Monitoring endocrine-disrupting chemicals and microbial diversity of wastewater treatment maturation ponds

Endocrine-disrupting chemicals (EDCs), including synthetic hormones, pesticides, and personal care products (PPCPs), are frequently detected in wastewater treatment plant (WWTP) effluents. EDCs' persistence in aquatic environments poses risks to human and ecological health, given that EDCs are not firmly regulated under South African legislation. The chemical and microbial compositions of a WWTP utilizing maturation ponds in Bloemfontein, South Africa, focusing on selected EDCs (atrazine [ATZ], 17α-ethinylestradiol [EE2], triclosan [TCS], and bisphenol A [BPA]) were investigated. The physicochemical parameters of wastewater samples collected over 6 months were measured onsite. LC-MS/MS analysis and bacterial 16S rRNA and eukaryotic sequencing were performed to determine the EDC concentrations and microbial compositions. Wastewater samples exhibited alkaline, oxic, mesophilic, and oxidative conditions. The EDC concentrations showed variability, with 17α-ethinylestradiol reaching 125 µg/L. Bisphenol A concentration ranged between 0.003 and 0.587 µg/L, that of atrazine from 0.009 to 0.134 µg/L, and that of triclosan from 0.069 to 0.316 µg/L, which were lower than those reported in other South African studies. Microbial community structures revealed Proteobacteria (35.12%) and Bacteroidetes (18.50%) as the dominant bacterial phyla. Among eukaryotes, Ascomycota and unclassified taxa accounted for 13.14% and 68.85%, respectively. Flavobacterium and Microcystis were the most abundant bacterial genera (9.50% and 6.22%), while unidentified taxa represented 85.88% of eukaryotic genera. Functional analysis revealed potential xenobiotic degradation pathways associated with bisphenol A and atrazine, indicating microbial potential for EDC degradation. These findings established the presence of EDCs and microbial compositions of maturation ponds with an estimated hydraulic retention time of ~9 days, emphasizing the need for improved wastewater treatment strategies and bioremediation approaches.IMPORTANCEEndocrine-disrupting chemicals (EDCs) are increasingly found in treated wastewater, yet their removal is not guaranteed in conventional treatment systems. This study examined maturation ponds of South African wastewater treatment plant and provided new insights into their chemical pollutant retention and microbial dynamics. By tracking selected EDCs together with bacterial and eukaryotic communities, the study showed how environmental conditions and microbial populations interact within the ponds. The detection of microbes with potential to degrade pollutants highlighted a natural capacity that could be strengthened for bioremediation. South Africa relies heavily on treated wastewater as a supplementary water source, and understanding the presence of EDCs and the biological process within these ponds is essential. These findings contribute to improving wastewater treatment practices and developing sustainable, microbially driven solutions for safer water management.