Waste animal fat with hydrothermal liquefaction as a potential route to marine biofuels.

Unused animal waste rendered fat is a potential feedstock for marine biofuels. In this work, bio-oil was generated using hydrothermal liquefaction (HTL) of nitrogen-free and low sulfur rendered bovine fat. Maximum bio-oil yield of 28 ± 1.5% and high heating value of 38.5 ± 0.16 MJ·kg‒1 was obtained at 330 °C at 50% animal fat solid load and 20 min retention time. The nitrogen and sulfur content were negligible, making the produced bio-oil useful marine biofuel, taking into account current stringent regulations on NOx and SOx emissions. The economic analysis of the process, where part of the bovine fat waste is converted to the bio-oil and the semi-solid residues can be used to supply the heat demand of the HTL process and alternately generate electricity, showed that our process is likely to generate a positive profit margin on a large scale. We also showed the growing economic importance of electricity in the revenues as commercial production becomes more energy efficient.

Mono-specific algal diets shape microbial networking in the gut of the sea urchin Tripneustes gratilla elatensis.

BACKGROUND: Algivorous sea urchins can obtain energy from a diet of a single algal species, which may result in consequent changes in their gut microbe assemblies and association networks. METHODS: To ascertain whether such changes are led by specific microbes or limited to a specific region in the gut, we compared the microbial assembly in the three major gut regions of the sea urchin Tripneustes gratilla elatensis when fed a mono-specific algal diet of either Ulva fasciata or Gracilaria conferta, or an algal-free diet. DNA extracts from 5 to 7 individuals from each diet treatment were used for Illumina MiSeq based 16S rRNA gene sequencing (V3-V4 region). Niche breadth of each microbe in the assembly was calculated for identification of core, generalist, specialist, or unique microbes. Network analyzers were used to measure the connectivity of the entire assembly and of each of the microbes within it and whether it altered with a given diet or gut region. Lastly, the predicted metabolic functions of key microbes in the gut were analyzed to evaluate their potential contribution to decomposition of dietary algal polysaccharides. RESULTS: Sea urchins fed with U. fasciata grew faster and their gut microbiome network was rich in bacterial associations (edges) and networking clusters. Bacteroidetes was the keystone microbe phylum in the gut, with core, generalist, and specialist representatives. A few microbes of this phylum were central hub nodes that maintained community connectivity, while others were driver microbes that led the rewiring of the assembly network based on diet type through changes in their associations and centrality. Niche breadth agreed with microbes' richness in genes for carbohydrate active enzymes and correlated Bacteroidetes specialists to decomposition of specific polysaccharides in the algal diets. CONCLUSIONS: The dense and well-connected microbial network in the gut of Ulva-fed sea urchins, together with animal's rapid growth, may suggest that this alga was most nutritious among the experimental diets. Our findings expand the knowledge on the gut microbial assembly in T. gratilla elatensis and strengthen the correlation between microbes' generalism or specialism in terms of occurrence in different niches and their metabolic arsenal which may aid host nutrition.

'Dual-reference' method for high-precision infrared measurement of leaf surface temperature under field conditions.

Temperature is a key control over biological activities from the cellular to the ecosystem scales. However, direct, high-precision measurements of surface temperature of small objects, such as leaves, under field conditions with large variations in ambient conditions remain rare. Contact methods, such as thermocouples, are prone to large errors. The use of noncontact remote-sensing methods, such as thermal infrared measurements, provides an ideal solution, but their accuracy has been low (c. 2°C) owing to the necessity for corrections for material emissivity and fluctuations in background radiation Lbg . A novel 'dual-reference' method was developed to increase the accuracy of infrared needle-leaf surface temperature measurements in the field. It accounts for variations in Lbg and corrects for the systematic camera offset using two reference plates. We accurately captured surface temperature and leaf-to-air temperature differences of needle-leaves in a forest ecosystem with large diurnal and seasonal temperature fluctuations with an uncertainty of ± 0.23°C and ± 0.28°C, respectively. Routine high-precision leaf temperature measurements even under harsh field conditions, such as demonstrated here, opens the way for investigating a wide range of leaf-scale processes and their dynamics.

Polyhydroxyalkanoates and biochar from green macroalgal Ulva sp. biomass subcritical hydrolysates: Process optimization and a priori economic and greenhouse emissions break-even analysis.

Although macroalgae biomass is an emerging sustainable feedstock for biorefineries, the optimum process parameters for their hydrolysis and fermentation are still not known. In the present study, the simultaneous production of polyhydroxyalkanoates (PHA) and biochar from green macroalgae Ulva sp. is examined, applying subcritical water hydrolysis and Haloferax mediterranei fermentation. First, the effects of temperature, treatment time, salinity, and solid load on the biomass and PHA productivity were optimized following the Taguchi method. Hydrolysis at 170 °C, 20 min residence time, 38 g L-1 salinity with a seaweed solid load of 5% led to the maximum PHA yield of 0.104 g g-1Ulva and a biochar yield of 0.194 ± 1.23 g g-1Ulva. Second, the effect of different initial culture densities on the biomass and PHA productivity was studied. An initial culture density of 50 g L-1 led to the maximum volumetric PHA productivity of 0.024 ± 0.002 g L-1 h-1 with a maximum PHA content of 49.38 ± 0.3% w/w Sensitivity analysis shows that within 90% confidence, the annual PHA production from Ulva sp. is 148.14 g PHA m-2 year-1 with an annual biochar production of 42.6 g m-2 year-1. Priori economic and greenhouse gas break-even analyses of the process were done to estimate annual revenues and allowable greenhouse gas emissions. The study illustrates that PHA production from seaweed hydrolysate using extreme halophiles coupled to biochar production could become a benign and promising step in a marine biorefinery.

Hydrothermal processing of a green seaweed Ulva sp. for the production of monosaccharides, polyhydroxyalkanoates, and hydrochar.

In the fermentation and bioenergy industry, terrestrial biomass is usually fractionated and the collected components, such as starch, are processed separately. Such a separation has not been reported for seaweeds. In this work, the direct hydrothermal processing of the whole green seaweed Ulva sp. biomass is compared to processing of separated starch and cellulose, to find the preferable route for monosaccharide, hydrochar, and polyhydroxyalkanoates (PHA) production. Glucose was the major released monosaccharide. A significant share of the glucose yield comes from the starch fraction. The highest hydrochar yield with the lowest ash content was obtained from the separated cellulose fraction. The highest PHA yield was obtained using a whole Ulva sp. hydrolysate fermentation with Haloferaxmediterranei. Economic analysis shows the advantage of direct Ulva sp. biomass fermentation to PHA. The co-production of glucose and hydrochar does not add significant economic benefits to the process under plausible prices of the two outputs.

Method for accurate measurement of infrared emissivity for opaque low-reflectance materials.

Accurate determination of infrared (IR) emissivity is important for non-contact temperature measurement and for energy balance evaluation in systems that exchange radiation. A method for accurate measurement is proposed based on active modulation of the background radiation. The hemispherical directional reflectance is measured as a proxy for directional emissivity using an IR camera and an integrating sphere, while the background radiation is modulated using an IR emitter and a mechanical shutter. Measurement of the apparent temperature observed by the camera under two different illumination conditions allows the extraction of reflectance and emissivity. The accuracy of the measurement and its sensitivity to surface properties are analyzed, showing uncertainty values as low as 0.004 in some cases. Example measurements of natural and artificial surfaces are presented.

Synergistic effect of heat and solar UV on DNA damage and water disinfection of E. coli and bacteriophage MS2.

The response of a representative virus and indicator bacteria to heating, solar irradiation, or their combination, was investigated in a controlled solar simulator and under real sun conditions. Heating showed higher inactivation of Escherichia coli compared to the bacteriophage MS2. Heating combined with natural or simulated solar irradiation demonstrated a synergistic effect on the inactivation of E. coli, with up to 3-log difference for 50 °C and natural sun insolation of 2,000 kJ m(-2) (compared to the sum of the separate treatments). Similar synergistic effect was also evident when solar-UV induced DNA damage to E. coli was assessed using the endonuclease sensitive site assay (ESS). MS2 was found to be highly resistant to irradiation and heat, with a slightly synergistic effect observed only at 59 °C and natural sun insolation of 5,580 kJ m(-2). Heat treatment also hindered light-dependent recovery of E. coli making the treatment much more effective.

Systematic errors in the measurement of emissivity caused by directional effects.

Accurate knowledge of surface emissivity is essential for applications in remote sensing (remote temperature measurement), radiative transport, and modeling of environmental energy balances. Direct measurements of surface emissivity are difficult when there is considerable background radiation at the same wavelength as the emitted radiation. This occurs, for example, when objects at temperatures near room temperature are measured in a terrestrial environment by use ofthe infrared 8-14-microm band.This problem is usually treated by assumption of a perfectly diffuse surface or of diffuse background radiation. However, real surfaces and actual background radiation are not diffuse; therefore there will be a systematic measurement error. It is demonstrated that, in some cases, the deviations from a diffuse behavior lead to large errors in the measured emissivity. Past measurements made with simplifying assumptions should therefore be reevaluated and corrected. Recommendations are presented for improving experimental procedures in emissivity measurement.