Enhancement of CO2 transfer and microalgae growth by perforated inverted arc trough internals in a flat-plate photobioreactor

Abstract

Flat-plate photobioreactor (PBR) with perforated inverted arc trough (PIAT) internals was proposed to promote CO₂ bio-fixation by microalgae. The PIAT internals can enhance CO₂ transfer from gas to culture medium by prolonging CO₂ gas-liquid contact time and generate periodic aeration in the suspension upper side the PIAT providing suspension mixing. Experimental results showed gas-liquid contact time was prolonged from 0.448 s to 256 s and the CO₂ partial pressure inside the PIAT internals was about 15.5 kPa during microalgae cultivation. Consequently, the dissolved CO₂ concentration in the microalgae suspension of the proposed PBR was increased by 26.0% compared to that in the PBR without PIAT internals when 15% CO₂ (v/v) was aerated at a rate of 15 mL min^-1. The elevated CO₂ transfer contributed to a 20.9% increment in biomass concentration (3.35 g L^-1) and a 26.2% increment in CO₂ fixation rate (36.6 mg L^-1 h^-1).

Keywords: CO(2) transfer; Carbon bio-fixation; Gas–liquid contact time; Microalgae; Perforated inverted arc trough.