Enhanced removal of emerging micropollutants by applying microaeration to an anaerobic reactor

Abstract

The present paper aimed to evaluate the impact of microaeration on both the removal performance of some emerging micropollutants (pharmaceuticals, hormones, and bisphenol A) and the microbial community structure of an anaerobic reactor treating synthetic wastewater. Under anaerobic conditions, the removal efficiencies of the micropollutants were very low (< 10%). However, the microaeration (1.0 mL air·min-1 at 27 °C and 1 atm, equivalent to a QAIR/QINF ratio of 0.1) expressively improved the removal efficiencies of all compounds (> 50%). Therefore, supplementing anaerobic reactors with low amounts of oxygen seems to be an interesting strategy to enhance the removal of the micropollutants tested. However, further studies should be carried out with other compounds in order to evaluate the wide applicability of microaeration to different classes of micropollutants in lab- and full-scale treatment systems. Concerning the microbiota structure, both bacterial and archaeal communities were not compromised by the different operational conditions and preserved their functional organization with high richness during the whole experiment.

Redox mediator, microaeration, and nitrate addition as engineering approaches to enhance the biotransformation of antibiotics in anaerobic reactors

“…In period I, when the reactor was operated under anaerobic conditions without AQDS addition, the REs of SMX and TMP were very low, with mean values close to only 6% (Table 3). These results are comparable to those by Buarque et al (2019), who registered mean REs below 10% in a UASB reactor (28 • C and HRT of 7 h) treating synthetic wastewater containing a mixture of seven OMPs (~230 μg L − 1 each), including SMX and TMP, in the presence of ethanol (1 g COD L − 1 ) as a primary substrate.…”

“…In general, wastewater treatment plants (WWTPs) are not specifically designed to remove OMPs, and, although removal efficiencies (REs) depend on both the compound and the treatment technology, they are usually limited (Grandclément et al, 2017;Jewell et al, 2016), especially in anaerobic systems operated at short hydraulic retention times (HRTs) (< 10 h) (Brandt et al, 2013;Buarque et al, 2019;Vassalle et al, 2020). Although increasing the HRT may improve the REs of some OMPs in such anaerobic systems (once the compound-biomass contact time increases), this is not a feasible option for domestic wastewater, especially in developing countries with low sanitation coverage, since larger treatment facilities are required, thus increasing capital expenditures (CAPEX) (Chernicharo et al, 2015;Harb et al, 2019).…”

“…Recent research has also demonstrated that microaeration (addition of less than 1 L O 2 L − 1 feed), a consolidated technology for hydrogen sulfide removal in anaerobic reactors (Krayzelova et al, 2015), is an effective strategy to enhance the biotransformation of recalcitrant compounds in these systems, such as BTEX (benzene, toluene, ethylbenzene, and xylenes) (Firmino et al, 2018;Siqueira et al, 2018) and even OMPs (Buarque et al, 2019). Additionally, another possibility could be using nitrate as an alternative terminal electron acceptor, which has a similar reduction potential to that of oxygen (dos Santos et al, 2007), as several studies have reported that, under nitrate-reducing (or anoxic) conditions, OMPs are more effectively biotransformed than under anaerobic conditions (Alvarino et al, 2016;Inyang et al, 2016;Lakshminarasimman et al, 2018;Ogunlaja and Parker, 2018;Zhao et al, 2018).…”

Reactive Adsorption of Parabens on Synthesized Micro- and Mesoporous Silica from Coal Fly Ash: pH Effect on the Modification Process

“…At pH 3, the adsorption capacity was higher; thus, this pH was chosen for the later studies. At pH values 5 and 7 (values generally found in surface water), − the material presented the adsorptive capacity approximate to the results identified at pH 3, indicating no relevant interference of this parameter in the studied range, which would facilitate the application of the adsorbent for resolving practical environmental problems.…”

Tratamento de água residuária da produção de café solúvel em ASBR com microaeração

“…Estudos recentes têm evidenciado as vantagens dessa abordagem como uma alternativa promissora para a remoção de compostos complexos e de difícil degradação, como materiais lignocelulósicos, compostos fenólicos e corantes (MENEZES, 2016;KHAN et al, 2019;XU et al, 2021;SILVA JÚNIOR, 2021). No entanto, conforme apontado por Buarque et al (2019), ainda são necessários mais estudos para avaliar a aplicabilidade da microaeração em diferentes tipos de substratos em escala piloto ou real.…”