Filamentous bulking control by sponge media in lab‐scale SBR process

Abstract

Polyurethane foam sponge media were examined with respect to their ability to control filamentous bulking in a sequencing batch reactor process. In a high‐rate nutrient removal study conducted with a 201 lab‐scale reactor and synthetic wastewater of approximately 200 mgBOD l^‐2, the presence of 20% v/v sponge media in the reactor improved the settling properties of biomass significantly, resulting in enhanced nutrient removal performance, i.e., <10 mgT‐N l^‐1 and <1 mgT‐P l^‐1 even at the HRT of 0.67 day. Without the support of sponge media, the suspended biomass was so bulky as to lead to its heavy washout from the reactor. A microscopic study under filamentous bulking revealed that the sponge media physically cut or broke biomass to shorter filaments and smaller flocs, mitigating the severe bulking condition. Indirect effects derived from the physical breakdown of biomass, such as more aerobic conditions in floes, are expected to further create favorable conditions for suppressing filamentous bulking.

Keywords:

• Bulking control
• sponge media
• filamentous bacteria
• sequencing batch reactor (SBR)
• nutrient removal