Attachment Characteristics of Biofilms in Fixed-Lock Media for Swine Wastewater Treatment

Abstract

A correlation between equilibrium biofilm thickness and biomass density in a laboratory-scale submerged media aeration system was evaluated. The system had lock-type media, and swine wastewater was used as a substrate. The influent wastewater had chemical oxygen demand and biochemical oxygen demand concentrations of 2940–3800 and 1310–1730 mg/L, respectively. The hydraulic retention time of the system was varied from 0.5 to 2 days. The following conclusions can be drawn from the operational results: (i) the maximum biofilm density was observed when the equilibrium biofilm thickness was 180–200 μm, (ii) the activated biomass represented as volatile suspended solids per unit area decreased after 10 days of operation, and (iii) the removal rate of chemical oxygen demand increased rapidly up for an equilibrium biofilm thickness up to 200 μm, but no further increase was observed for thicknesses of 200–1200 μm.

Keywords:

• Biofilm density
• Equilibrium biofilm thickness
• Lock-type media
• Swine wastewater