Tag Archives: anaerobic digestion

674–679 V. Dubrovskis and I. Plume
Suitability of oat bran for methane production
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Suitability of oat bran for methane production

V. Dubrovskis* and I. Plume

Latvia University of Agriculture, Faculty of Engineering, Institute of Energetics, Cakstes blvd 5, LV 3001 Jelgava, Latvia
*Correspondence: vilisd@inbox.lv

Abstract:

There is need to investigate the suitability of various cheaper biomasses for energy production. It is necessary to explore ways to improve the anaerobic fermentation process with the help of various catalysts. Biocatalyst Metaferm produced in Latvia previous studies with other biomass gave an increase in production. The purpose of study is evaluation of suitability of granular and crushed oat bran waste biomass for the production of methane and influence of catalyst Metaferm on anaerobic digestion (AD) process. The biomass anaerobic digestion process was investigated in 0.75 L digesters, operated in batch mode at temperature 38 ± 1.0 °C. The average biogas yield per unit of dry organic matter added (DOM) from digestion of granular oat bran was 0.400 L g-1 DOM and methane yield was 0.193 L g-1 DOM. Average biogas yield from digestion of crushed oat bran was 0.439 L L g-1 DOM and specific methane yield was 0.193 L L g-1 DOM. Adding of 1 mL Metaferm in substrates with not crushed or crushed oat bran increases specific methane yield by 0.227 L g-1
DOM or 0.236 L g-1 DOM respectively. Investigated oat bran can be used for methane production, but methane production was less than from traditional biomass, e.g. maize silage.

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830–847 L. Rocha–Meneses, M. Raud, K. Orupõld and T. Kikas,
Second-generation bioethanol production: A review of strategies for waste valorisation
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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.

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376–387 M. Collotta and G. Tomasoni
The economic sustainability of small–scale biogas plants in the Italian context: the case of the cover slab technology
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The economic sustainability of small–scale biogas plants in the Italian context: the case of the cover slab technology

M. Collotta* and G. Tomasoni

University of Brescia, Department of Mechanical and Industrial Engineering, Via Branze 38, IT25123 Brescia, Italy
*Corresponding author: m.collotta@unibs.it

Abstract:

The growing interest on renewable energies, together with the public financial incentive systems established in several countries, has driven a fast innovation in the field of energy technologies, with the main objective to increase their sustainability.
This paper focuses on the production of biogas from agro–residues and animal manure; with particular attention to small-scale plants.
Based on a real case located in northern Italy, and taking into consideration the Italian public  financial incentive system currently in force, the economic profitability of the cover slab technology is analysed, putting into evidence the main factors that affect it.

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069–078 V. Dubrovskis and I. Plume
Biogas from wastes of pumpkin, marrow and apple
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Biogas from wastes of pumpkin, marrow and apple

V. Dubrovskis* and I. Plume

Latvia University of Agriculture, Faculty of Engineering, Institute of Energetics, Cakstes blvd 5, LV 3001 Jelgava, Latvia
*Correspondence: vilisd@inbox.lv

Abstract:

A lot of vegetables and fruits, which have been grown in Latvia or were imported from foreign countries, become waste, often due to unconformity to the marketing standards or biodegradation process fouling during storage. Waste biomass piles emissions during storage that contributes to global warming. It is appropriate to use such biomass as raw material for anaerobic digestion. This article shows the results of studies on evaluation of suitability of vegetable and fruit waste biomass for the production of biogas. Anaerobic digestion was investigated in 0.75 L digesters, operated in batch mode at a temperature of 38 ± 1.0 °C. The average biogas yield per mass unit of dry organic matter added (DOM) from digestion of pumpkin biomass was 1.095 L g-1DOM and the specific methane yield was 0.422 L g-1DOM. Average biogas yield from digestion of marrow biomass was 0.768 L g-1ODM and the methane yield was 0.274 L g-1DOM. Average biogas yield from digestion of apple biomass was 1.020 L g-1DOM and the methane yield was 0.451 L g-1DOM. All investigated wastes can be a very good source for biogas production. Anaerobic digestion may be a solution to treat waste biomass from food production facilities or supermarkets.

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1548-1561 I. Černá, J. Pecen, T. Ivanova and Z. Piksa
The dependence of the durability of digestate briquettes and sorption properties on represented particle sizes
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The dependence of the durability of digestate briquettes and sorption properties on represented particle sizes

I. Černá, J. Pecen, T. Ivanova* and Z. Piksa

Czech University of Life Sciences Prague, Faculty of Tropical AgriSciences, Department of Sustainable Technologies, Kamýcká 129, CZ 16521 Prague 6, Czech Republic
*Correspondence: ivanova@ftz.czu.cz

Abstract:

Digestate, a product of the anaerobic digestion process, is traditionally used as liquid fertiliser. Besides agriculture use, it became possible to dry its separated solid part and compress it into briquette or pellet form. In the context of the characterisation of briquettes, the description here largely covers the mechanical properties of texture components and the distribution of particles within the briquette space. In order to define these properties and understand the relations between the mechanical part and any influencing factors, researchers started to identify the relationship between particles size distribution in briquettes and sorption properties and therefore mechanical properties. The objective of the present research was to compare size distribution in particles in different digestate samples and to study the connection to water sorption by briquettes and the durability of briquettes that have been made from two kinds of digestate material. For a comparison, two types of digestate were used, for which particles were split into a few size files according to the sieve size. By using digital image analysis, the dimensions of particles were specified and compared with values that were measured by means of a calliper. Sorption properties were defined through experimentation: exposing briquettes to a water source with water adsorption being determined via moisture content. Other mechanical properties were represented by toughness and the rate of abrasion. As result, digestate is an appropriate sorption matter which can multiply its initial mass by a factor of five if the water supply is sufficient. In the case of a dimension measurement of particles, digestate texture is represented by particles with one prevalent dimension, in most cases this being length. The length of particles was between approximately 1mm to 9mm. The digestate has been proven to be a good water sorbent material and can be applied in various sectors of agriculture.

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745–753 V. Dubrovskis and I. Plume
Microalgae for biomethane production
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Microalgae for biomethane production

V. Dubrovskis* and I. Plume

Latvia University of Agriculture, Faculty of Engineering, Institute of Energetics, Cakstes blvd 5, LV 3001 Jelgava, Latvia; *Correspondence: vilisd@inbox.lv

Abstract:

 Competition for arable land between food and energy producers has begun in Latvia. Biogas producers are seeking to use the hitherto unused land. There is a need to investigate the suitability of various biomasses for energy production. Maize is the dominating crop for biogas production in Latvia, but it is expensive to grow. The cultivation of more varied biomass with good economics and low environmental impact is thus desirable. Microalgae can be grown in pipes, basins and also in open ponds. This paper shows the results from the anaerobic digestion of microalgae Chlorella vulgaris, cultivated with fertilizer Varicon in open pond and harvested on 27 October and centrifuged (Study 1). The anaerobic digestion process was investigated for biogas production in sixteen 0.75 l digesters, operated in batch mode at temperature 38 ± 1.0 °C. The average methane yield per unit of dry organic matter added (DOM) from digestion of Chlorella vulgaris was 0.331 l gDOM-1. The second investigation (Study 2) used fresh biomass of Chlorella vulgaris harvested on 10–15 June with low dry matter content, as it was obtained from 4 m deep open pond without centrifugation. Anaerobic digestion process was provided in 4 digesters with volume of 5 l each. Average methane yield from the digestion of Chlorella vulgaris was 0.290 l gDOM-1, which is comparable to methane yield obtainable from maize silage or other energy crop silages. Microalgae Chlorella vulgaris can be successfully cultivated for biogas production from May to October or at least 170–180 days in a year under the agro-ecological conditions in Latvia.

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25-32 V. Dubrovskis and I. Plume
Biogas production from sugar rich waste
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Biogas production from sugar rich waste

V. Dubrovskis* and I. Plume

Latvia University of Agriculture, Faculty of Engineering, Institute of Energetics, Cakstes blvd 5, LV 3001 Jelgava, Latvia;
*Correspondence: vilisd@inbox.lv

Abstract:

56 biogas plants are working today in Latvia. There is need to investigate the suitability of various biomasses for energy production. Sweets production factories by-products are organic waste and wastewater featuring a high sugar content. Wastewater have a high chemical oxygen demand (COD) level and requires special treatment that results in additional input of energy and financial resources. 

This article shows the results of two studies evaluating sugar-containing biomass suitability for the production of biogas.
The anaerobic digestion process of damaged jam and sweets factory wastewater was investigated for biogas production in 0.75 L digesters, operated in batch mode at temperature 38 ± 0.1 °C. The average biogas yield per unit of organic dry matter (ODM) from digestion of damaged jam was 1.114 L g-1ODM and methane yield was 0.716 L g-1ODM. Average biogas yield from digestion of sweets production factory wastewater was 1.058 L g-1ODM and methane yield was 0.663 L g-1ODM. All investigated sugar rich wastes can be utilised for biogas production successfully thus providing an environmental solution for wastewater problem of sweets production factories.

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294-302 V. Dubrovskis and I. Plume
Anaerobic digestion of vegetables processing wastes with catalyst metaferm
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Anaerobic digestion of vegetables processing wastes with catalyst metaferm

V. Dubrovskis* and I. Plume

Latvia University of Agriculture, Faculty of Engineering, Institute of Agriculture Energetics, 5, Cakstesblvd, LV3001 Jelgava, Latvia *Correspondence: vilisd@inbox.lv

Abstract:

There are 54 active biogas plants in Latvia today. It is necessary to investigate the suitability of various biomasses for energy production. Maize is the dominating crop for biogas production in Latvia. The cultivation of more varied crops with good economical characteristics and a low environmental impact is thus desirable. One of the ways for improving biogas yield in Latvian conditions is using biological catalysts. This paper explores the results of the anaerobic digestion of vegetables’ processing wastes using the new biological catalyst Metaferm. The digestion process was investigated in view of biogas production in sixteen 0.7 l digesters operated in batch mode at the temperature of 38 ± 1.0 °C. The average methane yield per unit of dry organic matter added (DOM) from the digestion of onions was 0.433 l g–1DOM; with 1 ml ofMetaferm: 0.396 l g–1–1DOM, and with 2 ml of Metaferm: 0.394 l gDOM . The average methane yieldfrom the digestion of carrots was 0.325 l g–1–1DOM; with 1 ml of Metaferm: 0.498 l gDOM , and with2 ml of Metaferm: 0.426 l g–1DOM. The average additional methane yield per unit of dry organicmatter from the digestion of 50%:50% mixed onions and carrots was 0.382 l g–1DOMwith 2 mlof Metaferm. The average additional methane yield per unit of dry organic matter from the digestion of cabbage leftovers was 0.325 l g–1–1DOM; with 1 ml of Metaferm: 0.375 l gDOM , andwith 2 ml of Metaferm: 0.415 l g–1DOM. The average additional methane yield per unit of dryorganic matter from the digestion of potato cuttings was 0.570 l g–1DOM; with 1 ml ofMetaferm: 0.551 l g–1–1DOM, and with 2 ml of Metaferm:0.667 l gDOM . The average additionalmethane yield per unit of dry organic matter from the digestion of 50%:50% mixed cabbages and potatoes was 0.613 l g–1DOMwith 2 ml of Metaferm. All investigated vegetable wastes canbe successfully cultivated for energy production under agro-ecological conditions in Latvia. Adding the catalyst Metaferm increased methane yield, except for onions.

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372-381 S. Pehme and E. Veromann
Environmental consequences of anaerobic digestion of manure with different co-substrates to produce bioenergy: A review of life cycle assessments
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Environmental consequences of anaerobic digestion of manure with different co-substrates to produce bioenergy: A review of life cycle assessments

S. Pehme* and E. Veromann

Estonian University of Life Sciences, Kreutzwaldi 1, EE51014 Tartu, Estonia; *Correspondence: sirli.pehme@emu.ee

Abstract:

Consequential life cycle assessment approach is needed to assess the environmental impacts of increase in biogas production. To see the full impacts of anaerobic co-digestion all possible environmental consequences caused by this change, i.e. the impacts of changed management and possible substitution impacts of substrates, should be taken into account. Generally anaerobic digestion of manure shows great environmental benefit instead of managing it conventionally, especially for the global warming potential. Environmental performance of co-digestion depends strongly on the initial use of the substrate. Co-digestion with wastes/residues has a great potential to produce bioenergy and reduce global warming potential. Co-digestion with land dependant special energy crops increases the bioenergy output but also increases the environmental impacts due to the need to substitute the substrate and thus should be avoided or limited.

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526-532 K. Rugele,, G. Bumanis, L. Mezule, T. Juhna and D. Bajare
Application of industrial wastes in renewable energy production
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Application of industrial wastes in renewable energy production

K. Rugele¹⋅²,*, G. Bumanis³, L. Mezule¹, T. Juhna¹ and D. Bajare³

¹Riga Technical University, Faculty of Civil Engineering, Department of Water Engineering and Technology, Kalku 1, LV1047 Riga, Latvia
²Riga Technical University, Faculty of Materials Science and Applied Chemistry, Institute of General Chemical Engineering, Kalku 1, LV1047 Riga, Latvia,
³Riga Technical University, Faculty of Civil Engineering, Department of Building Materials and Products, Kalku 1, LV1047 Riga, Latvia *Correspondence: kristine.rugele@rtu.lv

Abstract:

This research focuses on the industrial waste application as raw materials to create composite material and its characterisation for their possible application in anaerobic digestion. As the limitation of effective biogas digestion process is associated with inhibition of the some elements and acidification of biodegradable organic matter, therefore a highly porous alkaline composite material was evaluated in this research as buffer capacity increasing material. Batch experiments were provided with composite material additive in anaerobic digesters. Results indicate that alkaline composite materials in anaerobic digesters treated acidic whey could increase BMP up to 22%, but pH value could be kept in the optimal range (7.2–7.4) to ensure the effective digestion process.

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