Abstract:
Over the last thirty years, several techniques of groundwater (GW) remediation based
on the principles of physical (air sparging), biological (bioventing), and chemical (e.g.,
ion exchange) processes have proven to be effective; however, only a handful of
them could successfully be implemented at a community or regional scale due to
issues like longevity, a requirement of significant investment and operation cost, skilled
labours, and others. Therefore, considering the scope of Permeable Reactive Barriers
(PRBs) to be implemented on a regional scale and its capability to be a significant
replacement for several existing GW treatment methods, this review was prepared with
the following objectives: (i) to compare the PRB method with the conventional methods
of groundwater treatment along with the possibility and problems associated with the
PRB installation in pilot-scale; (ii) to enlist all the probable sets of adsorbents (reactive
materials) that can be used for different types of organic and inorganic contaminants;
(iii) to understand the key mechanisms of degradation/removal of contaminants involved
in PRB design; and (iv) to put forward the future research perspectives of this domain.
Review augments that PRBs certainly has a low maintenance cost and a longer life span
of ˜30 years that requires very ordinary skills. PRBs promise to be effective in developing
countries like India, Bangladesh, and Sri Lanka for the removal of geogenic contaminants
like arsenic and fluoride given the appropriate aquifer depth and hydrogeological
settings like hydraulic gradient and transmissivity. Furthermore, reactive fillers required
in PRBs are readily available, have longer expected life, and operate with no surrounding
disturbances. With the advent of several green nanomaterials based adsorbents, PRB’s
performance can achieve another height, but it needs the experiences from several
pilot and larger scale projects. Indeed PRBs are the need of the hour, but a more
programming-based investigation would be expected for its superior comprehension.
