The disposal of hypersaline wastewaters containing hydrocarbons produced by the petroleum industry is a relevant issue. According with the current Italian Regulation, the water produced during the petroleum extraction (Produced Water) cannot be discharged into deep geological units due to their content of chemicals and biocide added during the extraction process. Adsorption on activated carbon is one of the better available technologies for the removal of synthetic organic chemicals (SOCs) form water. However, the replacement and disposal of exhausted carbon is quite expensive and the spent carbon may have to be handled as hazardous waste. Biodegradation of adsorbed organics can be achieved either by mixing bacteria with saturated activated carbon in systems or in the course of Biological Activated Carbon (BAC) systems. Since the hypersaline wastewaters, like produced water from oil extraction, are often recalcitrant to biological process due to strongly inhibition by salts (mainly NaCl), elevated temperature and presence in solution of biocides, Offline Biological Regeneration (OBR) process is the only possible way to regenerate with microbial activities the carbon saturated with the organic substances present in the water. The objective of the this study are to investigate the effectiveness of the adsorption process onto activated carbon at laboratory scale for the removal of hydrocarbons in hypersaline wastewater and to explore the biological regeneration of the saturated carbon. Adsorption kinetics, isotherms, and Rapid Small Scale Column Tests were performed to select the type of GAC and to investigate the adsorption capacity of target monoaromatic compounds (Benzene and Toluene) onto selected activated carbon. Continuous-flow presaturated GAC bioregeneration experiments were conducted with both synthetic and actual hypersaline wastewaters (Produced Water), using solutions containing selected microorganisms. Benzene and Toluene were analyzed by UV absorbance or with a GC/MS with a head space (HS) system. The microbial grow was analyzed by using the optical density (OD) and the colony count (CFU). The CO2 produced from the bacteria during their respiration was also estimated by the BaCO3 produced from the reaction of CO2 with a solution containing Ba(OH)(2). The genetic characterization of the isolated bacteria was carried out using Polymerase Chain Reaction (PCR). GAC adsorption was found very effective to remove target compounds (Benzene and Toluene) from hypersaline wastewaters. The biological regeneration of saturated carbon was found promising at laboratory scale. The genetic characterization of the isolated bacteria has shown the presence of Pseudomonas, Sphingomonas, Alcaligenes, Arthrobacter e Mycobacterium which are well known for the degradation of hydrocarbons. The maximum value of OD, CFU and BaCO3, indicating the highest biomass grow, occurred simultaneously with the maximum bioavailability of Benzene and Toluene.
The disposal of hypersaline wastewaters containing hydrocarbons produced by the petroleum industry is a relevant issue. According with the current Italian Regulation, the water produced during the petroleum extraction (Produced Water) cannot be discharged into deep geological units due to their content of chemicals and biocide added during the extraction process. Adsorption on activated carbon is one of the better available technologies for the removal of synthetic organic chemicals (SOCs) form water. However, the replacement and disposal of exhausted carbon is quite expensive and the spent carbon may have to be handled as hazardous waste. Biodegradation of adsorbed organics can be achieved either by mixing bacteria with saturated activated carbon in systems or in the course of Biological Activated Carbon (BAC) systems. Since the hypersaline wastewaters, like produced water from oil extraction, are often recalcitrant to biological process due to strongly inhibition by salts (mainly NaCl), elevated temperature and presence in solution of biocides, Offline Biological Regeneration (OBR) process is the only possible way to regenerate with microbial activities the carbon saturated with the organic substances present in the water. The objective of the this study are to investigate the effectiveness of the adsorption process onto activated carbon at laboratory scale for the removal of hydrocarbons in hypersaline wastewater and to explore the biological regeneration of the saturated carbon. Adsorption kinetics, isotherms, and Rapid Small Scale Column Tests were performed to select the type of GAC and to investigate the adsorption capacity of target monoaromatic compounds (Benzene and Toluene) onto selected activated carbon. Continuous-flow presaturated GAC bioregeneration experiments were conducted with both synthetic and actual hypersaline wastewaters (Produced Water), using solutions containing selected microorganisms. Benzene and Toluene were analyzed by UV absorbance or with a GC/MS with a head space (HS) system. The microbial grow was analyzed by using the optical density (OD) and the colony count (CFU). The CO2 produced from the bacteria during their respiration was also estimated by the BaCO3 produced from the reaction of CO2 with a solution containing Ba(OH)(2). The genetic characterization of the isolated bacteria was carried out using Polymerase Chain Reaction (PCR). GAC adsorption was found very effective to remove target compounds (Benzene and Toluene) from hypersaline wastewaters. The biological regeneration of saturated carbon was found promising at laboratory scale. The genetic characterization of the isolated bacteria has shown the presence of Pseudomonas, Sphingomonas, Alcaligenes, Arthrobacter e Mycobacterium which are well known for the degradation of hydrocarbons. The maximum value of OD, CFU and BaCO3, indicating the highest biomass grow, occurred simultaneously with the maximum bioavailability of Benzene and Toluene.
REMOVAL OF HYDROCARBONS FROM HYPERSALINE WATER BY ADSORPTION ON GAC AND OFFLINE BIOREGENERATION OF THE SATURATED CARBON
ROCCARO, PAOLO;VAGLIASINDI, Federico
2013-01-01
Abstract
The disposal of hypersaline wastewaters containing hydrocarbons produced by the petroleum industry is a relevant issue. According with the current Italian Regulation, the water produced during the petroleum extraction (Produced Water) cannot be discharged into deep geological units due to their content of chemicals and biocide added during the extraction process. Adsorption on activated carbon is one of the better available technologies for the removal of synthetic organic chemicals (SOCs) form water. However, the replacement and disposal of exhausted carbon is quite expensive and the spent carbon may have to be handled as hazardous waste. Biodegradation of adsorbed organics can be achieved either by mixing bacteria with saturated activated carbon in systems or in the course of Biological Activated Carbon (BAC) systems. Since the hypersaline wastewaters, like produced water from oil extraction, are often recalcitrant to biological process due to strongly inhibition by salts (mainly NaCl), elevated temperature and presence in solution of biocides, Offline Biological Regeneration (OBR) process is the only possible way to regenerate with microbial activities the carbon saturated with the organic substances present in the water. The objective of the this study are to investigate the effectiveness of the adsorption process onto activated carbon at laboratory scale for the removal of hydrocarbons in hypersaline wastewater and to explore the biological regeneration of the saturated carbon. Adsorption kinetics, isotherms, and Rapid Small Scale Column Tests were performed to select the type of GAC and to investigate the adsorption capacity of target monoaromatic compounds (Benzene and Toluene) onto selected activated carbon. Continuous-flow presaturated GAC bioregeneration experiments were conducted with both synthetic and actual hypersaline wastewaters (Produced Water), using solutions containing selected microorganisms. Benzene and Toluene were analyzed by UV absorbance or with a GC/MS with a head space (HS) system. The microbial grow was analyzed by using the optical density (OD) and the colony count (CFU). The CO2 produced from the bacteria during their respiration was also estimated by the BaCO3 produced from the reaction of CO2 with a solution containing Ba(OH)(2). The genetic characterization of the isolated bacteria was carried out using Polymerase Chain Reaction (PCR). GAC adsorption was found very effective to remove target compounds (Benzene and Toluene) from hypersaline wastewaters. The biological regeneration of saturated carbon was found promising at laboratory scale. The genetic characterization of the isolated bacteria has shown the presence of Pseudomonas, Sphingomonas, Alcaligenes, Arthrobacter e Mycobacterium which are well known for the degradation of hydrocarbons. The maximum value of OD, CFU and BaCO3, indicating the highest biomass grow, occurred simultaneously with the maximum bioavailability of Benzene and Toluene.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
