Phosphorus removal in wastewater treatment is commonly achieved by chemical precipitation, enhanced biological phosphorus removal (EBPR) or a simultaneous combination of the two. A defined anaerobic condition is widely regarded as the critical element to sustain EBPR. However, this study demonstrates that EBPR is indeed occurring in a 4.5 m3/h membrane bioreactor (MBR) pilot plant without a defined anaerobic condition. Although designed for chemical precipitation alone, a low average Fe/P molar ratio (iron dose/phosphorus removed) of 0.9 ± 0.1 suggests that EBPR could be contributing to a simultaneous phosphorus removal. Weekly flow-proportional grab samples through the process showed a phosphate (P) release between the primary anoxic tanks, followed by a larger uptake in the aerobic tanks. In laboratory batch tests with limited acetate supply in the presence of nitrates, the anoxic P-release began and then abruptly stopped whilst the nitrate concentration continued to decrease. This could be explained by denitrifiers out-competing PAOs for soluble substrate since a large P-release occurred when excess acetate was supplied in the presence of nitrates. It is therefore unlikely that PAOs are operating in the pilot despite the presence of nitrates as was concluded in a study with similar spontaneous EBPR observations. Instead, it is suggested that EBPR is enabled by intermittent anaerobic conditions in the primary anoxic tanks due to low nitrate concentrations (< 1 mg NO3/l) recirculating back after post-denitrification. The external carbon source supplied to the pilot was changed from glycerol to ethanol to assess any effect on the spontaneous EBPR. After ethanol had been supplied for 30 days, increased P-release rates were observed in batch tests supplied with ethanol (0.1 to 0.4 mg P/g VSS∙h) and batch tests supplied with acetate (8.6 ± 0.4 to 10.3 ± 0.4 mg P/g VSS∙h). However, the overall consumption of glycerol was less than that of ethanol, whilst the total phosphorus removal and the Fe/P ratio remained similar whether ethanol or glycerol was supplied to the pilot plant. Should operators wish to avoid any possible spontaneous P-release in the post-denitrification step, methanol is recommended as the external carbon source when considering laboratory P-release results, past research and operation costs. / Fosforrening av avloppsvatten uppnås vanligtvis genom kemisk utfällning, enhanced biological phosphorus removal (EBPR) eller en kombination av dessa två samtidig. Ett definierat anaeroba förhållanden betraktas allmänt som det kritiska elementet för att upprätthålla EBPR. Dock visar denna studie att EBPR verkligen förekommer i en pilotanläggning med membranbioreaktor (MBR) utan ett definierat anaeroba förhållanden. Veckovis flödesproportionella stickprover genom processen visade en ökad fosfat (P) halt mellan de primära anoxisk tankarna, följt av ett upptag i de aerobiska tankarna. Även om det är planerat för bara kemisk fosforrening, ett lågt medel Fe/P molförhållande (järndos/fosfor bortagning) på 0,9 ± 0,1 föreslår att EBPR kan bidra till ett samtidigt fosforrening. Laboratorie-P-utsläppningstest bekräftade EBPR-aktivitet med en hög medel P-utsläpp av 9,3 ± 0,9 mg P/g VSS∙h med acetat. Tillsammans indikerar dessa resultat att biologiskt fosforrening kompletterade den kemiska fosforrening under undersökningsperioden. P- utsläppningstest visade att närvaron av nitrater inte påverkade PAO-aktiviteter när acetat tillfördes i överskott. Med begränsad acetattillförsel förhindrade emellertid närvaron av nitrater någon initial P-utsläpp och inga efterföljande fermenteringsbiprodukter observerades. Slutsatsen dras att effektiv nitrifikation-denitrifikation och hög recirkulation resulterar i låga nitrathalt i primär anox tankar. Detta orsakar intermittenta anaerobisk förhållanden som, tillsammans med lämpliga substrathalt i inloppsvatten, möjliggör EBPR att ske. Den externa kolkällan som levererades till MBR-piloten ändrades från glycerol till etanol för att undersöka potentialen att öka EBPR-andelen av fosforrening. P-utsläpp i labbtester med etanol dosering ökade från 0,1 till 0,4 mg P/g VSS∙h och tester med acetat dosering ökade från 8,6 ± 0,4 till 10,3 ± 0,4 mg P/g VSS∙h när slam hade anpassats till etanol i 30 dagar. Vid pilotanläggningens drift konsumerades i alla fall mindre glycerol under dess användningsperiod än etanol, och Fe / P- förhållandet var likadant oavsett om glycerol eller etanol tillsatts. Olika andra kolkällor testades i parallella P-utsläppningstest. VFA producerat genom jäsning av matavfall och primärt slam i ett pågående projekt, och huvudsakligen bestående av kapronsyra, resulterade i den näst högsta P- utsläpp. P-utsläpp från alkoholer var märkbart lägre än VFA-baserade kolkällor. Det betyder att risken är låg för oväntat P-utsläpp i den slutliga biologiska zonen om en alkoholbaserad kollkällan doseras där. Minskad förluftning och en liten dos VFA-baserat substrat i den första biologiska zonen skulle bidra till en betydande EBPR som skulle möjliggöra en ytterligare reducerad basdos av järnsulfat.

Intensification refers to utilizing wastewater treatment processes that decrease chemical and energy demands, increase energy recovery, and reduce the process footprint (or increased capacity in an existing footprint) all while providing the same level of nutrient removal as traditional methods. Shortcut nitrogen removal processes; including nitrite shunt, partial nitritation/anammox, and partial denitrification/anammox, as well as low-carbon biological phosphorus removal, were critically-evaluated in this study with an overall objective of intensification of existing infrastructure. At the beginning of this study, granular sidestream deammonification was becoming well-established in Europe, but there was virtually no experience with startup or operation of these processes in North America. The experience gained from optimization of the sidestream deammonification moving bed biofilm reactor (MBBR) in this study, including the novel pH-based aeration control strategy, has influenced the startup procedure and operation of subsequent full-scale installations in the United States and around the world. Long startup time remains a barrier to the implementation of sidestream deammonification processes, but this study was the first to show the benefits of utilizing media with an existing nitrifying biofilm to speed up anammox bacteria colonization. Utilizing media with an established biofilm from a mature integrated fixed film activated sludge (IFAS) process resulted in at least five times greater anammox activity rates in one month than virgin media without a preliminary biofilm. This concept has not been testing yet in a full-scale startup, but has the potential to drastically reduce startup time. False dissolved oxygen readings were observed in batch scale denitrification tests, and it was determined that nitric oxide was interfering with optical DO sensors, a problem of which the sensor manufacturers were not aware. This led to at least one sensor manufacturer reevaluating their sensor design and several laboratories and full-scale process installations were able to understand their observed false DO readings. There is an industry-wide trend to utilize influent carbon more efficiently and realize the benefits of mainstream shortcut nitrogen removal. The A/B pilot at the HRSD Chesapeake Elizabeth Treatment provides a unique chance to study these strategies in a continuous flow system with real wastewater. For the first time, it was demonstrated that the presence of influent particulate COD can lead to higher competition for nitrite by heterotrophic denitrifying bacteria, resulting in nitrite oxidizing bacteria (NOB) out-selection. TIN removal was affected by both the type and amount of influent COD, with particulate COD (pCOD) having a stronger influence than soluble COD (sCOD). Based on these findings, an innovative approach to achieving energy efficient biological nitrogen removal was suggested, in which influent carbon fractions are tailored to control specific ammonia and nitrite oxidation rates and thereby achieve energy efficiency in the nitrogen removal goals downstream. Intermittent and continuous aeration strategies were explored for more conventional BNR processes. The effect of influent carbon fractionation on TIN removal was again considered, this time in the context of simultaneous nitrification/denitrification during continuous aeration. It was concluded that intermittent aeration was able to achieve equal or higher TIN removal than continuous aeration at shorter SRTs, whether or not the goal is nitrite shunt. It is sometimes assumed that converting to continuous aeration ammonia-based aeration control (ABAC) or ammonia vs. NOx (AvN) control will result in an additional nitrogen removal simply by reducing the DO setpoint resulting in simultaneous nitrification/denitrification (SND). This work demonstrated that lower DO did not always improve TIN removal and most importantly that aeration control alone cannot guarantee SND. It was concluded that although lower DO is necessary to achieve SND, there also needs to be sufficient carbon available for denitrification. While the implementation of full-scale sidestream anammox happened rather quickly, the implementation of anammox in the mainstream has not followed, without any known full-scale implementations. This is almost certainly because maintaining reliable mainstream NOB out-selection seems to be an insurmountable obstacle to full-scale implementation. Partial denitrification/anammox was proven to be easier to maintain than partial nitritation/anammox and still provides significant aeration and carbon savings compared to traditional nitrification/denitrification. There is a long-standing interest in combining shortcut nitrogen removal with biological phosphorus removal, without much success. In this study, biological phosphorus removal was achieved in an A/B process with A-stage WAS fermentation and shortcut nitrogen removal in B-stage via partial denitrification. / Doctor of Philosophy / When the activated sludge process was first implemented at the beginning of the 20th century, the goal was mainly oxygen demand reduction. In the past few decades, treatment goals have expanded to include nutrient (nitrogen and phosphorus) removal, in response to regulations protecting receiving bodies of water. The only practical way to remove nitrogen in municipal wastewater is via biological treatment, utilizing bacteria, and sometimes archaea, to convert the influent ammonium to dinitrogen gas. Orthophosphate on the other hand can either be removed via chemical precipitation using metal salts or by conversion to and storage of polyphosphate by polyphosphate accumulating organisms (PAO) and then removed in the waste sludge. Nitrification/denitrification and chemical phosphorus removal are well-established practices but utilize more resources than processes without nutrient removal in the form of chemical addition (alkalinity for nitrification, external carbon for denitrification, and metal salts for chemical phosphorus removal), increased reactor volume, and increased aeration energy. Intensification refers to utilizing wastewater treatment processes that decrease chemical and energy demands, increase energy recovery, and reduce the process footprint (or increased capacity in an existing footprint) all while providing the same level of nutrient removal as traditional methods. Shortcut nitrogen removal processes; including nitrite shunt, partial nitritation/anammox, and partial denitrification/anammox, as well as low-carbon biological phosphorus removal, were critically-evaluated in this study with an overall objective of intensification of existing infrastructure. Partial nitritation/anammox is a relatively new technology that has been implemented in many full-scale sidestream processes with high ammonia concentrations, but that has proven difficult in more dilute mainstream conditions due to the difficulty in suppressing nitrite oxidizing bacteria (NOB). Even more challenging is integrating biological phosphorus removal with shortcut nitrogen removal, because biological phosphorus removal requires the readily biodegradable carbon that is diverted. Partial denitrification/anammox provides a viable alternation to partial nitritation/anammox, which may be better suited for integration with biological phosphorus removal.

Over the last two decades, livestock operations have become highly concentrated due to growing trends towards larger, more confined facilities and a decrease in cropland on smaller farms. This has led to greater amounts of excess manure nutrients on farms, increasing the potential for nutrient pollution of water bodies from runoff. The purpose of this study was to determine if enhanced biological phosphorus removal (EBPR) is a viable alternative for managing excess manure nutrients on dairy farms. Assessment of EBPR involved the investigation of various aspects of wastewater treatment modeling and design and farm nutrient management. The fermentation potential (volatile fatty acid (VFA) production) of dairy manure was determined through laboratory analysis to be 15.3% of the total COD. Total VFA production was composed of 57, 23, and 20% acetic, propionic, and butyric acids, respectively. The EBPR component of the BioWin wastewater treatment model was evaluated through a sensitivity analysis. The parameters to which effluent phosphate (PO4) concentration was most sensitive were maximum specific growth rate, growth yield, aerobic PO4 uptake rate per unit poly-b-hydroxybutyrate (PHB) utilized, PHB yield from VFA, PO4 release per unit VFA uptake, and fraction of releasable PO4. An EBPR sequencing batch reactor (SBR) was designed for a dairy farm with 700 lactating cows and 325 ha of corn silage. An economic analysis of EBPR for dairy farms employing P-based manure applications was completed. The cost of hauling excess manure to nutrient deficient farms was the most significant expense in comparing costs of manure management with and without EBPR. For a herd of 700 lactating cows, utilizing EBPR was more economical for farms with 270 ha or less cropland, while EBPR did not offer an economic advantage for farms over 270 ha. / Master of Science

Waste Stabilisation Ponds (WSPs) are characterised by low phosphorus (P) removal capacity. Heterotrophic bacteria are principal microbial agents in WSPs in addition to algae. As treatment proceeds in WSPs, algal growth increases and pH rises, this has lead to believe that P removal is mainly through sedimentation as organic P algal biomass and precipitation as inorganic P. In activated sludge treatment plants (AS), microbial P removal has been improved and is termed as enhanced biological phosphorus removal. There was a need to establish whether it was possible to enhance P removal in WSPs. A performance assessment of pond system at the University of Dare s Salaam (UDSM), Tanzania, has shown that 90% of the P removed was in the primary pond (facultative) and the rest in the maturation pond (aerobic). In these studies, a pure strain A. hydrophyla was isolated from an activated sludge wastewater treatment plant in Sweden. This plant has a train that functions with enhanced biological phosphorus removal. The strain was tested for P uptake in minimal media supplemented with glucose, succinate or acetate, grown aerobically and anaerobically/aerobically. This strain was able to take up P without having been subjected to the anaerobic phase. It was observed that P uptake was enhanced after the anaerobic phase with media supplemented with glucose, but not with succinate or acetate. Phosphorus uptake repeatedly followed the bacterial growth pattern with correlation coefficients of more than 95%. Therefore P removal has a direct correlation with bacterial growth. Two isolates Acinetobacter sp. (isolated from the primary facultative pond) and E .coli (isolated from the maturation pond) were obtained from a tropical WSP treatment system at the UDSM. They were subjected to aerobic P uptake experiment similar to those of A.hydrophyla. The uptake per unit absorbance of bacterial growth was found to be comparable to that of A.hydrophyla, isolated from AS. These results showed that heterotrophic activity is important in WSPs. It is possible to enhance P removal in these systems by designing the primary ponds for maximum heterotrophic activity and probably enrichment. / QC 20101119

It is generally accepted that a decrease in temperature causes the rates of chemical and biochemical reactions to slow down, usually resulting in poorer performance of biological wastewater treatment systems. Despite this, early researchers repeatedly showed that excess biological phosphorus removal (EBPR) was more efficient at colder temperatures. Recent studies, however, have demonstrated that the reaction rates of EBPR processes decrease with temperature in accordance with Arrhenius' Law, resulting in an apparent contradiction in the literature. The objective of this study was to investigate the EBPR temperature controversy. The experimental systems used were two, lab-scale UCT configuration plants fed with acetate as the sole volatile fatty acid (VFA) source. The results showed that EBPR systems do perform more efficiently at colder temperatures, i.e., at 5°C compared to 20°C. The reason for better system performance was determined to be related to reduced competition for substrate in the non-oxic zones that results in an increased population of phosphate accumulating organisms (PAOs) relative to non-PAOs and, therefore, greater EBPR efficiency even though the reaction rates are slower. The proliferation of PAOs relative to non-PAOs at cold temperature indicates that some of the PAOs are psychrophilic, i.e., they have alternate biochemical pathways that give them a competitive advantage over bacteria dependent upon glycogen metabolism. The activated sludge acclimated to 20°C had relatively high polyhydroxyvalerate (PHV) and glycogen contents relative to sludge acclimated to 5°C. It was initially hypothized that there is a significant competition between PAO and glycogen accumulating organisms (GAOs) at 20°C and cold temperature (5°C) nearly eliminates this competition in favor of the PAOs. A series of batch test experiments revealed that despite similar acetate utilization by the sludges grown at the two temperatures nearly 30% less PHA was produced by the sludge taken from the 20°C reactor, indicating that GAOs were a small fraction of the population at 20°C. Transmission electron microscopy pictures showed that the biomass acclimated to 20°C had a much more diverse bacterial population than the biomass acclimated to 5°C. However, no GAO population was detected in electron microscopy samples under any temperature conditions. The decreased P removal efficiency at 20°C was then attributed to the presence of fermentative or other non poly-P bacteria that are capable of utilizing substrate under anaerobic conditions. PHA production greatly increased at 5°C, whereas glycogen metabolism substantially reduced. Even though glycogen is an essential requirement for EBPR mechanism, the EBPR microorganisms have the ability to adapt their metabolic pathways to environmental conditions and greatly reduce their need for glycogen. It is apperant that cold temperature inhibits some of the key enzymes in glycogen metabolism resulting in lower glycogen accumulation that in turn increases the EBPR performance. Therefore temperature not only exerts selective pressure on the dominant population but also alters the metabolic pathways of the EBPR process. Increased glycogen accumulation, as observed in this study at 20°C, may not be related to GAO proliferation as suggested by Filipe et al. (2001) instead it may be related to EBPR bacteria to efficiently use glycogen metabolism. Current models (Brdjanovic et al. 1997; Filipe et al. 2002) consider that GAO metabolism is an integral part of EBPR metabolism and the performance of EBPR processes depends on PAO/GAO fraction in the EBPR system. No GAO proliferation was observed even the A/O process was operated without P addition for more than 3 weeks at 10°C. Therefore such important concept should be further investigated before it is included in EBPR models. EBPR stoichiometry was presumed to be insensitive to temperatures (Brdjanovic et al. 1997). However, observed stoichiometric values of PHA storage per unit glycogen utilization and PHA utilization per unit glycogen rephlenishment were quite different at different temperatures. Temperature, therefore, not only affects the kinetics of EBPR systems but also affects the EBPR stoichiometry. Most prokaryotic cells have the ability to alter their cellular membrane fatty acid composition as temperature decreases to counteract the adverse effects of temperature on membrane fluidity (Becker et al., 1996). This unique ability is known as "homeoviscous adaptation". In this study, homeoviscous adaptation by EBPR activated sludge was investigated for a series of temperatures ranging from 20°C to 5°C using one of the lab scale EBPR systems. The fatty acid analysis results showed that the unsaturated to saturated fatty acid ratio increased from 1.40 to 3.61 as temperature dropped from 20 to 5°C. The increased cis-9-hexadecanoic acid (C16:1) at 5°C strongly indicated the presence of homeoviscous adaptation in the EBPR bacterial community. Thus the cell membranes of the EBPR community were still in a fluid state, and solute transport and proton motive force mechanisms were operable even at 5°C. It was concluded that loss of EBPR performance at low temperatures, as reported by McClintock et al. (1992) was not related to the physical state of the cellular membranes, but was probably caused by unsuitable operational conditions. Even though the transport of volatile fatty acids (e.g. acetate) is an integral part of EBPR biochemistry and stoichiometry, this important concept has been ignored. Fleet (1997) concluded that acetate entry into bacterial cells in EBPR sludge was simple passive diffusion based upon the results of a single study (Baronofsky et al. 1984). However, this study showed that neither acetate nor propionate can cross the cell membrane via simple passive diffusion. The existence of apparent saturation curves when the substrate uptake rates (acetate and propionate) were plotted against the substrate concentrations suggested that transport of volatile fatty acids obey facilitated or active transport. Following from the above results, an investigation of the impacts of operational conditions such as low solids retention time (SRT), presence of electron acceptors in the non-oxic zones, low anaerobic detention time, and lack of acclimation was performed. The results showed that the "critical, i.e., wash-out" SRT increased as temperature decreased, but if the biomass was permitted to acclimate to the lower temperature, a major population shift would occur which would increase the capacity of the system for phosphorus (P) removal. When the 5 °C sludge was allowed to acclimate at a relatively high SRT (18 d), the system's P-removal capacity greatly surpassed that of the 20 °C system. The decrease in EBPR performance because of the presence of nitrates in the non-oxic zones was determined to be greater than what would be predicted based on accepted stoichiometry. / Ph. D.

Although enhanced biological phosphorus removal (EBPR) and complete biological nutrient removal (BNR) systems can be operated successfully by experienced operators, the accuracy of design and strength of the scientific background need to be reinforced to enable accurate modeling and economically optimal design. One way to accomplish this would be through a better understanding of the biochemical mechanisms and microbial population dynamics that determine the reliability and efficiency of EBPR, and the utilization of this information to improve the design and operation of BNR plants. Such knowledge will also contribute to better structure of modeling tools that are used for design and educational purposes. The current body of knowledge is limited to observational studies that lack detailed biochemical explanations backed with a series of well planned experiments, and this has introduced uncertainties and inaccuracies into the biochemical and design models. Therefore, this study mainly covers a biochemical survey of the underlying metabolisms of active populations in BNR sludges. BNR biomass with biological phosphorus removal (BPR) capability was cultivated in continuous flow reactor (CFR) systems, configured as either University of Cape Town (UCT) and anoxic/oxic (A/O) systems. Following an acclimation period at 20°C, low temperature stress (5°C) was imposed on one UCT system for investigation of the response of the microbial consortium responsible from EBPR activity under cold temperature. Once a stable population with EBPR capabilities is established in each system, activities of ten enzymes that are hypothesized to be taking part in the EBPR metabolism were measured. These enzymes were selected among those that take part in major known pathways of bacterial energy and growth metabolism. Also, 13C-NMR was used as a tool to monitor the flux of labeled carbon in and out of pools of cellular storage; i.e. glycogen and polyhydroxyalkanoates (PHA). Combining the gathered information, accurate mass balances of carbons and reducing equivalents were calculated, eventually leading to determination of the biochemical pathways utilized by the EBPR consortium. Additionally, anaerobic stabilization of COD, a long debated but empirically established phenomenon, was addressed during the study. Considering the pathways proposed to be operative under different conditions imposed on the EBPR systems, a biochemical explanation for the occurrence of COD stabilization in wastewater treatment systems that incorporate anaerobic zones was proposed. Accordingly, depending on the pathways actively used by a microbial consortium, electrons stored in NADH and FADH2 can either be transferred to the terminal electron acceptor, oxygen, or they can be incorporated into storage polymers such as glycogen for future use. Such differences in metabolism reflect in the quantity of the oxygen consumed in the aerobic reactors. Thus, the correct incorporation of anaerobic stabilization of COD into process design would reduce design aeration requirements and result in economic savings during both construction and operation. / Ph. D.

Enhanced biological phosphorus removal (EBPR) has been widely used in municipal wastewater treatment, but no previous studies have examined the application of EBPR to treat dairy manure. This study was conducted to evaluate the (i) performance of pilot-scale EBPR systems treating liquid dairy manure, to balance the ratio of nitrogen to phosphorus in manure to meet crop nutrient requirements, (ii) effects of dissolved oxygen and solids retention time on the efficiency of EBPR, and (iii) effectiveness of gravity thickening for reducing the volume of harvested EBPR aerated mixed liquor. Two pilot-scale EBPR systems were used in this study. The ratio of the manure chemical oxygen demand expressed as volatile fatty acids to phosphorus used ranged from 18:1 to 45:1. The phosphorus removal efficiencies of the EBPR system were investigated at three solids retention times (4, 6 and 10 d), and three dissolved oxygen levels (3, 4 and 6 mg O₂/L). The total phosphorus removal was highest (84%) at 10 d solids retention time and lowest (63%) at 4 d solids retention time. The sludge from the 6 d solids retention time tests had better sludge settling characteristics with a sludge volume index of 62 mL/g compared to 80 mL/g for the 4 d solids retention time. The EBPR system achieved 90% dissolved reactive phosphorus removal when the system was operated at 4 mg O₂/L, and the ratio of nitrogen to phosphorus in effluent increased to about 5:1, which was higher than the normal ratio in dairy manure. On the other hand, phosphorus removal performance deteriorated when dissolved oxygen level was 3 mg O₂/L. In the gravity thickening tests, 93-95 % total suspended solids (TSS) was removed from the settled supernatant, with 1.2 to 1.54 % total solids (TS) in the settled solids after 90 min gravity-induced thickening. The extent of phosphorus release during gravity thickening process needs to be further investigated. / Master of Science

Esse trabalho buscou avaliar a possibilidade de utilização do glicerol como fonte de carbono para a desnitrificação conjunta à remoção biológica de fósforo de um efluente sintético em um reator de fluxo contínuo submetido à aeração intermitente e com biomassa suspensa. O regime operacional do reator foi dividido em duas fases: a primeira visando somente a remoção de nitrato, testando diferentes relações Carbono/Nitrogênio (C/N) em Tempo de Detenção Hidráulica (TDH) de 4 horas; e a segunda visando a remoção de nitrato e fosfato com períodos de aeração e não aeração de 2 e 4 horas respectivamente, para uma relação Carbono/Fósforo de 10 ± 1. Na primeira fase operacional foram testadas 3 relações C/N, a saber: 1,2 ± 0,1; 1,5 ± 0,1 e 1,8 ± 0,2. Para a relação C/N de 1,8 ± 0,2 foi possível atingir uma maior eficiência de desnitrificação com uma maior estabilidade operacional - 91 ± 8%. Para a segunda fase de operação que apresentou relação C/N de 3,5 ± 0,2, a desnitrificação foi completa na maior parte do tempo com 99 ± 2% de eficiência de remoção de NOx (nitrato mais nitrito), indicando que a desnitrificação com glicerol é favorecida para relações C/N mais altas. Não foi evidenciado uma remoção biológica de fósforo expressiva (9 ± 12%), indicando que não houve desenvolvimento dos organismos acumuladores de fósforo (OAPs), uma vez que a liberação de fosfato durante a fase não aerada não ocorreu. Isso pode ser explicado pela falta de ácidos graxos voláteis (AGV), que seriam provenientes da degradação anaeróbia do glicerol, sendo a maior parte desse consumida na desnitrificação. Portanto, o teor de nitrato pode ter sido um fator de impedimento ao desenvolvimento dos OAPs. Pelos ensaios de microscopia óptica foi observado a presença de bactérias filamentosas semelhantes às do gênero Beggiatoa, que também podem ter consumido parte dos substratos da fermentação do glicerol. Por essas razões, sugere-se avaliar outras configurações de reatores de modo a promover uma efetiva fermentação do glicerol previamente ao sistema de remoção de fósforo. / This study aimed to evaluate the feasibility of glycerol as a carbon source for denitrification and biological phosphorus removal of a synthetic wastewater in a continuous flow reactor with suspended biomass and subjected to intermittent aeration. The reactor operation was divided in two phases: the first one aimed only at removing nitrate, testing different C/N (Carbon/Nitrogen) ratios at an HRT (Hydraulic Retention Time) of 4 hours; and the second one aimed at the removal of nitrate and phosphate. During the second phase, the reactor was subjected to periods of aeration and non-aeration of 2 and 4 hours, respectively, for a C/P (Carbon/Phosphorus) ratio of 10 ± 1. In the first operational phase, three C/N ratios were tested, as follows: 1.2 ± 0.1; 1.5 ± 0.1 and 1.8 ± 0.2. For the C/N ratio of 1.8 ± 0.2, it was possible to achieve higher denitrification efficiency with greater operational stability - 91 ± 8%. For the second operational phase, with the C/N ratio of 3.5 ± 0.2, the denitrification was complete most of the time presenting 99 ± 2% of NOx (nitrate and nitrite) removal efficiency, indicating that the denitrification with glycerol is enhanced at higher C/N ratios. The biological phosphorus removal in this phase was not significant (12 ± 9%), indicating that there was no development of Phosphorus Accumulating Organisms (PAO), since the phosphate release during the anaerobic phase did not occur. This can be explained by the lack of Volatile Fatty Acids (VFA), which would come from the anaerobic degradation of glycerol that was consumed in denitrification. Therefore, the nitrate content may have been an interfering factor to the development of PAO. The optical microscopy analysis indicated the presence of filamentous bacteria similar to the genus Beggiatoa, which can also have consumed part of the substrates from the glycerol fermentation. For these reasons, it is suggested to evaluate other reactor configurations in order to promote the effective fermentation of glycerol previously to the phosphorus removal system.

Este trabalho buscou verificar a viabilidade do uso de fermentado de glicerol como fonte externa de carbono para a remoção biológica de nutrientes em um reator de leito estruturado, submetido à aeração intermitente (LEAI). O LEAI foi alimentado com efluente de reator UASB de bancada, usado no tratamento de esgoto sanitário. O reator LEAI possuía volume total de 12,3L e, devido às hastes cilíndricas verticais de espuma de poliuretano usadas como suporte para a biomassa, o volume útil foi de 8,6 L. Inicialmente, o reator foi operado sob aeração contínua com tempo de detenção hidráulica (TDH) de 24 horas e razão de recirculação de efluente igual a 3 para desenvolvimento de biomassa nitrificante no reator. Após a eficiência de nitrificação atingir 80%, o reator passou a ser operado com TDH de 12 horas e sob aeração intermitente, mantendo-se a razão de recirculação igual a 3. Foram então realizadas 4 fases em modo contínuo sob aeração intermitente (tempo de aeração/tempo sem aeração) de 2h/1h sem glicerol, 3h/1h sem glicerol, 2h/1h com glicerol, 3h/1h com glicerol. A adição de glicerol fermentado ocorreu somente durante os períodos não aerados. Em todas as fases, a DQO média efluente ao sistema variou entre 26±8 e 59±14 mg.L-1. Em relação à remoção de nitrogênio total (como NTK), verificou-se a baixa eficiência de remoção nas fases em que não houve a adição do fermentado, atingindo 49,6±13,5% (2h/1h) e 29,2±10,1% (3h/1h). Entretanto, nas fases em que houve a inserção do glicerol, as eficiências de remoção de N-total foram superiores, obtendo-se 64,9±21,6% (2h/1h) e 69,5±11,7% (3h/1h). Não foi observada remoção de fósforo em nenhuma das fases em que o reator foi operado com alimentação contínua. A fim de verificar a eficácia do fermentado de glicerol na remoção de N e P, o sistema foi modificado para que o reator LEAI operasse em bateladas sequenciais (RSB). Nessa etapa da pesquisa, observou-se o estabelecimento da comunidade acumuladora de fósforo no sistema, obtendo-se eficiência de remoção de fósforo de 56,1±8,5%. A eficiência de remoção de nitrogênio total também aumentou, atingindo 86,2±6,2%. Concluiu-se que o fermentado do glicerol apresenta potencial significativo para uso como fonte exógena de carbono no processo de remoção de fósforo e N-total. Concluiu-se também que, embora o glicerol fermentado contenha compostos favoráveis à remoção de fósforo em reatores de leito estruturado, a alimentação contínua do reator com aeração intermitente, não promove as condições ideais para o estabelecimento de processo estável de remoção de fósforo. No entanto, a elevada eficiência de oxidação de NTK, de remoção de matéria orgânica e de desnitrificação, aliadas à baixa produção sólida, mostram que o LEAI é uma alternativa interessante em comparação às tecnologias praticadas atualmente para pós-tratamento de efluentes de reatores anaeróbios. Contudo, quando a remoção de fósforo é necessária, a operação do reator em bateladas sequenciais é a alternativa viável. / This work aimed to verify the viability of the use of fermented glycerol as an external carbon source for the nutrient biological removal in structured-bed reactor subjected to recirculation and intermittent aeration (SBRRIA). The SBRRIA was fed effluent from UASB reactor bench scale, used in the treatment of domestic sewage. The SBTTIA reactor had a total volume of 12.3L and, due to the vertical cylindrical strips of polyurethane foam used as biomass support, the useful volume was 8.6 L. Initially, the reactor was operated under continuous aeration with hydraulic retention time (HRT) of 24 hours and effluent recirculation ratio of 3 for the development of nitrifying biomass in the reactor. After the nitrification efficiency reach 80%, the reactor started to be operated at the HRT of 12 h under intermittent aeration, maintaining the recirculation ratio equal to 3. Four phases were then carried out continuously under intermittent aeration (aeration / time without aeration) of 2h/1h without glycerol, 3h/1h without glycerol, 2h/1h with glycerol, 3h/1h with glycerol. The addition of fermented glycerol occurred only during time without aeration. In all phases, the average COD effluent of the system ranged between 26±8 and 59±14 mg.L-1. Low removal efficiency of total nitrogen (as TKN) was verified in the phases without addition of the fermented glycerol, reaching 49.6±13.5% (2h/1h) and 29.2±10.1% (3h/1h). However, the efficiency of total nitrogen removal efficiency was higher when fermented glycerol was added during the non-aerated period, attaining 64.9±21.6% (2h/1h) and 69.5±11.7% (3h/1h). No phosphorus removal was observed in any of the previous phases in which the reactor was operated under continuous feeding. In order to verify the feasibility of fermented glycerol in the removal of N and P, the system was modified so that the LEAI reactor operated in sequential batch mode (SRB). At this stage of the research, the establishment of the phosphorus accumulating community in the system was observed and phosphorus removal efficiency attained 56.1±8.5%. The efficiency of total nitrogen removal also increased up to 86.2±6.2%. It was concluded that the fermented glycerol presents significant potential for use as an exogenous carbon source in the process of phosphorus and nitrogen removal. It can be also concluded that fixed bed reactors can remove phosphorus from wastewaters using fermented glycerol presenting compounds favorable to the development of phosphorus accumulating microorganisms (PAO). However, reactors subjected to continuous feeding and intermittent aeration do not promote good conditions for the establishment of stable phosphorus removal process. Nevertheless, the high efficiency of TKN oxidation, organic matter removal and denitrification, coupled with low solid production, show that SBRRIA is an interesting alternative for the post-treatment of anaerobic reactor effluents. However, when phosphorus removal is required, sequential batch reactor operation is the viable alternative.

O excesso de nutrientes como nitrogênio e fósforo em efluentes de estação de tratamento de esgoto sanitário pode provocar a eutrofização nos corpos d\'aguas receptoras. Esse processo gera efeitos negativos para a engenharia sanitária, dependendo do grau de qualidade e do uso de água requeridos. Para o abastecimento público, são exigidos métodos e processos de tratamentos avançados, quando a fonte hídrica está eutrofizada. Neste sentido, sistemas aeróbios de lodos ativados passaram a se destacar também como removedores de nutrientes por processos biológicos, após sofrerem algumas modificações operacionais. Um meio para otimizar o processo de remoção biológica do fósforo em excesso (EBPR) é promover condições ideais para o crescimento dos organismos acumuladores de fósforo. Esse trabalho teve como objetivo avaliar uma estação piloto de lodos ativados modificados, para a remoção de fósforo em excesso, utilizados no tratamento de esgoto sanitário, localizada na ETE da cidade de Tóquio - Japão. Essa estação piloto constituía-se de três sistemas de reação (1, 2 e 3), sendo que cada sistema era compartimentado e submetido às condições anaeróbia, anóxica e aeróbia. A avaliação dos três sistemas de reação, consistiu na verificação do desempenho deles com relação a DBO e fósforo e monitoramento da estrutura da comunidade microbiana, pela técnica da eletroforese em gel de gradiente desnaturante (DGGE). O desempenho em relação a DBOs (mg/L) nos três sistemas de reação, sempre foi superior a 90% e a eficiência da remoção do fósforo (%) na forma de fosfato (P-PO4 - mg/L) foi superior, em geral, a 70%, considerando os valores de entrada das alimentações e saída no último compartimento dos três sistemas de reação. Verificou-se que a estrutura da comunidade microbiana apresentou uma grande diversidade, devido aos números de bandas padrões encontradas nas amostras analisadas. Observou-se também uma grande similaridade ) da estrutura da comunidade microbiana nos sistemas estudados, possivelmente, relacionada ao mesmo afluente (esgoto sanitário) e ao mesmo tipo de recirculação interna e do lodo. As mudanças das estruturas das comunidades microbianas foram pequenas, diante das mudanças temporais e operacionais. No entanto, observou-se que o sistema foi menos eficiente (parâmetros de desempenho), frente a essas mudanças, o que pode estar mais relacionado à redução das atividades dos microrganismos do que com as estruturas microbianas. / The excess of nutrients such as nitrogen and phosphate in effluents of treatment plants for sanitary sewage can cause eutrophication in the receiving body of water. Given that process generates negative effects for the sanitary engineering depending on the degree of the quality and of the requested use of water. For the public provisioning, methods and processes of advanced treatments are demanded, when the water body is eutrophic. In this sense, aerobic systems of activated sludge have been expanded also to the processes of biological removal of nutrients after some operational modifications. By means of the optimization process of enhanced biological phosphorus removal (EBPR) will promote ideal conditions for the growth of polyphosphate accumulating organisms. This work had as its objective to evaluate a pilot station modified activated sludge, used for the treatment of sanitary sewage, but specifically for the enhanced phosphorus removal, located in the ETE of the city of Tokyo - Japan. These pilot station was constituted of three reaction systems (1, 2 and 3), and each system were composed of compartments and were submitted to anaerobic, anoxic and aerobic conditions. The evaluation of the three reaction systems, consisted of the verification of the performance of the systems with regard to BOD and phosphate which were monitored through microbial community\'s structure, for the biological phosphorus removal technique (DGGE). The performance in relation to the BODS (mg/L) in the three reaction systems was always above 90% and the efficiency of the removal of phosphorus (%) in the form of phosphate (P-PO4 - mg/L) was in general better than 70%, considering the values of influent and effluent from the last compartment of the three reaction systems. It was verified that the microbial community structure presented a great diversity, due to the standard numbers of bands found in the analyzed samples. A great similarity of the microbial community structure was observed in the studied systems, possibly being related to the same influent (domestic sewage) and to the same type of intern recirculation and of the sludge. The changes of the microbial communities structures were small, before the temporary and operational changes. However, it was observed that the system was less effiecient (performance parametrs) front to those changes, what can be more related the reduction of the activities of the microorganisms than with the microbial structures.