Tag Archives: lignocellulosic biomass

1099–1106 A.R.P.P. Weerasuriya Arachchige, L. Mezule and T. Juhna
Separation of reducing sugars from lignocellulosic hydrolysate: Membrane experiments & system dynamic modelling
Abstract |
Full text PDF (354 KB)

Separation of reducing sugars from lignocellulosic hydrolysate: Membrane experiments & system dynamic modelling

A.R.P.P. Weerasuriya Arachchige*, L. Mezule and T. Juhna

Riga Technical University, Faculty of Civil Engineering, Department of Water Science and Technology, Paula Valdena street 1-204/205, LV-1048 Riga, Latvia
*Correspondence: antonrayan@hotmail.com

Abstract:

Separation of fermentable sugars after hydrolysis of lignocellulosic biomass plays a vital role in second-generation biofuel production. Byproducts and solid fractions generated during pretreatment and hydrolysis can have adverse effects on fermentation efficiency. Previous studies have shown that a maximum of 40% (w/w) of sugar yield can be obtained by sequential UF and NF permeate recovery. This study aimed to introduce a multi-step membrane filtration process to recover fermentable sugars while removing inhibitory bi-products. Fermentable sugar recovery was investigated using a recirculation flow between various stages of separation. The experimental results demonstrated that by introducing NF permeate recirculation to the UF unit a sequential UF/NF system can achieve 60% (w/w%) recovery of reducing sugars. Based on the experimental results, a ‘Simultaneous ultrafiltration and nanofiltration model’ was developed using system dynamics. The model was used to predict the final sugar concentration and sugar yield using sugar permeability in each membrane as the dynamic variability. The model predicts that high sugar permeability (or selective permeability) through the ultrafiltration mostly affects the efficiency of the system, which still is a challenge.

Key words:

, , ,



905–914 K. Tihomirova, V. Denisova, L. Jaudzema and L. Mezule
Hydrolysed biomass waste as a potential biosorbent of zinc from water
Abstract |
Full text PDF (297 KB)

Hydrolysed biomass waste as a potential biosorbent of zinc from water

K. Tihomirova*, V. Denisova, L. Jaudzema and L. Mezule

Riga Technical University, Faculty of Civil Engineering, Research Centre for Civil Engineering, Water Research Laboratory, Kipsalas 6a–263, LV–1048 Riga, Latvia
*Correspondence: kristina.tihomirova@rtu.lv

Abstract:

In the last 10 years recycling of various materials and metal recovery from waste with low cost biosorbents or agricultural biomass has become popular trend. Lignocellulosic biomass is regarded as a sustainable resource for biofuel production. In this process, lignocellulosic biomass is partly degraded during chemical or biological hydrolysis, as a result, these agricultural waste materials usually present a disposal problem and have no economic value. Therefore, reuse of lignocellulosic waste materials as inexpensive and alternative sorbent for heavy metals in polluted aqueous solution.
The aim of this research was to evaluate the applicability of hydrolysed biomass waste for zinc removal from water solution. To evaluate the potential use of lignocellulosic biomass for biosorption, experiments were performed with dry, washed from organic matter and hydrolysed hay. The results showed that hydrolysed hay have lower biosorption capacity than washed and dried hay, however, it still can be used as a low-cost biosorbent for the removal of Zn in polluted aqueous solutions, because it showed relatively high cink sorption capasity (336–391 mg g-1).

Key words:

, , , ,



897–904 M. Strods and L. Mezule
Alcohol recovery from fermentation broth with gas stripping: system experimental and optimisation
Abstract |
Full text PDF (268 KB)

Alcohol recovery from fermentation broth with gas stripping: system experimental and optimisation

M. Strods* and L. Mezule

Riga Technical University, Faculty of Civil Engineering, Research Centre for Civil Engineering, Water Research Laboratory, Kipsalas 6A–263, LV–1048 Riga, Latvia
*Correspondence: martins.strods_4@rtu.lv

Abstract:

Effective liquid biofuel production from various lignocellulosic waste resources is dependant not only on pre–treatment and hydrolysis but also on effective removal of alcohols from the fermentation media. Distillation and rectification is not suitable in low alcohol content systems (butanol production with clostridia) or in cases when the fermentation is performed in a continuous mode. One of the technologies offering continuous, in situ removal of alcohol is gas stripping. Despite the recognition of this technology, it is still under evaluation and adjustment. Thus, the aim of this study was to evaluate if gas stripping technology at rapid flow conditions is efficient enough to recover ethanol from the fermentation media. The results showed that 60 l min-1 flow rate was optimal to recover more than 45% of the available ethanol in 8 hours of stripping with nitrogen gas. The technology was efficient if the ethanol content in the fermentation broth was 10 wt%. At lower concentrations the recovery showed to be inefficient. Application of CO2 as the stripping gas was not suitable for ethanol recovery and should be tested prior use. In conclusion, the application of rapid N2 flow rate for gas stripping of ethanol from fermentation media showed to be an efficient technology and could replace long time, low flow rate stripping.

Key words:

, , ,



830–847 L. Rocha–Meneses, M. Raud, K. Orupõld and T. Kikas,
Second-generation bioethanol production: A review of strategies for waste valorisation
Abstract |
Full text PDF (694 KB)

Second-generation bioethanol production: A review of strategies for waste valorisation

L. Rocha–Meneses¹, M. Raud¹, K. Orupõld² and T. Kikas¹,*

¹ Institute of Technology, Estonian University of Life Sciences, Kreutzwaldi 56,
EE51014 Tartu, Estonia
² Institute of Agricultural and Environmental Sciences, Estonian University of Life
Sciences, Kreutzwaldi 5, EE51014 Tartu, Estonia
*Correspondence: Timo.Kikas@emu.ee

Abstract:

This paper reviews second–generation biofuel production chain and focuses on its energetic, economic and environmental impacts. The biggest challenge in the production of bioethanol from lignocellulosic material refers to the biomass waste that is left over after the separation of bioethanol in the distillation process. This waste still has high energetic value and could be further utilised to add value to the production chain. Furthermore, the environmental impact of untreated waste from bioethanol production is very high, which also requires attention. Anaerobic digestion of bioethanol production waste has been proposed as a possible solution to utilise the energetic potential of this waste and lower its environmental impact.

Key words:

, , , ,



1427-1434 L. Mezule, M. Strods and B. Dalecka
Influence of Mechanical Pre–treatment on Fermentable Sugar Production from Lignocellulosic Biomass
Abstract |
Full text PDF (323 KB)

Influence of Mechanical Pre–treatment on Fermentable Sugar Production from Lignocellulosic Biomass

L. Mezule*, M. Strods and B. Dalecka

Riga Technical University, Faculty of Civil Engineering, Research Centre for Civil Engineering, Water Research Laboratory, Kipsalas 6a–263, LV–1048 Riga, Latvia *Correspondence: linda.mezule@rtu.lv

Abstract:

Mechanical pre-treatment of lignocellulosic biomass has been extensively applied in biofuel production despite its high energy requirements. To balance the consumed energy with the energy produced, careful selection and evaluation of pre-treatment parameters, equipment and desired outcome is needed. The study aims to determine optimal hay and barley straw biomass particle size in view of sugar yields, energy consumption and treatment time. The results show that there is no significant difference (p > 0.05) in sugar yields from hay biomass with particle sizes 0.25 mm, 1 mm and 10 mm. Energy requirements for the production of 1 kg of sugar from hay range from 1.8–10.7 MJ. At the same time barley straw proved to be inappropriate for sugar extraction due to low sugar yields (below 40 mg g-1 dry mass) and high energy consumption (18.5–76.2 MJ to produce 1 kg sugar). Thus, after the careful selection of biomass, mechanical pre-treatment followed by enzymatic hydrolysis can be an effective technique in biofuel production from biomass.

Key words:

, , ,



1713-1719 K. Tihomirova, B. Dalecka and L. Mezule
Application of conventional HPLC RI technique for sugar analysis in hydrolysed hay
Abstract |
Full text PDF (254 KB)

Application of conventional HPLC RI technique for sugar analysis in hydrolysed hay

K. Tihomirova*, B. Dalecka and L. Mezule

Riga Technical University, Faculty of Civil Engineering, Research Centre for Civil Engineering, Water Research Laboratory, Kipsalas 6a–263, Riga LV–1048, Latvia
*Correspondence: kristina.tihomirova@rtu.lv

Abstract:

To determine the potential biofuel yield and necessary technological parameters a known concentration and type of fermentable sugars should be produced during chemical or biological extraction from lignocellulose. The most popular method for sugar interpretation and quantification is liquid chromatography (HPLC) using refractive index (RI) detector. The aim of this research was to show the applicability of the high–performance liquid chromatography using refractive index (HPLC RI) technique for sugar interpretation in hydrolysed hay and possible solutions for optimisation of this method. Analysis of hydrolysed hay with standard additive showed low recovery of sugar concentrations and inconsistencies with dinitrosalicylic acid (DNS) method, which was mostly due to low separation of peaks of these sugars on the chromatograms. As result HPLC RI method was useful for qualitative analysis of sugars only, not for its quantification.

Key words:

, , ,



287-293 B. Dalecka, M. Strods and L. Mezule
Production of fermentation feedstock from lignocellulosic biomass: applications of membrane separation
Abstract |
Full text PDF (297 KB)

Production of fermentation feedstock from lignocellulosic biomass: applications of membrane separation

B. Dalecka*, M. Strods and L. Mezule

Riga Technical University, Faculty of Civil Engineering, Department of Water Science and Technology, Azenes 16/20-263, LV1048 Riga, Latvia; *Correspondence: brigita.dalecka@gmail.com

Abstract:

The development of cost-efficient, highly productive technologies for fermentation feed production from lignocellulose biomass is still a challenge. In this paper, the production of fermentable sugars from lignocellulosic biomass using hydrolysis techniques with membrane separation systems is studied. The research was conducted on both a laboratory and pilot level to evaluate and optimize the efficiency of the proposed technology. The results demonstrated that UF and NF permeate recovery increased efficiency, and the highest sugar recovery rates were obtained when secondary waste recirculation was introduced after NF and UF, reaching an almost 40% yield from all produced sugars.

Key words:

, , ,



405-412 M. Raud, M. Tutt, J. Olt and T. Kikas
Effect of lignin content of lignocellulosic material on hydrolysis efficiency
Abstract |
Full text PDF (454 KB)

Effect of lignin content of lignocellulosic material on hydrolysis efficiency

M. Raud, M. Tutt, J. Olt and T. Kikas*

Estonian University of Life Sciences, Institute of Technology, Kreutzwaldi 56, EE51014 Tartu, Estonia; *Correspondence: timo.kikas@emu.ee

Abstract:

Lignocellulosic material is the most promising feedstock for bioethanol production; however, due to the varying physicochemical characteristics of different biomasses, it is necessary to select a biomass with a composition suitable for bioethanol production. For this purpose several different alternative non-food energy crops were chosen to investigate their suitability for bioethanol production, considering their cellulose, hemicellulose and lignin content. The traditional three-step bioethanol production process was used, where dilute acid was applied for biomass pre-treatment. Glucose and ethanol concentrations were measured during the process. Glucose and ethanol yields and hydrolysis efficiency were used to evaluate the suitability of different energy crops for bioethanol production. The results show that, with most biomass types, the glucose yield increases as the cellulose content in the biomass rises. However, a sharp decrease in hydrolysis efficiency was noted in the lignin content range of 7 to 9 g 100 g-1. The lower hydrolysis efficiency also resulted in a lower ethanol yield in the next step of the bioethanol production process for these samples.

Key words:

, , , ,



236-254 K. Ritslaid, A. Küüt and J. Olt
State of the Art in Bioethanol Production
Abstract |
Full text PDF (322 KB)

State of the Art in Bioethanol Production

K. Ritslaid¹, A. Küüt² and J. Olt²

¹ Estonian Aviation Academy,
58A Kreutzwaldi Str., EE51014 Tartu, Estonia;
² Institute of Technology, Estonian University of Life Sciences,
56 Kreutzwaldi Str., EE51014 Tartu;
e-mail, arne.kyyt@emu.ee

Abstract:

The objective of the present study is to provide an overview of available literature on problems and potential solutions in bioethanol production. The preparation of an overview of bioethanol as motor fuel requires knowledge of its chemical-physical properties and different production methods. The study points out the most popular opinions and test results to characterise the production of bioethanol. This overview considers potential methods for producing ethanol and production technologies suitable for ethanol as motor fuel, especially most recent achievements in converting carbohydrates into ethanol.

Key words:

, , , ,