Influence of metabolic cosubstrates on methanogenic potential and degradation of triclosan and propranolol in sanitary sewage.

Triclosan (TCS) and propranolol (PRO) are emerging micropollutants that are difficult to remove in wastewater treatment plants. In this study, methanogenic potential (P) of anaerobic sludge submitted to TCS (3.6 ± 0.1 to 15.5 ± 0.1 mg L ^-1 ) and PRO (6.1 ± 0.1 to 55.9 ± 1.2 mg L ^-1 ) in sanitary sewage, was investigated in batch reactors. The use of cosubstrates (200 mg L ^-1 of organic matter) ethanol, methanol:ethanol and fumarate was evaluated for micropollutant degradation. Without cosubstrates, P values for 5.0 ± 0.1 mgTCS L ^-1 , 15.5 ± 0.1 mgTCS L ^-1 and 55.0 ± 1.3 mgPRO L ^-1 were 50.53%, 98.24% and 17.66% lower in relation to Control assay (855 ± 5 μmolCH4) with sanitary sewage, without micropollutants and cosubstrates, respectively. The use of fumarate, ethanol and methanol:ethanol favored greater methane production, with P values of 2144 ± 45 μmolCH ₄ , 2960 ± 185 μmolCH ₄ and 2239 ± 171 μmolCH ₄ for 5.1 ± 0.1 mgTCS L ^-1 , respectively; and of 10,827 ± 185 μmolCH ₄ , 10,946 ± 108 μmolCH ₄ and 10,809 ± 210 μmolCH ₄ for 55.0 ± 1.3 mgPRO L ^-1 , respectively. Greater degradation of TCS (77.1 ± 0.1% for 5.1 ± 0.1 mg L ^-1 ) and PRO (24.1 ± 0.1% for 55.9 ± 1.2 mg L ^-1 ) was obtained with ethanol. However, with 28.5 ± 0.5 mg PRO L ^-1 , greater degradation (88.4 ± 0.9%) was obtained without cosubstrates. With TCS, via sequencing of rRNA 16S gene, for Bacteria Domain, greater abundance of phylum Chloroflexi and of the genera Longilinea, Arcobacter, Mesotoga and Sulfuricurvum were identified. With PRO, the genus VadinBC27 was the most abundant. Methanosaeta was dominant in TCS with ethanol, while in PRO without cosubstrates, Methanobacterium and Methanosaeta were the most abundant. The use of metabolic cosubstrates is a favorable strategy to obtain greater methanogenic potential and degradation of TCS and PRO.
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