Abstract
The role of wastewater treatment plants (WWTP) in environmental cycling of poly- and perfluoroalkyl substances (PFASs) through aqueous effluent, sludge and air emission has been critically reviewed here. Understanding the role of WWTPs can provide better understanding of global cycling of persistent PFASs and assist in formulating relevant environmental policies. The review suggests that WWTP effluent is a major source of perfluoroalkyl acids (PFAAs) in surface water. Land application of biosolids (treated sludge) has shown preferential bioaccumulation of short chain (<C7) PFAAs in various plant compartments, leading to possible contamination of the food cycle. Elevated air concentration (1.5 to 15 times) of ?PFASs have been reported at the aeration tanks on WWTP sites, compared to reference sites not contaminated with WWTP emission. The air emission of neutral PFASs has important implications considering the long-range transport and subsequent degradation of neutral compounds leading to the occurrence of recalcitrant PFAAs in pristine remote environments. Research gap exist in terms of fate of polyfluroalkyl compounds (neutral PFASs) during wastetwater treatment and in aquatic and terrestrial environment. Considering the wide range of commercially available PFASs, measuring only perfluorocarboxylic acid (PFCA) and perfluorosulfonic acid (PFSA) can lead to underestimation of the total PFAS load derived from WWTPs. Knowledge of the various pathways of PFAS from WWTPs to receiving environments, outlined in this study, can help in adopting best possible management practices to reduce the release of PFASs from WWTPs.
Highlights
Poly- and perfluoroalkyl substances (PFASs) are a diverse group of synthetic fluorinated compounds
While the occurrence of perfluoroalkyl (PFAA) compounds have been reported in many studies, precursor compounds and their intermediate degradation products have received much less attention so far
Despite the overall increase of perfluoroalkyl acids (PFAAs) observed in treated wastewater following biological treatment, the factors affecting the PFAA formation process are not well understood and require further study
Summary
Poly- and perfluoroalkyl substances (PFASs) are a diverse group of synthetic fluorinated compounds. Two of the most commonly detected PFAA, pefluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), have been detected in water (several ng/L range), human and animal blood and tissue, soil and sediment (concentration range of pg/g to ng/g) (Ahrens, 2011; Bartell et al 2010; Bossi et al 2008; Chen et al 2012; Houde et al 2011; Zareitalabad et al, 2013). This paper is complementary to previous publications on PFASs that reviewed physiochemical properties (Ding and Peijnenburg 2013; Buck et al 2011), microbial degradation (Liu and Avendano 2013), occurrence and fate in aquatic environment (Ahrens 2011), drinking water treatment processes (Rahman, Peldszus, and Anderson 2014) and WWTPs (Arvaniti and Stasinakis 2015)
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