Integrating biochar and microbial community for detoxification of wastewater industry containing analgesics

Abstract

Although anaerobic digestion is a simple, inexpensive, and viable technology for treating wastewater, its performance can be inhibited by the toxic effects of analgesics. Therefore, the objective of this study was to assess the effectiveness of biochar in driving the degradation of analgesics, shifting microbial communities, and biogas profitability in an anaerobic baffled reactor (ABR) for treating pharmaceutical wastewater containing analgesics. Biochar (BC) was synthesized from pomegranate peel and characterized in terms of its surface morphology, elemental composition, crystallization, and surface functional groups. ABR1, ABR2, ABR3, ABR4, and ABR5 were supplemented with mixed culture bacteria at biochar dosages of 0, 50, 75,100, and 150 mg BC/g VS. The removal efficiencies of ketoprofen, paracetamol, and salicylate were increased by values of 65.9 %, 20.4 %, and 53.6 %, respectively, in the ABR4 supplemented with 100 mg BC/gVS compared with the control reactor (ABR1). The bio-methane yield was significantly (p < 0.05) increased from 175.14 ± 13.67 mL/gCODremoved in the ABR1 to 225.58 ± 16.68 mL/g CODremoved in the ABR4. The relative abundances of Chlorobi, Bacteroidetes, Armatimonadetes, Synergistetes, Pseudomonas, Flavobacteriia, Euryarchaeota, Methanobacteria, and Methanomicrobia, resisting the analgesic toxicity and facilitating the organic bioconversion into CH4, were increased by 175.15 %, 112.45 %, 32.43 %, 29.21 %, 400 %, 200 %, 122.17 %, 70.3 %, and 230.5 %, respectively, after 100 mg BC/gVS application in the ABR4 compared with ABR1. Overall, 63 ± 3.9–71 ± 5.4 % and 23.2 ± 2–28.7 ± 2.1 % of the analgesics were primarily removed from wastewater via microbial biodegradation and biochar adsorption, respectively. Biochar application was associated with better biogas productivity, pollutant reduction, and carbon credits, which was equivalent to a profitable scenario with a payback period of 7.1 yr.