27 research outputs found
LCA for emerging waste treatment technologies: theoretical approach and practical application
Our work is focusing on the assessment of the life cycle environmental performance of emerging technologies on waste treatment, by applying the LCA principles and tools (EASETECH, SimaPro). These technologies aim at the valorisation of waste for the production of bio-based products, the recovery of materials from waste and the optimization of established waste treatment technologies. A summarizing scheme including the feedstock types and the main processes used as well as the resulting products is illustrated in Figure 1. The technology readiness level (TRL) of the examined treatment schemes ranges between 3-6, while this diversification is also obvious within the treatment schemes themselves. The main aim for conducting LCA in all of the aforementioned emerging technologies is to timely inform the design and development process in order to support decision making for future investments.
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PRODUCTION CHARACTERIZATION AND ADSORPTIVE CAPACITY OF ACTIVATED CARBONS FROM GREEK LIGNITE
ΟΙ ΣΤΟΧΟΙ ΤΗΣ ΕΡΓΑΣΙΑΣ ΑΥΤΗΣ ΗΤΑΝ ΝΑ ΕΞΕΤΑΣΤΕΙ Η ΔΡΑΣΗ ΤΩΝ ΑΝΟΡΓΑΝΩΝ ΣΥΣΤΑΤΙΚΩΝΣΤΗΝ ΑΝΑΠΤΥΞΗ ΤΗΣ ΠΟΡΩΔΟΥΣ ΔΟΜΗΣ ΚΑΙ ΣΤΗΝ ΤΑΧΥΤΗΤΑ ΑΝΤΙΔΡΑΣΗΣ ΚΑΤΑ ΤΗΝ ΠΑΡΑΓΩΓΗ ΤΩΝ ΕΝΕΡΓΩΝ ΑΝΘΡΑΚΩΝ ΜΕ ΤΗΝ ΠΡΟΣΡΟΦΗΤΙΚΗ ΤΟΥΣ ΙΚΑΝΟΤΗΤΑ ΚΑΙ ΝΑ ΑΝΑΠΤΥΧΘΕΙΕΝΑ ΜΑΘΗΜΑΤΙΚΟ ΜΟΝΤΕΛΟ ΠΡΟΣΡΟΦΗΣΗΣ ΣΕ ΣΥΣΚΕΥΕΣ ΑΣΥΝΕΧΟΥΣ ΚΑΙ ΣΥΝΕΧΟΥΣ ΛΕΙΤΟΥΡΓΙΑΣ. ΟΙ ΕΝΕΡΓΟΙ ΑΝΘΡΑΚΕΣ ΠΑΡΑΣΚΕΥΑΣΘΗΚΑΝ ΑΠΟ ΕΛΛΗΝΙΚΟ ΛΙΓΝΙΤΗ ΜΕ ΥΨΗΛΗ ΠΕΡΙΕΚΤΙΚΟΤΗΤΑ ΣΕ ΑΝΟΡΓΑΝΑ ΣΥΣΤΑΤΙΚΑ ΣΕ ΑΤΜΟΣΦΑΙΡΑ CO2 ΓΙΑ ΔΙΑΦΟΡΕΤΙΚΕΣ ΘΕΡΜΟΚΡΑΣΙΕΣ ΚΑΙ ΧΡΟΝΟΥΣ ΠΑΡΑΜΟΝΗΣ. ΕΝΕΡΓΟΙ ΑΝΘΡΑΚΕΣ ΠΑΡΑΧΘΗΚΑΝ ΕΠΙΣΗΣ ΑΠΟ ΛΙΓΝΙΤΗ ΠΟΥ ΥΠΟΒΛΗΘΗΚΕ ΣΕ ΚΑΤΕΡΓΑΣΙΑ ΜΕ ΔΙΑΦΟΡΕΤΙΚΑ ΔΙΑΛΥΜΑΤΑ ΟΞΕΩΝ ΓΙΑ ΤΗΝ ΑΠΟΜΑΚΡΥΝΣΗ ΤΩΝΑΝΟΡΓΑΝΩΝ ΣΥΣΤΑΤΙΚΩΝ. ΣΤΟ ΧΑΡΑΚΤΗΡΙΣΜΟ ΤΗΣ ΠΟΡΩΔΟΥΣ ΔΟΜΗΣ ΧΡΗΣΙΜΟΠΟΙΗΘΗΚΕ Η ΠΡΟΣΡΟΦΗΣΗ Ν2 ΣΤΟΥΣ 77Κ ΚΑΙ CO2 ΣΤΟΥΣ 298 Κ. Η ΑΠΟΜΑΚΡΥΝΣΗ ΤΩΝ ΚΑΤΑΛΥΤΙΚΩΝ ΑΝΟΡΓΑΝΩΝ ΣΥΣΤΑΤΙΚΩΝ ΠΡΟΚΑΛΕΣΕ ΤΗΝ ΕΛΑΤΤΩΣΗ ΤΗΣ ΤΑΧΥΤΗΤΑΣ ΕΝΕΡΓΟΠΟΙΗΣΗΣ ΚΑΙ ΤΗΝ ΠΑΡΑΓΩΓΗ ΕΝΕΡΓΩΝ ΑΝΘΡΑΚΩΝ ΜΕΛΕΤΗΘΗΚΕ ΓΙΑ ΤΗΝ ΑΠΟΜΑΚΡΥΝΣΗ ΦΑΙΝΟΛΗΣ, ΦΟΥΛΒΙΚΟΥ ΟΞΕΟΣ ΚΑΙ ΙΟΝΤΩΝ ΑΡΣΕΝΙΚΟΥ ΑΠΟ ΥΔΑΤΙΚΑ ΔΙΑΛΥΜΑΤΑ. (ΠΕΡΙΚΟΠΗ ΠΕΡΙΛΗΨΗΣ)THE OBJECTIVES OF THIS WORK WERE TO EXAMINE THE EFFECT OF MINERAL MATTER ON THEPORE STRUCTURE DEVELOPMENT AND THE REACTION RATE DURING THE PRODUCTION OF ACTIVATED CARBONS, TO INVESTIGATE THE RELATIONSHIP BETWEEN THE PHYSICO-CHEMICAL PROPERTIES OF ACTIVATED CARBONS AND THEIR ADSORPTION CAPACITY AND TO DEVELOP A MATHEMATICAL MODEL THAT DESCRIBES ADSORPTION ON ACTIVATED CARBON COLUMNS. ACTIVATED CARBONS PRODUCED FROM GREEK LIGNITE WITH A HIGH MINERAL MATTER CONTENT UNDER VARIOUS EXPERIMENTAL CONDITIONS USING CO2 AS OXIDING AGENT. REMOVAL OF INORGANIC IMPURITIES WAS ACCOMPLISHED BY ACID WASHING OF RAW LIGNITE WITH DIFFERENT ACID SOLUTIONS. ACTIVATED CARBONS WERE ALSO PRODUCED FROM ACID TREATED LIGNITE WITH DIFFERENT ASH CONTENT. FOR THE CHARACTERIZATION OF ACTIVATED CARBONS ADSOPTION OF N2 AT 77 K AND CO2 AT 298K WAS USED. REMOVAL OF INORGANIC IMPURITIES BROUGHT ABOUT A LOWERING IN REACTIVITY AND AN INCREASE IN THE MICROPORE SURFACE AREA OF ACTIVATED CARBONS. ADSORTION STUDIES WERE PERFORMED IN ORDER TO EVALUATE THE EFFICIENCY OF VARIOUS ACTIVATED CARBONS TO REMOVE TOXIC SUBSTANCES FROM WATER. TWO ORGANIC AND ONE ORGANIC SUBSTANCE WERE USED. THESE WERE PHENOL, FULVIC ACID AND ARSENIC IONS. THE ADSORPTIVE CAPACITY OF ACTIVATED CARBONS DEPENDED PRIMARILY ON THE ASH CONTENT AND THE COMPOUND. (ABSTRACT TRUNCATED
Microalgae-activated sludge treatment of molasses wastewater in sequencing batch photo-bioreactor
The aim of this work was the examination of the treatment potential of molasses wastewater, by the utilization of activated sludge and microalgae. The systems used included a sequencing batch bioreactor and a similar photo-bioreactor, favoring microalgae growth. The microalgae treatment of molasses wastewater mixture resulted in a considerable reduction in the total nitrogen content. A reduction in the ammonium and nitrate content was observed in the photo-bioreactor, while the effluent's total nitrogen consisted mainly of 50% organic nitrogen. The transformation of the nitrogen forms in the photo-bioreactor was attributed to microalgae activity, resulting in the production of a better quality effluent. Lower COD removal was observed for the photo-bioreactor than the control, which however increased, by the replacement of the anoxic phase by a long aeration period. The mechanism of nitrogen removal included both the denitrification process during the anoxic stage and the microalgae activities, as the replacement of the anoxic stage resulted in low total nitrogen removal capacities. A decrease in the photobioreactor performance was observed after 35 days of operation due to biofilm formation on the light tube surface, while the operation at higher temperature accelerated microalgae growth, resulting thus in the early failure of the photoreactor
Biodegradation and decolorization of melanoidin solutions by manganese peroxidase yeasts
The ability of selected manganese peroxidase (MnP) yeast strains, isolated from the mixed liquor of an activated sludge bioreactor treating melanoidins wastewater, was investigated in this work, aiming to examine the degradation potential of melanoidins, in the presence or absence of nutrients. Ten yeast strains were initially isolated from the mixed liquor; four yeast strains (Y1, Y2, Y3 and Y4) were selected for further studies, based on their tolerance towards synthetic melanoidins (SMs) degradation and MnP activity onto solid agar medium. The Y1 strain exhibited almost 98% homology to Candida glabrata yeast, based on 28S rRNA identification studies. During experiments carried out using SM at 30 °C, the four isolated yeast cultures showed a noticeable organic matter reduction and decolorization capacity reaching up to 70% within 2-5 days. However, the corresponding yeast cultures grown in glucose peptone yeast extract medium using real melanoidin wastewater at 30°C showed lower organic matter and color removal capacity, reaching about 60% within 2-5 days. Nevertheless, it was found that the removal of real and synthetic melanoidins could be carried out by these strains under non-aseptic conditions, without requiring further addition of nutrients
Membrane Fouling Controlled by Adjustment of Biological Treatment Parameters in Step-Aerating MBR
A promising solution for membrane fouling reduction in membrane bioreactors (MBRs) could be the adjustment of operating parameters of the MBR, such as hydraulic retention time (HRT), food/microorganisms (F/M) loading and dissolved oxygen (DO) concentration, aiming to modify the sludge morphology to the direction of improvement of the membrane filtration. In this work, these parameters were investigated in a step-aerating pilot MBR that treated municipal wastewater, in order to control the filamentous population. When F/M loading in the first aeration tank (AT1) was ≤0.65 ± 0.2 g COD/g MLSS/d at 20 ± 3 °C, DO = 2.5 ± 0.1 mg/L and HRT = 1.6 h, the filamentous bacteria were controlled effectively at a moderate filament index of 1.5–3. The moderate population of filamentous bacteria improved the membrane performance, leading to low transmembrane pressure (TMP) at values ≤ 2 kPa for a great period, while at the control MBR the TMP gradually increased reaching 14 kPa. Soluble microbial products (SMP), were also maintained at low concentrations, contributing additionally to the reduction of ΤΜP. Finally, the step-aerating MBR process and the selected imposed operating conditions of HRT, F/M and DO improved the MBR performance in terms of fouling control, facilitating its future wider application
Enhancement of the performance of a combined microalgae-activated sludge system for the treatment of high strength molasses wastewater
The treatment of molasses wastewater, by a combined microalgae-activated sludge process, for the simultaneous organics and total nitrogen reduction, was examined. Further enhancement of the performance of the combined process was accomplished, by means of biofilm carriers or electrocoagulation. A LED light tube was immersed into the reactor tank aiming to enhance the growth of photosynthetic microalgae, while in a similar unit, biofilm carriers were added to the system, representing a moving bed bioreactor. Exposure of the activated sludge biocommunity to light source, resulted in the growth of microalgae and photoreactors exhibited higher removal rates of total nitrogen and nitrates. However, operation at longer times resulted in low effluent quality due to the presence of microalgae cells as a result of high growth rates, and potential light shading effect. Nevertheless, the moving bed system was more beneficial than the single photoreactor, as biofilm carriers provided a self cleaning capacity of the light source, reducing the effect of microalgae deposition. Advanced treatment of the biological effluents, by electrocoagulation, increased even more the process efficiency: the combined photobioreactor and electrocoagulation process resulted in about 78% COD removal and more than 35% total nitrogen removal in the effluent, where nitrates represented almost the single form of total nitrogen
Least Cost Analysis for Biocorrosion Mitigation Strategies in Concrete Sewers
The changing role of the municipal water and wastewater authorities, together with the need for a sustainable maintenance treatment in the sewer systems, have been the catalysts for the integration of technical and financial information into asset management systems. This paper presents results from a cost-comparative analysis focusing on an annuities calculation for the evaluation of microbiologically induced corrosion (MIC) or biocorrosion mitigation methodologies used in the maintenance of concrete sewers. The replacement cost of deteriorated sewer concrete pipes is high, and MIC mitigation methods can be used to increase the current service life of concrete pipes. From the MIC mitigation methods that are frequently used, the authors examined those of flushing with high-pressure water (i.e., a common method used in Greece), and spraying with magnesium hydroxide slurry (MHS). The authors chose four different cities for the assessment, which presented different sewer characteristics and socioeconomic backgrounds. In addition, all methods for concrete sewer MIC mitigation were compared to the present value of replacement of sewer concrete pipes with new PVC ones. Results showed that flushing with high-pressure water is very cost demanding and should be avoided, while spraying with MHS could be a sustainable and economic solution in the long term
Fouling Issues in Membrane Bioreactors (MBRs) for Wastewater Treatment: Major Mechanisms, Prevention and Control Strategies
Membrane fouling is one of the most important considerations in the design and operation of membrane systems as it affects pretreatment needs, cleaning requirements, operating conditions, cost and performance. Given that membrane fouling represents the main limitation to membrane process operation, it is unsurprising that the majority of membrane material and process research and development conducted is dedicated to its characterization and amelioration. This work presents the fundamentals of fouling issues in membrane separations, with specific regard to membrane fouling in Membrane Bioreactors (MBRs) and the most frequently applied preventive-control strategies. Feed pretreatment, physical and chemical cleaning protocols, optimal operation of MBR process and membrane surface modification are presented and discussed in detail. Membrane fouling is the major obstacle to the widespread application of the MBR technology and, therefore, fouling preventive-control strategies is a hot issue that strongly concerns not only the scientific community, but industry as well
A Comparative Study between SVM and Fuzzy Inference System for the Automatic Prediction of Sleep Stages and the Assessment of Sleep Quality
This paper compares two supervised learning algorithms for predicting the sleep stages based on the human brain activity. The first step of the presented work regards feature extraction from real human electroencephalography (EEG) data together with its corresponding sleep stages that are utilized for training a support vector machine (SVM), and a fuzzy inference system (FIS) algorithm. Then, the trained algorithms are used to predict the sleep stages of real human patients. Extended comparison results are demonstrated which indicate that both classifiers could be utilized as a basis for an unobtrusive sleep quality assessment