Bioremediation Assessment of Massangana Mangrove Sediment Through Natural Attenuation and Bioaugmentation
Phenanthrene; Anaerobic degradation; Bioremediation; Biotransformation; Mangrove Sediments.
Sensitive biomes, such as coastal ecosystems, have become increasingly susceptible to the environmental impacts caused by oil logistics and storage, which, while more efficient today, still cause spills. Thus, bioremediation techniques draw attention for their low impact on the environment. Among petroleum-derived compounds, polycyclic aromatic hydrocarbons (HPAs) are known for their potential impact and persistence in the environment. Therefore, HPAs bioremediation is a technique capable of reducing these pollutants in the environment. However, there is a lack of understanding about conditions of the microbial growth process, leading to a less efficient choice of bioremediation methods.Sediment from the Massangana river mangrove, in Suape, Pernambuco, was used to assemble anaerobic biological reactors artificially contaminated with 100mg of Phenanthrene per kilogram of sediment. The analyzes were carried out from sacrifice reactors, monitoring the consumption of the compound of interest through high performance liquid chromatography (HPLC). This study suggests that the anaerobic degradation of sediments contaminated by Phenanthrene (and potentially other PAHs), allowed a decrease in concentration by more than 35% in 80 days of the experiment. The first order kinetic model was the one that best represented the degradation of Phenanthrene, being the best condition with a petrochemical inoculum, with a kinetic constant (k2) of 0.0078 d-1. Several microbial genera related to the degradation of PAHs were found in the samples of inoculum, bioaugmentation reactors and natural attenuation reactors. The presence of the genera Thiobacilus, Clostridium and Desulfotomaculum stands out. Simpson, Shannon, Chao-1 and equitability indexes were evaluated in order to assess the consistency and relevance of the results of molecular biology analyses. The presence of these genera suggests the occurrence of phenanthrene degradation through the methanogenic route, which is little discussed in the literature. Thus, the bioremediation of sediments contaminated by phenanthrene and potentially by other PAHs is a promising strategy that should be studied in order to minimize impacts on the remediation of areas affected by environmental accidents.