Dual role of microalgae: Phycoremediation of domestic wastewater and biomass production for sustainable biofuels production

Potential yields and properties of oil from the hydrothermal liquefaction of microalgae with different biochemical content.

Biomass can be utilized to produce bio-oil, a promising alternative energy source for the limited crude oil. There are mainly two processes involved in the conversion of biomass to bio-oil: flash pyrolysis and hydrothermal liquefaction. The cost of bio-oil production from biomass is relatively high based on current technologies, and the main challenges are the low yield and poor bio-oil quality. Considerable research efforts have been made to improve the bio-oil production from biomass. Scientific and technical developments towards improving bio-oil yield and quality to date are reviewed, with an emphasis on bio-oil upgrading research. Furthermore, the article covers some major issues that associated with bio-oil from biomass, which includes bio-oil basics (e.g., characteristics, chemistry), application, environmental and economic assessment. It also points out barriers to achieving improvements in the future.

Bio-oil production and upgrading research: A review

http://biodiesel.persiangig.com/Cultivation/(3)Microalgae%20biofuels-%20A%20critical%20review%20of%20issues,%20problems%20and%20the%20way%20forward%20Review%20Article.pdf

Microalgae biofuels: A critical review of issues, problems and the way forward

An overview of the organic and inorganic phase composition of biomass

Hydrothermal processing of microalgae using alkali and organic acids

Two major considerations of the emerging algae biofuel industry are the energy intensive dewatering of the algae slurry and nutrient management. The proposed closed loop process which involves nutrient recycling of the aqueous phase from the hydrothermal liquefaction of microalgae offers a solution to both aspects. Hydrothermal liquefaction has been shown to be a low energy process for bio-crude production from microalgae. For the purpose of this research, microalgae strains of Chlorella vulgaris , Scenedesmus dimorphus and the cyanobacteria Spirulina platensis and Chlorogloeopsis fritschii were processed in batch reactors at 300 °C and 350 °C. Following liquefaction the product phases were separated and the water phase recovered. The bio-crude yields ranged from 27 to 47 wt.%. The bio-crudes were of low O and N content and high heating value making them suitable for further processing. The water phase was analysed for all major nutrients, TOC and TN to determine the suitability of the recycled aqueous phase for algae cultivation. Growth trials were performed for each algae strain in a standard growth medium and compared to the growth rates in a series of dilutions of the recycled process water phase. Growth was determined by cell count and chlorophyll a absorbance. Growth occurred in heavy dilutions where the amount of growth inhibitors was not too high. The results show that the closed loop system using the recovered aqueous phase offers a promising route for sustainable oil production and nutrient management for microalgae.

Amanda Lea-Langton

Papers

Hydrothermal processing of microalgae using alkali and organic acids

Nutrient recycling of aqueous phase for microalgae cultivation from the hydrothermal liquefaction process

Catalytic hydrothermal gasification of algae for hydrogen production: composition of reaction products and potential for nutrient recycling.

The impact of fuel properties on the emissions from the combustion of biomass and other solid fuels in a fixed bed domestic stove

Filtration of microplastic spheres by biochar: Removal efficiency and immobilisation mechanisms