Insights into the removal of pharmaceutically active compounds from sewage sludge by two-stage mesophilic anaerobic digestion

The removal efficiencies (REs) of twenty-seven pharmaceutically active compounds (PhACs) (eight analgesic/anti-inflammatories, six antibiotics, four ?-blockers, two antihypertensives/diuretics, three lipid regulators and psychiatric drugs) were evaluated in a pilot-scale two-stage mesophilic anaerobic digestion (MAD) system treating thickened sewage sludge from A2O™ wastewater treatment plant (WWTP) which was fed with the pre-treatment full-scale WWTP Murcia Este (Murcia, Spain). MAD long-term operated using different sets retention times (SRTs) for acidogenic (AcD) methanogenic (MD) digesters (phase I, 2 12 days; phase II, 5 24 days, AcD MD, respectively). Quantitative PCR (qPCR) Illumina MiSeq sequencing used to estimate absolute abundance Bacteria, Archaea, Fungi investigate structure, diversity population dynamics their communities MD effluents. extension SRT I) days II) significantly linked an improved carbamazepine, clarithromycin, codeine, gemfibrozil, ibuprofen, lorazepam, propranolol. abundances total Bacteria Archaea higher regardless phase, while bacterial archaeal lower both digesters. Non-metric multidimensional scaling (MDS) plots showed strong negative correlations among phyla Proteobacteria Firmicutes between genera Methanosaeta Methanosarcina throughout full experimental period. Strong positive revealed relative Methanospirillum Methanoculleus methanogenesis performance parameters (volatile solids removal, CH4 recovery rate %CH4 biogas), also related longer SRT. REs several PhACs (naproxen, ketoprofen, ofloxacin, fenofibrate, trimethoprim, atenolol) correlated positively (r > 0.75) specific groups, suggesting participation biodegradation/biotransformation pathways.