Effects of different electron acceptors and donors on anaerobic biodegradation of polycyclic aromatic hydrocarbons in marine sediments

Polycyclic aromatic hydrocarbons ( PAHs ) are typical persistent organic pollutants accumulated in the environment. It is possible to promote the bioremediation of PAHs in sediments by adding electron acceptor ( EA ) and electron donor ( ED ). In this study, bicarbonate and sulfate were selected as two electron acceptors, and acetate and lactate were selected as two electron donors. Six groups of amendments including H ( bicarbonate ), S ( sulfate ), HA ( bicarbonate, acetate ), HL ( sulfate, lactic acid ), SA ( sulfate, acetate ) and SL ( sulfate, lactic acid ) were added to the anaerobic sediment system to investigate their effects on the anaerobic biodegradation of five PAHs, including phenanthrene, anthracene, fluoranthene, pyrene and benzo ( a ) pyrene. The concentrations of PAHs, EAs and EDs, ETS activity and microbial diversity were analyzed during 126 days of biodegradation. In addition, the degradation pathway was speculated by the determination of intermediate products. The degradation efficiency of PAHs in HA ( bicarbonate, acetate ) group was the highest ( 89.67 % ), followed by SL ( sulfate, lactic acid ) group ( 87.10 % ). The highest removal rate of benzo ( a ) pyrene in SL group was 83.52 %.The average ETS activity of SL group was the highest compared with other groups in the sediment. The PAH metabolites were identified in the SL group, including 9-hydroxyanthracene, 9-hydroxyphenanthrene, phenaleno-[1,9-bc] thiophene and 2-biphenyl acid. 9-hydroxyphenil and 9,10-phenanthrenequinone were identified in group H, and 1-hydroxypyrene were identified in group H.