Biotransformation of organic micro-pollutants in biological wastewater

The presence of organic micro-pollutants (OMPs) in wastewater has attracted increasing scientific community interest due to the risks they pose to the environment. Biological treatment systems have emerged as a promising technology for the removal of these compounds. Biotransformation is identified as the main mechanism for removing OMPs from wastewater in biological processes. This chapter summarizes current knowledge on the biotransformation of OMPs during aerobic and anaerobic biological wastewater treatment processes, respectively. In both aerobic and anaerobic treatment processes, the biotransformation of OMPs mainly occurs through cometabolism. The activity of ammonia-oxidizing bacteria and methanogen plays a very significant part in OMP biotransformation. The OMP biotransformation pathway and extent can be influenced by the biological processes’ operating parameters. These mainly include sludge retention time, hydraulic retention time, temperature, pH, and primary biotransformable substrates. Moreover, the combination of aerobic and anaerobic technologies in hybrid reactor systems is likely to enhance overall OMP biotransformation efficiency and degree. Further studies are required to investigate the biotransformation products of OMPs and their level of toxicity to the environment. More in-depth knowledge about parameters influencing OMP biotransformation as documented in this chapter and other possible factors is required to improve biological processes in terms of technical effectiveness and economic competitiveness in the future.