Fast cultivation and harvesting of oil-producing microalgae Ankistrodesmus falcatus var. acicularis fed with anaerobic digestion liquor via biogranulation in addition to nutrients removal
Journal
Science of the Total Environment
Journal Volume
741
Date Issued
2020
Author(s)
Abstract
This study examined the feasibility of cultivation and harvesting of oil-producing microalgae (i.e. Ankistrodesmus falcatus var. acicularis) via biogranulation in two identical sequencing batch reactors (SBRs) fed with synthetic anaerobic digestion liquor. Easily settled algae granules with compact structure appeared around day 90 and mature granules were obtained after 150 days' operation. The microalgae settleability was remarkably improved, signaling by the substantial decrease of sludge volume index (SVI30) from initially >3000 to 53.44 ± 3.31 mL/g, with settling velocity correspondingly increased from nearly 0 to 18.47 ± 0.23 m/h. Although the percentage of the target microalgae (Ankistrodesmus falcatus var. acicularis) decreased along with the granulation process, the biomass concentration (2–4 g/L) and biomass productivity (130–270 mg/L/d) using biogranulation were 10–20 times and 16–34 times that by the traditional suspension method. Compared to the seed microalgae cells, more extracellular polymeric substances (EPS) (162.54 ± 3.60 mg/g-mixed liquor volatile suspended solids (MLVSS)) with a higher proteins/polysaccharides ratio (7.62) were excreted from the mature algae granules. Moreover, the mature microalgae granules showed comparable nutrients removal, averagely 96% and 86% of dissolved organic carbon (DOC) and NH4+-N from the digestion liquor, respectively, reflecting its great potential for simultaneous microalgae cultivation, harvesting and wastewater treatment. © 2020 Elsevier B.V.
Subjects
Anaerobic digestion liquor; Ankistrodesmus falcatus var. acicularis; Biogranulation; Microalgae harvesting; Nutrients removal; Settleability
Other Subjects
Activated sludge process; Algae; Batch reactors; Granulation; Microorganisms; Nutrients; Organic carbon; Suspensions (fluids); Value engineering; Wastewater treatment; Biomass concentrations; Biomass productivity; Dissolved organic carbon; Extracellular polymeric substances; Microalgae cultivation; Sequencing batch reactors; Traditional suspensions; Volatile suspended solids; Anaerobic digestion; chemical compound; dissolved organic matter; extracellular polymeric substance; mixed liquor volatile suspended solid; oil; organic carbon; polysaccharide; protein; unclassified drug; anaerobic digestion; cultivation; harvesting; microalga; nutrient; settling velocity; wastewater treatment; anaerobic digestion; Ankistrodesmus; Ankistrodesmus falcatus; Article; biomass; concentration (parameter); energy consumption; feasibility study; liquid; nonhuman; nutrient; priority journal; scoring system; sludge volume index; species cultivation; suspension; time; waste water management; anaerobic growth; bioreactor; microalga; sewage; waste water; algae; Podohedriella falcata; Anaerobiosis; Biomass; Bioreactors; Microalgae; Nutrients; Sewage; Waste Water
Type
journal article