Microalgae and cyanobacteria have been evaluated for biological CO2 capture from flue gases for over 40 years; however, commercial open ponds and photobioreactors suffer many drawbacks including a slow rate of CO2 capture and high water usage. We evaluate an intensified 3D cell immobilisation approach with a small water demand, by coating latex binders onto defined surface area (947 m2 m-3) and void space (81.78 ± 4.41 %) loofah sponge scaffolds, forming porous 3D biocomposites with three microalgae species; freshwater Chlorella vulgaris, marine Dunaliella salina and Nannochloropsis oculata, and two strains of freshwater Synechococcus elongatus cyanobacteria. Binder toxicity and adhesion screening protocols were established ahead of eight weeks semi-batch and six weeks continuous CO2 fixation trials. Acrylic and polyurethane binders were effective for microalgae, and bio-based (Replebin®) binders were suited for cyanobacteria. The highest average net CO2 fixation rates from each species were 0.17 ± 0.01, 0.25 ± 0.01, 0.12 ± 0.01, 0.68 ± 0.18 and 0.93 ± 0.30 g CO2 g-1biomass d-1 for C. vulgaris, D. salina, N. oculata, S. elongatus PCC 7942 and S. elongatus CCAP 1479/1A respectively. This equates to predicted CO2 capture from scaled systems of up to 340.11 ± 110 tCO2 t-1biomass yr-1. Analysis of the kinetics of CO2 absorbtion and SEM imaging suggests that the cells were embedded within a polymer film that covered the scaffold. Biocomposites continuously fed with 5% CO2 had high lipid contents approaching 70 % dry weight. This biocomposite approach shows promise to intensify biological CO2 capture and possible application in bioenergy with carbon capture and storage (BECCS). © 2020 Elsevier Ltd.