Phytoremediation of pharmaceuticals and personal care products using the constructed wetland

Abstract

Pharmaceuticals and personal care products (PPCPs) are ubiquitously found pseudo-persistent group of emerging contaminants that causes ecotoxicity even at nano-concentrations. Due to their persistence and bio-accumulative behavior, long-term exposure to these pollutants increases the risk of severe health disorders in humans and poses ecological risks to aquatic life. Sedimentation, membrane filtration, advanced oxidation, activated sludge, and membrane bioreactors are a few of the treatment processes with treatment efficiency ranging from 50 to 95%, but they have limitations such as high investment, towering operating costs, use of chemicals, membrane fouling issues etc. Constructed wetlands (CW) are promising low cost, nature-based solutions having potential of PPCPs removal by simultaneous action of physical, chemical and biological processes. Herein, substrate material, plants and microbes play crucial roles in eliminating PPCPs. Phytoremediation of PPCPs occurs via plant uptake, translocation and degradation. Plants like Canna indica and Phragmites australis have shown ∼70–90% antibiotics removal efficiency. Biofilm formation and colonization of microbes lead to the microbial degradation of micro-pollutants apart from the synergistic effect of the plant-endophytic relationship. This bacterial property could be used in CWs for bioremediation of water and wastewaters, as substrates provide substratum for microbial adherence and biofilm formation. Quorum sensing (QS) is a density-based cell-communication system where bacterial cells send signals among themselves during biofilm formation. In this respect, QS-assisted biodegradation via augmentation of engineered bacteria with genes to enhance QS can be a novel approach for the degradation of organic pollutants in CWs with microbial richness.