Degradation of Major Classes Of Recalcitrant Chemicals Hindering The Reuse of Wastewater (A Review)

Abstract

In this recent age of advanced technology and biotechnology, the existing water bodies that serve
as a reservoir for lives are experiencing a surge in the occurrence of chemical contaminant. These classes of
contaminants were found to include both organic and inorganic, synthetic and natural pollutants of serious
environmental concern. Studies revealed that these contaminants were predominantly recalcitrant chemicals
that have been grouped as either toxic, hazardous and carcinogenic. There occurrence is not limited to their
numbers, types or variety but also a concentration that is alarming, leading to what is known as emerging
chemical contaminants (ECC). Sudden increase in the occurrence of chemical contaminants in our water,
wetlands, ponds, wastewaters and sludge were due to increasing population, high demand and consumption,
while their persistent in the environment is strongly linked to their recalcitrant nature and physiochemical
properties. Partial treatment of wastewater results in the accumulation of recalcitrant chemicals while
incomplete degradation of recalcitrant chemicals give birth to emerging contaminant (EC). Incorporation of
tertiary treatment systems to our conventional wastewater treatment system in combination with advance
treatment processes becomes paramount. Advance oxidation treatment (AOP) processes, membrane systems
coupled with bioreactors, biodegradations using bacteria and fungi could be used in combination to remove
these recalcitrant chemicals from wastewater. Test to proof the safety and safe reuse of these treated
wastewaters should also be conducted using model organism to achieve an ecofriendly treated wastewater.