Removal of Estrogenic Compounds from Filtered Secondary Wastewater Effluent in a Continuous Enzymatic Membrane Reactor. Identification of Biotransformation Products

Abstract

In the present study, a novel and efficient technology based on the use of an oxidative enzyme was developed to perform the continuous removal of estrogenic compounds from polluted wastewaters. A 2 L enzymatic membrane reactor (EMR) was successfully operated for 100 h with minimal requirements of laccase for the transformation of estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2)from both buffer solution and real wastewater (filtered secondary effluent). When the experiments were performed at high and low concentrations of the target compounds, 4 mg/L and 100 μg/L, not only high removal yields (80-100%) but also outstanding reduction of estrogenicity (about 84-95%) were attained. When the EMR was applied for the treatment of municipal wastewaters with real environmental concentrations of the different compounds (0.29-1.52 ng/L), excellent results were also achieved indicating the high efficiency and potential of the enzymatic reactor system. A second goal of this study relied on the identification of the transformation products to elucidate the catalytic mechanism of estrogens' transformation by laccase. The formation of dimers and trimers of E1, E2, and EE2, as well as the decomposition of E2 into E1 by laccase-catalyzed treatment, has been demonstrated by liquid chromatography atmospheric pressure chemical ionization (LC-APCI) analysis and confirmed by determination of accurate masses through liquid chromatography electrospray time-of-flight mass spectrometry (LC-ESI-TOF). Dimeric products of E2 and EE2 were found even when operating at environmental concentrations. Moreover, the reaction pathways of laccase-catalyzed transformation of E2 were proposed.

Hybrid bioreactor (HBR) of hollow fiber microfilter membrane and cross-linked laccase aggregates eliminate aromatic pharmaceuticals in wastewaters

“…To our knowledge, similar studies have not been published to date, although an approach combining UF and free laccase was recently reported [22]. The proposed hybrid system advantageously associates insolubilized biocatalysts and relatively low energy-consuming membranes, thus having a potential to become a cost-effective and sustainable technology for micropollutant elimination in wastewaters.…”

“…Breakthroughs in the filtrate ranging from 10 to 50 g/L are still considerable for treated micropollutants, hence the necessity to improve the removal performance. This could be achieved through enzymatic supplementation [22].…”

Green technology in wastewater treatment technologies: Integration of membrane bioreactor with various wastewater treatment systems

“…However, there has been increment in interests of enzymatic membrane reactors for environmental purposes. Lloret, et al [96] studied the removal of estrogenic compounds from filtered secondary wastewater effluent while Ba, et al [97] studied the removal of aromatic pharmaceuticals in wastewater. The enzymes were trapped in the membrane either using smaller pore size of membrane and/or insolubilized enzyme which aggregated sizes are larger than the pores of the membrane.…”

Potentiality of a ceramic membrane reactor for the laccase-catalyzed removal of bisphenol A from secondary effluents

“…The aim of the filtration was to remove particulate solids and other microorganisms, which could contribute to the elimination of BPA by adsorption or undefined biotransformation, and hence, the evaluation of the sole enzymatic transformation by laccase could be possible (Lloret et al 2013b). Figure 5a, b shows residual BPA concentration and laccase activity profiles along the continuous operation of the ceramic EMR operated with buffer solution (pH 6) and secondary effluent (pH~7.2) matrices, respectively (experiments 4 and 6 in Table 2).…”

“…In a previous study developed by our research group, an EMR using an ultrafiltration polyethersulphone membrane was successfully applied for the continuous enzymatic transformation of estrogens by laccase from Myceliophthora thermophila (Lloret et al 2013b). However, this system was not suitable for the removal of BPA, due to the adsorption of the micropollutant onto the hydrophobic membrane (Su-Hua et al 2010).…”