Most non-polymeric oilfield scale inhibitors contain aminomethylenephosphonate groups. They generally have poor biodegradability, limiting their use in regions with strict environmental regions, such as offshore Norway. From mono-and bisnitrile starting materials, we have synthesized and investigated compounds with one or two aminobisphosphonate groups, −C(NH 2 )(PO 3 H 2 ) 2 , for seawater biodegradability, their calcium carbonate and barium sulfate scale inhibition, and compatibility with Ca 2+ ions. The distance between these groups was shown to affect biodegradability, with aminobisphosphonate derived from adiponitrile, (1,6-diaminohexane-1,1,6,6-tetrayl)tetraphosphonic acid (BP-7), giving the highest biodegradation of 25% in 28 days by the OECD 306 seawater test. All of the synthesized inhibitors exhibited both carbonate and sulfate scale inhibition properties. In comparison to known commercial scale inhibitors, the scale inhibition performance was relatively poor for sulfate scale and moderate for carbonate scale. To improve the performance, the amine groups were converted to aminobismethylenephosphonate groups, −N(CH 2 PO 3 H 2 ) 2 , to give novel non-polymeric scale inhibitors with 4−8 phosphonate groups. The scale inhibition was much improved for carbonate and sulfate scales. One of these compounds, BP-9, was found to be the most potent scale inhibitor, with a fail inhibitor concentration at 5 ppm for carbonate scale and 20 ppm for sulfate scale. The new bisphosphonate compounds showed moderate biodegradation activity. For example, compound BP-8 gave 40% seawater biodegradation over 28 days in the OECD 306 test.

Naphthalene, the smallest polycyclic aromatic hydrocarbon (PAH), is found in abundance in crude oil, its major source in marine environments. PAH removal occurs via biodegradation, a key process determining their fate in the sea. Adequate estimation of PAH biodegradation rates is essential for environmental risk assessment and response planning using numerical models such as the oil spill contingency and response (OSCAR) model. Using naphthalene as a model compound, biodegradation rate, temperature response and bacterial community composition of seawaters from two climatically different areas (North Sea and Arctic Ocean) were studied and compared. Naphthalene degradation was followed by measuring oxygen consumption in closed bottles using the OxiTop(®) system. Microbial communities of untreated and naphthalene exposed samples were analysed by polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and pyrosequencing. Three times higher naphthalene degradation rate coefficients were observed in arctic seawater samples compared to temperate, at all incubation temperatures. Rate coefficients at in situ temperatures were however, similar (0.048 day(-1) for temperate and 0.068 day(-1) for arctic). Naphthalene biodegradation rates decreased with similar Q10 ratios (3.3 and 3.5) in both seawaters. Using the temperature compensation method implemented in the OSCAR model, Q10 = 2, biodegradation in arctic seawater was underestimated when calculated from the measured temperate k1 value, showing that temperature difference alone could not predict biodegradation rates adequately. Temperate and arctic untreated seawater communities were different as revealed by pyrosequencing. Geographic origin of seawater affected the community composition of exposed samples.

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The potential for resource recovery from wastewater can be evaluated based on a detailed characterisation of wastewater. In this paper, results from fractionation and characterisation of two distinct wastewaters are reported. Using tangential flow filtration, the wastewater was fractionated into 10 size fractions ranging from 1 kDa to 1 mm, wherein the chemical composition and biodegradability were determined. Carbohydrates were dominant in particulate size fractions larger than 100 μm, indicating a potential of cellulose recovery from these fractions. While the particulate size fractions between 0.65 and 100 μm show a potential as a source for biofuel production due to an abundance of saturated C16 and C18 lipids. Both wastewaters were dominated by particulate (>0.65 μm), and oligo- and monomeric (<1 kDa) COD. Polymeric (1-1000 kDa) and colloidal (1000 kDa-0.65 μm) fractions had a low COD content, expected due to degradation in the sewer system upstream of the wastewater treatment plant. Biodegradation rates of particulate fractions increase with decreasing size. However, this was not seen in polymeric fractions where degradation rate was governed by chemical composition. Analytical validation of molecular weight and particle size distribution showed below filter cut-off retention of particles and polymers close to nominal cut-off, shifting the actual size distribution.