Removal of triclocarban from treated wastewater using cell-immobilized biochar as a sustainable water treatment technology

Triclocarban (TCC), an emerging endocrine disruptor, has been commonly found in municipal treated wastewater. Pseudomonas fluorescens MC46 (MC46), an effective TCC-degrading bacterium, could be applied to remove TCC from wastewater. In addition, application of a cell immobilization technique could possibly enhance its removal performance. This study examined microbial cells immobilized on waste biochar (from wood vinegar production) as a highly effective advanced wastewater treatment unit for TCC removal. TCC removal was investigated from real wastewater samples using the following treatments: biochar only, cell-immobilized biochar, and free cell systems in batch (short-term) and semi-batch (long-term) modes. The TCC adsorption capacities of original and potassium hydroxide-modified biochars (no cells) were 8.43 and 9.17 mg/g, respectively. During the batch experiment, the cell-immobilized modified biochar exhibited the highest TCC removal, 79.80%, in the model TCC solution. Five-cycle semi-batch experiments were utilized to investigate the reusability and performance of the treatment systems. After five cycles, the cell-immobilized modified biochar still achieved stable TCC removal (52%) due to the integration of adsorption and biodegradation. Free MC46 cells and biochars (no MC46 cells) only removed 32% and 2% of TCC, respectively, due to cell washout/death and sorbent exhaustion. This important work clearly demonstrates the significant potential for the future utilization of cell-immobilized biochars in a sustainable wastewater treatment system. Furthermore, the use of renewable agro-industrial wastes aid in the development of a strong circular bio-based economy.