RESUMEN

The microalgae Chlorella sorokiniana was used for the treatment of winery wastewater (WWW). Batch experiments were initially conducted to investigate how biomass acclimatization in different media, dilution of wastewater, and addition of ammonium nitrogen (NH4-N) affect the growth of microalgae and the removal of major pollutants. Afterwards, two sequencing batch reactor (SBR) systems were tested applying different configurations and hydraulic retention times. The biomass collected at the end of the experiments was characterized for proteins, lipids, carbohydrates, amino acid profile, and the existence of lutein, ß-carotene, chlorophyll a, and tocopherols. Batch experiments showed that Chlorella sorokiniana acclimatization to urban wastewater enhanced the removal of NH4-N and total phosphorus (TP). The operation of a two-stage SBR system achieved COD and NH4-N removal equal to 85 ± 9% and 91 ± 20%, respectively, while the use of a single-stage system feeding with anaerobically pretreated WWW resulted to COD and NH4-N removal of 78 ± 9% and 95 ± 9%, respectively. Analyses of biomass showed higher protein content (up to 58.8%) in batch experiments with NH4-N addition as well as in SBR experiments. The cultivation of microalgae under SBR conditions enhanced the production of pigments and tocopherols. The maximum concentrations of 1075 mg kg-1, 45.5 mg kg-1, and 131.2 mg kg-1 were achieved for lutein, ß-carotene, and tocopherols, respectively, in the one-stage system. Our findings suggested that Chlorella sorokiniana cultivation in WWW not only removed nutrients from WWW but also could potentially serve for the production of value-added ingredients used in food industry, cosmetics, and animal feedstock.

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RESUMEN

Enzymatic treatment of microalgal biomass is a promising approach for extraction of microalgal lipid, but high cost of commercially sourcing enzyme is a major drawback in industrial implementation. Present study involves extraction of eicosapentaenoic acid-rich oil from Nannochloropsis sp. biomass using low cost cellulolytic enzymes produced from Trichoderma reesei in a solid-state fermentation bioreactor. Maximum total fatty acid recovery of 369.4 ± 4.6 mg/g dry weight (total fatty acid yield of 77%) was achieved in 12 h from the enzymatically treated microalgal cells, of which the eicosapentaenoic acid content was 11%. Sugar release of 1.70 ± 0.05 g/L was obtained post enzymatic treatment at 50 °C. The enzyme was reused thrice for cell wall disruption without compromising on total fatty acid yield. Additionally, high protein content of 47% in the defatted biomass could be explored as a potential aquafeed, thus enhancing the overall economics and sustainability of the process.

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RESUMEN

Improving the efficiency of using energy and decreasing impacts on the environment will be an inevitable choice for future development. Based on this direction, three kinds of medium (modified anaerobic digestion wastewater, anaerobic digestion wastewater and a standard growth medium BG11) were used to culture microalgae towards achieving high-quality biodiesel products. The results showed that microalgae culturing with anaerobic digestate wastewater could increase lipid content (21.8%); however, the modified anaerobic digestion wastewater can boost the microalgal biomass production to 0.78 ± 0.01 g/L when compared with (0.35-0.54 g/L) the other two groups. Besides the first step lipid extraction, the elemental composition, thermogravimetric and pyrolysis products of the defatted microalgal residues were also analysed to delve into the utilisation potential of microalgae biomass. Defatted microalgae from modified wastewater by pyrolysis at 650 °C resulted in an increase in the total content of valuable products (39.47%) with no significant difference in the content of toxic compounds compared to other groups. Moreover, the results of the life cycle assessment showed that the environmental impact (388.9 mPET2000) was lower than that of raw wastewater (418.1 mPET2000) and standard medium (497.3 mPET2000)-cultivated groups. Consequently, the method of culturing microalgae in modified wastewater and pyrolyzing algal residues has a potential to increase renewable energy production and reduce environmental impact.