Title: Towards sustainable pigments and bio bitumen production with carbon sequestration using desert microalgae
Abstract:
Over the past decade, development of renewable non-petroleum based sustainable processes for bitumen has attracted attention. Recently, proof of concept was established to transform algae-biomass residues into a material mimicking the rheological behaviour of a bitumen through a process called hydrothermal conversion. Production of bio-bitumen from algae can be applied to different types of algae, as the process does not target one specific metabolite, but rather a general group of biomass components. The applied conditions determine the properties of the resulting material, and researchers found that it had viscoelastic properties which were very similar to that of petroleum-based bitumen. However, although bio-bitumen can be a high-volume product, it is not exhibiting a high-value outcome. Hence, to design an economically feasible production process, it is necessary, as part of the biorefinery concept, to use the microalgae biomass to first produce a high-value product prior to bio-bitumen production from the leftover biomass. This would be highly favourable, maximise the profitability and can make the production process economically more attractive. In this sense, the goal of this work is to apply the algo refinery approach to first produce the phycobiliproteins from local algae isolate Pleurocapsa sp. QUCCCM 54, followed by an HTL process to the left-over biomass and study the possibility of producing bio-bitumen. Strain was cultivated outdoor at 200L open ponds using f/2media (Guillard, 1975) with 2 different nitrogen concentrations (10X and 2X), and the impact of outdoor culture conditions and biochemical composition on the growth and HTL product was investigated.Results showed that higher initial nitrogen concentrations of the nutrient medium (10X) slightly led to an increase in biomass productivity to reach 14g/m2/day compared to 12g/ m2/day in 2X highlighting that the nitrogen concentration didn’t tremendously influence the growth. With regards to the HTL conversion, the highest hydrophobic yield was observed for QUCCCM 54-2X followed by QUCCCM 54-10X with 59% versus 54% respectively. Moreover, the rheological data plotted in the Black diagram of the strain showed a viscoelastic material behaviour comparable to that of a conventional bitumen with a continuous curve from 90 °C, where the material is liquid, to 0 °C, where the material is an elastic solid. This continuity of the curve is highlighting the thermostability of the material molecular structures. Nonetheless, even though the overall viscoelastic signature was similar to conventional bitumen, the stiffness of the HTL fractions waslower than for the conventional
Audience Take Away Notes :
- The work demonstrate the application of biorefinery concept to demonstrate the production of algal biobased bitumen and pigments of local marine isolate from desert environment which is not heavily investigated
- The data can be used as reference to compare the bio bitumen previously issued from fresh algal strains from Europe, also the obtained biocrude can be used as a promising alternative for petrocrude in the petroleum refinery
- The process helps to reduce the climatic effects of increasing atmospheric CO2 levels. It refers to capture and long-term storage of carbon dioxide (or other forms of carbon) to reduce the atmospheric CO2 concentrations and can play an important role in addressing the issue of climate change. With a product lifetime of over 20 years, the sequestrated carbon within the product is stored for a long-term. Moreover, it might be possibility of recycling the bitumen into new roads, leading to an even longer retention of the sequestered CO2
