Abstract—Microalgae are unicellular photosynthetic organisms with industrial and economic perspectives. Their cultivation has a great deal of potential for many applications. Microalgae possess high growth and nutrient uptake rates, carbon capture and biomass generation. The cultivation of microalgae needs to be improved in order to reduce the cost of the produced biomass. Anaerobic digestion is a waste-to-energy technology employing a consortium of anaerobic microorganisms and resulting in continuous production of methane-rich biogas, with intermittent release of effluent digestate rich in undigested solids, organic and inorganic compounds and metal salts. The results in this work demonstrate the possibility of improving algal biomass accumulation using different anaerobic digestates and suitable algal strains. We investigated the growth and development of seven microalgal species – green, blue-green, red and yellowgreen in the resultant digestate from methane production. The digestate was decolorized with active charcoal and used as medium in non-diluted and diluted with water (1:1) form. Most abundant growth was registered after two weeks of extensive cultivation for the green algae Scenedesmus acutus, followed by Klebsormidium flaccidum, and yellow-green Trachydiscus minutus. Further intensive cultivation of Scenedesmus acutus was performed and good growth was confirmed by estimating the average specific growth rate (μ=0.30 d-1) and pigment accumulation (total pigment content 7.45% of DW).Our results showed that the digestate, obtained straight after a biomethane generating anaerobic process, with no additional water, is a suitable cultivation medium. Compared to the control with a standard medium, it enhanced the growth of Scenedesmus acutus 6.5 times in one week. This is a good precondition for a reliable application of this digestate in practice for production of algal biomass with its metabolites, instead of being released as a waste.
 

Index Terms—microalgae, digestate, growth rate, pigments, Scenedesmus acutus

Cite: Juliana G. Ivanova, Ivanina A. Vasileva, and Lyudmila V. Kabaivanova, "Enhancement of Algal Biomass Accumulation Using Undiluted Anaerobic Digestate," International Journal of Pharma Medicine and Biological Sciences, Vol. 9, No. 3, pp. 111-116, July 2020. doi: 10.18178/ijpmbs.9.3.111-116

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