Alternated phenol and trichloroethylene biodegradation in an aerobic granular sludge reactor

Co-metabolic removal of a synthetic solvent, trichloroethylene (TCE) was conducted. Phenol was used as the primary substrate, and aerobic granules as the biocatalyst. An airtight reactor was designed and constructed with glass, and the configuration was verified of its applicability with volatile solvent. Phenol and TCE were fed into the reactors alternately, and both were efficiently removed during 6 weeks of operation. Compared with the control reactor receiving no TCE, biomass in the TCE-fed reactors had lower phenol-dependent specific oxygen utilization rate, but higher concentration, bigger size, and better settling ability. The morphology of the biomass in TCE and control reactors exhibited distinct characteristics. Granules in the TCE reactors slightly broke up early in the operation, but generally retained their shape and structure throughout. The biomass in the control reactor, however, lost its granular structure and totally disintegrated into flocs. Therefore, TCE co-metabolism likely improved the structural integrity of aerobic granular sludge, and co-metabolic degradation of TCE by phenol-grown aerobic granules showed long term stability.