Biotechnologies for Water Treatment

Abstract

Too low concentrations of organic pollutants as well as too high loads of toxic contaminants and/or other extreme conditions of (waste)waters may impede their efficient treatment by conventional biological technologies. Micropollutants typically occur in only minute amounts in the aquatic environment, which is not in favor of their productive biodegradation and may lead to infinitely low degradation rates. Conventional bioprocesses could even collapse in response to too toxic or otherwise extreme conditions of the waters to be treated. Advanced biological water treatment processes aim to overcome the performance limits of conventional biological processes, and make use of isolated enzymes and whole organisms. Current approaches involve enzyme immobilization to yield biocatalytically active nanomaterials, and bioelectrochemical systems employing immobilized microorganisms for wastewater treatment along with energy production. Such applications are mostly still at the experimental stage, and issues related to process upscaling, long-term stability, and cost efficiency still need to be solved. Membrane bioreactors (MBRs) retain the biocatalytically active sludge in the system. They can be augmented with additional degrader organisms or used in combination with physicochemical processes such as activated carbon adsorption and ozonation. MBRs have already successfully been tested at the pilot and sometimes even at full scale. Constructed wetlands also have also the potential to remove micropollutants from urban wastewater. They may be considered as an alternative for wastewater treatment in small and scattered communities, and for the final step in the treatment of special wastewaters.