Carbonaceous oxidation using a new vertically moving biofilm system

This laboratory study consisted of the construction and testing of a new experimental biofilm system for the carbonaceous oxidation of a synthetic wastewater. In the system, a biofilm cuboid module with a high surface area was vertically and repeatedly immersed in and lifted out of the wastewater in a reactor. The performance of two different biofilm modules were compared: one module was constructed from crossflow corrugated plastic sheets with a specific surface area of 410 m²m⁻³ and had a calculated surface area of 6.24 m²; the other consisted of honeycombed plastic with hexagonal vertical columns and an estimated surface area of about 2.8 m². Filtered chemical oxygen demand (COD) removal rates per bulk fluid volume for the corrugated and honeycombed modules of 7.2 kg COD m⁻³ d⁻¹ and 7.6 kg COD m⁻³ d⁻¹ were respectively achieved and these rates compare favourably with other wastewater treatment systems. The new biofilm system was simple to construct and operate, and was very effective in removing biodegradable COD from the synthetic wastewater. The system offers potential for reduced reactor volumes, energy saving, low solids production and easy solids removal.