation: after the Oxidation phase, when the pollutants have been completely degraded, the blower stops for a certain time to allow decantation, the quiet situation inside the oxidation tank determines the precipitation of the activated sludge on the bottom of the tank leaving the purified water on the surface.
Discharge of purified water and excess sludge: after decanting, the purified water present on the surface is taken by a special pump and automatically re-launched at the discharge in accordance with current regulations. This phase takes place in absolute quiet, using the entire surface of the SBR basin as a sedimentation tank. The tank discharge mechanism is one of the most delicate points of the system, as it is necessary to ensure the good quality of the effluent, avoiding the discharge of biomass or the entrainment of suspended solids. The removal of the excess mud is carried out in conjunction with the discharge of the effluent. At this point the cycle will start again from the 1st feeding phase.
Applications: small and medium potential domestic wastewater treatment. Agri-food industrial wastewater treatment as they are not very sensitive to the variations in both hydraulic and organic load that characterize industrial effluents linked to the operating rhythms of the processing departments:
Dairies, dairies
Slaughtering and meat processing
Wine cellars
Canning industries
Advantages: high resistance to hydraulic and organic overloads, excellent retention capacity of the active biomass, better oxygen transfer efficiency, better treatment flexibility by changing the times of the various phases, lower energy cost of treatment and installation for elimination of the sedimentation basin, less space required.
