Assessment of the anaerobic biodegradability of bitumen fume condensate wastewater by mesophilic AnMBR

Abstract

Certain industrial wastewaters have posed a challenge to water treatment systems because of their composition. The bitumen from the reclaimed asphalt process is heated by the BAM Infra Asfalt and produces fumes, which are usually sent to the air filters and then out through the chimney. To recover the heat lost through the fume, it is condensed. The bitumen fume condensate contains aromatic hydrocarbons of petroleum origin and this poses a threat to health and the environment. The removal of these compounds by anaerobic biodegradation was assessed with a mesophilic anaerobic membrane bioreactor (AnMBR). The bitumen condensate contained over 800 compounds, out of which some were p-cresol, o-cresol and 2-napthalenemethanol. The inhibition to the methanogenic activity and toxicity to the biomass of this wastewater on three different inocula were studied under batch-test conditions. A phenol-degrading sludge was less inhibited (IC₅₀= 870 mg COD_bitumen/L) and more resistant to the toxicity than granular sludge from a petrochemical wastewater treatment plant (IC₅₀= 187 mg COD_bitumen/L) and a municipal sludge (sludge from a municipal wastewater treatment plant, IC₅₀= 127 mg COD_bitumen/L). In continuous operation, the bitumen condensate was degraded efficiently with 89%±12% (S.D)COD removal from the influent of the AnMBR. Maximum organic conversion rate of the bitumen condensate was 26.0 mg COD/g VSS.d. This research demonstrated the efficiency of AnMBR technology to degrade bitumen condensate. Further research must be done to improve the organic conversion rate and optimise the technology for large scale implementation.