Acute and Chronic impact of Bisphenols on Activated Sludge systems using Respirometry
Abstract
Bisphenol A (BPA) is a compound produced mainly for polycarbonate plastic (PC). Due to its endocrine disruptive effects to humans and animals, industries have shifted to alternative BP analogues, namely Bisphenol F (BPF) and Bisphenol S (BPS). In order to find the effects that this has on wastewater treatment plants (WWTPs), seed sludge gathered from IVAR at SNJ Mekjarvik (Stavanger) were used to set up reactors to estimate the acute and chronic impact that BPA, BPF and BPS have on biological wastewater treatment systems by the use of respirometry and activated sludge modeling. Respirometry were used to measure the oxygen utilization rate (OUR) of the biomass and were exposed at the first time and after the chronic period an already established EC50 concentration of 30 mg BP/L and during the chronic period of 30 days with an environmental relevant concentration of 12 mg BP/L. Solids concentration, pH and COD removal was measured during operation time of all reactors. During respirometry tests, addition of BP analogues caused a significant decrease in OUR and worsened after the chronic period. It was found that the BP analogues caused competitive and un-competitive inhibition for growth, un-competitive inhibition for hydrolysis and non-competitive inhibition for storage on polyhydroxyalkanoates (PHA’s). Furthermore, from chronic exposure, the endogenous decay rate increased while the activity of the biomass decreased from BP exposure. Finally, the solids concentration and COD removal decreased from BP addition. BPF and BPS had an equal or worse effect of that of BPA after chronic exposure.