Effect of occupational exposure on hematological and biochemical parameters in workers at oil and gas companies

Petroleum refineries are largest chemical industries that are responsible for emission of several pollutants into the atmosphere. Benzene and its metabolites are regarded as the most hazardous compounds that are emitted by petroleum refineries. These contribute to toxic oxidants, which cause many serious health risks to petroleum refineries workers. This study was aimed to analyze the effects of chemical exposure on hematological and biochemical parameters among workers at Zawia oil refinery and Mellituh oil and gas refinery companies. A total of 200 workers participated in this study which consisting of two equal groups (each group: n = 100). The first group consists of petroleum refineries workers and the second group consists of non-oil work civil servants serving were recruited as exposed and control subjects, respectively. The results of blood picture, liver enzymes and kidney functions were compared between the groups. Mean white blood cells counts, platelet counts, and hematocrit count were significantly higher, while the mean red blood cells count was insignificantly changed in petroleum refineries workers. While the mean hemoglobin and corpuscular hemoglobin concentration levels were significantly lower, whereas the mean corpuscular volume and mean corpuscular hemoglobin levels were insignificantly changed in petrol refineries workers. Liver enzymes and renal functions were significantly higher in petrol refineries workers. The present findings indicate that occupational exposure to benzene causes significant alterations in hematological and biochemical parameters and workers are at high risk of developing blood, hepatic or renal related disorders. Protection and frequent medical attention should be given to petroleum refineries workers.

Characterization of a hyperthermophilic sulphur-oxidizing biofilm produced by archaea isolated from a hot spring

Background: Sulphur-oxidizing microorganisms are widely used in the biofiltration of total reduced sulphur compounds (odorous and neurotoxic) produced by industries such as the cellulose and petrochemical industries, which include high-temperature process steps. Some hyperthermophilic microorganisms have the capability to oxidize these compounds at high temperatures (N60°C), and archaea of this group, for example, Sulfolobus metallicus, are commonly used in biofiltration technology. Results: In this study, a hyperthermophilic sulphur-oxidizing strain of archaea was isolated from a hot spring (Chillán, Chile) and designated as M1. It was identified as archaea of the genus Sulfolobus (99% homology with S. solfataricus 16S rDNA). Biofilms of this culture grown on polyethylene rings showed an elemental sulphur oxidation rate of 95.15 ± 15.39 mg S l-1 d-1, higher than the rate exhibited by the biofilm of the sulphur-oxidizing archaea S. metallicus (56.8 ± 10.91 mg l-1 d-1). Conclusions: The results suggest that the culture M1 is useful for the biofiltration of total reduced sulphur gases at high temperatures and for other biotechnological applications.

Bioleaching of nickel from spent petroleum catalyst using Acidithiobacillus thiooxidans DSM-11478.

The present work deals with optimization of culture conditions and process parameters for bioleaching of spent petroleum catalyst collected from a petroleum refinery. The efficacy of Ni bioleaching from spent petroleum catalyst was determined using pure culture of Acidithiobacillus thiooxidans DSM-11478. The culture conditions of pH, temperature and headspace volume to media volume ratio were optimized. EDX analysis was done to confirm the presence of Ni in the spent catalyst after roasting it to decoke its surface. The optimum temperature for A. thiooxidans DSM-11478 growth was found to be 32 °C. The enhanced recovery of nickel at very low pH was attributed to the higher acidic strength of sulfuric acid produced in the culture medium by the bacterium. During the bioleaching process, 89% of the Ni present in the catalyst waste could be successfully recovered in optimized conditions. This environment friendly bioleaching process proved efficient than the chemical method. Taking leads from the lab scale results, bioleaching in larger volumes (1, 5 and 10 L) was also performed to provide guidelines for taking up this technology for in situ industrial waste management.

Tratamento de efluentes de refinaria de petróleo em reatores com Aspergillus niger / Treatment of petroleum refinery wastewater by reactors inoculated with Aspergillus niger

Neste trabalho, avaliou-se o efeito do tempo de detenção hidráulica (TDH) no desempenho de três reatores aeróbios inoculados com Aspergillus niger AN400, usados para tratamento de efluentes de refinarias de petróleo. Cada reator foi operado com um tempo de detenção hidráulica diferente: 4, 8 e 12 horas, durante 152 dias. Eles possuíam leito fixo de espuma de poliuretano e o escoamento era ascendente e contínuo. Determinaram-se: pH, fenóis, demanda química de oxigênio (DQO), amônia, nitrito e nitrato, no afluente e efluentes dos reatores. O TDH de oito horas foi o melhor para remoção de DQOsolúvel e não houve diferença entre os TDHs para remoção de fenóis totais. No período estável não houve remoção de nitrato; no entanto ocorreu remoção de nitrito de aproximadamente 99 por cento. Além disto, houve produção de amônia devido à amonificação a partir do nitrito presente no meio.

This paper evaluated the effect of hydraulic retention time (HRT) on the performance of three upflow aerobic reactors, with polyurethane foam as support material, inoculated with Aspergillus niger AN400, used for the treatment of petroleum refinery wastewater. Each reactor was operated with a different HRT: 4, 8 and 12 hours, during 152 days. The performance was evaluated based on pH; phenols; COD, nitrate and nitrite. The results show that for the COD removal, it is more reasonable to operate the reactor with HRT of eight hours. However, there was no difference among results of phenol removal efficiency of the different HRTs. During steady state condition, nitrite was removed in approximately 99 percent, but there was no reduction on the nitrate concentration. Ammonia was produced in all reactors, probably due to ammonification of nitrite.