Effect of Acetic Acid on Denitrification and Dephosphatation Process Efficiencies in Sequencing Batch Biofilm Reactor

Abstract

This study investigates the feasibility of using an organic substrate in the form of acetic acid to enable wastewater denitrification in a Sequencing Batch Biofilm Reactor (SBBR). The impact of nitrates presence on the yield of biological dephosphatation were determined as well. The experiment included 296 cycles and was divided into 4 series differing in the load of nitrates. Ratio N:(C and P) was: 7:(140 and 7); 35:(140 and 7); 70:(140 and 7) and 140:(140 and 7). Hydraulic retention time in the reactor was 12h (6h mixing – dissolved oxygen concentration below 0,1 and 6h aeration – concentration of dissolved oxygen 3.0±0.8 mgO2•dm-3). Study demonstrated that the 30-day adaptation period (60 cycles) was sufficient for the development of a stable biofilm. The C:N ratio of 2 ensured total nitrogen concentration in the effluent below 1 mgN•dm-3. Mean efficiency of biological dephosphatation reached 7.0, 17.4, 18.7, and 30.3% in series 1-4, respectively. In the case of series 2 and 3, no significant differences were demonstrated in total phosphorus concentration in the effluent. In the other series, the differences turned out to be significant.

Keywords

• sequencing batch biofilm reactor
• denitrification
• dephosphatation
• acetic acid