Abstract
Abstract
Polyester manufacturing wastewater consists of water formed as a coproduct of step-growth polymerization reactions, typically performed between diols and dicarboxylic acids. Due to the solubility of the reactants and byproducts of polymerization, the wastewater is typically heavily contaminated and can possess considerable toxicity that can strongly inhibit biological wastewater treatment processes. However, very little has been published on the treatment of wastewater produced during polyester manufacture. We have demonstrated that the toxicity of the wastewater is largely attributable to volatile organic compounds (VOCs). Gas chromatography and mass spectrometry analysis of the wastewater revealed highly toxic and mutagenic α,β-unsaturated aldehydes (acrolein congeners) as major components of the VOCs present. Activated sludge treatment was performed under two aeration regimes, coarse bubble sparging and passive aeration through the surface layer, to access their effect on biodegradation/volatilization. After 24 h of incubation in the presence of 10% polyester plant wastewater, coarse bubble sparging resulted in 88% reduction in chemical oxygen demand compared to 45% with passive aeration, both largely attributable to VOC volatilization. The polyester wastewater demonstrated high toxicity as indicated by a net decline in volatile suspended solids under both culture conditions, consistent with previous toxicity assays. Results indicate that significant VOC volatilization would occur during activated sludge treatment of polyester manufacturing wastewater containing the identified acrolein congeners. To prevent toxic VOCs exposure to plant workers and improve biodegradability, we recommend polyester wastewater containing α,β-unsaturated aldehydes be pretreated by air stripping to remove VOCs and incineration of the stripped VOCs before activated sludge treatment.
Get full access to this article
View all access options for this article.