Ioannis Skiadas

Ioannis Skiadas
Technical University of Denmark | DTU · Department of Chemical and Biochemical Engineering

PhD

About

96
Publications
17,857
Reads
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4,060
Citations
Citations since 2017
40 Research Items
2109 Citations
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
Additional affiliations
April 2015 - present
Technical University of Denmark
Position
  • Professor (Associate)
August 2008 - April 2015
Aalborg University
Position
  • Professor (Associate)
January 2004 - June 2006
University of Patras
Position
  • Research Associate

Publications

Publications (96)
Article
Biomethanation of biomass-derived syngas represents a promising bioenergy conversion technology that can be operated within integrated plants to deliver ancillary services such as carbon capture and storage (CCS), seasonal energy storage and fuel densification. In the present study, we developed a set of techno-economic process models considering s...
Article
The Extended UNIQUAC electrolyte activity coefficient model was used for modeling the aqueous terephthalic acid, disodium terephthalate, sodium chloride, sodium hydroxide, ethylene glycol system. Data for solid-liquid equilibrium (SLE) and vapor-liquid equilibrium (VLE) was used for determining the parameters of the model. Model parameters were det...
Article
Full-text available
The production of succinic acid from fermentation is a promising approach for obtaining building-block chemicals from renewable sources. However, the limited bio-succinic yield from fermentation and the complexity of purification has been making the bio-succinic acid production not competitive with petroleum-based succinic acid. Membrane electrolys...
Article
Full-text available
The increasing amount of seaweed accumulated in the coasts calls for a proper disposal or treatment in order to reduce secondary pollution effects. Anaerobic digestion of seaweed is a treatment technology that simultaneously produces biogas, supporting the further expansion of the renewable energy production through sustainable bioresources. In thi...
Article
Full-text available
Biomass gasification generates a gas mixture (syngas) that constitutes a rich source of carbon and energy for the production of second-generation renewable fuels such as biomethane. However, the produced syngas composition (H2/CO/CO2) cannot be converted to natural gas grade biomethane due to stoichiometric limitations, and a waste stream of CO2 is...
Article
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Contemporary challenges in decreasing Green House Gas emissions and finding alternative carbon and energy sources for fueling our society brought in the forefront processes based on biological conversions of gaseous substrates, such as syngas and carbon dioxide. Generation of synthesis gas or syngas (a gaseous mixture mainly of CO, H2 and CO2 gener...
Article
Full-text available
Globally, the reserves of heavy crude oil are seven times more abundant than that of light crude, and yet, they are underutilized because of their high viscosity and density, which is largely due to the presence of large amounts of asphaltenes. Biotransformation of heavy oil asphaltenes into smaller metabolites can be used for reducing their viscos...
Article
Plant saponins are attractive biosurfactants and have been used to enhance phytoremediation. There are only limited reports on saponins produced by bacteria. Here, we report structural and functional characterization of a novel saponin produced by Bacillus sp. IITD106. Biosurfactant production was determined by emulsion index, drop collapse, oil di...
Article
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Gas fermentation processes have attracted considerable attention in recent years as they hold high potential for capturing and converting C1 waste gases into a range of biofuels and commodity chemicals. The production of solvents in gas fermentation is typically achieved by exploiting the solventogenic metabolism of acetogenic cultures, which is ge...
Article
Biomethane constitutes an important biofuel for the transition towards a biobased circular economy with a sustainable energy sector. An environmentally friendly pathway for its production is through the gasification of 2nd generation biomass that generates syngas (H2, CO, and CO2), followed by syngas biomethanation. A novel design thermophilic tric...
Article
Full-text available
Swine manure mono-digestion results in relatively low methane productivity due to the low degradation rate of its solid fraction (manure fibers), and due to the high ammonia and water content. The aqueous ammonia soaking (AAS) pretreatment of manure fibers has been proposed for overcoming these limitations. In this study, continuous anaerobic diges...
Article
Full-text available
Forward Osmosis (FO) is a promising technology that can offer sustainable solutions in the biorefinery wastewater and desalination fields, via low energy water recovery. However, microbial biomass and organic matter accumulation on membrane surfaces can hinder the water recovery and potentially lead to total membrane blockage. Biofouling developmen...
Article
Full-text available
Aqueous ammonia soaking (AAS) at ambient temperature was applied to wheat straw under different conditions in order to maximize the CH4 yield through mesophilic anaerobic digestion. The effects of the NH3 concentration, duration of AAS and solid-to-liquid ratio were studied on the resulting CH4 yield and the solubilization degree of the pretreated...
Article
One of the factors limiting the economic viability of polyhydroxyalkanoates (PHA) is the low volumetric productivity obtained with second-generation feedstocks, resulting from their low carbon concentration. In the present study, the use of membrane bioreactors (MBRs) was evaluated as a strategy to retain the microbial cells in the reactor and to e...
Article
Over the last decades, the use of mixed microbial communities has attracted increasing scientific attention due to their potential biotechnological applications in several emerging technological platforms such as the carboxylate, bioplastic, syngas and bio-electrochemical synthesis platforms. However, this increasing interest has not been accompani...
Article
Syngas, mainly consisting of CO, H2 and CO2, can be generated from the gasification of biomass and organic waste and constitutes an important energy and carbon source. However, its biological conversion is still challenging due to the low solubility and the toxic nature of its components. In this study, enriched mixed microbial consortia were inocu...
Article
Full-text available
Mixed culture-based syngas biomethanation is a robust bioconversion process with high versatility in terms of exploitable feedstocks and potential applications, as it could be operated independently, or coupled to anaerobic digestion systems and in-situ biogas upgrading processes. Typically, the syngas biomethanation consists in the stepwise conver...
Article
Full-text available
Two identical trickle-bed reactor setups were designed and operated under mesophilic conditions and atmospheric pressure, without pH control, for the biomethanation of syngas consisted of 45% H2, 25% CO2, 20% CO and 10% CH4. The reactors were inoculated with mixed methanogenic microbial consortia formerly adapted to the gaseous mixture. During the...
Article
The syngas biomethanation process is a promising bioconversion route due to its high versatility, as it could be applied as a stand-alone technology, coupled to gasification plants, and integrated in anaerobic digestion or bioelectrochemical conversion systems. The biomethanation of syngas typically takes place through a rather complex network of i...
Article
BACKGROUND Purification of polyhydroxyalkanoates (PHA) is a challenging step, given the difficulty of achieving high PHA purity, while maintaining polymer integrity, in a sustainable and cost‐efficient manner. This study evaluated the potential of dilute ammonia digestion as a method to purify PHA from mixed microbial consortia. RESULTS Digestion...
Article
Full-text available
(1) Background: The continuously increasing demand for renewable energy sources renders anaerobic digestion as one of the most promising technologies for renewable energy production. Due to the animal production intensification, manure is being used as the primary feedstock for most biogas plants. Their economical profitable operation, however, rel...
Article
Syngas fermentation for fuels and chemicals is limited by the low rate of gas-to-liquid mass transfer. In this work, a unique bulk-gas-to-atomized-liquid (BGAL) contactor was developed to enhance mass transfer. In the BGAL system, liquid is atomized into discrete droplets, which significantly increases the interface between the liquid and bulk gas....
Article
BACKGROUND Clostridium pasteurianum is a well described strain for the conversion of glycerol into butanol. In general, cell growth kinetics depends on the type of glycerol used and the concentration of butanol in the fermentation broth. However, despite the numerous studies existing on the subject, there is limited information in the literature re...
Article
Full-text available
Forward osmosis (FO) is a low energy-intensive process since the driving force for water transport is the osmotic pressure difference, Δπ, between the feed and draw solutions, separated by the FO membrane, where πdraw > πfeed. The potential of FO in wastewater treatment and desalination have been extensively studied; however, regeneration of the dr...
Article
Full-text available
Background: The production of ethanol through the biochemical conversion of syngas, a mixture of H2, CO and CO2, has been typically studied using pure cultures. However, mixed microbial consortia may offer a series of benefits such as higher resilience and adaptive capacity, and non-sterile operation, all of which contribute to reducing the utilit...
Article
Implementation of biofuels as an alternative to fossil fuels has been established as an answer to climate change by limiting GHG emissions. Syngas fermentation has emerged as a promising process for the conversion of waste biomasses to valuable products with bioethanol being on the main focus. However, the bottleneck of the mass transfer of syngas...
Article
Full-text available
Crude glycerol (CG), an abundant by-product of bio-diesel production, has been identified as a suitable co-substrate for improving the biogas production of livestock manure through anaerobic digestion (AD). In this study, the potential of utilizing CG generated from the esterification of animal fats for biogas production was studied in both batch a...
Article
This study investigated the possibility to perform statistical optimization of an enriched mixed microbial consortium, MMC, fed in continuous with a highly inhibiting 2G glycerol, for the joint production of 1,3 propanediol (1,3 PDO) and butyric acid (BuA). Key variables taken into consideration were HRT, pH and feed concentration. The optimized pr...
Article
Crude glycerol is an important by-product of the biodiesel industry, which can be converted into volatile fatty acids (VFA) and/or 1,3-propanediol (1,3-PDO) by fermentation. In this study, a selective conversion of VFA to polyhydroxyalkanoates (PHA) was attained while leaving 1,3-PDO in the supernatant by means of mixed microbial consortia selectio...
Article
Significant research efforts are currently being made worldwide to develop more efficient biomethane production processes from a variety of waste streams. The biomethanation of biomass-derived syngas can contribute to increasing the potential of methane production as it opens the way for the conversion of recalcitrant biomasses, generally not fully...
Article
The economic feasibility of biochemical conversion of wheat straw to butyric acid was studied in this work. Basic process steps included physicochemical pretreatment, enzymatic hydrolysis and saccharification, fermentation with in-situ acids separation by electrodialysis and product purification. Two scenarios (S1 and S2) were examined assuming a p...
Article
Crude glycerol, a by-product from the biodiesel industry, can be converted by mixed microbial consortia into 1,3-propanediol (1,3-PDO) and volatile fatty acids. In this study, further conversion of these main products into polyhydroxyalkanoates (PHA) was investigated with the focus on 1,3-PDO. Two different approaches for the enrichment of PHA accu...
Article
(FREE ACCESS to the article. Anyone clicking on this link before November 25, 2017 https://authors.elsevier.com/c/1VrDy,V9BZ6ufx) This study investigated the performance of different mixed microbial cultures (MMC) able to ferment crude glycerol generated from animal fat-based biodiesel to produce 1,3 propanediol (1,3 PDO) and butyric acid, under no...
Article
Full-text available
Swine manure mono-digestion often results to economically non-feasible processes, due to the high dilution and ammonia concentration together with the low degradation rates it presents. The effects of different parameters of Aqueous Ammonia Soaking (AAS) as a pretreatment for improving the digestion of manure fibers when coupled to an ammonia remov...
Article
A great amount of research has been performed during the last 10 years focusing on forward osmosis (FO) processes. The main driving force is to find an effective and low energy demanding methodology for water recovery as well as up-concentration of valuable products. Nevertheless, the energetic and financial benefits of this technology can be under...
Article
Anaerobic digestion of manure fibers presents challenges due to their low biodegradability. Aqueous ammonia soaking (AAS) has been tested as a simple method to disrupt the lignocellulose and increase the methane yield of manure fibers. In the present study, mesophilic anaerobic digestion of AAS pretreated manure fibers was performed in CSTR-type di...
Article
Spent coffee grounds (SCG) are an abundant by-product of the coffee industry with a complex composition that makes them a promising feedstock for a biorefinery. The objective of this study was to evaluate SCG as a substrate for combined chlorogenic acid and bioethanol production after dilute acid hydrolysis. The effect of phenolics extraction on th...
Article
Full-text available
In the present study, the effect of potassium ions and increasing concentrations of glucose and xylose on the growth of a strain of Clostridium tyrobutyricum, adapted to wheat straw hydrolysate, was investigated. Application of continuous fermentation of a mixture of glucose and xylose and in situ acid removal by reverse electro enhanced dialysis (...
Article
Full-text available
Objective of this study was the selection and adaptation of mixed microbial cultures (MMCs), able to ferment crude glycerol generated from animal fat-based biodiesel and produce building-blocks and green chemicals. Various adaptation strategies have been investigated for the enrichment of suitable and stable MMC, trying to overcome inhibition probl...
Data
Graphical representation of the change in composition of mixed microbial cultures, at the major levels of taxonomic classification (species, genus, family, order, class, and phylum). Results from batch transfer during the enrichment of activated sludge, and for the anaerobic sludge enriched on hexane-pretreated crude glycerol in batch tests and wit...
Article
Full-text available
Laboratory experiments have shown that aqueous ammonia soaking (AAS) is a promising treatment for increasing the methane yield of the solid fraction of manure (fibers). AMMONOX is a new concept based on the sustainable use of ammonia for enhancing biogas production at biogas plants digesting manure. The proposed process is based on an optimized AAS...
Article
In the present study aqueous ammonia soaking (AAS) has been tested as a pretreatment method for the anaerobic digestion of three lignocellulosic biomasses of different origin: one agricultural residue: sunflower straw, one perennial crop: grass and a hardwood: poplar sawdust. The methane production yield was evaluated in batch experiments at differ...
Article
Full-text available
The present study focused on fermentative butyric acid production by Clostridium tyrobutyricum from pre-treated and hydrolysed wheat straw (PHWS) based on continuous operation mode and in situ acids extraction by reverse electro enhanced dialysis (REED). Different dilutions of PHWS in a synthetic medium (60–100 % v/v) were tested. It was found that...
Conference Paper
Full-text available
A major step towards the development of a sustainable industrial society is a shift from petroleum-based resources to renewable resources. An ongoing effort is focused on developing bio-refineries as an alternative way of producing fuels and chemical building-blocks from renewable resources. Thus, today’s organic residues and wastes may become tomo...
Conference Paper
Laboratory experiments have shown that Aqueous Ammonia Soaking (AAS) is a very promising treatment for increasing the methane yield of the solid fraction of manure (fibers). AMMONOX is a new concept based on the sustainable use of ammonia for enhancing biogas production at biogas plants digesting manure. The proposed process is based on an optimize...
Article
Full-text available
The continuously increasing demand for renewable energy sources renders anaerobic digestion one of the most promising technologies for renewable energy production. Due to the animal production intensification, manure is being used as the primary feedstock for most biogas plants. Thus, their economical profitable operation relies on increasing the m...
Conference Paper
For a couple a decades, in the frame of bio-based chemicals and materials, there has been focus on biological butyric acid production due to the wide application of butyric acid in chemical, pharmaceutical and food industries. Major challenges for biological production are strain selection and development, and process improvement for higher yield,...
Article
The necessity of increasing the methane productivity of manure based biogas plants has triggered the application of anaerobic digestion to the separated solid fraction of manure, with the challenge that its high lignocellulosic fibers content is difficult to digest and thus makes anaerobic digestion process slow and economically unfavourable. In th...
Article
The increasing demand for methane production cannot be satisfied by the use of anaerobic digestion only from waste/wastewater treatment. Perennial energy crops, such as miscanthus and willow, as well as agricultural residues can be considered as options for increasing the methane production through biomass digestion, due to their high organic conte...
Article
Export Date: 24 April 2013, Source: Scopus, CODEN: IJHED, :doi 10.1016/j.ijhydene.2011.09.081, Language of Original Document: English, Correspondence Address: Gavala, H.N.; Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University Copenhagen (AAU Cph), Lautrupvang 15, DK 2750, Ballerup, Denmark; email: hari_gavala@yah...
Article
The present study focused on the application of the Anaerobic Digestion Model 1 on the methane production from acidified sorghum extract generated from a hydrogen producing bioreactor in a two-stage anaerobic process. The kinetic parameters for hydrogen and volatile fatty acids consumption were estimated through fitting of the model equations to th...
Article
The aim of the present study was to assess the influence of substrate concentration on the fermentative hydrogen production from sweet sorghum extract, in a continuous stirred tank bioreactor. The reactor was operated at a Hydraulic Retention Time (HRT) of 12 h and carbohydrate concentrations ranging from 9.89 to 20.99 g/L, in glucose equivalents....
Article
Cited By (since 1996):15, Export Date: 24 April 2013, Source: Scopus, CODEN: IJHED, :doi 10.1016/j.ijhydene.2009.12.175, Language of Original Document: English, Correspondence Address: Antonopoulou, G.; Department of Chemical Engineering, University of Patras, 1 Karatheodori st, GR 26500 Patras, Greece; email: geogant@chemeng.upatras.gr, References...
Article
Renewable energy sources have received increased interest from the international community with biomass being one of the oldest and the most promising ones. In the concept of exploitation of agro-industrial residues, the present study investigates the pre-treatment and ethanol fermentation potential of the olive pulp, which is the semi solid residu...
Article
This paper deals with a biorefinery classification approach developed within International Energy Agency (IEA) Bioenergy Task 42. Since production of transportation biofuels is seen as the driving force for future biorefinery developments, a selection of the most interesting transportation biofuels until 2020 is based on their characteristics to be...
Article
The continuously increasing demand for renewable energy sources renders anaerobic digestion to one of the most promising technologies for renewable energy production. Twenty-two (22) large-scale biogas plants are currently under operation in Denmark. Most of these plants use manure as the primary feedstock but their economical profitable operation...
Article
The present study focused on the anaerobic biohydrogen production from olive pulp (two phase olive mill wastes, TPOMW) and the subsequent anaerobic treatment of the effluent for methane production under mesophilic conditions in a two-stage process. Biohydrogen production from water-diluted (1:4) olive pulp was investigated at hydraulic retention ti...
Article
The present study focuses on a two-step process for treatment and stabilisation of primary sludge. The process consists of a hyper-thermophilic hydrolysis step operated at 70 degrees C and a hydraulic retention time (HRT) of 2 days followed by a thermophilic (55 degrees C) anaerobic digestion step at a HRT of 13 days. A one-step anaerobic digester...
Article
Full-text available
Perennial crops need far less energy to plant, require less fertilizer and pesticides, and show a lower negative environmental impact compared with annual crops like for example corn. This makes the cultivation of perennial crops as energy crops more sustainable than the use of annual crops. The conversion into biogas in anaerobic digestion plants...
Article
The present study focuses on the exploitation of sweet sorghum biomass as a source for hydrogen and methane. Fermentative hydrogen production from the sugars of sweet sorghum extract was investigated at different hydraulic retention times (HRT). The subsequent methane production from the effluent of the hydrogenogenic process and the methane potent...
Article
The low ethanol tolerance of thermophilic anaerobic bacteria (<2%, v/v) is a major obstacle for their industrial exploitation for ethanol production. The ethanol tolerance of the thermophilic anaerobic ethanol-producing strain Thermoanaerobacter A10 was studied during batch tests of xylose fermentation at a temperature range of 50-70 degrees C with...
Article
Full-text available
The present study focuses on the exploitation of sweet sorghum biomass as a source for hydrogen in continuous and batch systems. Sweet sorghum is an annual C4 plant of tropical origin, well-adapted to sub-tropical and temperate regions and highly productive in biomass. Sweet sorghum biomass is rich in readily fermentable sugars and thus it can be c...