Polycyclic Aromatic Hydrocarbons: Sources, Toxicity, and Remediation Approaches

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are widespread across the globe mainly due to long-term anthropogenic sources of pollution. The inherent properties of PAHs such as heterocyclic aromatic ring structures, hydrophobicity, and thermostability have made them recalcitrant and highly persistent in the environment. PAH pollutants have been determined to be highly toxic, mutagenic, carcinogenic, teratogenic, and immunotoxicogenic to various life forms. Therefore, this review discusses the primary sources of PAH emissions, exposure routes, and toxic effects on humans, in particular. This review briefly summarizes the physical and chemical PAH remediation approaches such as membrane filtration, soil washing, adsorption, electrokinetic, thermal, oxidation, and photocatalytic treatments. This review provides a detailed systematic compilation of the eco-friendly biological treatment solutions for remediation of PAHs such as microbial remediation approaches using bacteria, archaea, fungi, algae, and co-cultures. In situ and ex situ biological treatments such as land farming, biostimulation, bioaugmentation, phytoremediation, bioreactor, and vermiremediation approaches are discussed in detail, and a summary of the factors affecting and limiting PAH bioremediation is also discussed. An overview of emerging technologies employing multi-process combinatorial treatment approaches is given, and newer concepts on generation of value-added by-products during PAH remediation are highlighted in this review.

The Total Solubility of the Co-Solubilized PAHs with Similar Structures Indicated by NMR Chemical Shift

“…PAHs are carcinogenic, toxic and mutagenic, which can cause serious pollutions to humans and ecosystems [ 6 , 7 , 8 ]. Therefore, there is a great demand in the removal of PAHs from contaminated soil or sediment water, and various methods have been developed to remove PAHs, such as chemical, physical, microbial or phytoremediation, surfactant enhanced remediation (SER) methods [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. SER methods are based on the amphiphilic properties of surfactants.…”

TiO2 Photocatalysis for the Transformation of Aromatic Water Pollutants into Fuels

“…Another kind of organic pollutants that causes water contamination is the PAHs, which are classified as hazardous persistent environmental pollutants [47]. They are a group of over 100 different organic compounds containing two or more fused aromatic benzene rings connected linearly, angularly, or in a cluster arrangement [48,49]. PAHs are found naturally and released into the environment by anthropogenic sources.…”

“…Under these conditions, carbon containing-compounds are not oxidized completely to carbon dioxide, rather, hydrocarbon fragments that are generated during incomplete combustion interact with each other to yield complex polycyclic structures. Many other resources for the PAHs [49,53] are shown in Figure 1.…”

“…Under these conditions, carbon containing-compounds are not oxidized completely to carbon dioxide, rather, hydrocarbon fragments that are generated during incomplete combustion interact with each other to yield complex polycyclic structures. Many other resources for the PAHs [49,53] are shown in Figure 1. PAHs have low aqueous solubility and are considered as lipophilic organic compounds that are widely distributed in the environment and characterized by their high toxicity, genotoxicity, and carcinogenicity.…”

“…PAHs have low aqueous solubility and are considered as lipophilic organic compounds that are widely distributed in the environment and characterized by their high toxicity, genotoxicity, and carcinogenicity. [49,55]. Table 1 shows the physicochemical properties of 16 compounds of the PAHs that have been listed as priority pollutants by the United States Environmental Protection Agency [50,56].…”