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Temperature effect on hydrothermal liquefaction (HTL) of Nannochloropsis gaditana and Chlorella sp. was investigated with 10% biomass loading at HTL temperatures of 180-330 o C, and reaction time of 30 minutes. Maximum yields of 47.5% for Nannochloropsis sp. and 32.5 % biocrude oil yields for Chlorella sp. were obtained at 300 o C. The higher heating values of biocrude oils produced in this work ranged between 34 and 39 MJ/kg. 79% of energy in the Nannochloropsis sp. was recovered at 300 o C and 62% of energy recovery from Chlorella sp. was achieved at 200 o C. Valuable nutrients (NH 3-N and PO 4 3-) produced during the HTL process were quantified from the aqueous phase for both strains of biomass. The aqueous phase samples obtained at all temperatures were also analyzed for amino acids and carbohydrates. The suitable temperatures for extraction of lipids, amino acids and carbohydrates have been identified. Sequential HTL experiments conducted have shown the prospect of recovering nutrients and other valuable byproducts along with biocrude oil. The experimental results and analysis indicate that sustainable biofuel production requires the development of strain based strategies for the hydrothermal liquefaction process.

Produced water (PW), the largest waste stream generated in oil and gas industries, has the potential to be a harmless product rather than being a waste. Biological processes using microorganisms have proven useful to remediate PW contaminated by petroleum hydrocarbons, complex organic chemicals, and solvents. In particular, the bioremediation of PW using algae is an eco-friendly and low-cost approach due to algae’s ability to utilize certain pollutants as nutrient sources. Therefore, the utilization of PW as an algal growth medium has a great potential to eliminate chemicals from the PW and minimize the large volumes of freshwater needed for cultivation. Although several reviews describing the bioremediation of PW have been published, to the best of our knowledge, no review has exclusively focused on the algae-based PW treatment. Therefore, the present review is dedicated to filling this gap by portraying the many different facets of the algae cultivation in PW. Several algal species that are known to thrive in a wide range of salinity and the critical steps for their cultivation in hypersaline PW have been identified. Overall, this comprehensive review highlights the PW bioremediation using algae and brings attention to utilizing PW to grow biomass that can be processed to generate biofuels and useful bioproducts.

This work investigates the hydrothermal liquefaction (HTL) of Cyanidioschyzon merolae algal species under various reaction temperatures and catalysts. Liquefaction of microalgae was performed with 10% solid loading for 30min at temperatures of 180-300°C to study the influences of two base and two acid catalysts on HTL product fractions. Maximum biocrude oil yield of 16.98% was obtained at 300°C with no catalyst. The biocrude oil yield increased to 22.67% when KOH was introduced into the reaction mixture as a catalyst. The algal biocrude and biochar has a higher heating values (HHV) of 32.22MJkg and 20.78MJkg respectively when no catalyst was used. Gas chromatography time of flight mass spectrometry (GC/TOFMS) was employed to analyze the biocrude oil composition, and elemental analysis was performed on the algae, biocrude and biochar samples. Analysis of the HTL aqueous phase revealed the presence of valuable products.