Energy efficient harvesting of Arthrospira sp using ceramic membranes: analyzing the effect of membrane pore size and incorporation of flocculant as fouling control strategy

BACKGROUND: Biomass harvesting is an important issue in commercialization of algal biofuel production. In the present study focus has been given to develop a robust ultrafiltration membrane on low cost ceramic substrate for efficient harvesting of Arthrospira sp. The effect of membrane pore size and flocculant addition as fouling reduction strategy was investigated. The study represents a comparative analysis in terms of flux, fouling, volume reduction factor (VRF) and energy consumption of different processes, viz. microfiltration (MF), ultrafiltration (UF), guar gum induced bioflocculation followed by MF and bioflocculation followed by UF, respectively. RESULTS: The MF process showed higher volume reduction factor (11.11) and concentration factor (12.5) with stabilized flux of 230 Lm(-2) h(-1) under optimized conditions. In terms of fouling, the UFmembraneswere less prone to fouling, with a flux recovery of about 93% during long-term operation. Incorporation of bioflocculant caused significant reduction in fouling of both the MF and UF membrane. Energy uptake in the MF process was lower (0.908 kWh m(-3)) than that of the UF process (2.625 kWh m(-3)). Among the various processes permeate from the UF showed the highest CO2 dissolution capacity (657 +/- 7mg L-1), hence could be reused for algal cultivation with negligible reduction in growth. CONCLUSION: The present study reveals that clay-alumina based ceramic MF and UF membrane can be effectively used in harvesting of algal biomass with suitable fouling control strategy based on the algal species and required biomass concentration. The processes developed exhibited less energy consumption compared with other existing processes. (C) 2017 Society of Chemical Industry.