Experimental study on sequencing batch biofilm reactor with biological filtration (SBBR-BF) for wastewater treatment

A novel wastewater treatment technology combining a sequencing batch biofilm reactor and biological filtration in an SBBR-BF system was presented. Elastic plastic filaments were fixed as biofilms carrying media. Particle materials (sand or anthracite) and the settled sludge constituted the filtration layer. In the laboratory studies, operating results of SBR, SBBR and SBBR-BF were compared. Better quality and stable water quality of effluent could be achieved in SBBR-BF because the fixed film and filtration layer were added in the reactor. Other laboratory experiment results indicated that slow filtration, cycle water stirring and backwashing making use of the settled supernatant are successful methods for preventing clogging and saving energy. The velocity and headloss of filtration were significantly impacted by different MLSS concentration. The MLSS concentration in the reactor must be less than 1,400 mg/L for optimal results. The average velocity of filtration ranging from 0.6 to 1.0 m/h, the backwash velocity of 10-15 m/h and the backwash time of 20 seconds are recommended according to the laboratory experiment. On-site experiment and study showed that SBBR-BF is a stable and efficient system for domestic wastewater treatment, and is particularly suited for small wastewater treatment plants, because of the simple operation and compact installation.