Prospectives and challenges of wastewater treatment technologies to combat contaminants of emerging concerns

Various anthropogenic activities result in a continuous discharge of contaminants of emerging concerns (CECs) into the natural environs. The remediation of these substances is an emerging concern to safeguard life on earth. The main aim of this research article is to provide a deep imminent into the available conventional and advanced wastewater treatment processes and to analyze their removal efficiencies, long term application prospects while comparing them technically and economically. Several traditional approaches and advanced oxidation processes (AOPs) experimented in the recent past. Ozonation and powdered activated charcoal remove iohexol, iomeprol, and iopromide with an efficiency of > 97% and 90% for diatrizoate. Algal technologies have excellent removal efficiency for heavy metals (37-100%) and remove noxious nutrients. AOPs significantly remove hazardous contaminants from wastewaters. Interestingly, engineered biochar cleans heavy metals, toxic dyes, COD, pesticides, and harmful aromatic compounds effectively. Moreover, nanofiltration nowadays considered as the boon for treating the wastewater with a dye removal efficiency achieved to be 98%. The removal efficiencies by exploring AOPs vary 45-100% for specific contaminants but, increase the energy consumption cost by 60-150%. Undoubtedly, AOPs overweighed to conventional remediation technologies for efficiency, but are specific to remove a particular contaminant. Furthermore, based on past research, these techniques appreciably remove one or more kinds of pollutants but are inadequate to remove most of the toxic substances efficiently from wastewater. Therefore, a comprehensive research is required to find an appropriate low cost, ecofriendly, and efficient technology to remediate different kinds of CECs from wastewater.