Corrigendum: Microalgae-based wastewater treatment for developing economic and environmental sustainability: Current status and future prospects.

[This corrects the article DOI: 10.3389/fbioe.2022.904046.].

Microalgae-based wastewater treatment for developing economic and environmental sustainability: Current status and future prospects.

Over the last several decades, concerns about climate change and pollution due to human activity has gained widespread attention. Microalgae have been proposed as a suitable biological platform to reduce carbon dioxide, a major greenhouse gas, while also creating commercial sources of high-value compounds such as medicines, cosmetics, food, feed, and biofuel. Industrialization of microalgae culture and valorization is still limited by significant challenges in scaling up the production processes due to economic constraints and productivity capacities. Therefore, a boost in resource usage efficiency is required. This enhancement not only lowers manufacturing costs but also enhancing the long-term viability of microalgae-based products. Using wastewater as a nutrient source is a great way to reduce manufacturing costs. Furthermore, water scarcity is one of the most important global challenges. In recent decades, industrialization, globalization, and population growth have all impacted freshwater resources. Moreover, high amounts of organic and inorganic toxins in the water due to the disposal of waste into rivers can have severe impacts on human and animal health. Microalgae cultures are a sustainable solution to tertiary and quaternary treatments since they have the ability to digest complex contaminants. This review presents biorefineries based on microalgae from all angles, including the potential for environmental pollution remediation as well as applications for bioenergy and value-added biomolecule production. An overview of current information about microalgae-based technology and a discussion of the associated hazards and opportunities for the bioeconomy are highlighted.

A novel oleaginous yeast Saccharomyces cerevisiae CU-TPD4 for lipid and biodiesel production.

This study reports on the novel Saccharomyces cerevisiae CU-TPD4 that was isolated from coconut waste residues obtained from a coconut factory in Thailand. The CU-TPD4 isolate was confirmed to be a S. cerevisiae by molecular analysis and to be an oleaginous yeast with more than 20% (w/w) of the cell dry weight (CDW) present in the form of lipids. The lipid content and lipid yield of CU-TPD4 (52.96 ± 1.15% of CDW and 1.78 ± 0.06 g/L, respectively) under optimized growth conditions were much higher than those under normal growth conditions (22.65 ± 1.32% of CDW and 1.24 ± 0.12 g/L, respectively). The major fatty acids produced by CU-TPD4 were oleic (C18:1), palmitoleic (C16:1), stearic (C18:0), and palmitic (C16:0) acids. Mathematical estimation of the physical properties of the biodiesel obtained by transesterification of the extracted lipid suggested it was suitable as biodiesel with respect to the ASTM D6751 and EN 14214 international standards. Consequently, S. cerevisiae CU-TPD4 is expected to emerge as a promising alternative for biodiesel production.

Performance of an air membrane bioreactor for methanol removal under steady and transient state conditions.

The main aim of this study was to evaluate the performance of an air membrane bioreactor (aMBR) for the treatment of gas-phase methanol. A laboratory-scale hollow fiber aMBR was operated for 150 days, at inlet methanol concentrations varying between 2 and 30 g m-3 and at empty bed residence times (EBRT) of 30, 10 and 5 s. Under steady-state conditions, a maximum methanol removal efficiency (RE) of 98% was obtained at an EBRT of 30 s and a decrease in RE of methanol was observed at lower EBRTs. On increasing the inlet loading rate, some portion of gas-phase MeOH was stripped into the liquid phase due to its solubility in water. Under transient conditions, the MeOH removal efficiency dropped from an average value of 95%-90% after 5 h of 10-fold shock load and dropped from an average value of 95%-88% under 5-fold increase in shock load. During transient-state tests, the aMBR performed well under different upset loading conditions and a drop in RE of ∼ 5-10% was observed. However, the aMBR performance was restored within 1-2 days when pre-shock conditions were restored. The results from microbial structure analysis revealed a big shift of the dominant methanol degrader, from Candida boidinii strain TBRC 217 to Xanthobacter sp. and Fusicolla sp., respectively.

Draft Genome Sequence and Annotation of Paracoccus versutus MAL 1HM19, a Nitrate-Reducing, Sulfide-Oxidizing Bacterium.

Paracoccus versutus MAL 1HM19 is a mixotrophic nitrate-reducing sulfide-oxidizing bacterium which plays a crucial role in hydrogen sulfide (H2S) and nitrate (NO3 -) removal. In this study, we report the draft genome sequence of P. versutus MAL 1HM19.

Comparison of sulphide and nitrate removal from synthetic wastewater by pure and mixed cultures of nitrate-reducing, sulphide-oxidizing bacteria.

In this study, the activities of hydrogen sulphide (H2S) oxidation and nitrate (N-NO3-) reduction by three pure and mixed strains of nitrate-reducing, sulphide oxidizing bacteria (NR-SOB) were determined. Batch experiments were performed at 35 °C and pH 7.0-8.0 with initial H2S concentrations of 650-900 ppmv and N-NO3- concentrations of ∼120 mg/L. The strains MAL 1HM19, TPN 1HM1 and TPN 3HM1 were capable of removing 100% gas-phase H2S. The co-cultures showed better performance for H2S and N-NO3- removal. The mixed NR-SOB strains showed a higher H2S oxidation rate (143 ±â€¯18 ppmv/h), while the highest N-NO3- removal rate (5.5 ±â€¯0 and 5.1 ±â€¯0.6 N-NO3- mg/L·h) was obtained by a mixture of two NR-SOB strains. The 16S rDNA sequence analysis revealed that all strains belonged to the sub-class Alphaproteobacteria and are closely related to Paracoccus sp. (>99%).