Stable wastewater treatment with Neochloris oleoabundans in a tubular photobioreactor

Abstract

The potential of a wastewater treatment and biomass production process with the green microalgae Neochloris oleoabundans in a 45-L tubular photobioreactor was tested. In a stable and reliable alga-based process, wastewaters should undergo pre-treatment to remove colored substances. Our data show that further optimization steps may be required, such as adjustment of the N:P ratio and addition of essential metals. As a final result, parameters were established for a continuous-mode photobioreactor run with optimized wastewater for five times the hydraulic retention time (157 h) at the dry biomass concentration of 0.47 ± 0.03 g L −1 . During that period, 75% and 99.6% removal efficiencies for NH 4 + and PO 4 3− , respectively, were achieved.

Differences in susceptibility to photoinhibition do not determinegrowth rate under moderate light in batch or turbidostat - a studywith five green algae

“…Besides the difference in the attenuation of light, the growth medium develops differently during a batch than during a continuous growth experiment and many of these differences are likely to be strongly dependent on the experimental conditions and species studied. In the batch mode, main nutrients are usually consumed in a few days (e.g., Valev et al 2020), whereas in the turbidostat mode, the growth medium is continuously replenished. Depletion of nutrients may partially explain why the batch growth rates during the time the algae had reached the concentration that was later used for the turbidostat mode were slower than the growth rates during the turbidostat cultivation phase (Fig.…”

“…The light attenuation is assumed to be at a minimum during an apparently exponential growth phase, but there is no factual proof for this assumption. In industrial systems, on the other hand, microalgal cultures are often continuously maintained at a constant cell density by frequent additions (influent) of culture medium and simultaneous removal (effluent) of the same amount of culture (see, e.g., Valev et al 2020). Cell density is commonly followed by measuring the turbidity of the culture, and therefore this cultivation system is called a turbidostat.…”

Neochloris oleoabundans from nature to industry: a comprehensive review

“…The superior efficacy of mixotrophic or even fully heterotrophic cultivation conditions (Giovanardi et al 2013;Baldisserotto et al 2016;Silva et al 2016) has triggered the application of N. oleoabundans for waste treatment and valorisation. Neochloris biomass has been successfully cultivated on chicken manure (Altunoz et al 2017), sewage sludge (Jeong et al 2017), secondary wastewater from urban plants (Aravantinou et al 2013), apple vinegar (Giovanardi et al 2013), pig manure (Olguín et al 2015a), vinasse digestate (Olguín et al 2015b), pharmaceutical effluent (Singh et al 2020), swine wastewater (Wang et al 2017), biogas slurry (Zhao et al 2015) and general municipal waste (Valev et al 2020). 6 6.…”

Testing the Potential of Regulatory Sigma Factor Mutants for Wastewater Purification or Bioreactor Run in High Light

“…Depending on the KA2 batch, it contained ammonium 5.9 to 6.9 mmol/l and phosphate 0.073 to 0.077 mmol/l. The KA2 wastewater had a biochemical oxygen demand/chemical oxygen demand ratio of 0.055 (see Valev et al [19]), which is the characteristic of "old" landfill leachate [38]. The high turbidity appearance of the KA2 wastewater indicated high total suspended solids that were removed by filtrating through a home-made granular activated carbon filter.…”

“…Phosphate metabolism is regulated by a two-component system consisting of a histidine kinase SphS and a response regulator SphR and by a negative regulator SphU [15][16][17]. To achieve fast and stable growth, aquatic phototrophs require adequate concentrations of N and P and in some cases P or N have to be adjusted for long-term cultivations in wastewaters [18,19].…”