A Pilot-Scale Evaluation of the ‘Biocarbone Process' for the Treatment of Settled Sewage and for Tertiary Nitrification of Secondary Effluent

Abstract

The BIOCARBONE process is a recently developed method for wastewater treatment. High concentrations of active biomass attach to an expanded shale medium in an aerated, packed-bed filter. High-rate biological treatment and in-situ removal of suspended solids are claimed as advantages of the process. The pilot-scale evaluation aimed to assess the performance of the process and its economic feasibility for use in the UK. Carbonaceous oxidation of settled sewage and tertiary nitrification of secondary effluent were investigated in two pilot-scale reactors. Carbonaceous oxidation produced a good-quality effluent at volumetric loading rates up to 4.1 kg BOD5/m3.d (9.2 kg COD/m3,d). Automatic backwashing of the filter was required and problems were encountered with blockages of the process aeration grid. Tertiary nitrification achieved greater than 90% ammoniacal nitrogen (NH3-N) removal at volumetric loading rates up to 0.58 kg NH3-N/m3.d (0.63 kg KJN/m3.d). The economic evaluation indicated that costs of sewage treatment using the BIOCARBONE process would be comparable to those of the activated sludge process for sewage treatment works greater than 50,000 population equivalent. The results show that the BIOCARBONE process is suitable for both the carbonaceous oxidation of settled sewage and the tertiary nitrification of secondary effluent. The process may be an economic option for large sewage treatment works in the UK.