scholarly journals The Role of Heterotrophic Microalgae in Waste Conversion to Biofuels and Bioproducts

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1090
Author(s):  
Teresa Lopes da Silva ◽  
Patrícia Moniz ◽  
Carla Silva ◽  
Alberto Reis

In the last few decades, microalgae have attracted attention from the scientific community worldwide, being considered a promising feedstock for renewable energy production, as well as for a wide range of high value-added products such as pigments and poly-unsaturated fatty acids for pharmaceutical, nutraceutical, food, and cosmetic markets. Despite the investments in microalgae biotechnology to date, the major obstacle to its wide commercialization is the high cost of microalgal biomass production and expensive product extraction steps. One way to reduce the microalgae production costs is the use of low-cost feedstock for microalgae production. Some wastes contain organic and inorganic components that may serve as nutrients for algal growth, decreasing the culture media cost and, thus, the overall process costs. Most of the research studies on microalgae waste treatment use autotrophic and mixotrophic microalgae growth. Research on heterotrophic microalgae to treat wastes is still scarce, although this cultivation mode shows several benefits over the others, such as higher organic carbon load tolerance, intracellular products production, and stability in production all year round, regardless of the location and climate. In this review article, the use of heterotrophic microalgae to simultaneously treat wastes and produce high value-added bioproducts and biofuels will be discussed, critically analyzing the most recent research done in this area so far and envisioning the use of this approach to a commercial scale in the near future.

2021 ◽  
Vol 4 ◽  
Author(s):  
Debomitra Dey ◽  
Jana K. Richter ◽  
Pichmony Ek ◽  
Bon-Jae Gu ◽  
Girish M. Ganjyal

The processing of agricultural products into value-added food products yields numerous by-products or waste streams such as pomace (fruit and vegetable processing), hull/bran (grain milling), meal/cake (oil extraction), bagasse (sugar processing), brewer's spent grain (brewing), cottonseed meal (cotton processing), among others. In the past, significant work in exploring the possibility of the utilization of these by-products has been performed. Most by-products are highly nutritious and can be excellent low-cost sources of dietary fiber, proteins, and bioactive compounds such as polyphenols, antioxidants, and vitamins. The amount of energy utilized for the disposal of these materials is far less than the energy required for the purification of these materials for valorization. Thus, in many cases, these materials go to waste or landfill. Studies have been conducted to incorporate the by-products into different foods in order to promote their utilization and tackle their environmental impacts. Extrusion processing can be an excellent avenue for the utilization of these by-products in foods. Extrusion is a widely used thermo-mechanical process due to its versatility, flexibility, high production rate, low cost, and energy efficiency. Extruded products such as direct-expanded products, breakfast cereals, and pasta have been developed by researchers using agricultural by-products. The different by-products have a wide range of characteristics in terms of chemical composition and functional properties, affecting the final products in extrusion processing. For the practical applications of these by-products in extrusion, it is crucial to understand their impacts on the qualities of raw material blends and extruded products. This review summarizes the general differences in the properties of food by-products from different sources (proximate compositions, physicochemical properties, and functional properties) and how these properties and the extrusion processing conditions influence the product characteristics. The discussion of the by-product properties and their impacts on the extrudates and their nutritional profile can be useful for food manufacturers and researchers to expand their applications. The gaps in the literature have been highlighted for further research and better utilization of by-products with extrusion processing.


2014 ◽  
Vol 2014 (1) ◽  
pp. 000718-000723
Author(s):  
Jared Pettit ◽  
Alman Law ◽  
Alex Brewer ◽  
John Moore

As the 3DIC market matures, more is understood about the technical and cost challenges [1]. At the 2013 Semicon-West gathering, a panel of global experts identified these technical challenges to represent some of the most significant barriers to the industry's efforts to maintain progress with Moore's Law [2]. Searching and achieving high value manufacturing of 3DIC devices requires wrestling with several technologies and processes, all which may assert a different value for the manufacturer [3]. Current technologies for thin wafer support use a wide range of adhesives applied to the device wafer, bonded to a carrier, backside processed, and de-bonded by an array of methods. Daetec has been investigating temporary bonding for nearly 15yrs, is producing a range of products for semiconductor (e.g. WaferBondTM (Brewer-Science, Inc.)) [4], and for the display market using a low-cost tunable adhesion-force material that is peeled by simple means [5]. Daetec has developed a new technology, DaeBond 3DTM, allowing de-bonding to occur in a batch process while thinned wafers are affixed to film frames. This new approach provides a shift in conventional practice. Our paper presents several temporary bonding options with DaeBond 3DTM in an effort to define value-added approaches for thin wafer handling.


2019 ◽  
Vol 7 (12) ◽  
pp. 670 ◽  
Author(s):  
Teresa Lopes da Silva ◽  
Patrícia Moniz ◽  
Carla Silva ◽  
Alberto Reis

Microbial oils have been considered a renewable feedstock for bioenergy not competing with food crops for arable land, freshwater and biodiverse natural landscapes. Microalgal oils may also have other purposes (niche markets) besides biofuels production such as pharmaceutical, nutraceutical, cosmetic and food industries. The polyunsaturated fatty acids (PUFAs) obtained from oleaginous microalgae show benefits over other PUFAs sources such as fish oils, being odorless, and non-dependent on fish stocks. Heterotrophic microalgae can use low-cost substrates such as organic wastes/residues containing carbon, simultaneously producing PUFAs together with other lipids that can be further converted into bioenergy, for combined heat and power (CHP), or liquid biofuels, to be integrated in the transportation system. This review analyses the different strategies that have been recently used to cultivate and further process heterotrophic microalgae for lipids, with emphasis on omega-3 rich compounds. It also highlights the importance of studying an integrated process approach based on the use of low-cost substrates associated to the microalgal biomass biorefinery, identifying the best sustainability methodology to be applied to the whole integrated system.


2020 ◽  
Vol 104 (20) ◽  
pp. 8567-8594 ◽  
Author(s):  
Martina Cappelletti ◽  
Alessandro Presentato ◽  
Elena Piacenza ◽  
Andrea Firrincieli ◽  
Raymond J. Turner ◽  
...  

Abstract Bacteria belonging to Rhodococcus genus represent ideal candidates for microbial biotechnology applications because of their metabolic versatility, ability to degrade a wide range of organic compounds, and resistance to various stress conditions, such as metal toxicity, desiccation, and high concentration of organic solvents. Rhodococcus spp. strains have also peculiar biosynthetic activities that contribute to their strong persistence in harsh and contaminated environments and provide them a competitive advantage over other microorganisms. This review is focused on the metabolic features of Rhodococcus genus and their potential use in biotechnology strategies for the production of compounds with environmental, industrial, and medical relevance such as biosurfactants, bioflocculants, carotenoids, triacylglycerols, polyhydroxyalkanoate, siderophores, antimicrobials, and metal-based nanostructures. These biosynthetic capacities can also be exploited to obtain high value-added products from low-cost substrates (industrial wastes and contaminants), offering the possibility to efficiently recover valuable resources and providing possible waste disposal solutions. Rhodococcus spp. strains have also recently been pointed out as a source of novel bioactive molecules highlighting the need to extend the knowledge on biosynthetic capacities of members of this genus and their potential utilization in the framework of bioeconomy. Key points • Rhodococcus possesses promising biosynthetic and bioconversion capacities. • Rhodococcus bioconversion capacities can provide waste disposal solutions. • Rhodococcus bioproducts have environmental, industrial, and medical relevance.


e-xacta ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 11
Author(s):  
Najla Postaue ◽  
Leila Cristina Moraes ◽  
Rosa Maria Farias Asmus

A biomassa de microalgas tem apresentado potencial para produção de biodiesel, contudo a viabilidade do cultivo de microalgas depende de fonte de nutrientes de baixo custo. O presente estudo objetivou utilizar o chorume como fonte de nutrientes para microalgas. Os experimentos foram conduzidos visando avaliar a obtenção da biomassa microalgal, conversão de lipídios e rendimento em ésteres metílicos de ácidos graxos, para os meios de cultivos utilizando 5%, 12% e 20% de chorume, com concentrações de 0,02, 0,05 e 0,08 g N. L-1 e para meio de controle contendo 1% de, Nitrogênio (N), Fósforo (P) e Potássio (K), na concentração de 20 g L-1, 5 g L-1 e 20 g L-1, respectivamente. A microalga utilizada neste trabalho foi a de classe Chlorophyceae e família Coccomyxaceae. Os resultados demonstraram que o meio com concentração de 12% de chorume obteve melhores resultados, possibilitando alcançar 1,19 g de biomassa, conversão de 108,15 mg g-1 de lipídios e conteúdo de ésteres de 410,77mg g-1, a microalga utilizada apresentou ainda predominância dos ácidos graxos palmítico e oleico, apresentando baixa quantidade de ácidos graxos saturados o que pode fornecer ao combustível, resistência ao frio. E tais aspectos demonstraram que o chorume pode ser uma fonte promissora de nutrientes para o cultivo das microalgas estudadas. AbstractMicroalgae biomass has presented potential for biodiesel production, however the viability of microalgae cultivation depends on low cost nutrient source. The present study aimed to use leachate as a source of nutrients for microalgae. The experiments were conducted to evaluate the microalgal biomass, lipid conversion and yield in fatty acid methyl esters, for the culture media using 5%, 12% and 20% leachate, with concentrations of 0.02, 0.05 and 0.08 g N. L-1 and for control medium containing 1% Nitrogen (N), Phosphorus (P) and Potassium (K), at a concentration of 20 g L-1, 5 g L-1 and 20 g L-1, respectively. The microalgae used in this work was Chlorophyceae class and Coccomyxaceae family. The results showed that the medium with a concentration of 12% of leachate obtained better results, allowing to reach 1.19 g of biomass, conversion of 108.15 mg g-1 of lipids and esters content of 410,77 mg g-1. The microalgae used also presented predominance of palmitic and oleic fatty acids, presenting low amount of saturated fatty acids which can provide the fuel with cold resistance. And these aspects demonstrated that the leachate can be a promising source of nutrients for the cultivation of the studied microalgae.


2022 ◽  
Vol 34 (2) ◽  
pp. 453-458
Author(s):  
Lakhvinder Kaur ◽  
Shachi Shah

Fruits and vegetables have the highest wastage rates of 45% of any food. One of the recent research areas is food waste valorization as a potential alternative to the disposal of a wide range of organic waste using microorganisms as one of the strategies known as microbial valorization. Bacterial cellulose is best known microbial valorization product because of its low cost, environmentally friendly nature, renewability, nanoscale dimensions, biocompatibility and extremely high hydrophilicity. Therefore, present study focuses on the isolation, characterization and identification of cellulose producing bacteria from decaying apple waste. Cellulose producers were isolated from decaying apple waste. The bacterial isolates obtained were identified through the morphological biochemical, physiological and molecular identification. The bacterial isolates exhibited potential remediation options to biovalorize decaying fruit waste by producing value added products as well as in safe disposal of waste.


2021 ◽  
Author(s):  
Matthew Wiatrowski ◽  
Bruno C Klein ◽  
Ryan W Davis ◽  
Carlos Quiroz-Arita ◽  
Eric C D Tan ◽  
...  

Abstract BackgroundMicroalgae possess numerous advantages for use as a feedstock in producing renewable fuels and products, with techno-economic analysis (TEA) frequently used to highlight the economic potential and technical challenges of utilizing this biomass in a biorefinery context. However, many historical TEA studies have focused on the conversion of biomass with elevated levels of carbohydrates and lipids and lower levels of protein, incurring substantial burdens on the ability to achieve high cultivation productivity rates relative to nutrient-replete, high-protein biomass. Given a strong dependence of algal biomass production costs on cultivation productivity, further TEA assessment is needed to understand the economic potential for utilizing potentially lower-cost but lower-quality, high-protein microalgae for biorefinery conversion. ResultsIn this work, we conduct rigorous TEA modeling to assess the economic viability of two conceptual technology pathways for processing proteinaceous algae into a suite of fuels and products. One approach, termed mild oxidative treatment and upgrading (MOTU), makes use of a series of thermo-catalytic operations to upgrade solubilized proteins and carbohydrates to hydrocarbon fuels, while another alternative focuses on the biological conversion of those substrates to oxygenated fuels in the form of mixed alcohols (MA). Both pathways rely on the production of polyurethanes from unsaturated fatty acids and valorization of unconverted solids for use as a material for synthesizing bioplastics. The assessment found similar, albeit slightly higher fuel yields and lower costs for the MA pathway, translating to a residual solids selling price of $899/ton for MA versus $1,033/ton for MOTU as would be required to support a $2.50/gallon gasoline equivalent (GGE) fuel selling price. A variation of the MA pathway including subsequent upgrading of the mixed alcohols to hydrocarbon fuels (MAU) reflected a required solids selling price of $975/ton.ConclusionThe slight advantages observed for the MA pathway are partially attributed to a boundary that stops at oxygenated fuels versus fungible drop-in hydrocarbon fuels through a more complex MOTU configuration, with more comparable results obtained for the MAU scenario. In either case, it was shown that an integrated algal biorefinery can be economical through optimal strategies to utilize and valorize all fractions of the biomass.


2021 ◽  
Vol 13 (6) ◽  
pp. 3063
Author(s):  
Lourdes Orejuela-Escobar ◽  
Arleth Gualle ◽  
Valeria Ochoa-Herrera ◽  
George P. Philippidis

Microalgae are increasingly viewed as renewable biological resources for a wide range of chemical compounds that can be used as or transformed into biomaterials through biorefining to foster the bioeconomy of the future. Besides the well-established biofuel potential of microalgae, key microalgal bioactive compounds, such as lipids, proteins, polysaccharides, pigments, vitamins, and polyphenols, possess a wide range of biomedical and nutritional attributes. Hence, microalgae can find value-added applications in the nutraceutical, pharmaceutical, cosmetics, personal care, animal food, and agricultural industries. Microalgal biomass can be processed into biomaterials for use in dyes, paints, bioplastics, biopolymers, and nanoparticles, or as hydrochar and biochar in solid fuel cells and soil amendments. Equally important is the use of microalgae in environmental applications, where they can serve in heavy metal bioremediation, wastewater treatment, and carbon sequestration thanks to their nutrient uptake and adsorptive properties. The present article provides a comprehensive review of microalgae specifically focused on biomaterial production and environmental applications in an effort to assess their current status and spur further deployment into the commercial arena.


Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3488
Author(s):  
Tomasz Janek ◽  
Eduardo J. Gudiña ◽  
Xymena Połomska ◽  
Piotr Biniarz ◽  
Dominika Jama ◽  
...  

Most biosurfactants are obtained using costly culture media and purification processes, which limits their wider industrial use. Sustainability of their production processes can be achieved, in part, by using cheap substrates found among agricultural and food wastes or byproducts. In the present study, crude glycerol, a raw material obtained from several industrial processes, was evaluated as a potential low-cost carbon source to reduce the costs of surfactin production by Bacillus subtilis #309. The culture medium containing soap-derived waste glycerol led to the best surfactin production, reaching about 2.8 g/L. To the best of our knowledge, this is the first report describing surfactin production by B. subtilis using stearin and soap wastes as carbon sources. A complete chemical characterization of surfactin analogs produced from the different waste glycerol samples was performed by liquid chromatography–mass spectrometry (LC-MS) and Fourier transform infrared spectroscopy (FTIR). Furthermore, the surfactin produced in the study exhibited good stability in a wide range of pH, salinity and temperatures, suggesting its potential for several applications in biotechnology.


Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2351 ◽  
Author(s):  
Ashiqur Rahman ◽  
Saumya Agrawal ◽  
Tabish Nawaz ◽  
Shanglei Pan ◽  
Thinesh Selvaratnam

Produced water (PW), the largest waste stream generated in oil and gas industries, has the potential to be a harmless product rather than being a waste. Biological processes using microorganisms have proven useful to remediate PW contaminated by petroleum hydrocarbons, complex organic chemicals, and solvents. In particular, the bioremediation of PW using algae is an eco-friendly and low-cost approach due to algae’s ability to utilize certain pollutants as nutrient sources. Therefore, the utilization of PW as an algal growth medium has a great potential to eliminate chemicals from the PW and minimize the large volumes of freshwater needed for cultivation. Although several reviews describing the bioremediation of PW have been published, to the best of our knowledge, no review has exclusively focused on the algae-based PW treatment. Therefore, the present review is dedicated to filling this gap by portraying the many different facets of the algae cultivation in PW. Several algal species that are known to thrive in a wide range of salinity and the critical steps for their cultivation in hypersaline PW have been identified. Overall, this comprehensive review highlights the PW bioremediation using algae and brings attention to utilizing PW to grow biomass that can be processed to generate biofuels and useful bioproducts.


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