Bioethanol Production from UK Seaweeds: Investigating Variable Pre-treatment and Enzyme Hydrolysis Parameters

Abstract

This study describes the method development for bioethanol production from three species of seaweed. Laminaria digitata, Ulva lactuca and for the first time Dilsea carnosa were used as representatives of brown, green and red species of seaweed, respectively. Acid thermo-chemical and entirely aqueous (water) based pre-treatments were evaluated, using a range of sulphuric acid concentrations (0.125-2.5 M) and solids loading contents (5-25 % [w/v]; biomass: reactant) and different reaction times (5-30 min), with the aim of maximising the release of glucose following enzyme hydrolysis. A pre-treatment step for each of the three seaweeds was required and pre-treatment conditions were found to be specific to each seaweed species. Dilsea carnosa and U. lactuca were more suited with an aqueous (water-based) pre-treatment (yielding 125.0 and 360.0 mg of glucose/g of pretreated seaweed, respectively), yet interestingly non pre-treated D. carnosa yielded 106.4 g g −1 glucose. Laminaria digitata required a dilute acid thermo-chemical pre-treatment in order to liberate maximal glucose yields (218.9 mg glucose/g pre-treated seaweed). Fermentations with S. cerevisiae NCYC2592 of the generated hydrolysates gave ethanol yields of 5.4 g L −1 , 7.8 g L −1 and 3.2 g L −1 from D. carnosa, U. lactuca and L. digitata, respectively. This study highlighted that entirely aqueous based pretreatments are effective for seaweed biomass, yet bioethanol production alone may not make such bio-processes economically viable at large scale.

Evaluation of seasonal variation and the optimization of reducing sugar extraction from Ulva prolifera biomass using thermochemical method

“…These methods are applied for examining the relationship between the measured responses and the number of independent variables with the purpose of optimizing a method or process. In this milieu, in accordance with the earlier investigated optimization approaches (Kostas et al 2016 ; Alfonsín et al 2019 ; Kostas et al 2020 ), the TAH parameters, such as biomass dosage, acid concentration, temperature, and hydrolysis time, showed a great impact on the reducing sugar extraction from the macroalgal biomass. Therefore, in our study, an attempt was made to enhance the RSY by optimizing the TAH process parameters (dosage, acid concentration, and hydrolysis time) under the controlled temperature (121°C) for cellulolysis as shown in Table 2 .…”

Introducing a Marine Biorefinery System for the Integrated Production of Biofuels, High-Value-Chemicals and Co-products: A Path Forward to a Sustainable Future

“…The lipid content in seaweed is generally low -0.1-4.5 % of dry weight [19] but even so, seaweed is still a very attractive substrate for bioenergy production due to its high carbohydrate content. For this reason, several researchers have investigated the potential of seaweed for biofuel production [20][21][22][23].…”

Aquaculture Production of the Brown Seaweeds Laminaria digitata and Macrocystis pyrifera: Applications in Food and Pharmaceuticals

“…In 2009, alginate production was moved from Scotland to Norway by Pronova, a Norwegian alginate producer, but L. hyperborea is still sourced in Scotland and Ireland and Ascophyllum nodosum is also sourced in Scotland, Ireland, Iceland, and Norway for Pronova [ 26 ]. Recently, the UK’s interest in alternatives to fossil fuels saw the inclusion of L. digitata in method development for bioethanol production [ 27 ].…”