Microalgae cultivation using undiluted anaerobic digestate by introducing aerobic nitrification–desulfurization treatment

Sekine, Mutsumi; Yoshida, Akari; Akizuki, Shinichi; Kishi, Masatoshi; Toda, Tatsuki

doi:10.2166/wst.2020.153

Cited by 18 publications

(7 citation statements)

References 37 publications

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“…The specific growth rate was calculated using Equation (2). μ = ln(x2/x1)/(t2 − t1), where μ is specific growth rate (d −1 ) and x1 and x2 are the OD750 at time t1 and t2, respectively, according to [ 41 ].…”

Section: Methodsmentioning

confidence: 99%

Optimal Nitrate Supplementation in Phaeodactylum tricornutum Culture Medium Increases Biomass and Fucoxanthin Production

Afonso

Bragança

Rebelo

et al. 2022

Foods

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Phaeodactylum tricornutum is a model diatom with numerous potential applications in the industry, including the production of high-value carotenoid pigments such as fucoxanthin. This compound is a potent antioxidant currently extracted mainly from brown macroalgae. Fucoxanthin exhibits several biological properties with well-known beneficial effects in the treatment and prevention of lifestyle-related diseases. P. tricornutum offers a valuable alternative to macroalgae for fucoxanthin production as it has a specific productivity that is 10-fold higher as compared with macroalgae. However, production processes still need to be optimised to become a cost-effective alternative. In this work, we investigated the optimal supplementation of nitrate in a cultivation medium that is currently used for P. tricornutum and how this nitrate concentration affects cell growth and fucoxanthin production. It has previously been shown that the addition of sodium nitrate increases productivity, but optimal conditions were not accurately determined. In this report, we observed that the continuous increase in nitrate concentration did not lead to an increase in biomass and fucoxanthin content, but there was rather a window of optimal values of nitrate that led to maximum growth and pigment production. These results are discussed considering both the scale up for industrial production and the profitability of the process, as well as the implications in the cell’s metabolism and effects in fucoxanthin production.

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Section: Methodsmentioning

confidence: 99%

Optimal Nitrate Supplementation in Phaeodactylum tricornutum Culture Medium Increases Biomass and Fucoxanthin Production

Afonso

Bragança

Rebelo

et al. 2022

Foods

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“…30 mg L -1 NH 4 + (Belkin and Boussiba, 1991;Dai et al, 2008). Sometimes, strong dilution (Park and Craggs, 2011;Xia and Murphy, 2016) or nitrification (Sekine et al, 2020;Casagli et al, 2021;Das et al, 2022;Liu et al, 2022) of ammonium-rich wastewaters are crucial prior to feed photosynthetic microorganisms. Nevertheless, here, we quantified a putative deficiency in ready-to-use nitrogen sources, such as NO 3 − and NH 4 + .…”

Section: Discussionmentioning

confidence: 99%

Coupling dairy wastewaters for nutritional balancing and water recycling: sustainable heterologous 2-phenylethanol production by engineered cyanobacteria

Usai,

Cordara,

Mazzocchi

et al. 2024

Front. Bioeng. Biotechnol.

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Microalgae biotechnology is hampered by the high production costs and the massive usage of water during large-volume cultivations. These drawbacks can be softened by the production of high-value compounds and by adopting metabolic engineering strategies to improve their performances and productivity. Today, the most sustainable approach is the exploitation of industrial wastewaters for microalgae cultivation, which couples valuable biomass production with water resource recovery. Among the food processing sectors, the dairy industry generates the largest volume of wastewaters through the manufacturing process. These effluents are typically rich in dissolved organic matter and nutrients, which make it a challenging and expensive waste stream for companies to manage. Nevertheless, these rich wastewaters represent an appealing resource for microalgal biotechnology. In this study, we propose a sustainable approach for high-value compound production from dairy wastewaters through cyanobacteria. This strategy is based on a metabolically engineered strain of the model cyanobacterium Synechococcus elongatus PCC 7942 (already published elsewhere) for 2-phenylethanol (2-PE). 2-PE is a high-value aromatic compound that is widely employed as a fragrance in the food and cosmetics industry thanks to its pleasant floral scent. First, we qualitatively assessed the impact of four dairy effluents on cyanobacterial growth to identify the most promising substrates. Both tank-washing water and the liquid effluent of exhausted sludge resulted as suitable nutrient sources. Thus, we created an ideal buffer system by combining the two wastewaters while simultaneously providing balanced nutrition and completely avoiding the need for fresh water. The combination of 75% liquid effluent of exhausted sludge and 25% tank-washing water with a fine-tuning ammonium supplementation yielded 180 mg L−1 of 2-PE and a biomass concentration of 0.6 gDW L-1 within 10 days. The mixture of 90% exhausted sludge and 10% washing water produced the highest yield of 2-PE (205 mg L−1) and biomass accumulation (0.7 gDW L−1), although in 16 days. Through these treatments, the phosphates were completely consumed, and nitrogen was removed in a range of 74%–77%. Overall, our approach significantly valorized water recycling and the exploitation of valuable wastewaters to circularly produce marketable compounds via microalgae biotechnology, laying a promising groundwork for subsequent implementation and scale-up.

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“…An alternative solution in this case is to dilute the culture medium, which directly reduces the sulfur concentration in the technological system. However, it is a method that extends the time needed for sulfur exhaustion and creation of anaerobic conditions [37]. Therefore, the membrane method was deployed in the presented research to separate the microalgal biomass from the culture medium.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Autotrophic Cultivation of Platymonas subcordiformis in Waters from the Natural Aquatic Reservoir on Hydrogen Yield

et al. 2022

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Biological processes run by microalgae are prospective but still little known methods of hydrogen production. A prerequisite for their increased advancement is the development of economically viable and efficient technologies. The study presented in this manuscript focused on determining the efficiency of biohydrogen production by P. subcordiformis using a culture medium prepared based on natural waters. The rate of P. subcordiformis biomass growth reached 317.6 ± 42.3 mgODM/dm3·d and ensured a biomass concentration of 3493 ± 465 mgODM/dm3. The percentage concentration of hydrogen in the biogas reached 63.2 ± 1.4%, and its production rate ranged from 0.53 ± 0.05 cm3/h to 0.70 ± 0.01 cm3/h.

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Microalgae cultivation using undiluted anaerobic digestate by introducing aerobic nitrification–desulfurization treatment

Cited by 18 publications

References 37 publications

Optimal Nitrate Supplementation in Phaeodactylum tricornutum Culture Medium Increases Biomass and Fucoxanthin Production

Optimal Nitrate Supplementation in Phaeodactylum tricornutum Culture Medium Increases Biomass and Fucoxanthin Production

Coupling dairy wastewaters for nutritional balancing and water recycling: sustainable heterologous 2-phenylethanol production by engineered cyanobacteria

The Effect of Autotrophic Cultivation of Platymonas subcordiformis in Waters from the Natural Aquatic Reservoir on Hydrogen Yield

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