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Polyhydroxyalkanoates (PHAs) are biobased and biodegradable polymers that may be considered to replace fossil-based materials. However, their widespread deployment is slowed down because of the high production cost and their low quality. Using methane during the generation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-co-HV) could reduce the production costs, which are usually owed to the carbon source used, and enhance the performance of the material. In fact, the properties of PHB-co-HV make it more suitable than the most common homopolymer, named poly(3-hydroxybutyrate) (PHB), for many applications since it is more flexible, has a wider thermal processing range, a lower crystallinity and permeability to water. In this work, the production of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) was simulated using an innovative process scheme consisting of two bioreactors working in series equipped with a gas recycling unit, which was designed to increase the methane mass transfer from the gas to the liquid. During the first step, a Methylocystis dominated culture was grown on ammonia and methane to reach a high cell concentration; then, the cells were moved to the second bioreactor and subjected to nutrients starvation to favour the metabolic pathway addressed to the accumulation of PHB-co-HV. The effect of the variation of valeric acid concentration (100-400 ppm), which was used as co-substrate, on the fraction of PHB-co-HV stored in the cells and the percentage of 3-hydroxyvalerate (3-HV) was investigated: results showed that the highest the valeric acid concentration, the lower the total polymer content and the higher the HV fraction accumulated.

Thanks to their properties, fossil fuel-based plastics are widely used daily (for industrial, domestic and environmental applications). However, they are not biodegradable, and their end of life is the cause of one of the most dangerous pollution in the world. Plastic, if recovered, can be recycled or used to recover energy, but it is not possible to recover all the tons of waste produced, so some end up in landfills. Therefore all non-recycled and non-collected plastic can take up to a thousand years to degrade. So the scientific idea is to produce biodegradable plastic capable of replacing conventional plastics. One possible solution is the poly(3Hydroxybutyrate) (PHB) of the polyhydroxyalkanoates (PHA) family. PHB is a biopolymer accumulated in intracellular granules, under unfavourable growth conditions, by many prokaryotes and can be extracted with eco-friendly solvents. In particular, the extraction phase consists of the disruption of the cells and the subsequent separation of the biopolymer from the non-biopolymeric material (non-PHB). Currently, solvent extraction is the most used method for PHB recovery because it guarantees a high recovery yield and keeps the characteristics of the extracted biopolymer almost unaltered. In this study, the extraction of PHB with eco-friendly solvents was investigated. Simulations were carried out using 1,2-propylene carbonate as the solvent and acetone as the anti-solvent. Two process schemes were analyzed, without and with the recirculation of solvents (by distillation) and with two different types of biomass (wet and dry). The present work aims to study the final recovery yield in different operating conditions and the influence of PHB solubility on the process. The simulation results confirm the importance of solubility for optimizing the extraction process and underline the problem related to the lack of data in the literature.

Bubble column reactors basically consist of a vertical cylinder filled by a liquid phase in which a gas phase is distributed in the liquid at the column bottom by an appropriate distributor system and moves along the column in the form of bubbles. The aim of a bubble column is to control the rate of mass transfer and reaction between the phases. The liquid phase is modelled as a continuous phase and can be operated in batch mode, or it may move co-currently or counter-currently to the flow of the gas phase. Two-phase and slurry bubble columns are widely used in the chemical- and biochemical industry for carrying out gas-liquid and gas-liquid-solid (catalytic) reaction; in particular, they are used for microalgae growth, aerobic fermentations processes, aerobic treatment of small quantities of highly polluted effluents, as well as oxidation, hydrogenation, chlorination, chemical gas cleaning and, also various biotechnological applications. In this paper, the mass transfer of CH4 to liquid in a bubble column was investigated by means of Computational Fluid Dynamic simulations in a turbulent regime. The effects of the variation of the most significant fluid dynamic parameters, such as inlet gas velocity, on CH4 concentration in the liquid phase and mass transfer from gas to liquid were studied by using COMSOL Multiphysics® Modeling Software. Results point out that the higher inlet velocities, the higher the mass transfer rate, which trend shows a pick after which it reduces to zero when CH4 concentration in the liquid becomes equal to saturation one.

Microalgae have been long recognized as potential food and feed solution, since they are able to meet the population growth on demand for a more sustainable food and feed, especially with respect to protein production. In addition, bioactive components, such as eicosapentaenoic acid (EPA), with well-known antioxidant and anti-inflammatory properties, can be extracted and incorporated in food supplements. Microalgae cultivation and processing becomes even more sustainable if simultaneously coupled to green technologies for the environmental protection. One of the most promising techniques is the supercritical fluid extraction which allows to extract bioactive compounds without loss of their activity and free from extraction solvents. In this work, a pilot scale supercritical CO2 (ScCO2) extraction plant was exploited for performing the extraction of active components from microalgae biomass potentially usable in the food and the feed sectors. Nannochloropsis gaditana microalga was selected as natural producer of EPA. The extract obtained after ScCO2 tests was enriched of EPA and protein, therefore suitable for food applications. The exhausted biomass, having a high content of carbohydrates and total dietary fiber, might be proposed as feed supplement.

Lutein is a powerful carotenoid that is used as a feed additive for the colouring properties and as supplement in nutraceutical products. Its principal healthy properties are antioxidant, anti-inflammatory and protective against age-related macular degeneration. Lutein is indeed a macular pigment in human eyes between zeaxanthin and their function is very important for the eyes health. Lutein is found in some vegetables as spinach, parsley, and kale with a content of around 1-10 mg/100 g. The commercial and recognized source of lutein is the plant marigold (Tagetes erecta L.). Lutein is extracted from marigold petals as oleoresin and the lutein content can be around 0.03% (based on dry biomass weight). Since the costs for harvesting are expensive, land and water use are requested for marigold cultivation and due to the seasonality of the growth, an alternative source of lutein has been searched among microalgae. Scenedesmus almeriensis is considered a promising source for lutein production whose content is around 4.5 mg/g dry weight. The aim of this paper is to improve lutein extraction from Scenedesmus almeriensis by using pressurized liquid extraction through accelerated solvent extractor (ASE 200©Dionex). Extractions were performed using different solvent as the mixture chloroform:methanol (1:1 v/v), ethanol, hexane, acetone. Several temperatures were tested from 20° to 80°C and biomass was mechanically pre-treated. Each extraction cycle was repeated until to complete biomass decolouring.

This work presents a risk analysis of a plant that uses supercritical fluid extraction technology with carbon dioxide as a solvent to obtain bioproducts from microalgae. Given the high pressure at which it operates, the extraction plant called "Luwar" could be affected by dangerous events, such as the gas release in concentrations that are harmful to human health. In order to limit the damage, the risk analysis is of primary importance. The gas release could occur following the breakage of a pipe, which was the scenario being considered. It was analyzed using the commercial software "Phast & Safeti", an alternative tool to the methods traditionally used in the literature in hazard events of this type, such as the Threshold Limit Value-Time Weighted Average (TLV-TWA) and the Threshold Limit Value-Short Term Exposure Limit (TLV-STEL), that are defined on the basis of the characteristics of the substance dispersed in the air. Since the pressure of the extraction vessel is the highest in the system, the risk analysis was carried out on the breakage of a pipe coming out of the extractor. The results obtained made it possible to identify the risk parameters on the basis of which to make the best choices in terms of safety to cope with the type of hazard analyzed.

In this work, a risk analysis of a supercritical fluid extraction plant is presented. The plant aims to extract valuable compounds from microalgae and uses carbon dioxide as a solvent at high temperature and pressure. Hazard events that could occur are related to the high pressure at which equipment operate and they, in addition to causing damage to the plant structure, could cause the release of CO2, which in high concentrations endangers the health of workers involved in the activities, therefore, an assessment of this type is crucial. The hazard scenario considered in this work is the equipment rupture. Generally, the rupture is analysed through methods based on indices determination such as the Fire and Explosion Index, the Probit analysis and the Safety Weighted Hazard Index. In this case, the commercial software “Phast & Safeti” of DNV GL Company was used, based on the modelling of the plant together with the process conditions definition. Among the equipment present in the plant, the extraction vessel was chosen since the extraction pressure of bioproducts is the highest in the plant and is equal to 500 bar. Risk parameters obtained after the analysis allow to select the most appropriate safety system able to limit the damage to structures and people.

The Supercritical Fluid Extraction (SFE) technology is currently used in many industrial fields thanks to the advantages that it can offer. Experimental tests are carried out for different purposes such as decaffeination of coffee/tea, extraction of aromas and herbal flavours as well as spices, extraction of fats and oils, extraction of cholesterol and extraction of alcohol from beverages. SFE plants safety is closely linked to the high pressure they operate, a condition that can lead to a risk status for plant operations and above all workers. For this reason it is necessary to adopt preventive safety measures and a risk analysis is the means that allows to define and examine hazardous scenarios in order to identify safety devices. Risk scenarios related to an extraction plant as explosions are analysed through methods based on indices determination such as the Fire and Explosion Index (F&EI), the Safety Weighted Hazard Index (SW&HI) and the Probit method. This work presents the risk analysis of a SFE plant named "Luwar" using the commercial software "Phast & Safeti" provided by the DNV GL Company. In the plant is used CO2 as extraction fluid and the process purpose is valuable compounds extraction from microalgae. The risk analysis is performed on the extraction vessel considering the plant placed inside a structure (indoor condition). The results allow to identify two risk parameters, i.e. The distance and the area within which CO2 concentration in the air assumes a value considered unsafe for human health. On the basis of the outputs it is possible to identify the safety system to be adopted in order to limit the damage deriving from the occurrence of a risk situation.

The growing consciousness for environmental issues have stimulated the search for more sustainable biochemical processes. One of the most attracting chemicals with enormous potential in a biobased economy is succinic acid (SA, butanedioic acid or 1, 2-ethanedicarboxylic acid). This compound represents the chemical building block for various high value-added substances which find applications in the detergent/surfactant, food, ion chelator and pharmaceutical markets. Nowadays, the SA market is estimated to be about 20000-30000 ton per year worldwide and its industrial manufacture is mainly based on the catalytic hydrogenation of petrochemically derived maleic acid or maleic anhydride. However, since SA is fermentative product and an intermediate of several biochemical pathways, including the tricarboxylic acid cycle, it can be produced by many microorganisms. The biological SA production at commercial scale and potentially for the commodity chemical market is still a challenging target and requires the development and the optimization of microorganisms-based processes able to guarantee high product concentrations to justify economically feasible recovery. The aim of this paper is the conversion of a mixture of sugars, mainly containing glucose, into SA by SA-producing strain Actinobacillussuccinogens, that was isolated from the bovine rumen. It is a facultative anaerobic, pleomorphic, Gram-negative rod. Experimental tests were carried out by using Actinobacillussuccinogens bought by Culture Collection of Goteborg and by using TBS (Tryptic Soy broth) by changing the concentration of glucose as well as that of other sugars as fructose, xylose, sucrose with the main focus to evaluate the effect of the fermentation for the Actinobacillussuccinogens with the single sugars in a concentration range from 1 to 15 g/l. All the experiments were carried out in anaerobic conditions at 37°C and in a pH range 7-8 for several days. For each test, carboxylic acids and sugars were analyzed by using u-HPLC while the growth of the selected microorganism was monitored by means of a spectrophotometer at 600nm for OD tests.

A contribution to the knowledge of the coastal benthic fauna of a Thyrrenian sea area is the aim of this work. Hard and mobile sea bed taxa, living either on an antitrawling artificial reef and in its proximity, have been identified and studied. Hard bottom fauna has been sampled by professional scuba divers, while mobile bottom fauna has been sampled using a dredge. Taxonomic identification has been carried out to the species level, only in few taxa to genus or family level. Polychaetes was the most frequent taxon, followed by Bivalve Molluscs, both on hard and mobile bottom. The Salerno anti-trawling reef allowed the reappearance of taxa that had not been recorded in this area for a very long time.

The use of sustainable biobased resources is the basis of the European strategy for bioeconomy development. Microalgae represent one of the most interesting biological source, since they are relatively simple microorganisms containing high-value compounds with potential applications in numerous industrial sectors. The global nutraceutical market is well developed and with an enormous potential for growth: suffice to say that it has shown considerable growth with a value in 2016 between 168 and 174 billion euros, with a growth forecast that will allow it to reach between 285 and 313 billion euros in 2024. In accordance with the National Center for Biotechnology Information, by 2050, microalgae will constitute ∼18% of protein source among the more diverse market. Healthy properties and excellent nutritional values have been conferred to microalgae, with particular regard to the high content of carbohydrates, vitamins, carotenoids and polyunsaturated fatty acids (PUFAs). The omega-3 PUFAs are extremely important throughout life and are a dietary need found predominantly in Nannochloropsis gaditana oleaginous microalga. In fact, although fish contain long-chain omega-3, they acquire PUFAs mainly from their microalgal diet. Additionally, considering depleting fish supplies, the use of microalgae as alternative raw material might be considered of increasing importance in the near future. Herein we report the assessment of the economic feasibility of an integrated process which allows to extract PUFAs from Nannochloropsis gaditana, by taking into account the main operational parameters able to influence the final products yield.

The global cosmetic market is promptly growing, showing a strong boost with the growth of economic well-being. In this context, the demand of innovative, more and more specific cosmetic ingredients has been the key for searching alternative, preferably naturally-based, active components. Microalgae represent one of the most attracting microorganisms and natural deposit for bioactive compounds for their peculiar compositions and properties. In the cosmetic sector, their efficient application has recently been highlighted by the placing on the market of different cosmetic preparations. A powerful antioxidant, 550 times more effective than Vitamin E, with enormous potential for cosmetic and pharmaceutical applications, is astaxanthin. Although high-quality astaxanthin can be obtained from microalgae, particularly from H. pluvialis specie, actually the major part of the market is occupied by the synthetic form (99%), conferring substantial differences between their price. In fact, algal-based astaxanthin costs>6000 €/Kg, while the synthetic form 600 €/kg. Thus, along with novel natural product launch, the development of cost-effective technologies able to match the existing ones, represents the major challenge for the microalgae application. This study aims to determine the feasibility of microalgal-based astaxanthin production, by exploring both procedural issues and costs evaluation.

Nutraceuticals have gained growing attention during the last year, becoming one of the most relevant areas of investigation. Among the existing natural sources of high value bioactive compounds, microalgae have assumed paramount importance. Indeed, they are a natural source of carotenoids, essential omega-3 fatty acids, proteins, carbohydrates, pigments, vitamins and minerals. Among these components, beta-carotene, a potent antioxidant pigment, is particularly attractive to the nutraceutical and cosmetic sector, being an ingredient in many supplements, functional, cosmetic and pharmaceutical products. Moreover, beta-carotene is one of the forms (precursor) of Vitamin A, which may be used in the manufacture of food supplements according to Directive 2002/46/EC. Even though some cyanobacteria produce beta-carotene (80% of total carotenoids) as the major components followed by zeaxanthin, the commercial biological source of betacarotene is Dunaliella salina. This microalga lives in very saline environment and has the capacity to produce beta-carotene up to 10% of the dry weight. In this work, beta-carotenewas extracted by using supercritical CO2 under optimized operational conditions, resulting in increased amount of carotenoids (from 3.46% to 18.62%), proteins (from 10.03% to 43.08%), and lipids (from 3.49% to 7.93%). Then, the investigation on the main operational parameters affecting extraction from Dunaliella salina and a cost-effectiveness evaluation of the process are presented; the results evidence as 194.3-366.6 kWh/day reflecting a cost of 26.89- 52.60euros/day are required for natural based beta-carotene recovery(59.3%) from Dunaliella salina.

Microalgae are among the most interesting eukaryotic photosynthethic microorganisms able to use solar energy, nutrients and carbon dioxide to convert them into proteins, carbohydrates, lipids and other valuable organic compounds including carotenoids. Astaxanthin is one of the most interesting antioxidant molecules which has attracted crescent interest due to its positive effects on health and the numerous applications in different sectors, from nutraceutical to cosmetic and aquaculture. Even though the astaxanthin properties are well-known, its price still remains high if associated to the algal form, exceeding ∼6000 Eur/Kg. This can be explained by considering the process expenses related to the extraction and purification steps of microalga intracellular metabolites. In fact, the downstream stage of this biotechnological process often accounts for more than 60-70% of total production costs. Optimized extraction and purification operations might contribute to microalgae market with the advantage to commercialize a natural existing astaxanthin form. The aim of this paper is the evaluation of the use of commercial activated carbon Darco™ G-60 for the purification of astaxanthin from an extraction broth. Astaxanthin was firstly extracted from Haematococcus pluvialis red phase supplied by Micoperi Blue Growth, an Italian Company that is working for a long time and it is specialized in the microalgae growth. Extraction was performed by Accelerated Solvent Extractor (ASE®200 DIONEX) at 100 bar and 67°C by using ethanol as green solvent with the main advantage to separate all the unipolar fractions as well as insoluble fractions from astaxanthin extracts (fibers, carbohydrate, ashes). In the second step, astaxanthin was purified with a column filled with activated carbon. Experimental tests by changing the mass of activated carbon were carried out (50mg, 100mg and 200mg) and with a flow rate in the range 0.9-1.0ml/min. All the experimental tests were carried out at room temperature (20°C). Results showed that by using activated carbon, it is possible to obtain an adsorption capacity of DARCO G60 in the range 21, 9-23, 9 mg/g.

Immobilization of living cells is a useful technique that allows to enhance the biotechnological properties of many organisms. Currently, cell-immobilization is obtained via carrier adsorption, self-aggregation and entrapment. We are currently investigating the possibility to immobilize microalgae cells using magnetic nanoparticles on a magnetic surface. The principle is based on the introduction, inside the cell-body of microalgae, superparamagnetic nanoparticles through electroporation. Once microalgae have absorbed enough magnetic nanoparticles they will be responding to an external magnetic field. By using a flat magnetic surface, it will be possible to trap them in a specific position by means of magnetic force. Importantly, immobilized cells will be covered with a thin layer of water and during cell division only one of the daughter cells will keep the magnetic nanoparticles since they will face permanently the magnetic surface. The first step towards this goal is the introduction of magnetic nanoparticles in the microalgae cells. This work will present preliminary results of magnetic cells preparation. Magnetic nanoparticles covered with lipid, to make them biocompatible, and electroporation method to inset nanoparticles in the cells have been used. The protocol to obtain magnetic cells and viability assay that proved the feasibility of the method will be described.

In this work, a membrane-based separation was investigate for Scenedesmus almeriensis solutions dewatering. A commercial polyvinylidene fluoride (PVDF) membrane, having a pore size of 3 μm was used in order to allow the water passage through it (permeate), retaining, at the same time, algae biomass (retentate). The possibility to reuse the permeate for a second Scenedesmus almeriensis growth step, was also studied. The registered data evidenced the feasibility of the membrane-based dewatering as an alternative competitive technology, even though the recovery of water should need further investigations to be optimized.

The omega-3 group includes substances as eicosapentaenoic acid and docosapentaenoic acid that can be partially synthesized by human body and substances as alpha-linolenic acid that have to be necessarily introduced into the body from dietary intake. Omega-3 are important nutrients thanks to their anti-inflammatory properties and healthy properties in the reduction of cardiovascular diseases. The growth forecasts of omega-3 market will lead to an increase in the demand for EPA and DHA and therefore finding new potential sources, such as microalgae which are the first EPA and DHA producers in the marine environment, is very important. The aim of this work is to evaluate the feasibility of mechanical pretreatment on Nannochloropsis gaditana as source of EPA and at the same time evaluating the effect on the extraction yield of two solvents: a mixture of chloroform/methanol/water (Bligh & Dyer methods) and hexane that is GRAS (generally recognized as safe solvent) by using accelerated solvent extraction technology.

The request for natural products such as antioxidant pigments derived from microalgae, i.e. ß-carotene, lutein and astaxanthin, is growing. In this context, astaxanthin, a powerful antioxidant produced by Haematococcus pluvialis, used as an additive in animal feed and as a food supplement, has been extracted by accelerated solvent extraction using acetone and ethanol as green and safe solvents, and hexane and chloroform:methanol (1:1) performing the best operating conditions. The obtained extracts showed not only the recovery of mainly astaxanthin but also other carotenoids, such as lutein and in lesser part of ß-carotene. In addition, the composition of the extracts was analyzed by highlighting the content of other valuable bio-products such as proteins, carbohydrates, lipids and Total Dietary Fibers. The best extraction performance was found using acetone and ethanol as solvent.

Anaerobic digestion is a technology used to biologically convert organic substrates into biogas in the absence of oxygen. The resulting biogas is a renewable energy source mainly consisting of a mixture of methane (60÷70% v/v) and carbon dioxide (30÷40% v/v), with traces of some minor compounds, such as H2S and NH3. Anaerobic digestion takes place through a sequence of four biological phases - hydrolysis, acidogenesis, acetogenesis, and methanogenesis - performed by the action of particular species of bacteria. Operating parameters such as temperature, pH, pressure and organic substrates govern the process and affect the starting biomass transformation and the content of methane into the biogas. The biogas from anaerobic digestion can be upgraded to biomethane by removing CO2 and the minor compounds. The techniques commonly used for this purpose, like pressure swing adsorption and membrane separation, are energy-intensive as they require the compression of biogas. In this paper, an innovative energy-saving approach for biogas production and its upgrading to biomethane is proposed. The concept is based on anaerobic digestion carried out at a pressure higher than the atmospheric one, called pressured anaerobic digestion (PAD), in order to directly produce high pressure biogas that can be upgraded to high pure biomethane (CH4 ≥ 95% v/v) avoiding the compression phase during the upgrading. The variation of the main operating parameters has been simulated in order to investigate their effect on biomethane production and composition and to define the best operating conditions. The simulation of the process has been carried out by using Aspen Plus®.

© 2017, AIDIC Servizi S.r.l. In the last decades, iron oxide nanoparticle application has taken root in several technological fields, such as magnetic separation of biomolecules, biosensors, bio-fuel production, nano-devices and nano-adsorption. Various approaches can be found for the magnetic nanoparticle manufacturing. Among them a new technology to manufacture core-cell super-paramagnetic iron oxide nanoparticles (SPIONs), based on a vapour composition using single ion precursors, like cyclodextrines, has been recently developed. In this paper, we present the synthesis of functionalized SPIONs as well as the modelling for an innovative application of this magnetic nanotechnology. It consists on the use of SPIONs to trap target organic or inorganic molecules in a continuous-flow apparatus. SPIONs with proper ligands are immobilized on a magnetic surface. On that surface, the solution containing target molecules is circulated. We modelled the magnetic properties of the magnetic surface and SPIONs as well as the velocity of liquid needed in order to avoid removal of nanoparticles by the solution flow.