No abstract

Catalytic degradation of pentachlorophenol in soil by heme and hydrogen peroxide has been hypothesized to occur through nonspecific catalytic reactions similar to those involving ligninase. The present study examines the evidence for a heme catalytic mechanism for the oxidation of organic compounds. In the presence of hydrogen peroxide, heme is converted to the ferryl heme radical (Hm-Fe +4• ), which can oxidize organic compounds, such as 5-aminosalicylic acid (5-ASA). A second 5-ASA may later be oxidized by ferryl heme (Hm-Fe +4 ), which reverts to the ferric heme state (Hm-Fe +3 ) to complete the cycle. We believe that this catalytic cycle is involved in the degradation of hazardous pollutants, such as polycyclic aromatic hydrocarbons (PAHs). Remediation via heme catalytic reactions of PAHs in soil from a pole yard was evaluated, and about 96% of PAHs was found to disappear within 42 days after treatment with heme and hydrogen peroxide. In addition, benzo[a]pyrene and six other PAHs were undetectable among a total of 16 PAH compounds examined. Therefore, we propose heme catalysis as a novel technology for the remediation of hazardous compounds in contaminated soil.

Seven hundred ninety-eight oil wells were set fire, damaged, and gushed oil and resulted on a crude oil contaminated area over 300 km2 include dry oil lakes at the end of Iraqi war. The United Nation Compensation Commission (UNCC) recommended remediation of crude oil contaminated soil as physical chemical and thermal processes due to the oil sludge and high concentration of TPH. In this study, indigenous oil-emulsifying bacteria in Kuwait crude oil contaminated soil was cultured via enrichment culture method. Bacterial composition of enrichment culture investigated by phylogenetic analysis of 16S rRNA gene sequences obtained through high-throughput sequencing. The majority of enriched bacteria belonged to the order of Flavobacteriales (56.38%), Burkholderiales (16.13%), and Pseudomonadales (12.22%). Using those indigenous microorganisms, biological process consists of bio-washing, biocatalytic, and biopile was operated for 20 days in lab-scale. Initial TPH concentrations measured by hexane extraction method (HEM) and GC-FID method were 46,096 mg/kg and 34,153 mg/kg, respectively. Removal rates of TPH after 20days operation were 68% (HEM) and 86% (GC-FID). Therefore, Kuwait crude oil contaminated soil can be remediated by combine biological process such as bio-washing and biopile process.