Evaluation of perfluorinated compounds in seven wastewater treatment plants in Beijing urban areas

Abstract

The presence of perfluorinated compounds (PFCs) in seven major wastewater treatment plants (WWTPs) in Beijing was investigated in the current study. We detected nine PFCs in all the wastewater and sludge samples. Perfluorooctane acid (PFOA) is the dominant PFCs in influents and effluents, while perfluorooctane sulfonate (PFOS) is the major contaminant in sludge. The highest PFC concentration was found in plants at Qinghe and Jiuxianqiao WWTP, while the lowest was found at Fangzhuang WWTP. The total values of PFC range from 2.88 to 176 ng/L in influents, from 5.48 to 498 ng/L in effluents, and from 1.21 to 32.0 ng/g (dry wt) in sludge. The fact that effluents usually contain higher levels of PFCs than influents suggests that additional PFCs are produced during the wastewater treatment processes. However, PFOS decreases in effluents than in influents in 62% of the water samples. This may be due to the adsorption and removal of the sludge during the active process. Perfluoroalkyl carboxylates (PFCAs) were found significantly correlated with each other in the effluents, which may indicate their similar sources or the existence of their potential precursors in the wastewater or treatment processes. The mass flows of PFC discharges into WWTPs are 0.4-51.4 mg/day, and the mass flows of PFCs in effluents exceed those in influents by 127%. Domestic and commercial wastewaters are suggested to be the major sources of PFC pollution in WWTPs in Beijing. perfluorinated compounds, wastewater, sludge, mass flow

Occurrence of different classes of perfluorinated compounds in Greek wastewater treatment plants and determination of their solid–water distribution coefficients

“…PFOS was the dominant analyte in dewatered sludge samples from both WWTPs, as it was detected in 100% of collected samples. This result was similar to previous studies [9,10,12,28,29], but different from Sinclair and Kannan [8], who found that PFOA was the dominant PFC in sludge. PFOA was detected in all samples, except from three occasions.…”

“…Moreover, previous studies reported that the concentrations of other PFCs (PFNA, PFUdA, PFHxS) ranged from <LOD to <400 ng L −1 [7,8,12,[25][26][27][28]. On the other hand, the concentrations of PFPeA detected in this study were significantly higher than those previously reported [13].…”

Occurrence of organic microcontaminants in the wastewater treatment process. A mini review

“…In fact, in some cases it is often common to observe a phenomenon of negative removal or in-plant production [88]. Pan et al [89] suggested the same fate when confronted with overall higher levels of PFCs in the effluents comparing to the influent flows. According to Heidler and Halden [88], several mass balances performed for fluorochemicals also reflect a net mass flow increase at the WWTP effluents.…”

“…However, this family of compounds have dissimilar behaviour among them, depending on the functional groups [90]. For instance, some authors reported that perfluorooctanesulfonic acid or perfluorooctane sulfonate (PFOS) levels have a decreasing tendency after treatment in most WWTPs, whilst perfluorooctanoic acid or perfluorooctanoate (PFOA) showed an inverse pattern [89][90][91]. According to Guo et al [90], this could be due to the higher organic carbon-normalised distribution coefficient of perfluoroalkylsulfonate (PFASs) in comparison with the carboxylate analog, a sign of preferential uptake of PFASs by the sludge, which seems to be a key mechanism in the process.…”

Perfluoroalkyl substances (PFASs) in wastewater treatment plants and drinking water treatment plants: Removal efficiency and exposure risk

“…The mass loads of PFOA, PFOS, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUnDA) were found increased in the secondary biochemical treatment of a WWTP due to the biodegradation of precursors (Sinclair and Kannan, 2006). Concentrations of PFASs varied greatly among different WWTPs, and most studies focused on the activated sludge process (Bossi et al, 2008;Murakami et al, 2008;Guo et al, 2010;Pan et al, 2011;Zhang et al, 2013).…”