Abstract
The aim of this study is to compare the removal of organic micropollutants (OMPs) in wastewater by activated sludge (AS) and constructed wetlands (CWs). This analysis was carried out in a wastewater treatment plant (WWTP) of a rural community where they implemented two technologies in parallel: AS and a pilot plant of horizontal subsurface flow (HSSF) constructed wetlands. In this case, these systems were fed by the same influent and the removal efficiencies of 14 OMPs, including analgesics/anti-inflammatories, anticonvulsants, stimulants, antifungals, fragrances, plasticizers, and transformation products, were evaluated in each system. Regarding the presence of OMPs in the wastewater, the concentrations of these compounds in the influent ranged from 0.16 to 7.75 µg/L. In general, the removal efficiencies achieved by the AS system were between 10%–95% higher than those values reported by HSSFs with values above 80% for naproxen, ibuprofen, diclofenac, caffeine, triclosan, methyl dihydrojasmonate, bisphenol-A, 2-hydroxyl ibuprofen, and carboxy ibuprofen (p < 0.05). This behavior can be related to the aerobic conditions that promote the AS system with oxidation-reduction potential (ORP) and dissolved oxygen (DO) values above −281 mV and 0.24 mg/L, respectively. However, the removal of galaxolide was greater in HSSF system than in AS with significant difference of 70% (p < 0.05). Despite these results, this study reveals that comparing both technologies, AS had the best removal performance of these OMPs studied.
Highlights
One of the principal sources of organic micropollutants (OMPs) are wastewater treatment plants (WWTPs) that receive wastewater coming from domestic sewage, hospital sewage, and several human activities which contain a lot of different OMPs such as pharmaceutical and personal care products (PPCPs), pesticides, surfactants, industrial additives, and plasticizers [4,5]
Evapotranspiration process that takes place in the horizontal subsurface flow (HSSF) system was responsible for the salinity increment of the effluent [29]
Conflicting results have been reported when comparing the performance of conventional and non-conventional technologies on the OMPs removal that are presented in wastewater
Summary
The studies related to the occurrence and fate of organic micropollutants (OMPs) have increased due to their potential toxicological effects on human health and the environment [1,2,3]. The OMPs removal on WWTPs is generally influenced by the physicochemical properties of the compound; by the type of wastewater treatment technology (conventional and non-conventional) and by process-specific factors such as sludge retention time (SRT), temperature, and organic loading rates (OLR) [6]. Conventional treatment technologies are characterized by using mechanized technologies with high electrical energy requirements and the design, supervision, maintenance, and the general. The most common conventional wastewater treatment is activated sludge (AS) that has not been designed for removing. Several studies reported that some OMPs can be removed during AS by microbial processes (biodegradation) and adsorption onto sludge flocs. Naproxen, galaxolide, and caffeine, the removal efficiencies reported in these systems varied between
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