Christopher Q. Lan

BIOFUELS FROM MICROALGAE

Microalgae are a diverse group of prokaryotic and eukaryotic photosynthetic microorganisms that grow rapidly due to their simple structure. They can potentially be employed for the production of biofuels in an economically effective and environmentally sustainable manner. Microalgae have been investigated for the production of a number of different biofuels including biodiesel, bio‐oil, bio‐syngas, and bio‐hydrogen. The production of these biofuels can be coupled with flue gas CO2 mitigation, wastewater treatment, and the production of high‐value chemicals. Microalgal farming can also be carried out with seawater using marine microalgal species as the producers. Developments in microalgal cultivation and downstream processing (e.g., harvesting, drying, and thermochemical processing) are expected to further enhance the cost‐effectiveness of the biofuel from microalgae strategy.

CO2 bio-mitigation using microalgae

Microalgae are a group of unicellular or simple multicellular photosynthetic microorganisms that can fix CO2 efficiently from different sources, including the atmosphere, industrial exhaust gases, and soluble carbonate salts. Combination of CO2 fixation, biofuel production, and wastewater treatment may provide a very promising alternative to current CO2 mitigation strategies.

Novel alternatives to antibiotics: bacteriophages, bacterial cell wall hydrolases, and antimicrobial peptides

Extensive research has been conducted on the development of three groups of naturally occurring antimicrobials as novel alternatives to antibiotics: bacteriophages (phages), bacterial cell wall hydrolases (BCWH), and antimicrobial peptides (AMP). Phage therapies are highly efficient, highly specific, and relatively cost‐effective. However, precautions have to be taken in the selection of phage candidates for therapeutic applications as some phages may encode toxins and others may, when integrated into host bacterial genome and converted to prophages in a lysogenic cycle, lead to bacterial immunity and altered virulence. BCWH are divided into three groups: lysozymes, autolysins, and virolysins. Among them, virolysins are the most promising candidates as they are highly specific and have the capability to rapidly lyse antibiotic‐resistant bacteria on a generally species‐specific basis. Finally, AMP are a family of natural proteins produced by eukaryotic and prokaryotic organisms or encoded by phages. AMP are of vast diversity in term of size, structure, mode of action, and specificity and have a high potential for clinical therapeutic applications.

Biomass production and nitrogen and phosphorus removal by the green alga Neochloris oleoabundans in simulated wastewater and secondary municipal wastewater effluent

Biomass productivity of 350 mg DCW L(-1)day(-1) with a final biomass concentration of 3.15 g DCW L(-1) was obtained with Neochloris oleoabundans grown in artificial wastewater at sodium nitrate and phosphate concentrations of 140 and 47 mg L(-1), respectively, with undetectable levels of residual N and P in effluents. In secondary municipal wastewater effluents enriched with 70 mg N L(-1), the alga achieved a final biomass concentration of 2.1 g DCW L(-1) and a biomass productivity of 233.3 mg DCW L(-1)day(-1). While N removal was very sensitive to N:P ratio, P removal was independent of N:P ratio in the tested range. These results indicate that N. oleoabundans could potentially be employed for combined biofuel production and wastewater treatment.

Closed photobioreactors for production of microalgal biomasses.

Microalgal biomasses have been produced industrially for a long history for application in a variety of different fields. Most recently, microalgae are established as the most promising species for biofuel production and CO(2) bio-sequestration owing to their high photosynthesis efficiency. Nevertheless, design of photobioreactors that maximize solar energy capture and conversion has been one of the major challenges in commercial microalga biomass production. In this review, we systematically survey the recent developments in this field.

Production and Application of Bacteriophage and Bacteriophage-Encoded Lysins

The widespread resistance to antibiotics among pathogenic bacteria has made development of alternatives to antibiotics a pressing public concern. Extensive studies have established bacteriophages (phages) and phage-encoded lytic enzymes (virolysins) as two of the most promising families of alternative antibacterials for the treatment and prophylaxis of bacterial infections. They have shown great potential in veterinary and human medicine for the treatment and prophylaxis of infections. Technologies have also been patented employing phages and virolysins in other pathogen related applications including detection and decontamination.

Ice Cooling Vest on Tolerance for Exercise under Uncompensable Heat Stress

This study was conducted to evaluate the effectiveness of a commercial, personal ice cooling vest on tolerance for exercise in hot (35°C), wet (65% relative humidity) conditions with a nuclear biological chemical suit (NBC). On three separate occasions, 10 male volunteers walked on a treadmill at 3 miles per hour and 2% incline while (a) seminude (denoted CON), (b) dressed with a nuclear, biological, chemical (NBC) suit with an ice vest (V) worn under the suit (denoted NBCwV); or (c) dressed with an NBC suit but without an ice vest (V) (denoted NBCwoV). Participants exercised for 120 min or until volitional fatigue, or esophageal temperature reached 39.5°C. Esophageal temperature (Tes), heart rate (HR), thermal sensation, and ratings of perceived exertion were measured. Exercise time was significantly greater in CON compared with both NBCwoV and NBCwV (p < 0.05), whereas Tes, thermal sensation, heart rate, and rate of perceived exertion were lower (p < 0.05). Wearing the ice vest increased exercise time (NBCwoV, 103.6 ± 7.0 min; NBCwV, 115.9 ± 4.1 min) and reduced the level of thermal strain, as evidenced by a lower Tes at end-exercise (NBCwoV, 39.03 ± 0.13°C; NBCwV, 38.74 ± 0.13°C) and reduced thermal sensation (NBCwoV, 6.4 ± 0.4; NBCwV, 4.8 ± 0.6). This was paralleled by a decrease in rate of perceived exertion (NBCwoV, 14.7 ± 1.6; NBCwV, 12.4 ± 1.6) (p < 0.05) and heat rate (NBCwoV, 169 ± 6; NBCwV, 159 ± 7) (p < 0.05). We show that a commercially available cooling vest can significantly reduce the level of thermal strain during work performed in hot environments.

Effects of Inorganic Nano-Additives on Properties and Performance of Polymeric Membranes in Water Treatment

Separation using selective polymeric membranes has been well-established as an energy-efficient and cost-effective technology in water treatment and many other applications involving aqueous solutions. However, limited chemical, thermal, and mechanical resistances besides their tendency to fouling and inadequate pure water flux may often restrict their applications. To this end, inorganic materials as additives have been demonstrated to be able to enhance chemical, thermal, and fouling membrane resistances, which demonstrate their great potential for developing novel membranes by using them as additives in polymer matrices. Considering the excellent characteristics of the nanosized particles, this study reviews the effects of inorganic nano-additives on properties and performance of polymer/nanoparticle composite membranes. It has been demonstrated that using nanomaterials in a polymer matrix could enhance the mechanical strength and stiffness, wettability, selectivity, water permeability, and antifouling characteristics of the host polymer.

Control of protozoa contamination and lipid accumulation in Neochloris oleoabundans culture: Effects of pH and dissolved inorganic carbon

Combined effects of pH (i.e., 7.5, 8.5, and 9.5) and bicarbonate (i.e., 0, 80 and 160mM NaHCO3) on lipid accumulation and on biological contaminant viability in a protozoa-contaminated culture of the freshwater microalga Neochloris oleoabundans were studied. Cultures grown in the media containing 160mM NaHCO3 at pH 9.5 obtained the highest biomass concentration (DCWmax=1.32g/L), lipid content (LC=327mg/g), which corresponded to a lipid productivity of 56mg/(L·d), and the culture was protozoa free one day after inoculation. Other cultures, 160mM NaHCO3 at pH 8.5 (DCWmax=1.32g/L, LC=223mg/g), and 80mM NaHCO3 at pH 9.5 (DCWmax=1.25g/L, LC=264mg/g) could delay protozoan growth, but not inhibit it completely. These results suggest 160mM NaHCO3 or slightly above at pH levels of 8.5-9.5 may be used in outdoor cultivation processes of freshwater N. oleoabundans to control protozoa contamination while maintain a high lipid content.

Criteria for the selection of a support material to fabricate coated membranes for a life support device

Life support devices, specifically vacuum desiccant cooling devices require hydrophobic micro-porous membranes with high liquid entry pressure of water (LEPw), high mechanical strength and large vacuum distillation flux in the temperature range of 10–30 °C. To achieve this goal, membranes were prepared by casting polyvinylidene fluoride (PVDF) on various non-woven fabric (NWF) materials using the immersion precipitation technique at ambient temperature. Four porous polyester NWF materials were tested as the membrane support materials which were characterized by SEM analysis and by measuring the contact angle and porosity. The PVDF coated membranes were also characterized by SEM image analysis and LEPw. Finally, the coated membranes were tested for vacuum membrane distillation (VMD) performance at a relatively low feed temperature of 30 °C. The results of this study revealed a significant impact of the NWF materials on VMD performance. A suitable NWF material leads to a much enhanced VMD flux of the PVDF coated membrane that was approximately 15 times that of the unsupported PVDF membrane. These results suggest that the spongy-like layer may have strong impacts on the flux of membrane distillation. The studies provide understanding of the VMD phenomenon and provide new insights for the development of coated membranes used for life support devices.