ARTICLE INFO

ABSTRACT

Received date: 25/01/2016

Accepted date: 08/07/2016

The light intensity decreases logarithmically in the solution according to Lambert- Beer’s law that is given by equation P₂ = P₁ exp(-b(Z₂-Z₁)). Absorption coefficient is expressed as (b) = (ln (P₁)-ln (P₂))/(Z₂-Z₁), where P₁ and P₂ are photosynthetic photon flux densities (PPFDs) at depth Z₁ and Z₂, respectively, in the culture solution. The light absorption coefficients of culture solutions with different digestate concentrations and different microalgal densities were determined by spectrophotometer in the wavelength range of photosynthetic active radiation (400-700 nm). A linear regression was obtained between the absorption coefficient (cm^-1) and digestate concentration (%) expressed as b_digestate = 0.0546 × "digestate concentration" + 0.005. A linear regression was also obtained between the absorption coefficient and the microalgal density (cells ml^-1) expressed as b_microalgae = 0.0655 × "microalgal density" + 0.0402. In simulation experiment conducted with microalgal density of 30×10⁵ cells ml^-1, more than 10% of light was transmitted at the depths shallower than 15 mm, using 20% diluted digestate.

KEYWORDS

Digestate, light intensity, microalgae, Euglena gracilis, wavelength

Cited as: Khanh, N., and Yasuaki, M., 2016. Microalgal culture with digestate from methane fermentation - light environment in the culture solution with different digestate concentrations and microalgal cell densities. Can Tho University Journal of Science. Special issue: Renewable Energy: 57-63.