Enhanced biomass production and harvesting efficiency of Chlamydomonas reinhardtii under high-ammonium conditions by powdered oyster shell

• Published in: Bioresource technology 2024-07, Vol.403, p.130904-130904, Article 130904
• Main Authors: Sui, Jikang, Cui, Yuxuan, Zhang, Jinku, Li, Shiyang, Zhao, Yue, Bai, Mingkai, Feng, Guangxin, Wu, Haohao
• Format: Article
• Language: English
• Subjects: acidification; ammonium; Bio-flocculant; biomass production; bioreactors; calcium; carbon; Chlamydomonas reinhardtii; dissolved inorganic carbon; flocculation; Liming agent; Medium acidification; microalgae; nitrogen; oyster shells; Size-dependently; Supplement carbon source; unsaturated fatty acids
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2024.130904

[Display omitted] •Biomass production enhancement in C. reinhardtii in high-NH4+ medium was achieved.•The process was mediated with C. reinhardti and powdered oyster shell.•Powdered oyster shell as liming agent to alleviate medium acidification.•Inorganic carbon source supplyment by powdered oyster shell for algae growth.•Efficient harvesting of microalgae in high-NH4+ medium with powdered oyster shell. Chlamydomonas reinhardtii prefers ammonium (NH4+) as a nitrogen source, but its late-stage growth under high-NH4+ concentrations (0.5 ∼ 1 g/L) is retarded due to medium acidification. In this study, oyster shell powders were shown to increase the tolerance of C. reinhardtii to NH4+ supplementation at 0.7 g/L in TAP medium in 1-L bubble-column bioreactors, resulting in a 22.9 % increase in biomass production, 62.1 % rise in unsaturated fatty acid accumulation, and 19.2 % improvement in harvesting efficiency. Powdered oyster shell mitigated medium acidification (pH 7.2–7.8) and provided dissolved inorganic carbon up to 8.02 × 103 μmol/L, facilitating a 76.3 % NH4+ consumption, release of up to 189 mg/L of Ca2+, a 42.1 % reduction in ζ-potential and 27.7 % increase in flocculation activity of microalgae cells. This study highlights a promising approach to utilize powdered oyster shell as a liming agent, supplement carbon source, and bio-flocculant for enhancing biomass production and microalgae harvesting in NH4+-rich environments.