No description available.

No description available.

No description available.

The project aimed to extend the limited knowledge ofMBR (Membrane Bioreactor) operation for the treatment of stabilised (old) landfillleachate using an air-lift tubular membrane configuration and comparing the results with those obtained for sewage treatment under largely identical conditions. SRT (solids retention time) was used as the principal fixed variable in the two trials so as to allow comparison of process performance for the two different feedwaters. Supplementary tests were also conducted on: 1. bench-scale porous pots, used to identify the optimum HRT (hydraulic retention time) value for leachate treatment, and 2. intermittent aeration, used to minimise aeration demand. At bench scale removals of69 ± 1% and 99.9 ± 0.1% chemical oxygen demand (COD) and ammonia (NH/) respectively were achieved at an HR T of 5 d and temperatures ~ 21°C. For this trial the mixed liquor volatile suspended solids/mixed liquor suspended solids (MLVSSnvn.SS) ratio was 0.7 ± 0.03 and the volumetric loading rate (VLR) 0.4±0.02 kgCOD m- 3 dol and 0.15 ± 0.003 kgNlI/ m-3 dol; the COD and NH/ food to microorganism ratio (FIM) ratio values were respectively 0.1 ± 0.01 and 0.04 ± 0.004 dol; specific oxygen utilisation rate (SOUR) was 16 ± 7 mg02.gVSS- 1 .h- 1 and nitrifiers:heterotrophs ratio was around 80:20. This compared with similar nitrifiers proportions (i.e. 70 to 80%) reported in the literature. During pilot trials COD removals at the stabilised period were consistently larger for sewage (69 - 83%) than leachates at the pseudo stability phase (28 - 56%), the latter being somewhat lower than values reported in the literature for full-scale plants. However, for both feedwaters maximum was obtained at VLRs between 0.99 and 1.2 kgCOD.m- 3 .d- 1 • NRt + removals were readily achieved with values ~ 88.6%. Biomass characteristics, namely particle size distribution (PSD), extracellular polymeric substances (EPS) concentrations and dynamic viscosity (11) were found to be similar for both sewage and leachate sludges, while soluble microbial products (SMP), MLVSS!.MLSS, F/M, SOUR, and heterotrophslnitrifiers proportions differed. most likely i due to impact of the feedwater character. Microbial dynamics and speciation were highly dependent on feed water quality showing that highly variable feeds such as leachate and sewage would develop inconsistent bacterial communities but analogous to each other. Constant feeds, on the other hand, would develop highly consistent bacterial community profiles. Nevertheless species richness or abundance of neither group (i.e. inconsistent and consistent communities) was significantly correlated to microbial foulants production such as SMP andlor EPS. Even further it was found that either microbial community would have no effect on COD or TOC (total organic carbon) levels of the treated feeds. Critical flux (Je) tests revealed fouling of leachate biomass to be more severe than that imposed by sewage biomass. and that fouling by the leachate biomass is predominantly attributable to the feedwater itself. No correlation between fouling and conventional biomass foulants (i.e. SMP and EPS proteins and carbohydrates) was evident, whilst a stronger correlation of fouling was shown with TOC of the SMP fraction. The ceramic membrane material tested was, as expected, more resistant to fouling than the polymeric membranes used. The highest le values on continuous air-sparging for sewage and leachate were 36 and 24 L.m"2.h"1 respectively. for polymeric membranes, and about 30 L.m"z.h"l during intermittent air-lift conditions for sewage, while absent for leachate. For ceramic membranes no le values were observed at continuous air-sparging. whilst no fouling was evident for either polymeric or ceramic materials challenged with leachate operating with intermittent aeration (0.5 -1 Hz) up to a flux (1) ofl3 and 44 L.m"l.h"l. Cylindrical geometry lumens were found to be more effective during air-lift operations than square lumens.

No description available.

Many previous studies have demonstrated that electroosmotic dewatering is an effective technique to dewater sewage sludge. However, the technology has not yet been successfully applied in industry. This is because there are several technological barriers to the commercial exploitation of the technology that are yet to be resolved. One of these barriers is a scientifically robust design methodology. This aim of this study is to establisha qualitative and quantitative understanding model of electroosmotic dewatering of sewage sludge and from this produce a robust design methodology. This study is divided into three parts: The first part evaluates the feasibility of electroosmotic dewatering under constant voltage for range of sludge types. A number of experiments with four different sewage sludges were undertaken to examine the dewatering efficiency in terms of rate of dewatering, final solid concentration and energy consumption. The results showed that electroosmotic dewatering of sludge is both feasible and potentially economic. It is also shown that the use of the Helmholtz-Smolucowski flow eqPation, together with the assumptions of no electrochemical reaction and a constant electroosmotic permeability, to predict the dewatering process is not sound. The second part of this thesis presents an integrating framework for electroosmotic dewatering under constant voltage and constant current, founded on the mathematics of simple electricalc ircuits and demonstrated by laboratory experimentation. The derived equations and experimental results showed that electroosmotic flow rate decreases with time when dewatering with constant voltage and is constant when dewatering with constant current. Having a linear relationship between flow and time, electroosmotic dewatering with constant current not only enhances the sludge dewatering efficiency, but also has the advantage of simplifying design procedures. The third part explores in further detail each of the design parameters of electroosmotic dewatering under constant current, including sample thickness, current, time over which constant current could be maintained, power supply, pressure and type of electrodes. A detailed design methodology, including design equations to predict final solid content and treatment time, design requirements for each parameter and design procedures, is presented.

Intersex in river fish has been associated with unbiodegraded oestrogens in sewage treatment works (STW) effluents, leading to the proposal that they be regulated by Environmental Quality Standard. Previous literature indicated trickling filters (TF) were not as good as the activated sludge process (ASP) at removing steroid oestrogens. TF were more sustainable than ASP and there are more of them in the UK. One aim of this project was to investigate the performance of TF at removing these oestrogens. The removals of oestrone (E1), 17-β-oestradiol (E2) and 17-α-ethinyl oestradiol (EE2) by a well-controlled pilot-scale trickling filter were 41%–59% for once-through filtration.

The removal of nutrients from the wastewaters through biological processes is a cost effective and environmentally sound alternative to chemical treatment. The primary driver for the success of the biological nutrient removal (BNR) processes is the availability of suitable carbon sources in the influent wastewater. Unfortunately, in the UK the wastewaters considered being weak for the BNR carbon limited processes and hence many methods have been examined in the past for the enhancement of BNR. In this project an internal carbon source was proposed and examined. The carbon was produced from the disintegration of activated sludge by a mechanical process, which was explored and its impact on the BNR carbon limited processes was evaluated. The equipment used in this study for mechanical sludge disintegration was a deflaker, which was able to cause significant increase in chemical oxygen demand and volatile fatty acids (VFA) in the soluble phase of sludge. Laboratory scale tests revealed that this carbon source can improve the phosphorus release and denitrification process and hence the phosphorus and nitrogen removal. These results led us to investigate the carbon source produced from disintegration in pilot scale and two BNR reactors were used for this purpose. The mechanical disintegration of 5.8% of return activated sludge was able to increase the concentration of VFA in the influent wastewater by 2.5-7 mg l-1 and successfully replace the equivalent amount of acetic acid, which is normally considered to be the best carbon source for biological phosphorus removal. The performance of the test reactor in terms of nitrogen, suspended solids and chemical oxygen demand was also unaffected. In addition, the sludge disintegration affected the bacteria growth yield, which combined with the longer sludge age by 6 days compared to the control reactor caused a 20-26% reduction in sludge production. In order to examine whether this process could be used by the water utilities a cost analysis took place, which revealed that the operational cost of the specific disintegration process and under the conditions examined in this study outweighs the savings from the produced carbon source and reduced amount of sludge.

O φωσφόρος είναι ένα χημικό στοιχείο με πολλές λειτουργικότητες. Μία από τις βασικές χρήσεις του είναι ότι αποτελεί αναντικατάστατο λίπασμα ενώ επιπλέον είναι βασικό συστατικό του γενετικού υλικού, των κυτταρικών μεμβρανών, των οστών και των δοντιών, απαραίτητο στοιχείο της διατροφής ανθρώπων και ζώων κλπ. Η παρουσία υψηλών συγκεντρώσεων φωσφόρου στα υδάτινα οικοσυστήματα είναι ιδιαιτέρως βλαβερή καθώς αποτελεί την κύρια αιτία του ευτροφισμού. Αυξημένες ποσότητες φωσφόρου υπάρχουν στα αστικά υγρά απόβλητα, γεγονός που καθιστά αναγκαία την επεξεργασία τους για την απομάκρυνση του, πριν την τελική διάθεση τους στους υδάτινους αποδέκτες. Δεδομένου του ότι, ο φώσφορος προέρχεται από ορυκτά αποθέματα, τα οποία δεν είναι ανεξάντλητα, είναι επιβεβλημένη η ανάκτησή του, η οποία αποτελεί συμβολή στην αειφορία. Μία από τις μεθόδους ανάκτησης του φωσφόρου η οποία κερδίζει όλο και περισσότερο ερευνητικό ενδιαφέρον τα τελευταία χρόνια, είναι η καταβύθιση του με την μορφή στρουβίτη. Ο στρουβίτης, (MgΝΗ4PO4.6H2O) είναι ένα λευκό κρυσταλλικό στερεό το οποίο μπορεί να χρησιμοποιηθεί ως βραδέως αποδεσμευόμενο λίπασμα, εμπλουτίζοντας τις καλλιέργειες με τρία από πιο βασικά θρεπτικά συστατικά. Στην παρούσα εργασία μελετήθηκε η καταβύθιση στρουβίτη από υπέρκορα διαλύματα, η σύσταση των οποίων, προσομοιώνει την αντίστοιχη των αστικών υδατικών λυμάτων ως προς την περιεκτικότητα σε φωσφόρο και αμμωνία, σε αντιδραστήρα συνεχούς λειτουργίας του 1L. Η κινητική της καταβύθισης μελετήθηκε σε συνθήκες σταθερού υπερκορεσμού, pH 9.00 στους 25οC. Τα πειράματα πραγματοποιήθηκαν σε διαλύματα υπέρκορα ως προς στρουβίτη, στα οποία η στοιχειομετρική αναλογία των πλεγματικών ιόντων, ήταν 1:1:1 και 1:1:3 ως προς οποιοδήποτε από τα τρία ιόντα. Επίσης, μελετήθηκε καταβύθιση του στρουβίτη σε υπέρκορα διαλύματα παρουσία Na¬2SO4 και με διαβίβαση αέρα μέσω των διαλυμάτων. Τα αποτελέσματα των πειραμάτων έδειξαν, ότι ο ρυθμός καταβύθισης του στρουβίτη στα υπέρκορα διαλύματά του, εξαρτάται κυρίως από τον αντίστοιχο υπερκορεσμό, ο οποίος αποτελεί και την κινούσα δύναμη. Η ανάλυση των αποτελεσμάτων έγινε με την βοήθεια της κλασσικής θεωρίας πυρηνογένεσης. Η εξάρτηση του χρόνου επαγωγής, ο οποίος μεσολαβούσε μεταξύ της παρασκευής των υπέρκορων διαλυμάτων και της ανίχνευσης των πρώτων υπερκρίσιμων πυρήνων, από τον υπερκορεσμό, έδωσε τιμές για την επιφανειακή ενέργεια της σχηματιζόμενης φάσης ίσης με 15mJ/m2, ενώ ο αριθμός των δομικών μονάδων οι οποίες συγκροτούν τον κρίσιμο πυρήνα, βρέθηκε ίσος με 9. Επίσης, ο ρυθμός, φάνηκε να επηρεάζεται σε μικρό βαθμό από την σχετική αναλογία των πλεγματικών ιόντων. Συγκεκριμένα, όταν η αναλογία των ιόντων Mg :NH3 :P ήταν 3:1:1 ή 1:1:3, οι ρυθμοί οι οποίοι μετρήθηκαν ήταν μεγαλύτεροι σε σύγκριση με τους αντίστοιχους σε διαλύματα με αναλογία 1:1:1. Σε όλες τις περιπτώσεις, το βραδύ στάδιο στον μηχανισμό της καταβύθισης ήταν η επιφανειακή διάχυση των δομικών μονάδων στους υπερκρίσιμους πυρήνες. Το αποτέλεσμα αυτό είναι σε συμφωνία με τα αντίστοιχα σε διαφορετικές τιμές pH, και υποδηλώνει και στην περίπτωση αυτή, τον καθοριστικό ρόλο της επιφάνειας στην οποία λαμβάνει χώρα η πυρηνογένεση. Η παρουσία άλλων ουσιών στο διάλυμα, όπως το Na¬2SO4, είχε ως αποτέλεσμα την αύξηση του ρυθμού αυθόρμητης καταβύθισης του στρουβίτη στα υπέρκορα διαλύματά του. Η διαβίβαση αέρα μέσα από τα υπέρκορα διαλύματα, είχε ως αποτέλεσμα την επιτάχυνση του ρυθμού καταβύθισης σε βαθμό ανάλογο με τον αντίστοιχο παρουσία Na¬2SO4. / Phosphorus is a multifunctional chemical element. One of it’s significant uses is that it consists a non substituted fertilizer, moreover it is one of the basic components of DNA, of cell membranes, bones, teeth, an essential element in human and animal nutrition etc. Increased phosphorous concentration in water systems can be particularly damaging since it is the main cause of eutrophication. Increased amounts of phosphorous have been demonstrated in municipal wastewaters, so processing is required in order to remove phosphorous before final disposal to aquatic systems. Taking into consideration that phosphorus comes from mineral deposits that are not infinite, recovery is demanded, offering a contribution to sustainability. One of the recovery methods that is attracting more and more researcher’s interest over the past years is phosphorous precipitation as struvite. Struvite (MgΝΗ4PO4.6H2O) is a white mineral that can be used as a slow-release fertilizer, enriching agricultures with three of the basic nutrients. In the present study was investigated struvite precipitation in supersaturated solutions, with composition similar to that of municipal wastewaters in phosphorous and ammonia, in 1L continuously operated reactor. The kinetics of spontaneous precipitation was studied at constant solution supersaturation, pH 9.00 and 25οC. The experiments were carried out in supersaturated solutions with stoichiometric molar ratio of the ions 1:1:1 and 1:1:3 for any of the three ions. Struvite precipitation in supersaturated solutions was also studied in the presence of Na¬2SO4 and transmission of air in the solutions. The results showed that the rate of struvite precipitation in supersaturated solutions mainly depends on the supersaturation in respect to the precipitating solid, which is the driving force. Results analysis was performed in accordance to the classical nucleation theory. The dependence of the induction time, the period of time between the achievement of supersaturation and the formation of the first critical nucleus, from supersaturation, lead to surface energy for the newly formed phase 15mJ/m2, and the number of molecules in a critical nucleus was calculated p=9. The rate of struvite precipitation proved to have a minor dependence on the ratio of the ions. More specifically, when stoichiometric molar ratio of the ions Mg :NH3 :P was 3:1:1 or 1:1:3, the calculated rates were a bit higher compared to the ratios in supersaturated solutions with stoichiometric molar ratio 1:1:1. In all the cases the slow step in the mechanism of precipitation was surface diffusion of the solute molecules on the critical nuclei surface. The results are in accordance with those under different pH values and suggest the importance of the surface where nuclei formation takes place. The presence of other substances in the solution, such as Na¬2SO4, resulted in an increased rate of struvite spontaneous precipitation in supersaturated solutions. The transmission of air through the supersaturated solutions also increased the rate of precipitation in a way similar to that under the presence of Na2SO4.

En Lorraine, le drainage fréquent des sols argileux favorise les transferts des intrants agricoles (pesticides et engrais) vers les eaux de surface. Dans ce cas, les bandes enherbées réglementaires (BCAE de la PAC) installées en bordure de cours d’eau sont court-circuitées et ne jouent plus leur rôle épurateur vis-à-vis des eaux de surface. Ainsi, des zones tampons humides artificielles (ZTHA) sont préconisées pour prendre le relais des bandes enherbées. Généralement, ces ZTHA sont installées à l’échelle du bassin versant ou du groupe de parcelles et sont donc de taille conséquente, les rendant concurrentielles de la surface agricole utile (SAU). L’objectif de ce projet de recherche est donc d’évaluer l’efficacité de deux ZTHA de taille réduite, installées dans la bande enherbée entre la parcelle drainée et le ruisseau. Pour cela, une approche multi-échelles intégrant des expériences de laboratoire en batch, des suivis dynamiques en bacs pilotes et un monitoring à la parcelle a été mise en place. Afin d’évaluer l’efficacité des ZTHA au cours des saisons de drainage 2012/13 et 2013/14, le suivi des teneurs en nitrate et de 79 pesticides a été réalisé dans les eaux en entrée et en sortie des ZTHA, ainsi que dans diverses matrices environnementales (sols, sédiment, paille, végétaux). Pour les deux dispositifs, la réduction du flux de nitrate s’est montrée stable, comprise entre 5,4 et 10,9 %, alors que la réduction du flux de pesticides s’est montrée très variable, comprise entre -618,5 et 100 %. Cette variabilité a été expliquée par quatre comportements distincts des molécules. Les fortes valeurs négatives d’efficacité ont été expliquées par une contamination des dispositifs à la suite d’épisodes de ruissellement connexes pour des molécules solubles telles que le 2,4-MCPA ou l’isoproturon. Pour ces deux molécules, l’étude de sorption a montré leur faible affinité avec les matrices environnementales, facilitant leur transport par les eaux de ruissellement et de drainage. D’autres molécules, telles que le boscalide ou l’OH-atrazine, ont présenté des abattements proches de 0. Pour le boscalide, ce comportement a été montré au laboratoire, en accord avec ses fortes capacités d’adsorption et de désorption observées lors des études de sorption et en bacs pilotes. Enfin, certaines molécules ont montré des abattements, allant de 9,9 à 100 %, en lien avec leur faible persistance (2,4-MCPA, clopyralid, mésosulfuron-méthyl,…) ou leur forte affinité pour les matrices environnementales (diflufenicanil, propiconazole, propyzamide,…). Ces ZTHA de taille réduite, installées dans les bandes enherbées, sont donc efficaces pour limiter la contamination des eaux de surface par les eaux de drainage agricole. Ainsi, la multiplication de ces dispositifs à l’échelle de la parcelle dans le paysage agricole permettrait de réduire la contamination des eaux de surface par les pesticides et les nitrates tout en préservant la SAU. Toutefois, l’efficacité de ces ZTHA restant limitée vis-à-vis de certains pesticides présentant un Koc faible et une DT50 élevée, leur installation ne doit pas remettre en cause la réduction en amont des apports phytosanitaires sur les parcelles / In Lorraine, the drainage of clay soils contributes to transfer of agricultural inputs (pesticides and fertilizers) towards surface waters. In this case, the regulatory grass strips (CAP regulation) installed along rivers are bypassed and no longer effective in purifying surface water. Thus, constructed wetlands (CWs) are recommended to take over grass cover bands. Generally, these CWs are installed at watershed scale or at that of several plots and they are therefore quite huge, making them competitive in the cultivated land. The objective of this project is to assess the effectiveness of two small CW, installed in the grass cover band between the drained plot and the river. For this, a multi-scale approach was set up integrating laboratory experiments in batch, pilot study taking into account the water dynamics and monitoring at field scale. The effectiveness of CW was assessed during the 2012/13 and 2013/14 drainage seasons. The nitrate and 79 pesticides concentrations were monitored at inlet and outlet of CWs and in various substrates (soils, sediment, straw and plants). For both devices, the removal efficiencies measured for nitrate were stable and ranged from 5.4 to 10.9 % of inlet amounts while the reduction of pesticide flows was very variable, ranging from -618.5 to 100 %. This variability was explained by four distinct behaviors. The high negative efficiency values were attributed to neighboured runoff events after heavy rains, for soluble molecules such as 2,4-MCPA or isoproturon. For both molecules, the sorption study showed low affinity for environmental substrates, facilitating their transport by runoff and drainage water. Other molecules such as boscalid or OH-atrazine showed effectiveness close to 0 %. For boscalid, this behavior has been observed in laboratory sorption and pilots studies, in agreement with its strong adsorption and desorption capacities. Finally, some molecules have shown reductions ranging from 9.9 to 100 %, in agreement with their low persistence (2,4-MCPA, clopyralid, mesosulfuron-methyl, ...) or their high affinity for environmental substrates (diflufenican, propiconazole or propyzamide). These small CWs, located in the grass cover bands, are effective in minimizing the contamination of surface waters by agricultural drainage water. Thus, multiplying the number of these devices at the plot scale in the agricultural landscape would reduce the contamination of surface waters by pesticides and nitrates while preserving the cultivated land. However, the effectiveness of these CWs are limited for pesticides with a low Koc and a long DT50; thus their installation in plot must not call into question the reduction in the use of pesticides