Combined reverse osmosis and UV/H2O2 treatment of aqueous solutions of bisphenol A and 17α-ethinylestradiol: assessment of estrogenic activity.

Bisphenol-A (BPA) and 17α-ethinylestradiol (EE2) are considered endocrine disrupting compounds (EDC) and they may be harmful to the normal functioning of endocrine systems of humans and animals. Moreover, the presence of these compounds in superficial and groundwater may represent serious risks, even in low concentrations like ng·L-1. The objectives of this study were to remove BPA and EE2 from solutions containing a mixture of these compounds in ultrapure water at low concentrations through reverse osmosis (RO) membrane combined with a UV/H2O2 process. Furthermore, to assess the estrogenic activity reduction after such treatments, in vitro recombinant yeast-estrogen screen (YES) assay was used. The removal efficiencies of target micropollutants increased with the increase of H2O2 dosage. For RO permeate stream, they enhanced from 91% to 96% for EE2 and from 76% to 90% for BPA while, for the concentrate stream, from 70% to 81% for EE2 and 41% to 84% for BPA as the H2O2 concentration were increased from 100 to 1000 µg·L-1. The OH radicals' generation was the dominant factor in the degradation of EDC during the UV/H2O2 treatment since the photolysis itself was not enough to degrade BPA or EE2. The estrogenic activity reduction after UV/H2O2 treatment was high, ranging from 92% to 98% for the permeate stream and from 50% to 93% for the concentrate stream. The EE2 was responsible for the whole observed estrogenic activity since BPA does not present estrogenicity, by in vitro YES assay, in the concentrations observed.

Assessment of fouling mechanisms on reverse osmosis (RO) membrane during permeation of 17α-ethinylestradiol (EE2) solutions.

Fouling mechanisms are mainly caused by the deposition of organic compounds that reduce the removal efficiency on reverse osmosis (RO) membranes. It can be described by mathematical models. The aim of this study was to evaluate the membrane fouling and rejection mechanisms when aqueous solutions containing 17α-ethinylestradiol (EE2) in different concentrations are permeated at 5 and 10 bar in a bench-scale dead-end RO system. Adsorption tests were performed and the fouling mechanism was assessed by Hermia's model for solutions of EE2 at concentrations typically found in the environment (µg L-1). Fourier transform infrared spectroscopy (FTIR) has indicated the presence of EE2 on the fouled membrane surface. Membrane rejection of EE2 ranged from 90% to 98% and the main rejection mechanism was size exclusion at all experimental conditions. However, for the higher concentration of EE2 permeated at 5 and 10 bar, adsorption of 7 and 32 mg m-2, respectively, also took place. The rejection was influenced by fouling and concentration polarisation. Fouled membranes present higher rejection of hydrophobic neutral compounds and the concentration polarisation reduces rejection. Hermia's model demonstrated that the permeation values fitted better the standard blocking filtration and cake filtration equations for describing fouling mechanism. This study showed that fouling also occurs in the TFC RO membrane after permeation of EE2, which corroborates with studies using other pollutants.

Treatment of Bisphenol A (BPA) in water using UV/H2O2 and reverse osmosis (RO) membranes: assessment of estrogenic activity and membrane adsorption.

Removal of an endocrine disrupting compound, Bisphenol A (BPA), from water was investigated using two treatment processes, UV/H2O2 advanced oxidation (AOP) and reverse osmosis (membrane separation). Furthermore, changes in estrogenic activity using in vitro yeast estrogen screen assay as well as the adsorption of BPA by the membrane surface were evaluated. The best UV/H2O2 performance was obtained using the highest established values of all parameters, reaching 48% BPA removal. Within the investigated conditions of the AOP, when lower doses of UV were used, a higher removal efficiency was achieved at a higher initial concentration of BPA. However, the same behavior was not observed for the highest UV dose, in which the removal efficiency was not dependent on BPA initial concentration. In both cases, removal efficiency increased as H2O2 concentration increased. The formation of estrogenic by-products was observed in UV/H2O2. The membrane rejection efficiency varied from 60% to 84% and all experiments showed adsorption of BPA by the membrane surface. The RO membrane showed a greater BPA removal efficiency for samples containing 10 µg·L-1 than UV/H2O2 at the evaluated treatment conditions.

Assessment of combined treatment of landfill urban solid waste leachate and sewage using Danio rerio and Daphnia similis.

The co-treatment from Morro do Céu landfill leachate with domestic sewage in the Icaraí STP was monitored with regard to the behavior of toxicity of its inflows and outflow. Leachate not exceeded 1.5% in volume in the plant. The acute ecotoxicological tests showed that, although leachate is far more harmful to D. rerio (LC50 approximately = 4) and D. similis (LC50 approximately = 5) than sewage (LC50 approximately = 62; LC50 approximately = 22), statistically the mixture of leachate with sewage did not result in a more toxic inflow (LC50 approximately = 57; LC50 approximately = 12) for treatment than raw sewage. After treatment, the outflow toxicity (LC50 approximately = 76; LC50 approximately = 16) complied with the environmental laws.