Investigation of the light dynamics and their impact on algal growth rate in a hydraulically integrated serial turbidostat algal reactor (HISTAR)

There is a need for greater understanding of the light dynamics in photoautotrophic microalgal reactors as commercialization efforts move for-ward. This paper presents results of experiments performed to determine (1) surface irradiance (I-os(PAR)) as a function of lamp elevation; (2) depth (z) and biomass (X) dependent scalar irradiance (I-z(PAR)) and attenuation k(0)(PAR); (3) average scalar irradiance (I-a(PAR)) in the reactor as a function of biomass; and (4) specific growth rate as a function of I-a(PAR) and impacted by photoinhibition for the hydraulically integrated serial turbidostat algal reactor (HISTAR) illuminated by metal halide lamps. Selenastrum capricornutum was used as the test organism. Lamp elevation studies resulted in a light energy dissipation coefficient (ka) of 7.46 mu mol s(-1) m(-2) cm(-1). Light attenuation studies yielded a linear partition of the attenuation coefficient between the water and biomass; k(0)(PAR) = 1.97 + 0.0575X and an exponential relationship between I,(PAR) and X; I-a456 277 e(-0.0118X). Finally, net the specific growth rate was found to follow Steele's model for determination, resulting in a mu(max) = 1.73 d(-1) and I-opt(PAR) = 391 mu mol s(-1) m(-2). (c) 2005 Elsevier B.V. All rights reserved.