Bioavailability of organic contaminants in sediments.

The bioavailability of polycyclic aromatic hydrocarbons (PAHs) and chlorobiphenyls (CBs) in sediments is largely dependent on the freely dissolved concentration of these pollutants. However, measuring these is challenging, due to the low concentrations of lipophilic contaminants in the environment and their strong affinity for particles and for traditional sampling (filtration and centrifugation) equipment. An equilibrium passive sampling device made of silicone rubber was developed in this research to measure the freely dissolved concentrations of lipophilic contaminants and other parameters (water extractable proportions and sediment-water partition coefficients) that describe the availability of these contaminants in the environment. Equilibration between sampler and sediment for PAHs and CBs was found to be adequately achieved after 20 days shaking of a silicone rubber sampler in sediment slurry on an orbital shaker at 200 rpm. The reproducibility of uptake was better than 5 %. Silicone rubber-water partition coefficients for 34 PAHs and 32 CBs were measured in the laboratory using a co-solvent method using methanol as co solvent. Strong linear correlations of log K(sr,w), with octanol-water partition coefficients (log K(ow)). (log K(sr,w) = 0.97; log K(ow) -0.01; r2 = 0.94) and (log K(sr,w) = 1.17; log K(ow) -1.82; r2 = 0.90) were found for PAHs and CBs, with a systematic difference in correlations observed for the different classes of compounds which was attributed to structural differences of the compounds. The silicone rubber samplers were then used to measure concentrations of PAHs in the pore water of sediments from the Fladen Ground of the North Sea, Loch Shell, Firth of Forth, Firth of Clyde, Loch Etive and Aberdeen Harbour in Scotland and the Vefsn fjord, Norway. A proportion of the PAHs were found to be unavailable for exchange into the aqueous phase, and this was reflected in the high log K(oc) measured in all the sediments studied. The sediment-water partition coefficients also correlated positively with the octanol-water partition coefficients. Accumulation of PAHs in Nereis virens from sediments was better predicted from literature bio-concentration factors and pore-water concentrations obtained using the silicone rubber samplers, than from sediment concentrations traditionally used in risk assessments. Participation in an International Council for the Exploration of the Seas (ICES) passive sampling trial survey using silicone rubber in sediments and water is described, and demonstrated the potential of passive sampling in monitoring environmental pollution. The log BCF (bio concentration factor) for PAHs in mussels increased with increasing log K(ow) at both Loch Etive and Aberdeen Harbour locations, and could be used to estimate concentrations in mussels directly. The survey data also showed the use of silicone rubber in assessing the diffusive exchange of PAHs across sediment-water interfaces

Enantiospecific behaviour of chiral drugs in soil.

The importance of stereochemistry on the behaviour and effects of chiral pharmaceutical and illicit drugs in amended agricultural soils has been over looked to date. Therefore, this study was aimed at investigating the enantiospecific behaviour of a chemically diverse range of chiral drugs including naproxen, ibuprofen, salbutamol, bisoprolol, metoprolol, propranolol, acebutolol, atenolol, chlorpheniramine, amphetamine, fluoxetine and citalopram in soil microcosms. Considerable changes of the enantiomeric composition of ibuprofen, naproxen, atenolol, acebutolol and amphetamine were observed within 56 d. This is significant as enantiomer enrichment can favour the pharmacologically active (e.g., S(−)-atenolol) or less/non-active forms of the drug (e.g., R(−)-amphetamine). Single enantiomer microcosms showed enantiospecific degradation was responsible for enantiomer enrichment of atenolol and amphetamine. However, naproxen and ibuprofen enantiomers were subject to chiral inversion whereby one enantiomer converts to its antipode. Interestingly, chiral inversion was bidirectional and this is the first time it is reported in soil. Therefore, introduction of the less active enantiomer to soil through irrigation with reclaimed wastewater or biosolids as fertiliser can result in the formation of its active enantiomer, or vice versa. This phenomenon needs considered in risk assessment frameworks to avoid underestimating the risk posed by chiral drugs in amended soils

Screening reservoir candidates for enhanced oil recovery (EOR) in Angolan offshore projects.

The neuro-fuzzy (NF) approach presented in this work is based on five (5) layered feedforward backpropagation algorithm applied for technical screening of enhanced oil recovery (EOR) methods. Associated reservoir rock-fluid oilfield data from successful EOR projects were used as input and predicted output in the training and validation processes, respectively. The developed model was then tested by using data set from Block B of an Angolan oilfield. The results of the sensitivity analysis between the Mamdani and the Takagi-Sugeno-Kang (TSK) approach incorporated in the algorithm has shown the robustness of the TSK ANFIS (Adaptive Neuro-Fuzzy Inference System) approach in comparison to the other approach for the prediction of a suitable EOR technique. The simulation test results showed that the model presented in this study can be used for technical selection of suitable EOR techniques. Within the area investigated (Block B, Angola) polymer, hydrocarbon gas, and combustion were identified as the suitable techniques for EOR

Sand failure: effect of biocide on the geomechanical properties of outcrop carbonate rock under static conditions.

The effects of chemical interaction of a biocide with formation rocks on the rock geomechanical strength were examined. A combination of analytical tests (Scanning Electron Microscopy/Energy-Dispersive X-Ray Analysis-SEM/EDX, X-Ray Powder Diffraction-XRDP and Particle Size Distribution) and uniaxial compressive test was used in this study. The particle size distribution showed an increase in D50 with poor sorting for the chemically treated carbonate core sample. The XRPD shows evidence of altered minerals in the chemically treated samples. It was observed that the interaction led to precipitation of new materials that clogged the pore space of the rock samples leading to about 150% increase in compressive strength of the carbonate following treatment with the biocide. The results give more insight into the limitations of the existing sand production prediction models with respect to the effect of oilfield chemicals on the strength of the reservoir rocks

Sand failure : effect of biocide on the geomechanical properties of outcrop carbonate rock under static condition

Funding Information: The authors received funding from the Petroleum Technology Development Fund (PTDF), Nigeria, for the PhD work from which the materials and results presented in this paper originated.Peer reviewedPublisher PD

Mechanical, thermal, and flammability behaviour of low density polyethylene - oil based mud fillers nanocomposites.

Novel low density polyethylene (LDPE)/Oil based mud fillers (OBMF) nanocomposites were manufactured by a melt compounding process. Fourier Transform Infrared (FTIR) Spectroscopy was used to characterise the structure of the nanocomposites. The results revealed the influence of different clay minerals present in OBMFs in forming chemical bonds within microstructures. Scanning electron microscope (SEM) and Energy Dispersive X-Ray Analysis (EDXA) confirmed the materials were nanocomposites and also provided the elemental composition of the filler and nanocomposites. Thermal properties were investigated by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). The char yields of nanocomposites increased with OBMFs content. The TD5% (onset degradation temperature at 5 weight% loss) of the LDPE nanocomposite with 10.0 wt% OBMFs was 4° c higher than that of neat LDPE. Limiting Oxygen Index (L.O.I.) and UL94 tests revealed that the nanocomposites possess excellent flame retardancy which increased with increasing percentage of OBMFs. Tensile and flexural tests were also conducted which showed there was not any significant effect of OBMFs on tensile strength and flexural modulus of the nanocomposites and thereby offering an alternative material choice

Waste to want: polymer nanocomposites using nanoclays extracted from oil based drilling mud waste.

Due to the European Union (EU) waste frame work directive (WFD), legislations have been endorsed in EU member states such as UK for the Recycling of wastes with a vision to prevent and reduce landfilling of waste. Spent oil based drilling mud (drilling fluid) is a waste from the Oil and Gas industry with great potentials for recycling after appropriate clean-up and treatment processes. This research is the novel application of nanoclays extracted from spent oil based drilling mud (drilling fluid) clean-up as nanofiller in the manufacture of nanocomposite materials. Research and initial experiments have been undertaken which investigate the suitability of Polyamide 6 (PA6) as potential polymer of interest. SEM and EDAX were used to ascertain morphological and elemental characteristics of the nanofiller. ICPOES has been used to ascertain the metal concentration of the untreated nanofiller to be treated (by oil and heavy metal extraction) before the production of nanocomposite materials. The challenges faced and future works are also discussed

Targeted multi-analyte UHPLC-MS/MS methodology for emerging contaminants in septic tank wastewater, sludge and receiving surface water.

Septic tanks treat wastewater of individual houses and small communities (up to 2000 people in Scotland) in rural and semi-urban areas and are understudied sources of surface water contamination. A multi-analyte methodology with solid phase extraction (SPE), ultra-sonic extraction, and direct injection sample preparation methods was developed to analyse a comprehensive range of emerging contaminants (ECs) including prescription and over-the-counter pharmaceuticals and related metabolites, natural and synthetic hormones, and other human wastewater marker compounds in septic tank influent and effluent, river water, suspended solids, and septic tank sludge by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The number of quantifiable compounds in each matrix varied from 68 in septic tank wastewater to 59 in sludge illustrating its applicability across a range of matrices. Method quantification limits were 2.9 × 10−5-1.2 μg L−1 in septic tank influent, effluent and river water, with ≤0.01 μg L−1 achieved for 60% of ECs in all three water matrices, and 0.080-49 μg kg−1 in sludge. The developed method was applied to a septic tank (292 population equivalents) and the receiving river in the North-East of Scotland. Across all samples analysed, 43 of 68 ECs were detected in at least one matrix, demonstrating the method's sensitivity. The effluent concentrations suggest limited removal of ECs in septic tanks and a potential impact to river water quality for some ECs. However, further monitoring is required to better appreciate this. The developed methodology for a wide variety of ECs in a range of liquid and solid phases will allow, for the first time, a comprehensive assessment of ECs fate and removal in septic tanks, and their impact to surface water quality

Thermal stability, flame retardancy and mechanical properties of polyamide/montmorillonite nanocomposites prepared by melt processing.

The increase in thermal stability, flame retardancy, and mechanical properties of Polyamide 6 (PA6)/montmorillonite (MMT) nanocomposites open a new research window in respect to successful technical application of PA6/MMT nanocomposites on the industrial scale. This illustration provides important indication to understand a widely reported but poorly identified phenomena of catalysing effect of different ions, materials, or compounds present in MMT during the combustion of PA6/MMT nanocomposites

Oil based drilling fluid waste: an overview on environmentally persistent pollutants.

Operational discharges of spent drilling fluid, produced water, and accumulated drill cuttings from oil and gas industry are a continuous point source of environmental pollution. To meet the strict environmental standard for waste disposal, oil and gas industry is facing a numerous challenges in technological development to ensure a clean and safe environment. Oil and gas industry generates a large amount of spent drilling fluid, produced water, and drill cuttings, which are very different in every drilling operation in terms of composition and characterisation. This review article highlights the knowledge gap in identifying the different sources of waste streams in combined drilling waste. This paper also emphasises how different chemicals turn into environmentally significant pollutants after serving great performance in oil and gas drilling operations. For instance, oil based drilling fluid performs excellent in deeper drilling and drilling in the harsh geological conditions, but ended with (produces) a significant amount of persistent toxic pollutants in the environment. This review paper provides an overview on the basic concepts of drilling fluids and their functions, sources and characterisation of drilling wastes, and highlights some environmentally significant elements including different minerals present in drilling waste stream