Simultaneous removal of PAHs and phenols from coking wastewater under anaerobic conditions

The aim of the study was to evaluate concentration changes of selected polycyclic aromatic hydrocarbons (PAHs) and phenols during methane digestion of coke plant wastewater. Methane digestion was performed in a fixed bed one-stage reactor by complex microbial community. The temperature was held at 34 degrees C (mesophilic conditions); phenol load was equal to 0.13 kg/m(3) d. Concentration of phenols in influent was about 600 mg/L, whereas concentration of 16 PAHs total was up to over 600 ng/L. Up to 80% removal of phenols was observed; simultaneously, even 93% of PAHs were removed (60% in the case of carcinogenic compounds). Statistically significant, temporary increases in individual PAHs content in effluent were, however, observed. This indicates an important role of sorption/desorption processes on biomass in removal of PAHs from coking wastewater.