Nitrogen removal in a SBR operated with and without pre-denitrification: effect of the carbon:nitrogen ratio and the cycle time

摘要

The effects of cycle time (CT) (8, 12 and 16 h) and C/N ratio (3, 6 and 9) on nitrogen removal efficiencies in a bench top sequencing batch reactor treating slaughterhouse wastewater were investigated under different operating conditions: in condition I, the reaction comprises an aerobic/anoxic phase and in condition Ⅱ, the reaction comprises anoxic I/aerobic/anoxic Ⅱ phases (with pre-denitrification). The greatest percentages of nitrogen removal were obtained in the CT range from 12 to 16 h and C/N ratios from 3 to 6, with mean efficiency values of 80.76% and 85.57% in condition I and 90.99% and 91.09% in condition Ⅱ. Although condition II gave a higher removal of total inorganic nitrogen (NH_4~+ - N + NO_2~- - N + NO_3~- - N) than condition I, only condition I showed statistically significant and predictive regression for all the steps of nitrogen removal.