A second life for mining waste as an amendment for soil remediation

CRUE-CSIC agreement; Springer Nature; Project NATURESOIL (AEI/Spain) [TED2021-130375B-I00]; University of Oviedo and Banco Santander [PAPI-21-PF-27

Pyrolysis temperature influences the capacity of biochar to immobilize copper and arsenic in mining soil remediation

Ministerio de Economía y Competitividad (MINECO, Spain) [MCI-20-PID2019-106939 GB-I00]; European Union-NextGenerationEU, Ministerio de Universidades [grant MU-21-UP2021-030 32892642

Productivity and selective accumulation of carotenoids of the novel extremophile microalga Chlamydomonas acidophila grown with different carbon sources in batch systems

Cultivation of extremophile microorganisms has attracted interest due to their ability to accumulate highvalue compounds. Chlamydomonas acidophila is an acidophile green microalga isolated by our group from Tinto River, an acidic river that flows down from the mining area in Huelva, Spain. This microalga accumulates high concentrations of lutein, a very well-known natural antioxidant. The aim of this study is to assess use of different carbon sources (CO2, glucose, glycerol, starch, urea, and glycine) for efficient growth of and carotenoid production by C. acidophila. Our results reveal that growth of the microalga on different carbon sources resulted in different algal biomass productivities, urea being as efficient as CO2 when used as sole carbon source (*20 g dry biomass m–2 day–1). Mixotrophic growth on glucose was also efficient in terms of biomass production (*14 g dry biomass m–2 day–1). In terms of carotenoid accumulation, mixotrophic growth on urea resulted in even higher productivity of carotenoids (mainly lutein, probably via a-carotene) than obtained with photoautotrophic cultures (70% versus 65% relative abundance of lutein, respectively). The accumulated lutein concentrations of C. acidophila reported in this work (about 10 g/kg dry weight, produced in batch systems) are among the highest reported for a microalga. Glycerol and glycine seem to enhance b-carotene biosynthesis, and when glycine is used as carbon source, zeaxanthin becomes the most accumulated carotenoid in the microalga. Strategies for production of lutein and zeaxanthin are suggested based on the obtained results

Combined effect of nutrient and flashing light frequency for a biochemical composition shift in Nannochloropsis gaditana grown in a quasi-isoactinic reactor

Artificial lighting may be an interesting opportunity for the cultivation of microalgae as an alternative to natural sunlight. In particular, light emitting diodes (LEDs) can be employed to tailor the lighting to the microalgal culture in a controlled mode in order to create flashing light. In order to establish the effect of the flashing frequency on growth and biochemical composition of a model microalga, a quasi-isoactinic reactor, in which the light distribution is almost homogeneous, was set up. In this work, it was employed for the cultivation of the heterokont Nannochloropsis gaditana in two growth media with limiting and nonlimiting nutrients. The combined effect of nutrient concentration and flashing frequency on the growth, lipid content, fatty acid content, and pigment content was assessed for the first time. The results indicate that both nutrient concentration and flashing frequency influence the above-mentioned parameters. In particular, under flashing light conditions, an increase of lipid content and a decrease of polyunsaturated fatty acids (PUFAs) and chlorophyll are observed when nutrients are deficient, while the opposite effects are shown when nutrients are abundant

Analysys of Spanish self-consumption normative: Profitability based on consumption profiles

This paper analyses the new Spanish normative on selfconsumption (Royal Decree 900/2015) and its effects and profitability depending on the consumption profiles. A model based on the discounted cash flows over the life cycle of the plant model is used to analyze the feasibility of a photovoltaic system of self-consumption. The impact of the Royal Decree in the return on investment of a solar photovoltaic system of selfconsumption is discussed for three different types of consumers, analysing the effect of the charges associated with the costs and services of the electrical system. In each case solutions are proposed to improve the viability and they are simulated with alternative regulatory schemes such as net metering. Finally, the effect of the difference in electricity production between two Spanish cities like Seville and Oviedo with very different climatic conditions is analyzed

Influence of pyrolysis temperature and feedstock biomass on Cu2+, Pb2+, and Zn2+ sorption capacity of biochar

AbstractBiochar has attracted significantly growing attention due to its effectiveness in terms of both cost and environmental safety in removing trace metals from soil and water. Its metal sorption capacity depends on its properties, which are in turn governed by pyrolysis temperature and type of biomass. Therefore, this study examines the role of pyrolysis temperature and biomass in biochars sorption capacity of Pb2+, Cu2+ and Zn2+. Biochars produced by pyrolysis of maize (Zea mays L.) cobs at different temperatures were used to assess the effect of temperature, whereas evergreen oak (Quercus ilex L.) pyrolyzed at 500 °C was used to assess the effect of biomass. Sorption isotherms were constructed by batch method and compared with Langmuir and Freundlich models. Most of the sorption isotherms displayed irregular curves and not all of the isotherms fitted the models. Therefore, sorption distribution coefficients and metal removal percentages were used to determine sorption capacities biochars for studied metals. Accordingly, Quercus ilex L. was most effective in sorbing all studied metals, which indicates the role of biomass. The maize biochar pyrolyzed at 500 °C was most effective among maize cob biochars, which revealed the influence pyrolysis temperature. The concentrations of added sorption solutions also played significant role in sorption, and consequently biochar pyrolyzed 350 °C was least effective. The targeted metals also affected the sorption as they compete for sorption sites. Thus, their selective sequence was in the order of Pb2+ ˃ Cu2+ ˃ Zn2+.</jats:p