Enhancement of oil & gas wastewater biological treatment including oilfield produced water

Les travaux de cette thèse portent sur le développement d’un procédé biologique hybride pour le traitement des eaux de production pétrolière. Ces eaux représentent la principale source d’eaux usées de l’industrie pétrolière. Les eaux de production pétrolière ont une composition particulièrement complexe dépendante de nombreux facteurs. Il convient de d’optimiser les filières de traitement pour développer des procédés compacts et performants. Pour cela la voie des réacteurs biologiques hybrides est envisagée. La première partie de l’étude a porté sur la caractérisation des transferts d’oxygène à l’intérieur du pilote de laboratoire. La deuxième partie de cette thèse a visé à étudier l’influence du temps de séjour hydraulique sur les performances de traitement d’une eau de production pétrolière synthétique par un réacteur biologique hybride à lit fixe en comparaison d’un réacteur à boue activée. Les résultats ont montré qu’il était possible de diminuer le temps de séjour hydraulique de 24h à 12h sur le réacteur biologique hybride à lit fixe sans affecter les performances de traitement. Le type de procédé a une influence significative sur la diversité bactérienne ainsi que la population peuplant la biomasse libre et le biofilm. Enfin, la dernière étude comparative entre un réacteur hybride à lit mobile et un réacteur hybride à lit fixe portant sur l’influence de la salinité sur les performances de traitement a montré qu’une augmentation de la salinité de 1,5 g.L-1 à 20 g.L-1 n’avait pas d’influence sur les performances de traitement. La salinité influence la diversité bactérienne avec une prédominance de certaines espèces marines qui s’accroît quand la salinité augmenteThis thesis was focused on the development of a hybrid biological process for produced water treatment. Produced water is the main source of wastewater of oil and gas industry. Produced water have a complex composition, which depends on several factors. Compact and efficient treatment processes need to be optimized. Here, hybrid biological reactors are studied. The first part of the study aimed to characterize oxygen transfer inside the laboratory pilot plant. The second part of this thesis aimed to study the influence of the hydraulic retention time on treatment efficiencies of a synthetic produced water in a fixed bed hybrid biological reactor in comparison with a conventional activated sludge reactor. Results showed that the fixed bed hybrid biological reactor could be operated under hydraulic retention time ranging from 24 h to 12 h without affecting treatment efficiencies. Furthermore, the assessment of microbial population between the two bioreactors showed that the type of operated process has a significant influence on the bacterial diversity as well as bacteria populating the free biomass and the biofilm. Finally, the last study comparing a moving bed biofilm reactor and a fixed bed hybrid biological reactor and aiming to study the influence of salinity on treatment efficiencies showed that an increase of salinity from 1.5 g.L-1 to 20 g.L-1 had no influence on treatment efficiencies. The analysis of bacterial population showed that the salinity has an influence on the bacterial diversity (decrease in the diversity indices) and that some marine bacteria became preponderan

Proposed mechanisms of toluene removal by vermicompost and earthworms Eisenia fetida

International audienceFor potential use in air treatment by biofiltration, a new material composed of vermicompost and earthworms () was tested for the removal of a volatile organic compound (VOC), toluene. The removal rate of toluene was measured during batch experiments in presence of vermicompost only, earthworms only and a mixture of both. In the chosen experimental conditions, no mortality of earthworms was recorded and the results showed that the presence of earthworms allowed an increase in toluene removal rate (0.213 mg h) compared to vermicompost only (0.084 mg h) and earthworms only (0.136 mg h). From the experimental data, mechanisms of toluene transfer and adsorption/biodegradation by microorganisms from vermicompost and/or earthworms were proposed

Application of Moving Bed Biofilm Reactor and Fixed Bed Hybrid Biological Reactor for Oilfield Produced Water Treatment: Influence of Total Dissolved Solids Concentration

International audienceThis experimental paper deals with the development of a hybrid biological reactor for the treatment of a synthetic oilfield produced water under an increase in total dissolved solids (TDS) concentration. To comply with strengthening regulations concerning produced water discharge and peculiar produced water compositions, a moving bed biofilm reactor (MBBR) consisting in a combination of free activated sludge and moving biofilm supports was compared to a fixed bed hybrid biological reactor (FBHBR) consisting in a combination of free activated sludge and a fixed biofilm support. After a 216 days experimental period, the MBBR and the FBHBR were efficient to treat a synthetic produced water with chemical oxygen demand (COD) removal rate above 90% under an increase in TDS concentrations from 1.5 to 8 g·L−1. Ecotoxicity measurements on freshwater and marine microorganisms revealed an absence of toxicity on treated waters. A decrease in bacterial diversity indices with respect to the inoculum was observed in both bioreactors. This suggests that the increase in TDS concentrations caused the predominance of a low number of bacterial species

Développement d’un procédé biologique hybride pour le traitement d’eau de production pétrolière

International audienc

Development of a hybrid biological process for oilfield produced water treatment

International audienc

A comparative study of conventional activated sludge and fixed bed hybrid biological reactor for oilfield produced water treatment: influence of hydraulic retention time

International audienceThis study focuses on the development of a hybrid biological reactor for the treatment of synthetic oilfield produced water. To face increasingly strict regulations concerning produced water discharge, a fixed bed hybrid biological reactor (FBHBR) containing a combination of free activated sludge and a fixed biofilm support was compared to a conventional activated sludge reactor (CAS). After gradual microbial acclimation, a 133-day experiment showed that both bioreactors were able to efficiently remove phenol, toluene, xylenes, and polycyclic aromatic hydrocarbons (PAHs) from a synthetic wastewater with a chemical oxygen demand (COD) removal rate above 95%, at hydraulic retention times (HRT) of 24 h and 18 h, and that only the FBHBR was able to maintain high removal efficiency at an HRT of 12 h. Ecotoxicity tests showed that outlet waters from both bioreactors were non-toxic. Assessment of the bacterial population revealed notable differences between the CAS reactor and FBHBR. In particular, wider diversity was observed in the FBHBR. The marked similarity between the bacterial composition of the free sludge and that of the biofilm in the FBHBR suggests that biofilm detachment played an important part role in bacterial development in the free sludge

Biological Treatments of Oilfield Produced Water: A Comprehensive Review

International audienc