Sorption behavior of a synthetic antioxidant, polycyclic musk, and an organophosphate insecticide in wastewater sludge

摘要

Emerging contaminants (ECs) are chemicals that are currently unregulated due to limitednunderstanding of health effects and limited data regarding occurrence. Wastewater treatmentnplants (WWTP) receive many ECs as components of influent waste and the removal of organicncontaminants, such as ECs, occurs primarily by sorption to sludge. Therefore, it is important tondevelop measures of sorption behavior by ECs to sludge. This study evaluates sorption of threenECs: 3-tert-butyl-4-hydroxyanisole (BHA) a synthetic antioxidant, 1,3,4,6,7,8-hexahydro-4,6,6,7,8,n8-hexamethyl-cyclopenta(g)-2-benzopyrane (HHCB) a polycyclic musk, and chlorpyrifos anorganophosphate insecticide.nTwenty-four hour laboratory-scale sorption experiments were conducted for each compoundnindividually and then in combination, which allowed the quantification of sorption ontonwastewater sludge and the affects of multiple compounds. ECs in both the liquid and solidnphases were analyzed using a gas chromatograph with flame ionization detector (GC/FID).nIsotherms of individual sorption behavior followed a linear trend (R 2n. 0.9) for individual ECs,nwhile Kd averaged 2,689 L kg21n, 27,786 L kg21nand 31,402 L kg21nfor BHA, chlorpyrifos and HHCB,nrespectively. Sorption behavior for BHA was linear during combined studies with Kd ofn1,766 L kg21nor a decrease of 34%, while HHCB and chlorpyrifos followed non-linear isothermnmodels. Synergistic effects were observed with spike concentrations $25mg L21nfor HHCB andn$20mg L21nfor chlorpyrifos. Kd values ranged from 16,984–6,000,000 L kg21nfor HHCB andn19,536–3,000,000 L kg21nfor chlorpyrifos. These distribution coefficients differed substantially fromnpreviously published values, mainly because few studies used sludge as the sorption media.nResults suggest that HHCB and chlorpyrifos may be contained in the sludge unlike BHA, which isnmore available in the aqueous phase. Future investigations should evaluate WWTP processes forndegrading ECs to harmless products and releases of ECs from sludge.