Comparison of Anammox Treatment Performances Using Different Kinds of Biomass Carriers

Abstract

The anammox process, as an alternative to conventional nitrogen removal technologies, has abstracted much attention in recent years. In this study, two column-type reactors using different support materials-net type acrylic fiber (Biofix) and polyester nonwoven-were used for anammox treatment. The nonwoven reactor was operated at 35℃ and the Biofix reactor at 25℃ (peak summer temperature, 31.5℃). Over 330 days of operation, the nitrogen loading rates of the Biofix and nonwoven reactors were increased to 3.6 kg-N/m 3 /d and 4.0 kg-N/m 3 /d and T-N removal efficiencies reached to 81.3% and 86.3%, respectively. A protein substance was shown to be the most abundant extracellular polymeric substances (EPS) in the anammox sludge with almost three times more in the granular sludge of the Biofix reactor than in the granular sludge of the nonwoven reactor. Considering the EPS levels and observation by scanning electron microscopy, the anammox granules in the Biofix reactor were denser than that in the nonwoven reactor. Results of DNA analyses indicated that the KSU-1 strain might prefer relatively low nutrient levels, while the KU2 strain might be better suited for the high media concentration. Other kinds of bacteria were also identified with the potentials for consuming the dissolved oxygen in the influent and facilitating anammox bacteria surviving under aerobic conditions.