Advanced treatment of the low concentration petrochemical wastewater by Tribonema sp. microalgae grown in the open photobioreactors coupled with the traditional Anaerobic/Oxic process

In this paper, the filamentous microalgae Tribonema sp. grown in the open photobioreactors (PBRs) was directly integrated with the traditional Anaerobic/Oxic (A/O) process for the advanced treatment of low concentration petrochemical wastewater. The COD removal rate was only 71.7% after direct treatment of wastewater effluent from the primary clarifier in the open PBRs, while in-depth purification could be achieved in the secondary clarifier with COD removal rates reached to 97.8% in the open PBRs. The NH ₃ -N and P of the two effluents were almost completely removed after 5–7 days in the open PBRs. The biomass concentration, productivity and the oil content in the open PBRs with the secondary clarifier effluent were all higher than those in the primary clarifier group. The filamentous microalgae Tribonema sp. as a post-treatment step for the A/O process can achieve deep removal of the pollutants and accumulate higher biomass concentration and oil content.