Compost stream as a potential biomass for humic acid production: Focus on compost seasonal and geographical variability

Compost is a voluminous stream rich in humic and fulvic acids, which may be recovered as high-added value compounds. These soluble bio-based lignin-like polymeric substances (SBO) can be extracted through a completely green process developed at pilot scale, whose main core is the hydrolytic route in aqueous solutions at relatively mild temperature (< 140 °C) at ACEA Pinerolese Industriale premises. Due to their chemical-physical properties, the SBO compounds can be used with advantage for myriads of industrial applications, from the formulation of detergents to the production of agriculture biostimulants, answering the increasing demand for bio-compound utilization. In view of LIFECAB project (LIFE16 ENV/IT/000179), the characterization of starting materials and the derived compost has been performed over four seasons and over three European countries (Italy, Greece ad Cyprus). In view of establishing a relationship between SBO molecules and compost properties, this work is a challenging opportunity for assessing the compost variability and its temporal evolution during the composting process. Analyses of pH, salinity, total carbon, total nitrogen and C/N ratio, critically assessed by means of a statistical approach, provide important information about compost composition according to the season and to the local environmental conditions

Biorefinery development for the production of polyphenols, algal biomass and lipids using olive processing industry waste

A biorefinery was developed employing olive pomace and table olive processing wastewater for the manufacture of polyphenols, lipids and algal biomass. Following extraction of pomace oil, olive pomace was subjected to dilute acid hydrolysis and enzyme hydrolysis under different conditions aiming to maximise the content of polyphenols and sugars formed in the hydrolysate produced for application in subsequent resin adsorption/desorption and microalgal fermentation processes. Hydrolysis of 100 kg exhausted olive pomace performed under the most efficient conditions yielded release of 54.5 kg of sugars and 3.2 kg of polyphenols. Polyphenols were recovered from olive pomace hydrolysates and table olive processing wastewater via adsorption/desorption employing different polymeric resins. Application of XAD16N and PAD900 resins exhibited the highest overall polyphenols recovery, that reached 79.5% and 58.0% for table olive processing wastewater and exhausted olive pomace extracts respectively. The hydrolysates generated following polyphenols recovery were evaluated as feedstocks for lipids production by Scenedesmus obliquus and Isochrysis galbana, demonstrating maximum biomass and lipid productivity that reached 190 mg L−1 d−1 and 61.4 mg L−1 d−1 for S. obliquus, as well as 32 mg L−1 d−1 and 8.4 mg L−1 d−1 for I. galbana respectively. I. galbana accumulated high docosahexaenoic acid content that ranged between 8.4 and 9.5 mg g−1 of ash-free dry weight in fermentations of the hydrolysates developed confirming that the strain could serve as an advanced bioproducer of polyunsaturated fatty acids in microalgal biorefineries

Development of a hybrid fermentation-enzymatic bioprocess for the production of ethyl lactate from dairy waste

This work explores the potential for the development of a hybrid fermentation-enzymatic process for the production of ethyl lactate from dairy waste. Cheese whey was used in Kluyveromyces marxianus and Lactobacillus bulgaricus batch cultures to produce ethanol and lactic acid respectively. Subsequently, the fermentation products were transferred into an organic phase through liquid-liquid extraction and ethyl lactate was formed in an esterification reaction catalyzed by lipases. The production of ethanol and lactic acid achieved under different conditions was 23gL-1 and 29gL-1, respectively. Furthermore, the efficiency of various organic solvents for the esterification reaction was evaluated and toluene was chosen for application in the process. The effect of water content was determined aiming to maximize the product yield and 40mgml-1 was the optimal enzyme concentration. The bioprocess achieved maximum conversion of 33% constituting a valuable alternative to the application of energy demanding chemically derived methods

The Effect of Trophic Modes on Biomass and Lipid Production of Five Microalgal Strains

Five microalgae strains, namely Isochrysis galbana, Microchloropsis gaditana, Scenedesmus obliquus, Nannochloropsis oculata and Tetraselmis suecica, were selected as potential candidates for polyunsaturated fatty acids’ production, evaluating biomass productivity and their capacity to accumulate high lipid contents under different trophic modes. Microalgae strains were cultivated in the presence of 1% glucose using mixotrophic and heterotrophic conditions, while autotrophic cultures served as control experiments. The results demonstrate that S. obliquus performed the highest biomass productivity that reached 0.13 and 0.14 g L−1 d−1 under mixotrophic and heterotrophic conditions, respectively. I. galbana and S. obliquus utilized elevated contents of glucose in mixotrophy, removing 55.9% and 95.6% of the initial concentration of the carbohydrate, respectively, while glucose consumption by the aforementioned strains also remained high under heterotrophic cultivation. The production of lipids was maximal for I. galbana in mixotrophy and S. obliquus in heterotrophy, performing lipid productivities of 24.85 and 22.77 mg L−1 d−1, respectively. The most abundant saturated acid detected for all microalgae strains evaluated was palmitic acid (C16:0), while oleic and linolenic acids (C18:1n9c/C18:3n3) comprised the most abundant unsaturated fatty acids. I. galbana performed the highest linoleic acid (C18:2n6c) content under heterotrophic nutrition, which reached 87.9 mg g−1 of ash-free dry weight. Among the microalgae strains compared, the biomass and lipid production monitored for I. galbana and S. obliquus confirm that both strains could serve as efficient bioproducers for application in algal biorefineries

High temperature alcoholic fermentation of orange peel by the newly isolated thermotolerant Pichia kudriavzevii KVMP10

This work explores the potential for the development of orange peel based ethanol bioprocesses through isolation of the thermotolerant Pichia kudriavzevii KVMP10. A model solution of hydrolysed Valencia orange peel was employed to determine the ethanologenic potential of the yeast, which was maximized at 42°C producing 54 g l-1 of ethanol. The effect of orange peel oil on bioethanol formation was investigated at 30 and 42°C confirming that the minimum inhibitory peel oil content was 0.01% (v/v). Pichia kudriavzevii KVMP10 demonstrated significant technological advantages for the production of sustainable bioenergy, such as utilization of both hexoses (glucose, sucrose, fructose and galactose) and pentoses (xylose) at high temperatures, exemplifying its great potential for application in orange peel based biorefineries for ethanol production