Two stage process of microalgae cultivation for starch and carotenoid production

Biotechnological processes based on microalgae cultivation are promising for several industrial applications. Microalgae are photoautotrophic microorganisms and can thus grow by using renewable and inexpensive resources as sunlight, inorganic salts, water and CO2. They can store high amounts of neutral lipids (bioil), carbohydrates (mainly starch), carotenoids (such as lutein, astaxanthin, beta-carotene), proteins and other molecules. Productions of lipids and carbohydrates have recently received an increasing interest for biofuel production, while proteins, carotenoids and other minor products are usable as feed additives and nutraceutical compounds. Biofuel production from microalgae is not yet economically sustainable, while there are different industrial plants in the world for the production of high values chemicals as carotenoids. Starch production from microalgae has been investigated mainly for the production of biofuels (e.g. bioethanol) by successive fermentation. However, purified starch can be used for other aims such as the production of bioplastics. Superior plants as corn, potato and wheat are currently used for this purpose. However, there are different environmental and economic issues related to the use of fertile lands and edible plants for these kinds of productions. Microalgae can solve these social and ethical issues because they can grow on nonfertile lands and also reach starch productivity per hectare higher than plants. In this work, the production of starch and carotenoids from Scenedesmus sp. microalgal strain is reported. A two-stage process has been developed in order to reduce operative and investment costs. In the first stage, microalgae are cultivated in photoautotrophic conditions and then, when biomass concentration rises and light becomes a limiting factor for growth, microalgae are transferred to a heterotrophic reactor. In this reactor, microalgae are cultivated by using wastewaters as source of nutrients (mainly organic carbon). Microalgae use organic carbon to synthesize starch and simultaneously reduce the content of pollutants in the wastewater (codepuration). Biomass separated by the culture medium is treated for the extraction of lipids containing different antioxidant carotenoids (such as astaxanthin and lutein) and starch granules as raw material for biopolymers

Microalgae cultivation for lipids and carbohydrates production

Microalgae are photoautotrophic microorganisms that can produce energy both by using sunlight, water and CO2 (phototrophic metabolism) and by using organic sources such as glucose (heterotrophic metabolism). Heterotrophic growth is a key factor in microalgae research, due to its increased productivity and the lower capital and operative costs compared to photoautotrophic growth in photobioreactors. Carbohydrate production from microalgae is usually investigated for the production of biofuels (e.g. bioethanol) by successive fermentation, but also other applications can be envisaged in biopolymers. In this work an increment in carbohydrate purity after lipid extraction was found. Protein hydrolysis for different microalgae strains (Scenedesmus sp. and Chlorella sp.) was investigated. Microalgae were cultivated under photoautotrophic or heterotrophic conditions, collecting biomass at the end of the growth. Biomass samples were dried or freeze dried and used for carbohydrate and lipid extraction tests. Lipid extraction was achieved using different organic solvents (methanol-chloroform and hexane-2propanol). Basic protein hydrolysis has been carried out testing different temperatures and NaOH concentrations values. Lipids were spectrophotometrically quantified, while residual biomass was saccharificated and the total amount of sugars was measured. Significant differences about the purity of extracted carbohydrates were found comparing dried with freeze dried biomass. However, not a very promising purification of carbohydrates was achieved after protein hydrolysis, asking for further analysis. © Copyright 2017, AIDIC Servizi S.r.l

Analysis on High Temperature Gasification for Conversion of RDF into Bio-Methanol

Municipal solid waste (MSW) is one of the residue materials considered as a potential source for biofuel production in the EU Renewable Energy Directive (RED), which establishes that a minimum of 10% biofuels for transport shall be used in every Member State by 2020, thus promoting advanced biofuel from waste. A high-temperature gasification technology transforms MSW into a syngas rich in hydrogen and carbon monoxide and free of tar, char and harmful compounds like dioxins appearing as a promising root for methanol production. The overall process including MSW high-temperature gasification, syngas purification and conditioning up to methanol synthesis has been modeled with Aspen Plus analyzing the influence of waste composition and operating conditions on syngas composition and methanol yield. The evaluation of CAPEX and OPEX has been carried out to obtain a cost of production (COP) estimation. The greenhouse gas (GHG) emission has also been estimated and compared with the conventional waste incineration process and methanol production. The technology assessment shows interesting results technically and economically, when compared with waste to energy processes: over 50% of incoming carbon is fixed into methanol molecule, and due to the negative cost paid for RDF disposal, the bio-methanol COP provides a reasonable industrial margin

Estimate of the height of molten metal reactors for methane cracking

Methane Cracking represents one of the most promising routes to CO2-free hydrogen production.The methane decomposition reaction is typically carried out in fixed or fluidized catalytic beds, where the metal catalyst is supported on porous ceramic particles. By proper choice of the metal catalyst, the catalytic reaction environment allows to obtain sizeable reaction rates at operating temperatures as low as 700°C. Besides, in solid catalytic beds, the catalyst is swiftly deactivated due to the massive (i.e. stoichiometric) deposition of the solid carbon product. One way to bypass carbon deposition is to use a molten metal bath (which may or may not contain catalytic metal components) as a reaction environment, where methane bubbles are introduced at the bottom of the bath and are progressively converted as they rise through the liquid metal. The key point of this process is that, owing to a large density difference between the solid carbon phase and the molten metal, the solid product of the reaction floats on top of the liquid metal and can be thus mechanically skimmed. In this article, we develop an analytical approach to the estimate of the bath height, which constitutes one of the most critical design parameters of the process. Specifically, based on the observation that in practical applications the reacting bubble is in the kinetics-controlled regime, we obtain the conversion vs time solution for a bubble of given initial size. On the assumption of ideal gaseous mixture behaviour, the knowledge of the conversion curves allows to estimate the bubble diameter as a function of time during the rise of the bubble through the molten metal. This piece of information is then post-processed to obtain the bubble motion as a function of time. The elimination of the time parameter between the two solutions allows to construct a conversion-height map for different diameters of the bubbles

Electroencephalography of mechanically ventilated patients at high risk of delirium.

Neurophysiological exploration of ICU delirium is limited. Here, we examined EEG characteristics of medical-surgical critically ill patients with new-onset altered consciousness state at high risk for ICU delirium. Pre-planned analysis of non-neurological mechanically ventilated medical-surgical ICU subjects, who underwent a prospective multicenter randomized, controlled EEG study (NCT03129438, April 2017-November 2018). EEG characteristics, according to the 2012 ACNS nomenclature, included background activity, rhythmic periodic patterns/epileptic activity, amplitude, frequency, stimulus-induced discharges, triphasic waves, reactivity, and NREM sleep. We explored EEG findings in delirious versus non-delirious patients, specifically focusing on the presence of burst-suppression and rhythmic periodic patterns (ictal-interictal continuum), and ictal activity. We analyzed 91 patients (median age, 66 years) who underwent EEG because of new-onset altered consciousness state at a median 5 days from admission; 42 patients developed delirium (46%). Burst-suppression (10 vs 0%, p = .02), rhythmic/periodic patterns (43% vs 22%, p = .03) and epileptiform activity (7 vs 0%, p = .05) were more frequent in delirious versus non-delirious patients. The presence of at least one of these abnormal EEG findings (32/91 patients; 35%) was associated with a significant increase in the likelihood of delirium (42 vs 15%, p = .006). Cumulative dose of sedatives and analgesics, as well as all other EEG characteristics, did not differ significantly between the two groups. In mechanically ventilated non-neurological critically ill patients with new-onset alteration of consciousness, EEG showing burst-suppression, rhythmic or periodic patterns, or seizures/status epilepticus indicate an increased risk of ICU delirium

Chapter Natural Gas Catalytic Partial Oxidation: A Way to Syngas and Bulk Chemicals Production

Computer modelling & simulatio