Thomas Kotsopoulos - Academia.edu (original) (raw)

Papers by Thomas Kotsopoulos

Bioresource Technology, 2021

Three continuously stirred-tank reactors fed with manure operating under high ammonia levels (5.0... more Three continuously stirred-tank reactors fed with manure operating under high ammonia levels (5.0 g NH3-N L-1) and with increased organic loading rate (OLR), (2.09 R1, 3.02 R2 and 4.0 R3 g VS L-1 d-1), achieved through glucose amendment in R2 and R3, were inoculated with an ammonia-acclimatized microbial culture. Successful bioaugmentation was endured only in R2 and R3, both reactors characterized by high OLR, resulting in 19.6 and 24.5% increase in methane production, respectively. The high OLRs in these reactors favored the co-occurrence of the hydrogenotrophic (Methanobacteriaceae), methylotrophic (Methanomethylophilaceae) and aceticlastic methanogenic pathways. The latter was supported by the successful establishment of ammonium-tolerant Methanosarcina, prevailing in the inoculum. Oppositely in R1, the low OLR prevented the establishment of Methanosarcina, leading to an exclusive hydrogenotrophic methanogenesis and reduced methane production. HRT shortening resulted in limited effect on biomethane performance, indicating a well establishment of the introduced bioaugmentation culture in the reactors.

Green Energy and Sustainability

Background: Today there is a variety of desalination systems supporting the production of water f... more Background: Today there is a variety of desalination systems supporting the production of water for agricultural uses. However, these systems are still characterized by relatively high installation and operation costs and are not particularly suitable for isolated areas. The present work proposes the development and operation of an innovative and sustainable greenhouse structure that utilizes simultaneously its roof to produce irrigation water, with the method of solar desalination, and its inside space to house livestock and poultry. Aims: The main objective of this work is to study the agricultural livestock uses that can be welcomed by this greenhouse-solar desalination construction. The design and operation of this unit aims to produce irrigation water in arid areas, creating significant environmental and social benefits by protecting the water resources of these areas as well and by developing agricultural economic activity in drought conditions. Moreover, multiple land use suc...

The effect of the natural zeolites on anaerobic decomposition of swine waste was investigated. Es... more The effect of the natural zeolites on anaerobic decomposition of swine waste was investigated. Especially the effect of the addition of zeolite, on different amounts, on the increase of energy yield of waste (more methane production in shorter the attribution of the energy in short time) was examined. On top of this, the impact of the addition of zeolite on the reduction of total solids as well as on the reduction of volatile solids and on BOD5 (environmental factors) was, also, investigated. Two preliminary measurements were conducted in order to be used for the design of the main experiment. The duration of each preliminary measurement was 30 days. The results of the above measurements were used as guides for both: a) the amounts of zeolite which were used in the main experiment, and b) the duration of each replication. The doses of zeolite which decided for the main experiment were 0, 4, 8, 12 g zeolite / l waste. The main experiment included 5 replications in time. The duration ...

World Academy of Science, Engineering and Technology, International Journal of Environmental and Ecological Engineering, 2015

Journal of Chemical Technology & Biotechnology, 2020

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Energy and Buildings, 2019

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights  Passive techniques and systems can reduce heat gains on livestock buildings  Shading plays a major role on the cooling of livestock buildings  Initial architecture design leads to energy conservation for cooling  Natural ventilation decreases the temperature levels in a livestock structure  Passive techniques in urban buildings might be suitable for livestock buildings

Acta Horticulturae, 2017

The wind flow over a greenhouse structure is a complex and complicated phenomenon which mainly de... more The wind flow over a greenhouse structure is a complex and complicated phenomenon which mainly depends on the wind characteristics (speed, direction etc.), the geometry of the structure and the type of the greenhouse. One of the main stress factors of the bearing structure of the greenhouse is the wind. For the calculation of the wind load, the wind pressure coefficient (c p) is used. A high pressure coefficient value leads to an increase of the construction weight and subsequently to an increase in the construction cost. This value must satisfy two requirements: the safety of the structure and a reduced construction cost. The ventilation flow pattern is the link between the outdoor environment and the agriculture structures microclimate. The experimental studies require expensive technical facilities and are often supplemented with numerical approaches based on modeling. Computational fluid dynamics (CFD) provides an alternative approach to calculate ventilation rates and detailed airflow distributions in and around greenhouses. The aim of this work was to investigate how the ventilation openings position affects the pressure coefficient values inside and outside of a greenhouse. Therefore, a CFD study was conducted to investigate the influence of steady flow in different Reynolds numbers on local pressure coefficients computed on a single duo pitched roof greenhouse with and without ventilation roof openings. The Navier-Stokes and continuity equations were solved numerically with the finite element method (Galerkin Method) in order to simulate the two dimensional, incompressible, viscous air flow. Numerical results, such as streamlines, distributions of stream wise (u) and crosswise (v) velocities, as well as the distributions of the pressure coefficient are presented in detail.

Science and Technology for the Built Environment, 2016

The present work studied, numerically, the airflow inside and outside an agricultural structure w... more The present work studied, numerically, the airflow inside and outside an agricultural structure with openings. The governing Navier-Stokes and continuity equations were solved with finite

Journal of Chemical Technology & Biotechnology, 2016

BACKGROUND The baker's yeast industry is a major market and due to the intensified production... more BACKGROUND The baker's yeast industry is a major market and due to the intensified production large quantities of waste are generated. Wastewater from the baker's yeast industry with high content of molasses was treated anaerobically in an upflow anaerobic sludge blanket (UASB) reactor for the production of methane (CH4). RESULTS The molasses wastewater obtained from industry had a high pH value around 8.0 ± 0.5, which remained constant during the experimental period. The system was operated at an organic loading rate (OLR) of 2.4–7.65 g of volatile solids per liter per day (g VS L−1 d−1) and the best results were observed at 4 g VS L−1 d−1, where methane production exceeded 350 L CH4 kg−1 VS. Anaerobic chemical oxygen demand removal was also examined and it was found that for the latter conditions of optimum OLR, it was more than 35%. VFA analysis revealed that acetic acid concentration in the reactor was more than 25 mmol L−1 even under optimum conditions. CONCLUSIONS The tested hydraulic retention time (HRT) values did not affect methane production, unlike the OLR. The increased acetic acid concentration in the UASB reactor and the high pH were credited to the inhibition of aceticlastic microorganisms. © 2016 Society of Chemical Industry

Applied microbiology and biotechnology, Jan 4, 2016

In this study, a novel process for phosphorus (P) recovery without excess sludge production from ... more In this study, a novel process for phosphorus (P) recovery without excess sludge production from granular sludge in simultaneous nitrification-denitrification and P removal (SNDPR) system is presented. Aerobic microbial granules were successfully cultivated in an alternating aerobic-anaerobic sequencing batch reactor (SBR) for removing P and nitrogen (N). Dense and stable granular sludge was created, and the SBR system showed good performance in terms of P and N removal. The removal efficiency was approximately 65.22 % for N, and P was completely removed under stable operating conditions. Afterward, new operating conditions were applied in order to enhance P recovering without excess sludge production. The initial SBR system was equipped with a batch reactor and a non-woven cloth filter, and 1.37 g of CH3COONa·3H2O was added to the batch reactor after mixing it with 1 L of sludge derived from the SBR reactor to enhance P release in the liquid fraction, this comprises the new system ...

Biotechnology and Bioengineering, 2006

Hyper-thermophilic hydrogen production without methane was demonstrated for the first time in gra... more Hyper-thermophilic hydrogen production without methane was demonstrated for the first time in granular up-flow anaerobic sludge blanket (UASB) system fed with glucose using mixed cultures. The maximum hydrogen yield in this study was 2.47 +/- 0.15 mol H2/mol glucose. This high yield has never been previously reported in mixed culture systems and it was likely due to more favorable thermodynamic conditions at hyper-thermophilic temperatures. Different start-up strategies (bromoethanosulfonate (BES) addition and flow recycle) were evaluated. BES addition during start-up prevented the establishment of methanogenic cultures in granules. Flow recycle was important to achieve higher hydrogen yield through enriching better hydrogen-producing organisms and reduced the start-up period as well. This study indicated UASB system was a promising system for hydrogen production.

Energy and Buildings, 2015

An innovative hybrid solar heating system for farrowing houses was investigated in terms of energ... more An innovative hybrid solar heating system for farrowing houses was investigated in terms of energy performance. The hybrid solar system consisted of a roof solar collector, a solar mass wall, one heat storage tank, one heat supply tank and a creep heating slatted floor. The experimental period for the evaluation of the system performance had a duration of eight months; this period was to include both warm and cold periods within a year. During the warm period around 70% of the heating needs were supplied by this system, while during the cold period the achieved energy saving was approximately 25-30%. The performance of the roof solar collector was better for the creep heating than the performance of the mass solar absorber throughout the experimental period, in fact the latter contributed more to the heating of the farrowing room. It was also found, that a larger heating storage is necessary for this system in order to achieve improved performance of the excess energy produced during daylight. The results of this research will encourage the promotion of this system as a more economical and ecological for heating livestock buildings.

Sustainability, 2021

Wastewater treatment plants have been traditionally developed for the aerobic degradation of effl... more Wastewater treatment plants have been traditionally developed for the aerobic degradation of effluent organic matter, and are associated with high energy consumption. The adoption of sustainable development targets favors the utilization of every available energy source, and the current work aims at the identification of biomethane potential from non-conventional sources derived from municipal wastewater treatment processes. Byproducts derived from the primary treatment process stage were collected from four sewage treatment plants in Greece with great variation in design capacity and servicing areas with wide human activities, affecting the quality of the influents and the corresponding primary wastes. The samples were characterized for the determination of their solids and fats content, as well as the concentration of leached organic matter and nutrients, and were subjected to anaerobic digestion treatment for the measurement of their biomethane production potential according to s...

Green Energy and Sustainability, 2021

$Research paper thumbnail of A review of advances in valorization and post-treatment of anaerobic digestion liquid fraction effluent$

Waste Management & Research: The Journal for a Sustainable Circular Economy, 2022

Traditionally, digestate is considered a waste, which is used as fertiliser in the agriculture in... more Traditionally, digestate is considered a waste, which is used as fertiliser in the agriculture industry. Recent studies focus on increasing the profitability of digestate by extracting reusable nutrients to promote biogas plants cost-effectiveness, sustainable management and circular economy. This review focuses on the post-treatment and valorization of liquor which is produced by solid–liquid fractioning of digestate. Nutrient recovery and removal from liquor are possible through mechanical, physicochemical and biological procedures. The processes discussed involve complex procedures that differ in economic value, feasibility, legislative restrictions and performance. The parameters that should be considered to employ these techniques are influenced by liquor characteristics, topography, climate conditions and available resources. These are key parameters to keep in mind during designing and manufacturing a biogas plant. In the following chapters, a discussion on available liquor t...