Luis Samaniego-Moreno

Algal biorefineries constitute an emerging platform for the sustainable production of renewable bioproducts; however, their economic viability remains constrained by the high costs associated with microalgal cultivation and biomass harvesting. This study investigated an integrated strategy combining macronutrient optimization with electrocoagulation–flocculation (ECF) harvesting for Chlorella vulgaris. A Central Composite Design (CCD) was employed to optimize concentrations of NaNO₃, KH₂PO₄, and MgSO₄ with the dual objective of maximizing biomass yield and enhancing biocompound content. Subsequently, the ECF process parameters—current density, electrolysis duration, pH, and electrolyte concentration—were optimized to improve harvesting efficiency. Under the optimal macronutrient conditions (NaNO₃: 100.00 mg/L; KH₂PO₄: 222.12 mg/L; MgSO₄: 100.84 mg/L), the model predicted a maximum biomass concentration of 0.475 g/L, along with 32.79% w/w carbohydrates and 6.79 mg/L chlorophyll-a. Optimal ECF harvesting conditions (current: 0.57 A; pH: 4.00; electrolysis time: 12.70 min; electrolyte: 1.74 g/L) achieved a biomass recovery efficiency of 89.51% w/v. These results demonstrate that coupling nutrient optimization with ECF-based harvesting offers a synergistic, scalable, and cost-effective pathway to improve the sustainability of algal biorefineries.

For efficient irrigation timing in arid land agriculture, it is essential to know the daily evapotranspiration rate of each crop (ETc) established in a specific location. ETc can be obtained from the reference evapotranspiration rate (ETr) according to the procedure of the FAO-56 method and the crop coefficient development (Kc). However, the daily rates of ETr obtained with calculated values of net radiation (Rn) and soil surface heat flux (G) may differ from those obtained when Rn and G are measured in the same automated weather station. The objective of this study was to evaluate the difference between the daily rate of ETr obtained with the FAO-56 method using calculated and measured data of net radiation and soil surface heat flux in an arid land. On an arid land of northern Mexico, a Campbell-brand automated weather station (Campell Sci., Inc. Logan, Utah, USA) was located at the center of a circular area of 12 m in diameter, with a green grass of full surface coverage 12 cm height with no soil moisture deficit, to measure at a height of 2 m (1 s scan and 30 min averaged values) the air temperature and relative humidity, wind speed and direction, incident solar radiation, barometric pressure, and rainfall. Furthermore, the net radiation over the grass and the soil surface heat flux were also measured. The data generated by the automated weather station was used to calculate the daily rate of ETr (FAO-56 method) using both calculated and measured values of net radiation and soil surface heat flux. The results of this study showed that the ETr (FAO-56 method) obtained with Rn and G measured was 17.63% higher than the ETr (FAO-56 method) determined with Rn and G calculated. The Rn measured (using a net radiometer) was 14.08% larger than the Rn calculated (FAO-56 method). G measured was 36.6% smaller than G calculated as 10% of the Rn (FAO-56 method). The daily ETr rate (FAO-56 method) using Rn and G measured in the automated weather station was higher than the ETr rate (FAO-56 method) obtained with Rn and G calculated, due to a bigger value of Rn and a lower value of G measured in the automated weather station than the values of Rn and G calculated by the FAO-56 method.

In this paper, the production of biomass, pigments, lipids, and carbohydrates and the elimination of ammonium and orthophosphate by the microalgae Chlorella vulgaris, grown in synthetic wastewater (SWW), were studied under different light intensities (3000–10,000 lux), pH (7.5–9.5) and daily illumination time (8–16 h). The best conditions for the autotrophic culture of microalgae were predicted using response surface methodology (RSM). The results showed that the adaptation of the microalgae for this nutrient source was effective. The best conditions for the cultivation of Chlorella vulgaris in SWW were 8.44 pH and a light intensity of 8433 lux in the daily illumination time of 16 h. Under optimal conditions, the production of microalgal biomass, chlorophyll-a, chlorophyll-b, carotenoids, lipids and carbohydrates was 0.534 g/L, 7.46 mg/mL, 3.53 mg/mL, 2.01 mg/mL, 21.40% and 28.46%, respectively. The removal efficiencies of ammonium and orthophosphate from SWW were 97.66% and 58.78% in autotrophic cultures. This investigation introduces a new aspect by verifying the optimized cultivation conditions with real municipal wastewater, indicating that the procedure could be utilized for sustainable production of bioproducts and efficient treatment of municipal wastewater.

Arsenic contamination in water demands effective, low-cost removal methods. This study introduces nanomagnetite-coated biochar derived from pecan nutshells for efficient arsenic adsorption. Utilizing a solvothermal method, uniform magnetite crystals were grown on biochar in a controlled process at 200 °C. The resulting bioadsorbent, characterized by XRD, SEM, and FTIR, exhibited a narrow size distribution and consistently high arsenic removal rates (97.30–98.76%). Biochar with varied particle sizes, synthesized at a short reaction time (6 h), showed the highest removal efficiency of arsenic (98.76%) and adsorption capacity (7.974 mg/g). This approach offers a sustainable for arsenic remediation, and ease of magnetic separation.

The wastewaters of nejayote and food waste leachate are polluting effluents with a high load of organic matter that cause great problems when discharged to water receptors. In this work, we investigated the treatment of nejayote wastewaters and food waste leachate for the production of microalgae Scenedesmus acutus and Haematococcus pluvialis. For Scenedesmus acutus, treatment with 10% food waste leachate and 90% growth medium resulted in a concentration of 5.34 g/L in 20 days (μmax = 0.16/day). Meanwhile, 10% nejayote and 90% medium growth produced 4.45 g/L at 20 days (μmax = 0.13/d). A significant reduction of up to 82.6% ammonium, 84.1% orthophosphate, and 87.25% COD was also observed between the different treatments. For Haematococcus pluvialis, the treatment of 90% food waste leachate and 10% growth medium produced a concentration of 4.73 g/L at 6 days (μmax = 0.71/day), while the mixture of 25% najayote, 25% food waste leachate, and 50% growth medium produced a concentration of 5.5 g/L at 20 days (μmax = 0.25/dat). A reduction of up to 97.8% ammonia, 97.4% orthophosphate, and 73.19% COD was also recorded. These findings demonstrated the potential to cultivate microalgae and extract biomolecules for commercial purposes.