6 research outputs found

    Hydrothermal carbonization of milk/dairy processing sludge: Fate of plant nutrients

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    Dairy processing sludge (DPS) is a byproduct generated in wastewater treatment plants located in dairy (milk) processing companies (waste activated sludge). DPS presents challenges in terms of its management (as biosolids) due to its high moisture content, prolonged storage required, uncontrolled nutrient loss and accumulation of certain substances in soil in the proximity of dairy companies. This study investigates the potential of hydrothermal carbonization (HTC) for recovery of nutrients in the form of solid hydrochar (biochar) produced from DPS originating from four different dairy processing companies. The HTC tests were carried out at 160 ◦C, 180 ◦C, 200 ◦C and 220 ◦C, and a residence time of 1h. The elemental properties of hydrochars (biochars), the content of primary and secondary nutrients, as well as contaminants were examined. The transformation of phosphorus in DPS during HTC was investigated. The fraction of plant available phosphorus was determined. The properties of hydrochar (biochar) were compared against the European Union Fertilizing Products Regulation. The findings of this study demonstrate that the content of nutrient in hydrochars (biochars) meet the requirements for organo-mineral fertilizer with nitrogen and phosphorus as the declared nutrients (13.9–26.7%). Further research on plant growth and field tests are needed to fully assess the agronomic potential of HTC hydrochar (biochar).</p

    Preliminary Assessment of Pyrolysis Biochar Derived from Milk/ Dairy Processing Sludge as a Potential Component of Fertilizers

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    Disposal of waste-activated sludge [dairy processing sludge, (DPS)] from wastewater treatment plants located in milk processing companies is an increasing concern. DPS is usually applied to farmlands in the vicinity of the dairy companies. This practice is becoming unsustainable due to uncontrolled nutrient loss and potential soil contamination. We propose to recover nutrients in the form of biochar. This paper examines the properties of biochars obtained from slow pyrolysis of DPS. DPS samples were pyrolyzed at laboratory and pilot scale at 600 and 700 °C. The elemental properties of biochars, the content of primary and secondary nutrients, as well as contaminants were examined and compared against the European Union Fertilizing Products Regulation. The biochars meet the specified limits for hydrogen-to-organic carbon ratio, chloride, and polycyclic aromatic hydrocarbons intended for gasification and pyrolysis component category materials. In six out of eight biochars, the content of phosphorus (P) as a single declared nutrient and the level of contaminants meet those required for an organo-mineral fertilizer. Only two biochars meet the required concentrations of nitrogen, phosphorus, and potassium. A minimum solid content of 30% in DPS is required to make the process of biochar production energetically sustainable </p

    Purification and characterisation of a fungal β-1,6-glucanase for the production of gentio-oligosaccharides from brewer’s spent yeast

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    Gentio-oligosaccharides (GnOS) are an emerging class of prebiotics derived from β-1,6-glucan, a polysaccharide found within the cell walls of fungi such as Saccharomyces cerevisiae, or Brewer’s yeast (BSY). The generation of GnOS from BSY by enzymatic hydrolysis could create functional food additives, as well as minimize waste and waste-disposal costs, thereby contributing to the circular economy. In this study, a β-1,6- glucanase from the mycoparasitic fungus Trichoderma virens was cloned and expressed in Pichia pastoris, and subsequently purified and characterized in order to assess its suitability for the production of GnOS from BSY. Tvir30 was purified by IMAC to a yield of 47.5% with a purification factor of 5.63. The pH and temperature optima of Tvir30 were determined to be 5.0 and 45oC respectively. The enzyme was found to be glycosylated, and substrate specificity analysis revealed it to be specific to β-1,6-linkages only. Tvir30 was relatively heat sensitive, with 50% relative activity remaining after 15 min incubation at 50oC. However, at 40oC the stability of Tvir30 was improved, with activity reaching 80% at 100 h of incubation. Kinetic analysis revealed classic Michaelis-Menten kinetics, with a Vmax of 214.4 μmol mg-1 min-1 , a Km of 1.873 mg mL-1 , and a Kcat of 161 sec-1 . Finally, analysis of hydrolysis products revealed Tvir30 to have an endolytic mode of action, capable of generating GnOS with DP>2, including from yeast β-glucan</p

    Prediction of yields and composition of char from fast pyrolysis of commercial lignocellulosic materials, organosolv fractionated and torrefied olive stones

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    This study investigated the fast pyrolysis behaviour of torrefied olive stones, fractionated olive stones and lignocellulosic commercial compounds. Olive stones were reacted in a continuous industrial torrefaction unit. The olive stones were also fractionated into their main components in an organosolv reactor at temperatures from 170 to 190 ◦C in both the presence and absence of an acidic catalyst. All samples were reacted in a wire mesh reactor at different temperatures (800–1150 ◦C) and heating rates (400–1150 ◦C/s), and the solid product was characterised for its yield, morphology, and elemental composition. The char yields from fast pyrolysis of commercially available cellulose, hemicelluloses, and lignin were compared with yields of fractionated olive stones. A model was developed to compare the measured yields of olive stones with the predicted yields using fractionated or commercial components. The presence of acid during fractionation had a stronger effect than the temperature, particularly on the lignin fraction. The fractionated lignocellulosic compounds provided more accurate predictions of the char yields of olive stones, as compared to the commercial lignocellulosic compounds. The fractionation at 180 ◦C without acid catalyst gave the cellulose, hemicellulose, and lignin with highest degree of purity and resulted in the most accurate predictions of the experimental yields of olive stones. The results showed that interactions between the lignocellulosic components were not significant. The char yield of each fractioned compound and non-treated olive stones could be accurately predicted from the lignocellulosic content which has importance for biorefinery applications in which each fraction is used as a value-added product

    Microwave hydrolysis, as a sustainable approach in the processing of seaweed for protein and nanocellulose management

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    The nature of marine biomass is very complex for a material scientist due to the large seasonal variation in the chemical composition that makes it difficult to prepare standardized products. A systematic investigation of the interaction of microwave irradiation with seaweed from Norway and Caribbean region was performed, covering a broad temperature range (130 → 170 ◦C) and without and with addition of ℽ-valerolactone (GVL) in ratios of 1:4 and 1:2. The temperatures above 150 ◦C and without addition of GVL led to the closure of mass balances up to 90 % that includes polysaccharides, “pseudo-lignin” fraction, fatty acids, and proteins. Fucoidan and mannose represented >50 % of all detected polysaccharides in ascophyllum nodosum (AN), while aegagropila linnaei (AL) contained mostly glucose. The presence of arabinose and rhamnose in the upper surface of the cell wall hinders the glucose release during microwave treatment. The differences in the polysaccharide composition among both algae samples hindered the definition of a parameters set that can be used in microwave treatment of various seaweed species. A large fraction of protein (> 95 %) remained in the seaweed solid residue. Higher amount of protein was determined in AL, which was dominated by leucine and lysine. Another potential barrier to the application of seaweed in industry is the limited knowledge on the chemical composition of “pseudo-lignin” and extractives. The total amino acid analysis was identified as the most accurate to characterize the protein yield and composition. The results showed that microwave treatment of seaweed is indeed a viable method for producing bioactives in the temperature range 120–150 ◦C, and proteins and nanocellulose at temperatures above 170 ◦C without using GVL. The microwave temperature and seaweed type played a dominating role in the mass closure balances leading to >95 % identified compound.</p

    Combined analytical strategies for chemical and physical characterization of tar from torrefaction of olive stone

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    The advance in analytical methodology is critical for progress in 1) biorefinery and 2) torrefaction product commercialization. The chemical characterisation of torrefaction liquid and concentrated tar produced by Arigna Fuels’ pyrolysis plant allowed identification of polar, volatile, non-volatile compounds, species containing organically bound sulphur and nitrogen heteroatoms. The results suggest that only combined use of ion chromatography with Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, and 1 H-13C HS-QC can provide comprehensive information on sugar-like material and lignin-derived compounds. Due to the technical robustness and short analysis time, Fourier Transform Ion Cyclotron Resonance Mass Spectrometer was found to be a promising tool for tar analysis containing heavy molecular compounds. Importantly from a technological standpoint, the presence of aromatic and saturated compounds in both liquid and concentrated tar samples indicated the predominance of lignin-derived compounds over products originating from cellulose and hemicellulose polymers
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