Immobilized-microbial bioaugmentation protects aerobic denitrification from heavy metal shock in an activated-sludge reactor

• DOI: 10.1016/j.biortech.2020.123185
• Publication Date: 2020-03-14T15:37:14Z
• Authors: Xuan Yu; Juanjuan Shi; Aman Khan; Hui Yun; Pengyun Zhang; Peng Zhang; Apurva Kakade; Yanrong Tian; Yaxin Pei; Yiming Jiang; Haiying Huang; Kejia Wu; Xiangkai Li
• Keywords: Bioaugmentation; Aerobic denitrification; Hexavalent Chromium

The inhibition of denitrification by heavy metals is a problem in nitrogen wastewater treatment, but the solutions are rarely studied. In this study, Pseudomonas brassicacearum LZ-4, immobilized in sodium alginate-kaolin, was applied in an activated-sludge reactor to protect denitrifiers from hexavalent chromium (Cr(VI)). Q-PCR result showed that the strain LZ-4 was incorporated into activated sludge under the help of immobilization. In the non-bioaugmentation system, the removal efficiency of nitrate was decreased by 86.07% by 30 mg/L Cr(VI). Whereas, denitrification was protected and 95% of nitrate was removed continuously in immobilized-cell bioaugmentation system. Miseq sequencing data showed that bioaugmentation decreased the impact of Cr(VI) on microbial communities and increased the abundance of denitrifiers. Based on the results of biomass and extracellular polymers, activated sludge was protected from Cr(VI) toxicity. This discovery will provide a feasible technique for nitrogen wastewater treatment in the presence of distressing heavy metals.