Appraisement, source apportionment and health risk of polycyclic aromatic hydrocarbons (PAHs) in vehicle-wash wastewater, Pakistan

- USEPA declared carcinogenic-16PAHs were observed in the vehicle-wash wastewater.
- The annual PAHs discharge was 5109.9 g with naphthalene as dominant compound.
- The detected PAHs belong to both pyrogenic and petrogenic origin.
- The highest TEQ value (21.6 μg/l) was observed for BaP in HVWS wastewater.
- All living beings especially workers of VWS were highly susceptible to PAHs.

Vehicle-wash wastewater (VWW) contains elevated concentrations of different petrochemicals including polycyclic aromatic hydrocarbons (PAHs), a carcinogenic group of organic compounds. This study investigates the discharge of PAHs present in the untreated wastewater of vehicle-wash stations (VWS) located in district Peshawar, Pakistan. The data obtained was being novel with the detection of 16 USEPA PAHs (both individuals and total) and compared with earlier studies and international standards. The ∑16PAHs in wastewater from light vehicle-wash stations (LVWS) and heavy vehicle-wash stations (HVWS) ranged from 245-429 μg/l and 957-1582 μg/l, respectively. A significant difference (p < 0.01) was observed in PAHs discharged from LVWS and HVWS. The projected ∑16PAHs discharge from both HVWS (92% of total generated PAHs) and LVWS (8%) was about 5109.9 g per annum. According to PAH diagnostic ratios, PAHs were both petrogenic (chrysene/benz(a)anthracene, low molecular weight/high molecular weight) and pyrogenic (phenanthrene/anthracene, fluoranthene/pyrene, fluoranthene/fluoranthene + pyrene) in origin. The highest toxic equivalent quotient (TEQ) value was shown by benzo(a)pyrene (21.6 μg/l) followed by dibenz(ah)anthracene (9.81 μg/l) in wastewater from HVWS. However, in LVWS the case was reversed with highest value (7.54 μg/l) for dibenz(ah)anthracene followed by benzo(a)pyrene (3.54 μg/l). The lowest TEQ value was indicated for phenanthrene (0.007 μg/l) in wastewater of LVWS, while pyrene showed the lowest value (0.007 μg/l) in wastewater of HVWS. The results indicated that VWS contribute significant amount of PAHs each year, which is of great concern regarding water quality, ecological and human health risk. This is the first systematic and comprehensive research related with generation of PAHs load per day, week, month and annum from VWS, their source apportionment and health effects in Pakistan.

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