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This study evaluated the role of C/N/P in the increase in the synthesis of carbohydrates, proteins, and lipids in two high-mountain strains of algae (Chlorella sp. UFPS019 and Desmodesmus sp. UFPS021). Three carbon sources (sodium acetate, sodium carbonate, and sodium bicarbonate), and the sources of nitrogen (NaNO3) and phosphate (KH2PO4 and K2HPO4) were analyzed using a surface response (3 factors, 2 levels). In Chlorella sp. UFPS019, the optimal conditions to enhance the synthesis of carbohydrates were high sodium carbonate content (3.53 g/L), high KH2PO4 and K2HPO4 content (0.06 and 0.14 g/L, respectively), and medium-high NaNO3 (0.1875 g/L). In the case of lipids, a high concentration of sodium acetate (1.19 g/L) coupled with high KH2PO4 and K2HPO4 content (0.056 and 0.131 g/L, respectively) and a low concentration of NaNO3 (0.075 g/L) drastically induced the synthesis of lipids. In the case of Desmodesmus sp. UFPS021, the protein content was increased using high sodium acetate (2 g/L), high KH2PO4 and K2HPO4 content (0.056 and 0.131 g/L, respectively), and high NaNO3 concentration (0.25 g/L). These results demonstrate that the correct adjustment of the C/N/P ratio can enhance the capacity of high-mountain strains of algae to produce high concentrations of carbohydrates, proteins, and lipids.

This paper explores the ability of Chlorella sp. and Scenedesmus sp. to convert landfill leachates into usable metabolites. Different concentrations (0.5, 1, 5, and 10% v/v) of leachate coupled with an inorganic carbon source (Na2CO3, and NaHCO3) were tested to improve biomass production, metabolites synthesis, and removal of NO3 and PO4. The result shows that both strains can effectively grow in media with up to 5% (v/v) leachate, while significantly reducing the concentrations of NO3, and PO4 (80 and 50%, respectively). The addition of NaHCO3 as a carbon source improved the final concentration of biomass, lipids, carbohydrates, and the removal of NO3 and PO4 in both strains.

The African palm is the main source of vegetable oil worldwide, representing about 29.60% of the total oil and fat production around the world. The rapid expansion of this sector has faced several concerns related to environmental and social aspects that have driven the search for sustainable alternatives. In this work, the inherent safety analysis and sustainability evaluation for the crude palm oil production process was performed using the inherent safety index (ISI) method and the sustainable weighted return on investment metric (SWROIM), respectively. The process was designed for a processing capacity of 30 t/h of palm bunches and under North-Colombian conditions. Three technical indicators were considered to evaluate the process sustainability including exergy efficiency, potential environmental impacts output (PEI output), and the total inherent safety index (ITI). The economic factor is directly considered since the SWROIM is an extension of the conventional return on investment (ROI). The resulting ITI at 11 indicated an inherently safe process, and the highest risk was observed for the process equipment safety subindex. The SWROIM reached a higher value (53%) compared to the conventional ROI (49.39%), which suggests positive impacts on sustainability. The novelty of this work lies in detecting the inherent risks and providing a decision making criteria for this project through a complete evaluation that relates economic, energy, environmental, and safety criteria.

Recently, microalgal biomass has attached much attention due to the wide diversity of compounds synthesized from different metabolic pathways. This work attempts to study metabolites recovery from Nannochloropsis sp. biomass concentrated by centrifugation and flocculation. Carbohydrates were obtained using acid and alkaline hydrolysis required for cell disruption. Protein extraction was performed after alkaline pretreatment and lipids were recovery by acid hydrolysis- Soxhlet and alkaline hydrolysis- Soxhlet extraction routes. It was found that carbohydrates were recovered by acid hydrolysis in 41 % and 35.39 % for centrifuged and flocculated biomass, respectively, values higher than thus reported using alkaline hydrolysis. For protein extraction, centrifuged biomass exhibited higher recovery yield (55.48%) than flocculated biomass (38.40%). The lipid extraction route that achieved highest yield (43.45%) was acid hydrolysis with HCl followed by Soxhlet extraction with hexane. In addition, statistical analysis by T test suggested that flocculants affect negatively biomass culture, hence, efficiency of metabolites extraction.

The increasing global demand for energy that has existed during many decades has affected the environment due to the greenhouse gas emissions, which are the result of the inadequate use of fossil fuels. This situation has contributed to the development of researchers regarding the microalgae production to capture the CO2 present in the atmosphere. Therefore, this paper presents the influence of the design variables (width and depth) of a flat-plate photobioreactor on the biomass productivity of Chlorella vulgaris UTEX 1803 and the evaporated volume for a period of 74 days, under the environmental conditions of Bucaramanga, Colombia. In addition, the effect of evaporated volume and temperature on biomass productivity was analyzed. It was verified that the average temperature of 29.72 °C is not an influential variable on biomass productivity. According to the results, the design of a photobioreactor with width dimensions greater than 15 cm and depth 3 cm is required to obtain a productivity of 0.35 g/L d.

Biological treatment is the most common process used to treat organics-containing wastewaters from industrial, domestic and agricultural activities. This work aims to remove organic pollutants using pilot-scale biological treatment system based on activated sludge. In addition, physical, chemical and microbiological characteristics of San Pablo Farm wastewaters were determined through analyses such as COD, DO, VSS, TSS and BOD and kinetic parameters were calculated by monod model. It was observed a significant decrease of this contaminant load in wastewater, achieving removal yields of 98% of BOD, 93% of COD and 99% of total coliforms. Kinetic coefficients obtained at pilot-scale registered similar values to those described by other researches and reveal a good performance of activated sludge in wastewater treatment.

Microalgae have received increasing attentions as an alternative treatment approach to remediate wastewater for both nutrient removal and biomass production. Wastewater from aquaculture industry contains high levels of nitrogen and phosphorus, which affect plant growth. Conventional methods for treating aquaculture wastewater generally are inefficient and unprofitable. In this work, microalgae Chlorella vulgaris growth was studied in aquaculture effluent medium in order to reduce its contents of NO3 and PO4. Furthermore, the effect of NaHCO3 and Na2CO3 concentrations and addition time on biomass productivity was evaluate to determine the most suitable conditions for biomass growth. It was found that highest biomass content (0.3 g/L) was achieved at 3.4 g/L of sodium bicarbonate concentration and 19 h of addition time.

Increasing energy needs have led to soaring fossil fuel consumption, which has caused several environmental problems. These environmental aspects along with the energy demand have motivated the search for new energy systems. In this context, biofuels such as biodiesel have been developing into a substitute for conventional fuels. Microalgae are considered a promising option for biodiesel production due to their high lipid content. Therefore, it is important to analyze the technical aspects of the biodiesel production system. In this work, the inherent safety analysis of three emerging topologies for biodiesel production from microalgae was performed using the inherent safety index (ISI) methodology. Selected topologies include biodiesel production via lipid extraction and transesterification, in-situ transesterification, and hydrothermal liquefaction (HTL). The results revealed that the processes are inherently unsafe achieving total inherent safety index scores of 30, 29, and 36. The main risks in the cases were associated with the chemical safety index. Operating conditions represented no risk for topologies 1 and 2, while for topology 3 pressure and temperature were identified as critical variables. In general, topology 2 showed better performance from a safety perspective.

Nowadays, Chlorella vulgaris has emerged as an attractive source of metabolites such as lipids, proteins and carbohydrates, which are widely applied to obtain high value products. This work is focused on evaluating the effect of flocculation on metabolites recovery from Chlorella vulgaris microalgae biomass. Carbohydrates were extracted through acid and alkaline hydrolysis in order to identify the efficiency of these treatments for cell wall disruption. Protein quantification was carried out under alkaline conditions and lipids were recovered by solvent extraction with hexane. It was found that carbohydrate recovery was higher using centrifuged biomass (40.55%) than flocculated biomass (24.31%) by acid treatment, while alkaline treatment exhibited yield of 20.37% and 13.19%, respectively. In addition, efficiency of 53.75% and 32.27% in protein recovery was obtained from both centrifuged and flocculated biomass. The highest lipid extraction yield (54.2%) was achieved using acid hydrolysis and hexane solvent route when centrifuged biomass was used as metabolite source. These results suggested that flocculation affect significantly the efficiency of metabolites extraction.

Microalgae have emerged as environment friendly alternative source of valuable products for energy, pharmaceutical and cosmetic industries. These microorganisms have been also studied in wastewater treatments due to its ability to remove CO2, nitrogen, phosphorus, and toxic metals. In this work, cultivation of microalgae Chlorella vulgaris was carried out in aquaculture wastewater in order to reduce its contents of NO3 and PO4. In addition, different concentration of inorganic carbon sources (NaHCO3 and Na2CO3) and addition times were considered for determining suitable conditions in microalgae culture to produce proteins. It was found that highest protein content (45 % w/w) was achieved at 3.4 g/L of NaHCO3 and 19 h of addition time.

Haematococcus pluvialis has attracted much global attention due to its ability to produce huge amounts of astaxanthin, a carotenoid pigment widely applied in pharmaceutical, cosmetic and food industries. In this work, production of astaxanthin from Haematococcus pluvialis was performed under three different salt concentrations (0, 0.45 and 0.9% v/v) and wavelengths (blue, white and red) in order to evaluate the effects of salinity and light wavelengths on microalgae growth. A multifactorial 32 experimental design was used and its results were studied by Manova analyzer with 95% of reliability. According to the results, the highest amount of astaxanthin (9.72 μg/mL) was obtained at 0.45 %v/v of salt concentration and blue wavelength.

Currently, microalgae have emerged as promising source of high-value products due to its biomass productivity, high photosynthetic efficiency and non-competitive environment for growth. In this work, biomass production from Haematococcus pluvialis was studied at three salt concentrations (0, 0.45 and 0.9% v/v) and blue, white and red wavelengths in order to evaluate the effects of these factors on microalgae growth. A 32 experimental design was performed and its results were analyzed by Manova test with 95% of reliability. The results obtained suggest that the best combination for biomass production consists of red wavelength and salt concentration of 0% v/v with a maximum productivity of 8172.2 mg/mL.

Microalgae has recently been highlighted as source of valuable products including biofuel. The production process of biofuels from microalgae involves mass cultivation, harvesting, deep dewatering, lipid extraction and biofuel conversion. In this work, lipids from microalgae Navicula sp. were obtained using multifunctional process that consists of acid hydrolysis or cellular disruption, oil extraction and in situ transesterification. The effect of alcohol added to produce ethyl and methyl esters on lipid extraction efficiency was evaluated using methanol and ethanol in order to determine the most suitable route for obtaining the high values of lipids and total reducing sugar. The highest lipid extraction efficiency and total reducing sugar (7.72 % and 2.63 mg/ml, respectively) was obtained for methanol. The low lipid extraction efficiency of multifuctional process is due to transesterification of lipids that gradually released into the system. The formation of alkyl esters was confirmed by FTIR with an increase in carbonyl peak as the reaction progressed, thus muntifuctional process reduce cost of alkyl esters production by eliminating the step of lipid extraction by solvent.