L'objectif principal de ce travail de thèse concerne l'étude de l' élimination de la DCO et de la nitrification dans une nouveau lit bactérien Multi-Section ( MSB ) . Après une caractérisation de l’hydrodynamique et du transfert d’oxygène de ce lit bactérien, les expériences biologiques menées sous des conditions opératoires contrastées (fortes et faibles charges organiques eteaux usées contenant ou pas des matières particulairs) ont été menées. En parallèle, des simulations avec le logiciel Biowin® ont été réalisées. Les principaux résultats sont résumés en suivant :- La rétention de liquide statique est majoritaire par rapport à la rétention dynamique que ce soit en présence ou en absence de biofilm. Le biofilm joue le rôle d’une "éponge" permettant un maintien de l’humidité du lit même à faible débit. Les expériences de DTS ont montré que le biofilm accroit le temps de séjour du liquide et conduit à une diminution de l’épaisseur du film liquide permettant ainsi de promouvoir le transfert de l'oxygène.- Le réacteur MSB montre une élimination efficace de la DCO (> 95 % ) et de la nitrification ( > 60 % de l’azote entrant), mais une accumulation de DCO particulaire a lieu dans le filtre ce qui conduira à un colmatage à terme. La nitrification cohabite avecl’élimination de la DCO même dans la première section et pour une charge organique élevée ce qui implique une bonne capacité d’oxygénation du MSB par l’aération naturelle.- Un modèle dynamique de MSB a été utilisé implémenté sur le simulateur - BioWin , afin d'obtenir la répartition des biomasses au sein du réacteur et d'évaluer le processus limitant dans chaque section. Le modèle partiellement calibré peut aider à estimer les besoins minimum d'oxygène pour la nitrification et peut rendre compte de la compétition entre la croissance hétérotrophe et la nitrification. / The main objective of this PhD work focused on the study of the COD removal and nitrification in a new designed Multi-Section Bioreactor (MSB). Hydrodynamic characterization of the reactor, biological experiments under contrasted conditions and simulations by Biowin® software were carried out:- Firstly, it was found that static liquid retention is the predominant part both without and with the presence of biofilm. Biofilm acts like a "sponge". RTD experiments showed that biofilm can promote liquid residence time, decrease the liquid film andpromote the oxygen transfer consequently.- Secondly, the MSB operated at contrasted organic loading rate (OLRs) and nitrogen loading rate (NLRs) showed that COD can be effectively removed (removal efficiency > 95%) and nitrification (> 60% of the N removal) occurred in this biofilter.Nitrification is efficient even in the first section implying no drastic oxygen limitation though only natural aeration is occurring.- Thirdly, a TF dynamic model has been used from a simulator - BioWin, in order to get more insights on the biomass distribution in the pilot and to assess the limiting process in each section of the bioreactor. Calibration of the model can help us to estimate theminimum oxygen requirement for nitrification for each zone inside the pilot and it can well represent the competition between heterotrophic growth and nitrification.

Les procédés membranaires hybrides (PMH) allient la filtration membranaire basse pression à l’usage du charbon actif en poudre (CAP). Afin de diminuer les coûts opérationnels du procédé, il a été proposé de laisser vieillir le CAP dans le PMH et donc de minimiser le dosage de CAP frais. Peu d’information est disponible quant à la capacité résiduelle d’adsorption de suspensions de CAP âgées. L’importance relative de l’adsorption et de la biodégradation dans les réacteurs à CAP âgés sur le traitement des composés dissous est inconnue, ce qui empêche notamment l’optimisation du procédé. <p><p>Le principal objectif de ce projet de recherche est de décrire la performance du contacteur à CAP du PMH pour l’enlèvement de l’azote ammoniacal, du carbone organique dissous (COD), du COD biodégradable (CODB) et des micropolluants. Dans ce projet, l’emphase est placée sur l’opération du PMH avec de hauts temps de rétention de CAP. <p><p>La première phase de ce projet a consisté en une série de développements méthodologiques, base nécessaire à l’étude du CAP âgé. Des méthodes permettant la quantification de la biomasse hétérotrophe et nitrifiante colonisant le CAP âgé ont mis en évidence des densités de biomasse similaires à celle du charbon actif en grain en surface de filtre biologiques. L’irradiation aux rayons gamma a été démontrée comme une méthode adéquate pour produire des témoins abiotiques à partir de CAP de 10 et de 60 jours.<p><p>La seconde partie de cette étude s’est concentrée sur la démonstration de l’efficacité du PMH pour l’enlèvement de l’azote ammoniacal, du COD, ainsi que d’un mélange de micropolluants. Les cinétiques d’enlèvements ayant lieu au sein de des contacteurs à CAP ont été simulées en laboratoire sous diverses conditions (température, concentration en CAP, âge de CAP, matrice d’eau variable, temps de contact). Deux modèles cinétiques prédisant l’enlèvement de l’azote ammoniacal et du COD dans le PMH ont été développés sur base des simulations en laboratoire suivies sur CAP neuf, colonisé et abiotique. <p><p>De manière générale, les travaux réalisés au cours de ce doctorat ont mis en évidence le rôle majeur de l’adsorption résiduelle sur l’enlèvement de la contamination dissoute. Alors que l’enlèvement d’azote ammoniacal a majoritairement eu lieu par nitrification, le COD et les micropollutants sont principalement adsorbés sur le CAP colonisé. Il a aussi été montré que la capacité d’adsorption résiduelle des suspensions de CAP âgées peut agir en tampon, permettant de faire face à une augmentation soudaine de la concentration en azote ammoniacal, en COD ou en micropolluants. Le suivi des cinétiques d’enlèvement a permis de démontrer que la concentration, l’âge de CAP et le temps de rétention hydraulique (TRH) sont trois paramètres clefs pour l’optimisation du procédé. D’un point de vue économique, un TRH inférieur à 15 min est néanmoins désiré pour limiter les coûts du procédé. Par ailleurs, l’intérêt économique associé à l’augmentation de l’âge du CAP peut-être atténué par le besoin d’augmenter la concentration en CAP si l’adsorption est le mécanisme visé. De façon générale, ce projet démontre qu’une optimisation à l’échelle pilote du procédé est nécessaire car les objectifs de traitement, la qualité de l’eau à traiter et le fait que les 3 paramètres d’opération soient inter-reliés complexifient l’optimisation du PMH. Étant donné l’impact du TRH sur le coût du PMH, de futures recherches devraient viser à l’optimisation du mélange. <p>Hybrid membrane processes (HMPs) couple membrane filtration with powdered activated carbon (PAC). In HMPs, low-pressure membranes ensure an efficient particle removal, including protozoan parasites such as Cryptosporidium, while the PAC contactor is devoted to the removal of dissolved compounds. Such processes are emerging as a promising alternative to conventional treatment chains, which no longer allow the drinking water facilities to comply with increasingly stringent regulations on the treated water quality. To decrease the operating costs associated with virgin PAC consumption, it was suggested to let the PAC age in the PAC contactor of the process. Until now, the potential of using aged PAC in HMPs has been demonstrated for ammonia and DOC removal, but the potential to remove micropollutants remains unknown. It is suggested that the biological activity in aged PAC contactors contributes significantly to the removal of the dissolved compounds. Yet, neither the extent of the biomass on the aged PAC, nor the residual adsorption capacity, was quantified. No study focused on discriminating the mechanisms responsible for the treatment when using aged PAC suspensions. Most of the data published on HMPs using aged PAC were gathered at pilot scale under warm water conditions, yet the efficiency of the process is most likely sensitive to temperature changes. There is currently little information available on the efficiency of HMPs under cold water conditions. This lack of information hinders the optimization of the HMP, leading to sub-optimal usage of aged PAC.<p><p>The main objective of this research project is to describe the performance of the PAC contactor of HMPs in removing ammonia, dissolved organic carbon (DOC), biodegradable DOC (BDOC) and micropollutants. In particular, emphasis was placed on the operation of the HMP under high PAC residence times. On a more detailed level, the objectives of this project were (1) to develop and compare methods to quantify the biomass developed on aged PAC, (2) to develop a method to produce an abiotic control for aged PAC, (3) to characterize the removal kinetics of ammonia, DOC, BDOC and micropollutants occurring in the carbon contactor of an HMP, (4) to evaluate the impact of water temperature on the performance of the carbon contactor of an HMP, (5) to discriminate the relative importance of adsorption versus biological oxidation as mechanisms responsible for ammonia, DOC and micropollutants removal in the PAC contactor of an HMP, and finally (6) to differentiate the relative importance of the hydraulic retention time (HRT), the PAC age and the PAC concentration as key operating parameters on the optimization of the performance of the PAC contactor of an HMP.<p><p><p>To set the basis on the study of aged PACs, the first part of this research project consisted in methodological developments i) to quantify the heterotrophic and nitrifying biomass colonizing aged PAC, and ii) to create a reliable abiotic control of the colonized PAC, which is required for discriminating the mechanisms occurring on aged PAC. Heterotrophic and nitrifying biomass quantifying methods developed for colonized granular activated carbon (GAC) were successfully adapted to the aged PAC. The preferred methods were the potential 14C-glucose respiration (PGR) rate and the potential nitrifying activity (PNA), as they quantify the active heterotrophic and nitrifying biomass, which is most likely responsible for the depletion of BDOC and ammonia. An alternative method to the PGR, the potential acetate uptake (PAU) rate, was developed to alleviate the logistical and budgetary issues associated with the utilization of radio-labeled glucose. The densities (per gram of dry PAC) of both active heterotrophic and nitrifying biomasses were found comparable to that of the GAC sampled from the surface of a biological GAC filter. The gamma-irradiation was demonstrated as a reliable method to produce abiotic samples from soils, and was therefore chosen to produce abiotic colonized PAC samples in this project. In order to determine the optimized dosage of gamma-rays, increased doses were applied on PAC samples. Heterotrophic plate counts and methylene blue adsorption kinetics were used to determine respectively the lowest gamma ray dose required to inhibit the bacterial activity, and the highest dose that could be applied without affecting the aged PAC adsorption capacity and kinetics. Refractory DOC (RDOC) adsorption kinetics confirmed the accuracy of the dose chosen as the adsorptive behavior of the aged PAC was not affected. PGR rates were decreased 83% at the optimized dose. The gamma-irradiation method was therefore proven efficient and used in the following work phases of this research.<p><p>The second part of this study focused on the removal of ammonia, DOC and a mixture of micropollutants. Firstly, the PAC contactor of an HMP was simulated at lab-scale to monitor ammonia removal kinetics. Three PAC concentrations (approximately 1-5-10 g/L) of three PAC ages (0-10-60 days) were tested at two temperatures (7-22°C), in settled water with ambient influent condition (100 µg N–NH4/L) as well as under a simulated peak pollution scenario (1000 µg N–NH4/L). The kinetics evidenced that ammonia flux at pilot scale limited biomass growth (HRT = 67 min). In contrast, PAC colonization was not limited by the available surface and thus, PAC concentration was not a key operating parameter under the colonizing conditions tested (5-10 g/L). Ammonia adsorption was significant onto virgin PAC but the ammonia nitrification was crucial to reach complete ammonia removal at 22°C. When using colonized PAC, the 60-d PAC offered a better resilience to temperature decreases (78% at 7°C) as well as lower operating costs than the 10-d PAC (<10% at 7°C). Significant ammonia adsorption was also evidenced on 60-d PAC suspension, most probably due to PAC and the presence of suspended solids, but not on 10-d PAC. Adsorption and nitrifying activity were superior on 60-d PAC than on 10-d PAC at 7°C. In case of peak pollution, the process was most probably phosphate-limited but a mixed adsorption/nitrification still allowed 50% ammonia removal on 10-d and 60-d PAC at 22°C. A kinetics based model was developed to predict ammonia removals and to determine the relative importance of the adsorption and nitrification on colonized PAC under the conditions tested. <p><p>DOC, BDOC and RDOC removals occurring in the PAC contactor of an HMP were also simulated at lab-scale. Similar conditions to that of the ammonia removal kinetics were tested. The initial ammonia concentration remained untouched in the water matrices (settled water and raw water) but the BDOC-to-DOC ratio was altered by pre-ozonation (0 to 1.5 g O3/g C). The 10-d and 60-d abiotic controls were used to discriminate DOC adsorption from biodegradation. DOC biodegradation contributed marginally to DOC removal in the investigated conditions and DOC adsorption was increased at higher temperature. An original model integrating the PAC age distribution was developed to predict DOC removal in aged PAC contactors operated at steady-state. At a mean PAC residence time of 60-d, the younger PAC fraction (25-d and less) was primarily responsible for DOC adsorption (> 80%). This fraction represents 34% of the mass of PAC in the contactor. When using a water matrix with a higher initial DOC concentration (raw water) or a lower affinity for PAC (pre-ozonated settled water), the residual adsorption capacity of that older fraction was proven useful. <p><p>Lastly, a mixture of micropollutants (atrazine, deethylatrazine (DEA), linuron, microcystin, caffeine, carbamazepine, sulfamethoxazole, diclofenac, progesterone and medroxyprogesterone) was spiked at environmentally relevant concentrations (from 130 ng/L to 33 µg/L) in settled water (0 and 0.85 gO3/gC). The micropollutants concentration depletion was monitored over a period of 7h to 48 h on 1 g/L of 0-d, 10-d, 60-d PAC and gamma-irradiated 60-d PAC. Even in presence of NOM, the spiked micropollutants were rapidly adsorbed on aged PAC. No biodegradation was observed. Removals superior to 95% were reached within 5 minutes, and direct competition with NOM did not impact the efficiency of the process when micropollutants were spiked at environmentally relevant concentrations. Therefore, HMPs operated to remove DOC and ammonia can control transient micropollutant pollution and comply with the World health Organization recommendations for atrazine (2 µg/L) and microcystin (1 µg/L). However, the stricter European regulations for atrazine and DEA (0.1 µg/L) could not be met with 10-d and 60-d PAC under the operating conditions tested. Reaching such strict treatment objective would require a specific optimization of the process. <p><p>In general, this PhD research evidenced the role of the residual adsorption of aged PAC suspensions for the treatment of dissolved compounds. From the results obtained in this project, the potential of HMPs using aged PAC to remove micropollutants was evidenced. Additional research is however required to validate this potential under varied operating conditions. The modeling work improved the understanding of aged PACs. Finally, this research work provides original information on the optimization of HMPs. The optimization of the operating parameters will vary with the water quality targeted and the quality of the influent water. The PAC concentration, PAC age and HRT are inter-related. Therefore, it is recommended to optimize the operation of HMPs at pilot scale. Seasonal variations should be accounted for. An HRT of at least 15 min is required when the biological activity is mandatory to reach the water quality objectives. Lower HRT might be applied if adsorption is favored. Finally, as the HRT has a strong impact on the total cost of the process (capital and operational expenditure), PAC contactors’ hydraulic should be the point of focus of future research.& / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished

Ett avgörande steg i avloppsvattenrening med aktivslammetoden är att slammet kan avskiljas från det renade vattnet. Detta sker oftast i sedimenteringsbassänger. Sedimenteringsproblem är dock vanliga på många avloppsreningsverk, vilket kan leda till att föroreningar följer med utgående vatten. Studier om slamegenskaper är därför viktiga för att öka förståelsen för vilka faktorer som påverkar sedimenteringen och vad som kan göras för att minska problemen. I detta examensarbete har ett mindre avloppsreningsverk i Lövsta utanför Uppsala studerats. Ungefär en tredjedel av flödet till verket kommer från ett närliggande slakteri. Verket har återkommande problem med flytslam i slutsedimenteringsbassängen. Syftet med arbetet var att – genom litteraturstudier, provtagning, fullskaleförsök och analys – identifiera orsaker till flytslamproblemen. Även förslag till åtgärder skulle läggas fram. En utvärdering av reningsprocessen genomfördes dels utifrån befintliga mätdata, dels genom utförligare provtagningar och mätningar som gjordes under en treveckorsperiod i oktober. Höga nitrathalter observerades i vattnet, särskilt i den utjämningstank där flödesutjämning och förbehandling av slakterivattnet sker. De höga nitrathalterna, i kombination med en lång slamuppehållstid i slutsedimenteringsbassängen, bedömdes vara orsaken till flytslambildningen eftersom båda dessa faktorer gynnar uppkomsten av kvävgas genom denitrifikation. Det är denna gas som lyfter slammet från botten av bassängen till ytan. Två möjliga åtgärder för att lösa flytslamproblemen bedömdes vara genomförbara. Den ena var att öka bortpumpningen av slam från botten av slutsedimenteringsbassängen, för att förkorta slamuppehållstiden. Den andra var att denitrifiera vattnet innan det når slutsedimenteringen. Av dessa förslag ansågs det senare vara mer tilltalande ur både ekonomisk och miljömässig synvinkel. En strategi för att denitrifiera vattnet bedömdes vara intermittent luftning av utjämningstanken. Denna luftningsstrategi tillämpades under en försöksperiod på tio veckor. Nitrathalterna mättes en eller två gånger i veckan under försöksperioden. En sänkning av nitrathalterna observerades: från 182 mg/l till som lägst 60 mg/l i utjämningstanken och från 65 mg/l till som lägst 18 mg/l i luftningsbassängen. Sänkningen var dock inte tillräcklig för att förhindra flytslambildning i sedimenteringsbassängerna. Den ofullständiga denitrifikationen berodde troligtvis på för låga BOD-halter i utjämningstanken. Vidare undersökningar behövs för att utvärdera och optimera kvävereningen genom intermittent luftning. / One of the most crucial steps in wastewater treatment with activated sludge is the separation of sludge from the treated effluent. This is most often done by sedimentation in clarifiers. Sedimentation problems are, however, common in many wastewater treatment plants, causing higher concentrations of pollutants in the effluent. Research on sludge characteristics is therefore important to increase the knowledge about which factors affect the sludge settling properties and what can be done to minimize problems. In this master thesis a small wastewater treatment plant in Lövsta outside Uppsala, Sweden, was investigated. About a third of the influent water to the plant comes from a slaughterhouse situated nearby. The plant suffers from recurrent problems with rising sludge in the secondary clarifier. The purpose of this thesis was to – through literature studies, sampling, full scale experiments and analysis – identify causes for the rising sludge problem. Also, suggestions to remedy the problem were to be presented. An evaluation of the treatment process was conducted from existing measurement data and from sampling and measuring done for three weeks in October. High concentrations of nitrate were found in the water, especially in the equalization tank, where flow equalization and primary treatment of the slaughterhouse wastewater takes place. The high concentrations of nitrate, in combination with a long sludge retention time in the secondary clarifier, were judged to be the reason for the formation of rising sludge. Both of these factors stimulate the development of nitrogen gas through denitrification. This gas lifts the sludge from the bottom of the clarifier to the water surface. Two possible solutions to the rising sludge problem were considered feasible. One was to increase the pumping of sludge from the bottom of the secondary clarifier, to decrease the sludge retention time. The second was to denitrify the water before it reaches the clarifiers. Of these two suggestions, the second was regarded as more appealing from both an economical and an environmental point of view. One method to denitrify the water was deemed to be intermittent aeration in the equalization tank. This aeration strategy was implemented for ten weeks. Nitrate concentrations were measured one or two times a week for this period of time. A decrease in nitrate concentrations was observed: from 182 mg/L to at its lowest 62 mg/L in the equalization tank, and from 65 mg/L to at its lowest 18 mg/L in the aeration tank. The decrease was, however, not enough to prevent formation of rising sludge in the clarifiers. The incomplete denitrification process was thought to be due to low concentrations of BOD in the equalization tank. Further studies need to be carried out to evaluate and optimize the nitrogen removal through intermittent aeration.

Thesis (MScEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: Urine contains up to 80% of nitrogen, 50 % of phosphates and 90 % of potassium of the total load in domestic wastewater but makes up less than 1% of the total volume (Larsen et al., 1996). The source separation and separate treatment of this concentrated waste stream can have various downstream advantages on wastewater infrastructure and treated effluent quality. The handling of undiluted source separated urine however poses various challenges from the origin onward. The urine has to be transported to a point of discharge and ultimately has to be treated in order to remove the high loads of organics and nutrients. Wilsenach (2006) proposed onsite treatment of source separated urine in a sequencing batch reactor before discharging it into the sewer system. This study focused on the treatment of urine in a sequencing batch reactor (SBR) primarily for removal of nitrogen through biological nitrification-denitrification. The aim of the study was to determine nitrification and denitrification kinetics of undiluted urine as well as quantification of the stoichiometric reactions. A further objective was to develop a mathematical model for nitrification and denitrification of urine using experimental data from the SBR. The SBR was operated in 24 hour cycles consisting of an anoxic denitrification phase and an aerobic nitrification phase. The sludge age and hydraulic retention time was maintained at 20 days. pH was controlled through influent urine during volume exchanges. Undiluted urine for the study was obtained from a source separation system at an office at the CSIR campus in Stellenbosch. Conditions in the reactor were monitored by online temperature, pH and ORP probes. The OUR of the system was also measured online. One of the main challenges in the biological treatment of undiluted urine was the inhibiting effect thereof on nitrification rate. The anoxic mass fraction was therefore limited to 17 % in order to allow longer aerobic phases and compensate for the slow nitrification rates. Volume exchanges were also limited to 5% of the reactor volume in order to maintain pH within optimal range. Samples from the reactor were analysed for TKN, FSA-N, nitrite-N, nitrate-N and COD. From the analytical results it was concluded that ammonia oxidising organisms and nitrite oxidising organism were inhibited as significant concentrations of ammonia-N and nitrite-N were present in the effluent. It was also concluded that nitrite oxidising organisms were more severely inhibited than ammonia oxidising organisms as nitrate-N was present in very low concentrations in the effluent and in some instances not present at all. Ultimately the experimental system was capable of converting 66% of FSA-N to nitrite- N/nitrate-N of which 44% was converted to nitrogen gas. On average 48% of COD was removed. A mathematical model was developed in spreadsheet form using a time step integration method. The model was calibrated with measured online data from the SBR and evaluated by comparing the output with analytical results. Biomass in the model was devised into three groups, namely heterotrophic organisms, autotrophic ammonia oxidisers (AAO) and autotrophic nitrite oxidisers (ANO). It was found that biomass fractionation into these three groups of 40% heterotrophs, 30% AAO and 30% ANO produced best results. The model was capable of reproducing the general trends of changes in substrate for the various organism groups as well as OUR. The accuracy of the results however varies and nearexact results were not always achievable. The model has some imperfections and limitations but provides a basis for future work.

La caféiculture représente 7,5% des cultures permanentes mondiales et utilise généralement de grandes quantités de fertilisants azotés (jusqu'à 350 kg N ha-1 an-1). La caféiculture est souvent pratiquée sous couvert d'arbres dont certains sont fixateurs d'azote. La contribution des plantes fixatrices d'azote aux émissions de N2O est un sujet prégnant dans le cadre du développement durable, avec des résultats dans la littérature qui peuvent parfois apparaître contradictoires. Dans ce contexte, nous avons étudié le bilan des gaz à effet de serre (GES) dans deux cultures caféières fortement fertilisées (250 kg N ha-1 an-1), au Costa Rica : une monoculture et une culture ombragée par l'espèce légumineuse fixatrice de N2 Inga densiflora. Nous avons mesuré périodiquement les flux de N2O, CH4 et CO2 à l'interface solatmosphère, leurs déterminants édaphiques (humidité gravimétrique, espace poral occupé par l'eau, température et teneur en azote minéral) et les taux de minéralisation de l'azote dans le sol. Par ailleurs, nous avons caractérisé, au laboratoire, les paramètres biologiques de nitrification-dénitrification et leur production associée de N2O et N2 pour simuler en continu les émissions de N2O avec les modèles NGAS et NOE sur une durée d'un an. Enfin, nous avons évalué la dynamique du C du sol et l'accumulation de C dans les biomasses et la litière. Nos mesures ont montré une très forte contribution de la fertilisation azotée aux émissions de N2O, soit une proportion moyenne de 77% des bilans annuels (4,3 ± 0,3 et 5,8 ± 0,5 kg N-N2O ha-1 an-1, respectivement dans la monoculture et la culture ombragée). Les fertilisations ont également augmenté temporairement la respiration du sol. Les valeurs faibles des activités biologiques (notamment des potentiels de dénitrification < 1 kg N ha-1 j-1) ont expliqué les flux toujours inférieurs à 300 g N ha-1 j-1 observés dans des conditions environnementales pourtant favorables à la production de N2O (température, humidité et teneur en nitrate du sol élevées). La similarité entre les activités biologiques mesurées sur les deux cultures de café ainsi que celle entre les bilans annuels de N2O établis à partir de mesures et de modélisation permettent de conclure sur un effet de faible ampleur de l'espèce légumineuse fixatrice de N2 sur les émissions de N2O. Le bilan des flux de GES hors CO2 à l'interface sol-atmosphère et du stockage de C de la culture ombragée (11,93 ± 2,17 Mg CO2-equivalent ha-1 an-1) a été 4 fois supérieur au bilan de la monoculture (2,67 ± 1,94 Mg CO2-equivalent ha-1 an-1). Nos résultats tendent donc à confirmer que la culture de café conduite en agroforesterie, sur un Andosol, augmente le puits de GES et que, dans le contexte présent, l'utilisation d'une légumineuse fixatrice de N2 comme espèce ombragère ne contredit pas cette observation.

Submitted in fulfillment for the requirements for the Degree of Doctor of Technology: Biotechnology, Durban University of Technology, 2012. / Nitrification is a crucial step in biological nutrient removal (BNR) processes, mostly carried out by a group of nitrifying bacteria which includes ammonia-oxidising bacteria (AOB) and nitrite-oxidising bacteria (NOB). Nitrification failure has proven to be a common operational problem in full-scale wastewater treatment plants (WWTP) since nitrifying bacteria are very sensitive to sudden changes in environmental or plant operating conditions. The current investigation was carried out to advance our understanding of the distribution of nitrifying bacterial populations and their performance at three different BNR plants in KwaZulu-Natal, South Africa. The latest molecular techniques such as fluorescent in situ hybridisation (FISH)-confocal scanning laser microscopy (CSLM), polymerase chain reaction (PCR) and real-time quantitative PCR (Q-PCR) were applied to detect and quantify nitrifying bacteria. When using FISH to target the nitrifying population, it necessitated optimising pre-treatment protocols of the samples to improve accuracy during quantification. Sonication was found to be the superior method of dispersion based on the least disruption of nitrifier cell integrity, irrespective of the sludge type. The effect of plant configurations and wastewater characteristics on the distribution of the nitrifying bacterial population and subsequently on the nitrification performance was evaluated using FISH and PCR. FISH results revealed the dominance of Nitrosomonas (AOB), Nitrobacter (NOB) and Nitrospira (NOB) for all BNR plants. The 16S rRNA analysis of PCR products using genus-specific primers, revealed the presence of more than one species of the same group at these plants. Nitrosomonas spp. including Nitrosomonas halophila, Nitrosomonas eutropha, Nitrosomonas europaea, Nitrosomonas aestuarii and an unidentified Nitrosomonas spp. were found to dominate among the AOB and Nitrobacter vulgaris, Nitrobacter alkalicus, Nitrobacter hamburgensis and an unidentified Nitrobacter spp. were the dominant species for NOB. Among these species, Nitrosomonas aestuarii, Nitrosomonas europaea, Nitrobacter hamburgensis were detected only from the industrial wastewater samples. The efficiency of two commonly used techniques viz., FISH and Q-PCR for the detection of nitrifiers from WWTP were also studied and compared, specifically targeting Nitrobacter sp. Even though there were slight variations in the quantification results, changes in the Nitrobacter community at these plants were consistent for both FISH and Q-PCR results. Both techniques have their own limitations and advantages. This study has helped to add to the platform of understanding the distribution and activity of nitrifying bacteria by correlating population dynamics with the operational parameters at full-scale level. The observations made in this study will assist researchers and engineers to minimise future nitrification failure at full-scale BNR plants. This study also confirmed the highly complex activities of wastewater treatment processes, which is dependant on a number of factors. Specific AOB or NOB predominant in wastewater rather suggests that the wastewater type and characteristics may contribute to significantly different microbial environments. Among the AOB, Nitrosomonas dominated at all BNR plants throughout the study period and for NOB both Nitrobacter and Nitrospira were found in significant numbers but their dominance varied across the plants. These dissimilar, distinct distribution patterns could be attributed to their environment which in turn impacted on the nitrification performance of the system. It was also noted that the co-existence of more than one group of these communities at the same plant could help the plant escape complete functional failures such as nitrification, due to sudden changes in temperature and substrate concentrations, as this function can be performed by different groups. Although it would have been meritorious to conduct a nitrogen balance in this study, this was not possible since the research focused on full-scale systems. / National Research Foundation / D

A loss of soil organic matter (SOM), whether through natural means or management practices, results in soil degradation. Biochar as a soil amendment can alter soil properties, ultimately affecting the availability of nitrogen and water to plants and thus crop growth. The effects of biochar are not definitive, and often dependent on both the soil type and the biochar applied. Biochar properties can change according to the feedstock and production parameters, thus for their effective use further investigation is required to link biochar properties to its effects in soil. A high-temperature (600˚ C) biochar from a mixed-hardwood feedstock was investigated. The biochar increased the soil water retention, as demonstrated by a water release curve and field trials. This retention was predominant at higher water potentials, which was attributed to the greater number of meso (storage) pores in the biochar. Biochar did not affect the soil’s saturated hydraulic conductivity; this is thought to be due to the low number of macro (transmission) pores in the biochar. Thus there was no effect on the transmission rate in the soil. Biochar reduced gross ammonium levels in the soil via adsorption, but resulted in increased non-exchangeable ammonium levels, possibly due to physical entrapment. Where carbon was already abundant in the organically managed soil, the adsorbed ammonium reduced nitrification through lower substrate availability. The range of carbon fractions added as a result of the biochar amendment increased the total organic carbon (TOC) content of the soil, but this supplementary carbon was released by the microorganisms as carbon dioxide. Microorganisms in the relatively carbon poor conventionally managed soil (with lower TOC), assimilated the additional labile carbon increasing microbial biomass. The higher microbial biomass, combined with improvements in pH and the higher ammonium levels (as a result of the ammoniacal fertiliser) increased nitrification. These changes in water and nitrogen availability did not alter crop yields as measured in the glasshouse and field trials. The effects of this biochar in a sandy agricultural soil depended on the type and level of carbon and nitrogen present in the soil, thus consideration of these factors should be taken when applying.

A presente pesquisa teve a intenção de desenvolver reator biológico de 159 \'M POT.3\' de volume total, com leito de carvões granulares (ativado e antracito) expandido e parcialmente aerado, para promover remoções de matéria orgânica e nutrientes (N e P) do esgoto sanitário, devido a manutenção de ambientes anaeróbio e aeróbio, estratificados ao longo da altura do reator e ao longo do biofilme cultivado em seu interior. Para avaliar o impacto das modificações operacionais no comportamento biológico dos microrganismos presentes no reator, foram aplicados métodos para análise das atividades nitrificante (ANE), desnitrificante (ADE) e metanogênica (PME), embasados em testes respirométricos padrões descritos na literatura. A estratificação reacional também foi estudada dentro de filmes biológicos com a ajuda de microsensores amperométricos de OD em testes de bancada. Assim, após 451 dias de operação, foi possível verificar remoções médias de \'DQO IND.F\', NTK e fosfato total de, respectivamente 78%, 56% e 42%, quando o reator foi operado por 66 dias com tempo de detenção hidráulica médio de 8,8 h, injetor de oxigênio puro, instalado após placa de orifício em linha de recirculação aerada, a qual funcionava pressurizada (3 a 4 bar) e com razão média de recirculação igual a 3, comparada à vazão de alimentação. Para o restante do período, no qual foram aplicadas taxas de carregamentos volumétricos médios de 0,74 \'+ OU -\' 0,28 kg\'DQO IND.F\'/\'M POT.3\'.dia; 0,17 \'+ OU -\' 0,07 kg NTK/\'M POT.3\'.dia e 0,05 \'+ OU -\' 0,02 kg\'PO IND.4\'POT.-3\'/\'M POT.3\'.dia, o sistema demonstrou remoções médias de 65 \'+ OU -\' 20% para \'DQO IND.F\', 25 \'+ OU -\' 21% para o NTK e 48 \'+ OU -\' 18% para o fosfato total, mesmo operado com tempo de retenção celular médio de 15 \'+ OU -\' 7 dias. Os testes respirométricos foram sensíveis para avaliar a atividade microbiana do material biológico coletado ao longo do reator, com os quais foram verificados PME médio de 0,25 mL\'CH IND.4\'/gSVT.h, para as amostras de material biológico coletado na região anaeróbia, ao fundo do reator; ANE variando entre 1,3 a 4,4 mg\'O IND.2\'/gSVT.h, para as amostras coletadas na região aeróbia, intermediária ao reator; e ADE variando entre 0,024 e 5,20 mg\'N IND.2\'/gSVT.h, para amostras coletadas, respectivamente, no fundo e no topo do reator. As análises do material líquido também corroboram com a idéia de estratificação dos ambientes aeróbio, no fundo do reator, e micro-aerado, em sua região intermediária superior, apontando para região com alto potencial de ocorrerem nitrificação e desnitrificação conjuntas no topo da sua zona reativa. O microsensor amperométrico de OD com ponta entre 10 e 30 \'mü\'m de diâmetro, confeccionados em laboratório especializado, se mostrou sensível para a observação do gradiente de concentração de oxigênio dissolvido dentro de filme biológico, suficientes para a formação de regiões aeróbia e anaeróbia em seu interior, cuja informação pode ser útil para a aprimoramento de reatores com biofilme, projetados para remoções combinadas de matéria orgânica e nutrientes. Entretanto, quando se pretende definir parâmetros cinéticos ou de transferência de massa, maior rigor deve ser dispensado na definição dos locais para a aplicação do sensor, nos quais sejam reduzidos os efeitos da heterogeneidade do agregado microbiano no ajuste da modelagem matemática aplicada aos pontos experimentais / The current research aimed the development of a 159 \'M POT.3\' total volume biological reactor, with a expanded and partially aerated granular coal bed (activated and anthracite), to promote organic matter and nutrients (N and P) removal from wastewater due to the maintenance of anaerobic and aerobic environments, stratified throughout the height of the reactor and also all over the biofilm cultivated in its interior. Methods for the analyses of specific nitrifying activities (ENA), denitrifying (EDA) and methanogenic (EMA) were applied to assess the impact of the operational modifications in the biological behavior of microorganisms present in the reactor, based on standard respirometric tests found in literature. The reactional stratification was also studied inside the biological films with the help of DO microsensors in batch tests. Thus, after 451 of operation it was possible to verify mean \'COD IND.F\', TNK and phosphate removal of 78%, 56% and 42%, respectively, when the reactor was operated for 66 days with average hydraulic detention time of 8.8 h, pure oxygen injector which was installed after the aerated recirculation line which was working pressurized (3 to 4 bar) and with mean recirculation ratio equal to 3, when compared to the feeding flow. For the rest of the period where mean volumetric loading rates of 0.74 \'+ OR -\' 0.28 kg\'COD IND.F\'/\'M POT.3\'.day; 0.17 \'+ OR -\' 0.07 kgTNK/\'M POT.3\'.day and 0.05 \'+ OR -\' 0.02 kg\'PO IND.4\'POT.-3\'/\'M POT.3\'.day were applied the system demonstrated average removal of 65 \'+ OR -\' 20% for \'COD IND.F\', 25 \'+ OR -\' 21% for TNK and 48 \'+ OR -\' 18% for total phosphate, even when it operated with mean cellular retention time of 15 \'+ OR -\' 7 days. The respirometric tests were sensible enough to assess the microbial activity from the biological material collected throughout the reactor, and where mean PME of 0.25 mL\'CH IND.4\'/gSVT.h was verified for the samples of biological material collected in the anaerobic region, at the bottom of the reactor; ANE varying between 1.3 to 4.4 mg\'O IND.2\'/gSVT.h, for the samples collected in the aerobic region, reactor\'s intermediary; and ADE varying between 0.024 to 5.20 mg\'N IND.2\'/gSVT.h, for samples collected at the bottom and the top of the reactor, respectively. The analyses of the liquid material also support the idea of stratification of the aerobic environments, at the bottom of the reactor, and micro-aerated, in its superior intermediate region, pointing to the region as a high potential of occurring joint nitrification and denitrification at the top of the reactive zone. The DO amperometric microsensor, with tip between 10 and 30 \'mü\'m of diameter, produced in a special laboratory, is sensible to the determination of dissolved oxygen concentration gradient inside biological film, sufficient for the formation of anaerobic and aerobic regions in its interior, this information can be useful to the improvement of biofilm reactors, projected for the combined removal of organic matter and nutrients. However, when the definition of kinetic parameters or mass transference is intended more strictness must be applied when choosing the locals for microsensor application, where the effects of the microbial aggregate heterogeneity is reduced in the adjustment of the mathematical modeling applied to the experimental points.

O uso ineficiente do nitrogênio (N) é um problema global, que pode diminuir a sustentabilidade da produção agrícola da cana-de-açúcar para fins energéticos devido às emissões de N2O oriundas da fertilização nitrogenada. A eficiência de utilização de nitrogênio (EUN) tem sido pouco estudada em genótipos de cana-de-açúcar, o que pode ser preocupante devido a importância da cultura para o país. O objetivo desse estudo foi avaliar a EUN de genótipos de cana-de-açúcar, verificando se genótipos contrastantes tem preferência de absorção por amônio ao invés de nitrato, e checar se extratos radiculares de Brachiaria humidicola e Saccharum spontaneum aumentam a eficiência de utilização de N pela cultura. Para isso três experimentos foram desenvolvidos em condições controladas em casa-de-vegetação e câmara de crescimento. No primeiro deles, 18 genótipos foram submetidos a dois níveis de N: limitante (baixo N) e suficiente (alto N). Posteriormente, quatro genótipos selecionados quanto a EUN do primeiro experimento, foram cultivados em câmara de crescimento por 69 dias, onde receberam quantidades conhecidas de N-fertilizante marcado ou no 15NH4+ ou no 15NO3-, sendo avaliados 24 e 72 horas após a aplicação do fertilizante marcado. Um terceiro ensaio foi realizado, em que extratos radiculares de Brachiaria humidicola (BCH) e Saccharum spontaneum (SCS) foram aplicados ao solo com o intuito de verificar seu potencial como inibidor da nitrificação, comparando-os com a dicianodiamida (DCD), e seu efeito para o aumento do aproveitamento do N pela cana-de-açúcar. No experimento de EUN verificou-se grande variação entre os genótipos. Dos 18 genótipos avaliados, seis foram classificados como responsivos a N e eficientes na utilização de N, três foram não eficientes e responsivos; dois foram eficientes e não responsivos, e sete não eficientes e não responsivos. Esse resultado comprova que a recomendação da adubação nitrogenada pode realmente estar pouco precisa, pois não leva em consideração a EUN de cada genótipo, sendo realizada uma aplicação genérica. As medições de fotossíntese mostraram que os genótipos mais eficientes na utilização do N, não necessariamente possuem as taxas fotossintéticas mais elevadas, estando a EUN diretamente relacionada à quantidade de raízes das plantas. No segundo trabalho, verificou-se que o N na planta proveniente do fertilizante (NPPF), 72 horas após a aplicação do N, foi 36% menor quando a fonte marcada foi NO3-, atestando que a cana-de-açúcar tem preferência de absorção por amônio em relação ao nitrato nos primeiros dias após a adubação nitrogenada. Por fim, os resultados do terceiro ensaio mostraram que a aplicação de sulfato de amônio (SA), associado ao inibidor sintético DCD, manteve os valores de N-NO3- baixos ao longo de todo período de avaliação (durante 60 dias), enquanto que com SA, SA+BCH e SA+SCS houve um aumento na concentração de nitrato no solo já a partir de 15 dia após a fertilização. O uso de DCD reduziu o fluxo médio de N2O durante o período de avaliação em relação ao uso isolado do fertilizante, o que não foi observado com o uso de extratos de raízes de Brachiaria humidicola e Saccharum spontaneum / Low effectiveness of nitrogen (N) from fertilizers is a worldwide concern, which can threaten the sustainability of sugarcane production for energy purposes, due to N2O emissions from nitrogen fertilization. The nitrogen use efficiency (NUE) has been few studied in sugarcane genotypes, which can be an important issue due the importance of crop for Brazil. The aim of this study was to evaluate the NUE of sugarcane genotypes, checking if contrasting genotypes relating to NUE have preference by ammonium absorption instead of nitrate; and testing if root extracts of Brachiaria humidicola and Saccharum spontaneum have potential to increase NUE by sugarcane. For this, three experiments were performed under controlled conditions (glasshouse and growth chambers). In the first trial 18 genotypes were subjected to N rates: limiting (low N) and sufficient (high N). Further, four genotypes were selected regarding to NUE being grown for 69 days at growth chamber, when it received N fertilizer labeled whether 15NH4+ or 15NO3-. After that, the plants were assessed at 0, 24 and 72 hours after N application. The third experiment was carried out to evaluated if root extracts of Brachiaria humidicola (BCH) and Saccharum spontaneum (SCS) have potential as nitrification inhibitor compared to dicyandiamide (DCD) aiming to increase NUE by sugarcane. In the first trial there was great variation of NUE among genotypes. The results of NUE permitted to classify the genotypes relating to NUE as responsive to N and efficient to use N (six genotypes); not efficient and responsive to N (three genotypes); efficient and not responsive to N (two genotypes); not efficient and not responsive to N (seven genotypes). This result showed that recommendation of nitrogen fertilization currently used in Brazil is quite imprecision, because it not consider NUE of each genotype. The photosynthesis index not showed good correlation to NUE. The best NUE was obtained in genotypes with very well root growth (biomass). The second experiment was verified that sugarcane genotypes has preference by ammonium few days after 15N-fertilizer application (72h). The plants fertilized with 15N-nitrate uptake 36% less N than those plants fertilized with 15N-ammonium. The results of third experiment showed that the use of ammonium sulfate (AS) plus DCD kept low the NO3--N content in the soil for whole time of experiment (60 days), whereas with AS, AS + BCH and AS + SCS there was an increase in the nitrate content in the soil after 15 days of fertilization. The use of DCD together to AS reduced the N2O emission compared to plants fertilized with only with AS or with AS and others potential natural inhibitors of nitrification (root extracts of Brachiaria humidicola and Saccharum spontaneum)

Um Reator com Aeração Intermitente e Leito Estruturado (RAILE) foi testado como pós- tratamento de UASB tratando efluente doméstico. O RAILE foi submetido a ciclos de uma hora de aeração e duas de anoxia, visando obtenção de Nitrificação e Desnitrificação Simultâneas (NDS) para remoção de nitrogênio. A recirculação aplicada foi de 3 vezes a vazão de entrada, para equalização da qualidade do efluente. O reator tem formato cilíndrico e seu meio suporte é espuma de poliuretano na forma de cilindros dispostos verticalmente, suportados por hastes de cloreto de polivinila (PVC) presas nas extremidades. O estudo foi dividido em duas fases em que o RAILE recebeu efluentes de UASB com diferentes relações de DQO/N-Total. Na primeira fase a relação foi 2,44 e na segunda fase a relação foi 4,01. As remoções de N-Total foram 23,7% e 65,3%, respectivamente para primeira e segunda fase. As remoçôes de DQO para todo o sistema foram 94,8%, para a primeira fase, e 93,4%, para a segunda fase. A alcalinidade se mostrou um parâmetro efetivo pra monitorar a ocorrência de NDS. Embora tenha se mostrado viável como pós-tratamento de UASB em sistemas tratando efluente doméstico, a relação DQO/N-Total precisa ser controlada para garantir o processo de NDS / A Structured Bed Intermittently Aerated reactor (SBIA) was tested as post-treatment for UASB treating domestic wastewater. The SBIA underwent cycles of one hour of aeration and two hour of anoxia to obtain Simultaneous Nitrification and Denitrification (SND) for the removal of nitrogen. The recirculation flow applied was 3 times the input flow to equalize the effluent quality. The reactor had a cylindrical shape and its support medium is polyurethane foam in the form of cylinders arranged vertically, supported by polyvinyl chloride (PVC) rods attached at the ends. The study was divided into two stages in which the SBIA received the UASB reactor effluent with different COD/Total-N ratios. The first COD/Total-N ratio was 2,44 and the second was 4,01. The removal of N-total were 23.7% and 65.3% respectively for the first and second stages. The removal of COD, in all the system, was 94.8% for the first stage and 93.4% for the second stage. The alkalinity proved to be an effective parameter to monitor the occurrence of SND. Although the SBIA proved to be feasible as post-treatment of UASB systems treating domestic wastewater the ratio COD/N-total must be controlled to ensure the process of SND