Numerical modelling of temporal and spatial patterns of petroleum hydrocarbons concentration in the Bohai Sea

Exploration of Super-Gravity Rapid Dissolution Method of Polymer for Offshore Oil Repellent

The long dissolution time and large dispensed volumes of oil repellent polymers in offshore oil fields lead to a great increase in the volume and number of dissolution and maturation tanks in the polymer formulation system. However, there is limited space and load-bearing capacity at the offshore platform and only a small space is available for the dispensing system. To further optimize the polymer dispensing system and reduce its floor space, the super-gravity technology may be considered as a way to speed up the dissolution of the polymer. The mechanism of super-gravity rapid dissolution was investigated by establishing mathematical models and with indoor experiments. The effects of filler pore size and super-gravity factor on polymer dissolution time and solution viscosity were investigated using the super-gravity rapid dissolution device, then combined with established graded forced stretching devices for field magnification experiments. The results indicated that the super-gravity method can substantially shorten the polymer dissolution time. The basic dissolution time of the polymer AP-P4 was shortened by 35 min compared with the conventional formulation method after use of the super-gravity rapid dissolution device. The optimal process conditions for the preparation of polymer solution by the super-gravity rapid dissolution device were selected as the optimal super-gravity factor range of 1031~1298.

Development of an oil spill model adaptable to exposure and submergence conversion of tidal flats: A case study in the Changjiang Estuary

Through the application of the Water Pollution Emergency Response System (WPERS) in the Changjiang Estuary, it was found that tidal flats significantly affect the trajectory of an oil film, and the deposition of the oil film on tidal flats is remarkable. In this study, the Estuarine Oil Spill Model (EOSM) was developed to simulate the process of the oil film landing on tidal flats. The Lagrangian particle algorithm and oil fate experience algorithms were adopted. An algorithm for generating dynamic shorelines was also involved. Compared to the oil spill algorithm without wet-dry functionality, the spatial distribution of the oil film deposition simulated in the EOSM better matched the reanalysis data of the satellite remote sensing image. This indicated that the dynamic wet-dry switch phenomenon of tidal flats could be involved in the simulation of offshore oil spills to improve the accuracy of accident prediction and ecological loss assessment. PLAIN LANGUAGE SUMMARY: On December 30th, 2012, a vessel carrying 400 tons of heavy oil sank in the Changjiang Estuary, China. The heavy oil leaked at around 4 am the next day. In this study, a new oil spill model was developed to simulate the process of an oil film landing on land and tidal flats. An algorithm for generating the dynamic shorelines in an oil spill simulation was adapted for the wet-dry switch of tidal flats. The landing distribution of the oil film in this new model was well matched to the satellite image for this accident. This indicated that the dynamic wet-dry switch phenomenon of tidal flats could be involved in the simulation of oil spills offshore, to improve the accuracy of accident prediction and ecological loss assessment. The research results could provide some new ideas for the development of offshore oil spill simulation technology.

Kinetic modelling of total petroleum hydrocarbon in spent lubricating petroleum oil impacted soil under different treatments

The integration of first and second order kinetic model in parameter estimation for the degradation pattern of total petroleum hydrocarbon (TPH) in spent lubricating petroleum oil (SLPO) over a four-month period was the subject of the present investigation. Study design considered four treatment microcosms notably; sewage sludge (SB), monitored natural recovery (MNR), surfactant (SA) and control (SO). The rate of TPH degradation using sewage sludge as amendment material depicted effective TPH removal within ten weeks. A maximum allowable concentration of residual TPH (4300 mg kg^-1) was obtained through an amendment with sewage sludge. Degradation constant (k) produced by both first and second order rates significantly demonstrated the performance of sewage sludge biomass over the other three treatments applied, however, experimental data adequately fitted into the first order kinetics (k = 0.27 d^-1, t½ = 3.0 d). TPH removal efficiency of sewage sludge and detergent were 96.0% and 81.0% respectively. The use of sewage sludge biomass significantly (p < .05) improved soil biological characteristics and produced optimum dehydrogenase activity (DHA ≥ 8.8 TPFg^-1 d), germination index (%IG ≥ 88%), and chlorophyll content (chl ≥ 100 µg cm^-2), thus, recommended for field scale application in soil hydrocarbon pollution remediation.

Quantitative oil spill risk from offshore fields in the Bohai Sea, China

The oil spill risk in the environments surrounding the Bohai Sea is aggravated by increasing marine petroleum exploitation. There is a growing need to assess the risk of oil pollution in sensitive marine areas and coastlines. Both the recurrence frequency of spill accidents and the duration of exposure in marine areas and coastal shorelines are considered in our statistical model, which consists of a probabilistic oil spill model used to simulate various oil spill scenarios at twenty oil fields in the Bohai Sea based on high-resolution oceanographic, meteorological, and geomorphological data. The statistical results of the risk to marine areas integrate the probability of pollution in marine areas, oil slick thickness, and duration of water surface covered by a floating slick. The coastal risk index includes the probability of a shoreline hit, average mass of stranding oil, and time of oil beaching. The spatial distributions of environmental triggering factors and coastal/marine vulnerability are merged, and a map of the oil spill risk in the Bohai Sea is presented, which is useful for contingency planning and the assessment of environmental risk of marine petroleum exploitation.

Great correlation: Biodegradation and chemotactic adsorption of Pseudomonas synxantha LSH-7' for oil contaminated seawater bioremediation

Oil Contaminated Seawaters is treated by biological processes of sorption or degradation. Considering the chemotaxis of bacteria, they migrate towards a better way to survive. However, the information concerning the chemotactic biosorption of microorganism is severely limited thus far. Therefore, chemotactic biosorption a novel way of sorption was put forward. The equation was defined as: A _{chemotactic biosorption} = A _{extracellular biosorption} - A _{passive extracellular biosorption} + E _{intracellular}. Effects of controlling parameters like pollutant, fertilizer, sediments and surfactant on bacterial chemotactic sorption capacity of tetradecane, hexadecane, phenanthrene or pyrene were described in detail. The results showed bacterial chemotactic biosorption would be promoted under the conditions of low pollutant concentration, high sediment concentration and fertilizer. However, Tween 80 would promote the sorption of pollutants onto bacterial cells depending on the concentration of surfactant. Correlational analyses were conducted with the biodegradation rate and the concentration (mg/g) of hydrocarbons measured in the biomass. We concluded there existed great correlation between them. Biodegradation rate were all linearly correlated with the concentration (mg/g) of hydrocarbons measured in the biomass in all respects with tetradecane (R² = 0.9873), hexadecane (R² = 0.9705), phenanthrene (R² = 0.9098) and pyrene (R² = 0.9424). The above idea may provide a new insight into oil spill bioremediation from sorption to degradation.