Sustainability is a key principle in natural resource management, and it involves operational efficiency, minimisation of environmental impact and socio-economic considerations; all of which are interdependent. It has become increasingly obvious that continued reliance on fossil fuel energy resources is unsustainable, owing to both depleting world reserves and the green house gas emissions associated with their use. Therefore, there are vigorous research initiatives aimed at developing alternative renewable and potentially carbon neutral solid, liquid and gaseous biofuels as alternative energy resources. However, alternate energy resources akin to first generation biofuels derived from terrestrial crops such as sugarcane, sugar beet, maize and rapeseed place an enormous strain on world food markets, contribute to water shortages and precipitate the destruction of the world's forests. Second generation biofuels derived from lignocellulosic agriculture and forest residues and from non-food crop feedstocks address some of the above problems; however there is concern over competing land use or required land use changes. Therefore, based on current knowledge and technology projections, third generation biofuels specifically derived from microalgae are considered to be a technically viable alternative energy resource that is devoid of the major drawbacks associated with first and second generation biofuels. Microalgae are photosynthetic microorganisms with simple growing requirements (light, sugars, CO 2 , N, P, and K) that can produce lipids, proteins and carbohydrates in large amounts over short periods of time. These products can be processed into both biofuels and valuable co-products. This study reviewed the technologies underpinning microalgae-to-biofuels systems, focusing on the biomass production, harvesting, conversion technologies, and the extraction of useful co-products. It also reviewed the synergistic coupling of microalgae propagation with carbon sequestration and wastewater treatment potential for mitigation of environmental impacts associated with energy conversion and utilisation. It was found that, whereas there are outstanding issues related to photosynthetic efficiencies and biomass output, microalgae-derived biofuels could progressively substitute a significant proportion of the fossil fuels required to meet the growing energy demand.

/pdf/biofuels-from-microalgae-a-review-of-technologies-for-1t1wwr5e69.pdf

Biofuels from microalgae—A review of technologies for production, processing, and extractions of biofuels and co-products

Microalgae are a diverse group of prokaryotic and eukaryotic photosynthetic microorganisms that grow rapidly due to their simple structure. They can potentially be employed for the production of biofuels in an economically effective and environmentally sustainable manner. Microalgae have been investigated for the production of a number of different biofuels including biodiesel, bio-oil, bio-syngas, and bio-hydrogen. The production of these biofuels can be coupled with flue gas CO2 mitigation, wastewater treatment, and the production of high-value chemicals. Microalgal farming can also be carried out with seawater using marine microalgal species as the producers. Developments in microalgal cultivation and downstream processing (e.g., harvesting, drying, and thermochemical processing) are expected to further enhance the cost-effectiveness of the biofuel from microalgae strategy.

https://aiche.onlinelibrary.wiley.com/doi/pdf/10.1021/bp070371k

Biofuels from microalgae.

Effects of spray drying conditions on the physicochemical and antioxidant properties of the Gac (Momordica cochinchinensis) fruit aril powder.

The freshwater green microalgal strain Haematococcus pluvialis is the richest source for the production of astaxanthin. Astaxanthin is member of the xanthophyll family of carotenoids and constitutes the highest value product derived by microalgae. So far, algal astaxanthin amounts to

/pdf/commercial-astaxanthin-production-derived-by-green-alga-4jkn1p5tr6.pdf

Commercial astaxanthin production derived by green alga Haematococcus pluvialis: A microalgae process model and a techno-economic assessment all through production line

The microalga Dunaliella salina is the best commercial source of natural beta-carotene. Additionally, different species of Dunaliella can accumulate significant amounts of valuable fine chemicals such as carotenoids, glycerol, lipids, vitamins, minerals and proteins. They also have a large potential for biotechnological processes such as expressing of foreign proteins and treatment of wastewater. In this review, we discussed several biotechnological aspects of the mass cultivation of D. salina like strain selection, carotenoid induction, culture conditions, culture systems and downstream processes. We also discuss several traditional and new applications of the genus.

https://sfamjournals.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1365-2672.2009.04153.x

Dunaliella biotechnology: methods and applications

Powders of Dunaliella salina biomass were obtained by spray drying a cell concentrate under different drying regimes. A three-factor, two-level experimental design was employed to investigate the influence of inlet temperature, outlet temperature and feed solids on beta-carotene recovery. The effect of microencapsulation in a polymer matrix of maltodextrin and gum arabic was also studied. All powders were stored under specific conditions to assess the stability of the native beta-carotene. There was a trend indicating that lower outlet temperature yielded higher carotenoid recoveries, beta-carotene recovery varying between 57% and 91%. Microencapsulated biomass yielded 100% recoveries. All non-microencapsulated powders were unstable in terms of beta-carotene content in the presence of natural light and oxygen showing 90% degradation over a 7-day period. The incorporation of a microencapsulating agent had a significant increase in the storage stability. Results indicated a first-order degradation of the beta-carotene in micro encapsulated powders with kinetic constants of 0.06 day-1 and 0.10 day-1. HPLC analysis showed no effect of drying processes on isomer composition (9-cis-beta-carotene and all-trans-beta- carotene ratio). This behaviour was also observed during storage of the micro encapsulated powders.

Spray-drying of Dunaliella salina to produce a β-carotene rich powder

A new carotenoid-rich product was formed by entrapment of Duna- liella salina in calcium alginate beads of di†erent alginate concentrations, fol- lowed by drying in a Nuid-bed dryer. The drying process yielded b-carotene recoveries of between 79 and 89% and produced a change in the 9-cis/all-trans ratio of b-carotene isomers. The carotenoid stability of the product was depen- dant on both the storage conditions and alginate content (range 3E3E7E 3g litre~1) of the beads. In the presence of light and oxygen total carotenoid degraded following a "rst order kinetic model with degradation constants between 0E016 and 0E039 days~1, with the lowest degradation occurring with the lowest alginate concentration. Product stored in the dark and Nushed with nitro- gen produced "rst-order degradation constants of 0 E012 and 0E020 days~1 for the two higher alginate concentrations; that with the lowest alginate content showed no noticeable degradation after 58 days storage. During storage, the 9-cis isomer was signi"cantly more unstable showing a relative loss under all conditions, degrading almost completely when stored in the presence of light and oxygen and reaching an equilibrium ratio with the all-trans isomer when stored in the dark and Nushed with nitrogen. 1998 SCI. (

/pdf/production-of-a-carotenoid-rich-product-by-alginate-2evgn6lanu.pdf

Production of a carotenoid-rich product by alginate entrapment and fluid-bed drying of Dunaliella salina

This work consists on the evaluation of the in vitro performance of Ti6Al4V samples PLD (pulsed laser deposition) coated with hydroxyapatite, both pure and mixed with a CaO-P2O5 glass. Previous studies on immersion of PLD coatings in SBF, showed that the immersion apatite films did not present the usual cauliflower morphology but replicated the original columnar structure and exhibited good bioactivity. However, the influence of glass associated to hydroxyapatite concerning adhesion, proliferation and morphology of MG63 cells on the films surface was unclear. In this study, the performance of these PLD coated samples was evaluated, not only following the physical-chemical transformations resulting from the SBF immersion, but also evaluating the cytocompatibility in contact with osteoblast-like MG63 cells. SEM and AFM confirmed that the bioactive ceramic PLD films reproduce the substrate's surface topography and that the films presented good adherence and uniform surface roughness. Physical-chemical phenomena occurring during immersion in SBF did not modify the original columnar structure. In contact with MG63 cells, coated samples exhibited very good acceptance and cytocompatibility when compared to control. The glass mixed with hydroxyapatite induced higher cellular proliferation. Cells grown on these samples presented many filipodia and granular structures, typical features of osteoblasts.

/pdf/pld-bioactive-ceramic-films-the-influence-of-cao-p2o5-glass-2hbyl49jra.pdf

PLD bioactive ceramic films: the influence of CaO-P2O5 glass additions to hydroxyapatite on the proliferation and morphology of osteblastic like-cells.

https://www.econstor.eu/bitstream/10419/243723/1/1692902148.pdf

Biofixation of CO2 emissions from natural gas combined cycle power plant

The world population is ageing, in particular in the developed world, with a significant increase in the percentage of people above 60 years old. They represent a segment of the population that is more vulnerable to adverse environmental conditions. Among them, indoor air quality is one of the most relevant, as elders spend comparatively more time indoors than younger generations. Furthermore, the recent COVID-19 pandemic contributed immensely to raising awareness of the importance of breathing air quality for human health and of the fact that indoor air is a vector for airborne infections and poisoning. Hence, this work reviews the state of the art regarding indoor air quality in elderly centers, considering the type of pollutants involved, their emission sources, and their health effects. Moreover, the influence of ventilation on air quality is also addressed. Notwithstanding the potential health problems with the corresponding costs and morbidity effects, only a few studies have considered explicitly indoor air quality and its impacts on elderly health. More studies are, therefore, necessary to objectively identify what are the impacts on the health of elderly people due to the quality of indoor air and how it can be improved, either by reducing the pollutants emission sources or by more adequate ventilation and thermal comfort strategies.

https://www.mdpi.com/2076-3298/9/7/86/pdf?version=1658775514

Gisela Oliveira

Papers

Spray-drying of Dunaliella salina to produce a β-carotene rich powder

Production of a carotenoid-rich product by alginate entrapment and fluid-bed drying of Dunaliella salina

PLD bioactive ceramic films: the influence of CaO-P2O5 glass additions to hydroxyapatite on the proliferation and morphology of osteblastic like-cells.

Biofixation of CO2 emissions from natural gas combined cycle power plant

Indoor Air Quality in Elderly Centers: Pollutants Emission and Health Effects