Cultivation of aerobic granular sludge for the treatment of petrochemical wastewater

In this study, aerobic granular sludge was cultivated in a Granular sludge Sequencing Batch Reactor (GSBR) to evaluate the possibility of treating petrochemical wastewater produced by the Integrated Gasification Combined Cycle (IGCC) and characterized by high concentrations of organic matter (up to 260-380 mgTOC/L), ammonium (400-550 mgNH4-N/L) and toxic substances (e.g. cyanides, phenols and formates). Small granular aggregates appeared soon and progressively increased in size (granule diameter raised from 0.2 up to 2.1 mm) and density (up to 61 gTSS/Lgran). Total organic carbon (TOC) removal was high (up to 89.4±6%), while N and P removal efficiencies strongly fluctuated during the start-up, indicating unsteady conditions. Preliminary results observed during GSBR start-up showed that aerobic granular sludge can be a viable solution for the treatment of petrochemical wastewater, which is worthy of being further investigated.