Biotransformation of a highly chlorinated PCB mixture in an activated sludge collected from a Membrane Biological Reactor (MBR) subjected to anaerobic digestion.
The role of anaerobic digestion (AD) on the decontamination and biomethanization of a PCB-spiked sludge obtained from a Membrane Biological Reactor (MBR) pilot plant was investigated throughout a 10-month batch experiment. The study was carried out under mesophilic (35°C) and thermophilic (55°C) conditions and was monitored by means of an integrated chemical, microbiological and molecular biology strategy. Remarkable PCB depletions (higher than 50% of the overall spiked PCBs) and dechlorinations were achieved under methanogenic conditions. The process was not affected by yeast extract addition. Both acetoclastic and hydrogenotrophic methanogens, together with some fermentative eubacteria, were found to persist in all PCB biodegrading microcosms. This finding, together with those obtained from parallel microcosms where specific populations were selectively inhibited, suggested that native methanogens played a key role in the biodegradation and dechlorination of the spiked PCBs. Taken together, the results of this study indicate that AD is a feasible option for the decontamination and the efficient disposal (with the production of a CH(4)-rich biogas) of contaminated MBR sludge, which can be then employed as a fertilizer for agricultural purposes.
Department of Civil, Environmental and Material Engineering (DICAM), Faculty of Engineering, University of Bologna, via Terracini 28, 40131 Bologna, Italy. lorenzo.bertin@unibo.it
Lorenzo
L
Bertin
Serena
S
Capodicasa
Stefano
S
Fedi
Davide
D
Zannoni
Leonardo
L
Marchetti
Fabio
F
Fava
D000465:Algorithms; D000693:Anaerobiosis; D019149:Bioreactors; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification; D004785:Environmental Pollutants / Q000737:chemistry*; D010865:Pilot Projects; D011078:Polychlorinated Biphenyls / Q000737:chemistry*; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000302:isolation & purification; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000379:methods; D014871:Water Microbiology
D004785:Environmental Pollutants; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D004247:DNA; D011078:Polychlorinated Biphenyls