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12 pages, 1514 KiB

Open AccessArticle

Effect of Several Pretreatments on the Lactic Acid Production from Exhausted Sugar Beet Pulp

by Cristina Marzo, Ana Belén Díaz, Ildefonso Caro and Ana Blandino

Foods 2021, 10(10), 2414; https://doi.org/10.3390/foods10102414 - 12 Oct 2021

Cited by 10 | Viewed by 2794

Exhausted sugar beet pulp (ESBP), a by-product of the sugar industry, has been used as a substrate to produce lactic acid (LA). Due to the fact that ESBP contains a high percentage of pectin and hemicellulose, different pretreatments were studied to solubilize them and to facilitate the access to cellulose in the subsequent enzymatic hydrolysis. Several pretreatments were studied, specifically biological, oxidant with alkaline hydrogen peroxide (AHP), and thermochemical with acid (0.25, 0.5, or 1% w/v of H₂SO₄). Pretreated ESBP was enzymatically hydrolysed and fermented with the strain Lactiplantibacillus plantarum for LA production. The hydrolysis was carried out with the commercial enzymes Celluclast^®, pectinase, and xylanase, for 48 h. After that, the hydrolysate was supplemented with yeast extract and calcium carbonate before the bacteria inoculation. Results showed that all the pretreatments caused a modification of the fibre composition of ESBP. In most cases, the cellulose content increased, rising from 25% to 68% when ESBP was pretreated thermochemically at 1% w/v H₂SO₄. The production of LA was enhanced when ESBP was pretreated thermochemically. However, it was reduced when biological and AHP pretreatments were applied. In conclusion, thermochemical pretreatment with 1% w/v H₂SO₄ had a positive impact on the production of LA, increasing its concentration from 27 g/L to 50 g/L. Full article

(This article belongs to the Special Issue Value Added Products from Agro-Food Residues)

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18 pages, 2576 KiB

Open AccessArticle

Thermophilic Anaerobic Co-Digestion of Exhausted Sugar Beet Pulp with Cow Manure to Boost the Performance of the Process: The Effect of Manure Proportion

by Xiomara Gómez-Quiroga, Kaoutar Aboudi, Luis Alberto Fernández-Güelfo, Carlos José Álvarez-Gallego and Luis Isidoro Romero-García

Water 2021, 13(1), 67; https://doi.org/10.3390/w13010067 - 31 Dec 2020

Cited by 8 | Viewed by 3256

Abstract

Sugar beet by-products are a lignocellulosic waste generated from sugar beet industry during the sugar production process and stand out for their high carbon content. Moreover, cow manure (CM) is hugely produced in rural areas and livestock industry, which requires proper disposal. Anaerobic digestion of such organic wastes has shown to be a suitable technology for these wastes valorization and bioenergy production. In this context, the biomethane production from the anaerobic co-digestion of exhausted sugar beet pulp (ESBP) and CM was investigated in this study. Four mixtures (0:100, 50:50, 75:25, and 90:10) of cow manure and sugar beet by-products were evaluated for methane generation by thermophilic batch anaerobic co-digestion assays. The results showed the highest methane production was observed in mixtures with 75% of CM (159.5 mL CH₄/g VolatileSolids added). Nevertheless, the hydrolysis was inhibited by volatile fatty acids accumulation in the 0:100 mixture, which refers to the assay without CM addition. The modified Gompertz model was used to fit the experimental results of methane productions and the results of the modeling show a good fit between the estimated and the observed data. Full article

(This article belongs to the Special Issue Enhancement of Anaerobic Digestion for Energy and Resource Recovery)

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14 pages, 1607 KiB

Open AccessArticle

Conversion of Exhausted Sugar Beet Pulp into Fermentable Sugars from a Biorefinery Approach

by Cristina Marzo, Ana Belén Díaz, Ildefonso Caro and Ana Blandino

Foods 2020, 9(10), 1351; https://doi.org/10.3390/foods9101351 - 24 Sep 2020

Cited by 22 | Viewed by 3566

Abstract

In this study, the production of a hydrolysate rich in fermentable sugars, which could be used as a generic microbial culture medium, was carried out by using exhausted sugar beet pulp pellets (ESBPPs) as raw material. For this purpose, the hydrolysis was performed through the direct addition of the fermented ESBPPs obtained by fungal solid-state fermentation (SSF) as an enzyme source. By directly using this fermented solid, the stages for enzyme extraction and purification were avoided. The effects of temperature, fermented to fresh solid ratio, supplementation of fermented ESBPP with commercial cellulase, and the use of high-solid fed-batch enzymatic hydrolysis were studied to obtain the maximum reducing sugar (RS) concentration and productivity. The highest RS concentration and productivity, 127.3 g·L⁻¹ and 24.3 g·L⁻¹·h⁻¹ respectively, were obtained at 50 °C and with an initial supplementation of 2.17 U of Celluclast^® per gram of dried solid in fed-batch mode. This process was carried out with a liquid to solid ratio of 4.3 mL·g⁻¹ solid, by adding 15 g of fermented solid and 13.75 g of fresh solid at the beginning of the hydrolysis, and then the same amount of fresh solid 3 times every 2.5 h. By this procedure, ESBPP can be used to produce a generic microbial feedstock, which contains a high concentration of monosaccharides. Full article

(This article belongs to the Special Issue Value Added Products from Agro-Food Residues)

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11 pages, 1309 KiB

Open AccessArticle

Feasibility Assessment of a Bioethanol Plant in the Northern Netherlands

by Spyridon Achinas, Nienke Leenders, Janneke Krooneman and Gerrit Jan Willem Euverink

Appl. Sci. 2019, 9(21), 4586; https://doi.org/10.3390/app9214586 - 28 Oct 2019

Cited by 11 | Viewed by 4537

Abstract

Due to the exhaustion and increased pressure regarding the environmental and political aspects of fossil fuels, the industrial focus has switched towards renewable energy resources. Lignocellulosic biowaste can come from several sources, such as industrial waste, agricultural waste, forestry waste, and bioenergy crops and processed into bioethanol via a biochemical pathway. Although much research has been done on the ethanol production from lignocellulosic biomass, the economic viability of a bioethanol plant in the Northern Netherlands is yet unknown, and therefore, examined. In this thesis, the feasibility study of a bioethanol plant treating sugar beet pulp, cow manure, and grass straw is conducted using the simulation software SuperPro Designer. Results show that it is not economically viable to treat the tested lignocellulosic biomass for the production of bioethanol, since all three original cases result in a negative net present value (NPV). An alternative would be to exclude the pretreatment step from the process. Although this results in a lower production of bioethanol per year, the plant treating sugar beet pulp (SBP) and grass straw (GS) becomes economically viable since the costs have significantly decreased. Full article

(This article belongs to the Special Issue Optimization for Biofuel Production Process)

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15 pages, 1764 KiB

Open AccessFeature PaperArticle

Enhancement of Methane Production in Thermophilic Anaerobic Co-Digestion of Exhausted Sugar Beet Pulp and Pig Manure

by Xiomara Gómez-Quiroga, Kaoutar Aboudi, Carlos José Álvarez-Gallego and Luis Isidoro Romero-García

Appl. Sci. 2019, 9(9), 1791; https://doi.org/10.3390/app9091791 - 29 Apr 2019

Cited by 20 | Viewed by 3463

Abstract

In this paper, the viability of thermophilic anaerobic co-digestion of exhausted sugar beet pulp (ESBP) and pig manure (PM) was evaluated. The effect of the proportion of ESBP on biogas production was investigated by using a series of lab-scale batch assays, in duplicates. The following five ESBP:PM mixture ratios were studied: 0:100, 10:90, 25:75, 50:50, and 100:0. The highest cumulative methane production (212.4 mL CH₄/g VS_added) was reached for the mixture 25:75. The experimental results showed that the increase in the proportion of ESBP in the mixture led to the distortion of the process, due to acidification by the volatile fatty acids generated. Acetic acid was the predominant acid in all the cases, representing more than 78% of the total acidity. Moreover, the results obtained by operating at thermophilic temperatures have been compared with those obtained in a previous study conducted at mesophilic temperatures. The results have shown that in the individual digestion of ESBP, the activity of acetoclastic methanogens was affected in both temperatures, but especially in thermophilic conditions. Thus, the methane produced in the individual thermophilic digestion of ESBP came almost entirely from the activity of hydrogen-utilizing methanogenic archaea. Full article

(This article belongs to the Special Issue Anaerobic Co-Digestion of Lignocellulosic Waste)

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