The performance of a combined biological aerated filter (BAF) and an ultrafiltration (UF) system for the treatment of real and synthetic greywater, settled sewage, rainwater and borehole water has been assessed at both full-scale (at the Millennium Dome Water Recycling plant) and bench-scale. Irreversible membrane fouling was explained at bench-scale in terms of a simple but novel model whereby a proportion of the membrane area is progressively blocked, in proportion to the square root of the transmembrane pressure. This model provides a link between irreversible fouling and reversible cake filtration theory, as the predicted reduction in effective filtration area leads to increased solids loading on the unblocked area. In addition, the bulk properties (specific cake resistance and compressibility) of the filter cakes formed from biologically-treated real grey water and sewage were found to be indistinguishable. A statistical analysis of the results of longer term irreversible fouling trials at bench- scale led to numerical relationships between fouling rate and process conditions. These relationships facilitated the development of a process optimisation model, with the dual-aim of maximising output and minimising chemical consumption. At full-scale, a statistical technique was developed for calculating the relative fouling propensity of three water sources (real grey water, rainwater and borehole water) that were combined in the feed to a UP membrane. The technique was based on the relative volumes of the three sources and the mean operating trans membrane pressure. In addition, the impact of mechanical reliability on the financial viability of the full- scale plant was investigated. A Net Present Value analysis revealed that the break- even price (BEP) of the recycled water was reduced from £ 1.611m3 to £ 1.40/m 3 through increasing availability from 73.8% to 91.2%, and this can be achieved by investing in a targeted critical spares facility.

O presente trabalho buscou avaliar uma unidade de BAS (Biofiltro Aerado Submerso), em escala piloto, com volume útil de 66 litros, tratando esgoto doméstico, visando seu controle operacional, a remoção de matéria orgânica e nitrificação. O esgoto afluente passa por pré-tratamento e decantação antes de seguir para o BAS em estudo. A unidade piloto é constituída, basicamente, por um BAS de fluxo ascendente. O meio suporte utilizado é composto por biomídias de sistemas MBBR, as quais apresentam elevadas porosidade (>85%) e área superficial específica (650 m2/m3), além de baixa densidade (0,95 kg/L). Para avaliação do biofiltro em estudo, o trabalho foi divido em quatro fases (I a IV) para avaliação do comportamento do reator em diferentes condições operacionais. Para isso foram efetuadas variações no tempo de detenção hidráulica (I=8h, II=14h, III=10h e IV=6h) e na velocidade de escoamento (I=0,13m/h, II=0,07m/h, III=1,0m/h e IV=1,1m/h) através da recirculação do efluente tratado (I e II sem recirculação, III e IV com recirculação). Com relação à remoção de matéria orgânica, o BAS demonstrou bom desempenho em todas as fases de estudo, resultando em um efluente tratado com concentrações médias de DBO abaixo de 30 mg/L, com uma eficiência de remoção de DBO próxima de 90% ao longo de toda a pesquisa. Em termos de DQO, as concentrações médias ficaram abaixo de 82 mg/L, com uma eficiência de remoção de DQO próxima de 85% ao longo de todas as fases da pesquisa. Já com relação ao processo de nitrificação, na fase II o biofiltro estudado apresentou um efluente com 16 mgN/L de N-NTK e 35 mgN/L de NO3-, demonstrando potencial do processo para as situações em que se exige remoção de matéria orgânica e nitrificação. Nas fases I, III e IV a nitrificação não ocorreu de forma satisfatória. Com relação ao controle operacional do processo de lavagem, o intervalo necessário para a realização do processo de lavagem, de acordo com os processos definidos, foi consideravelmente prolongado, acima de 10 dias, ao longo de todas as fases do estudo, demostrando uma grande capacidade de retenção de sólidos no biofiltro estudado. Com relação à utilização de recirculação nas fases III e IV, esta operação não demonstrou vantagens com relação às fases sem recirculação. Dessa forma, neste trabalho foi possível observar que a qualidade do efluente final e a estabilidade operacional do biofiltro aerado submerso preenchido com biomídias reforçam a condição desta unidade como alternativa viável a ser considerada na concepção de sistemas de tratamento de esgotos sanitários. / The present work sought to evaluate a unit of a BAF (Biological Aerated Filter), in pilot scale, with working volume of 66 liters, treating domestic sewage, aiming its operational control, organic matter removal and nitrification. The affluent sewage is pre-treated and decanted before proceeding to the BAF under study. The pilot unit consists, basically, of an upflow BAF. The media used is composed of biocarriers of MBBR systems, which have high porosity (>85%) and specific surface area (650 m2/m3), besides low density (0,95 kg/L). For evaluation of the biofilter under study, the work was divided in four phases (I to IV) to evaluate the behavior of the reactor in different operating conditions. For this, variations were made in the hydraulic retention time (I=8h, II=14h, III=10h and IV=6h) and at the flow rate (I=0,13m/h, II=0,07m/h, III=1,0m/h and IV=1,1m/h) by recirculating the treated effluent (I and II without recirculation, III and IV with recirculation). Regarding the removal of organic matter, the BAF demonstrated good performance in all study phases, resulting in an effluent treated with avarage concentrations of BOD under 30 mg/L, with an efficiency of removal of BOD near 90% throughout the research. In terms of COD, the average concentrations were below 82 mg/L, with an efficiency of removal of COD near 85% throughout all phases of the research. Regarding the nitrification process, in the phase II the studied biofilter presented an effluent with 16 mgN/L of N-NTK and 35 mgN/L of NO3 -, demonstrating process potential for situations where organic matter removal and nitrification are required. In phases I, III and IV nitrification did not occur satisfactorily. Regarding the operational control of the washing process, the interval required to carry out the washing process, according to the defined processes, was considerably extended, over 10 days, throughout all phases of the study, demonstrating a great solids retention capacity in the biofilter studied. Regarding the use of recirculation in phases III and IV, this operation did not demonstrate advantages in comparison with the phases without recirculation. Thus, in this work, it was possible to observe that the final effluent quality and the operational stability of the biological aerated filter filled with biocarriers reinforce the condition of this unit as a viable alternative to be considered in the design of domestic sewage treatment systems.

<p> The Biological Aerated Filter is a novel biological wastewater treatrrent process consisting of.an activated sludge zone followed by an unstratified sand filter for solids separation. Three evaluation studies of the BAF to date have yielded results indicating low solids production or possibly total oxidation. On the basis of these studies, Tymflo Process Limited, the patent holding corrpany, clairred up to 50% cost savings for wastewater.treabrent as there would be no excess biological solids produced, and therefore no sludge disposal costs. The object of this report was to evaluate the BAF capabilities to treat degritted municipal sewage with respect to the above claims. Two pilot scale BAF units were operated at the Canada Centre for Inland Waters continuously for 97 days treating degritted Burlington Skyway sewage at various operating conditions. The conclusions of the tests are that the BAF cannot be operated as a total solids retention system treating degritted nnmicipal sewage on a 24 hour cycle at a 12 hour hydraulic detention ti.Ile. The inert fraction of the influent is retained in the system resulting in high mixed liquor concentrations which overload the filter thereby decreasing treatrrent tine. The system is capable of 88% CDD rerroval, essentially corrplete nitrification and 97% SS rerroval. The system yields are in the order of 0.24 gm MLVSS/grn COD rercoved at organic loadings of approximately 0.08 gm COD removed/gm MLVSS day. </p> / Thesis / Master of Engineering (MEngr)

The biomass from a pilot-scale two-stage (carbon oxidation first stage, ammonia oxidation second stage) fixed-film biological aerated filter (BAF) was divided in three fractions depending on their attachment strength to the media: detached, easily detachable and strongly attached. VSS measurement showed that the detached and easily detachable fractions accounted for 25 to 40% of the biomass in the bed and are present even after backwash. Protein was the major constituent of all fractions of the biomass. The ratio of carbohydrate to protein differed between fractions and between type of biofilms, with a larger value for detached and detachable fractions and a lower value for a largely heterotrophic biofilm, implying a difference in the composition of the biomass matrix that could be related to the attachment state of the biomass. The biomass did not appear to be substrate-limited anywhere in the system, although the specific activity of the biomass was dependent upon the position in the column. Activity of the strongly attached biomass was less than 70% of the total activity, even after backwash. A mass balance on VSS showed that the backwash flushed a mass equivalent to less than 35% to 45% of the detached and detachable fractions, which was less than 15% of the total biomass present in the system. Data also suggested that during backwash, part of the strongly attached biomass was sheared off the media and regenerated the mass of biomass in the detached phase. In conclusion, it can be stated that a non-negligible part of the biomass in a BAF is in a detached state. Actual mechanistic BAF models based solely on biofilm modeling may be overlooking the role of that biomass, especially in the performance recovery of BAF systems after backwash. / Master of Science

Biological aerated filters (BAFs) are an emerging wastewater treatment technology designed for a wide range of municipal and industrial applications. BAFs utilize an inert media, either dense granular or floating, which supports biomass retention in the filter bed. BAFs offer an alternative to typical biological treatment processes; however, knowledge of the process is often limited, especially in the US market. Through various studies, process improvements were made for filter media selection, backwash protocols, and hydraulic load effects. During the summertime monitoring, seeded and unseeded nitrified effluent BOD5 samples were performed on a full-scale BAF. Discrepancies were found between seeded and unseeded samples, which warranted further investigation. Four biological treatment seeds and a commercial microbial seed were screened for appropriate seed volumes in comparison to the glucose:glutamic acid (GAA) assay, a standard for BOD5 analysis. After initial screening, a range of seed samples was applied to the BAF effluent for BOD5 and cBOD5 analysis, and to GGA and carbonaceous GGA (cGGA) analysis. A proposed seed screening protocol was developed using a ratio of measured BOD5 values in comparison to theoretical GGA standard BOD5 values. Biomass observed yield values were calculated for the full-scale BAF. Three individual mass balances were conducted to quantify the consumption of soluble COD in the filter and the mass of influent particulate matter filtered from the waste stream. Retained particulate matter is a substrate source for the biomass; however, the particles must be hydrolyzed into metabolizable monomers before being consumed by the biomass. A bench-scale BAF was designed and constructed to investigate the degree to which particle hydrolysis occurred in the full-scale system. Additionally, fluorescein diacetate was used during one of the experiments as a model particulate substrate to quantify the activity associated with hydrolytic enzymes in the bulk-liquid. Hydrolytic activity by cell-free extracellular enzymes in the bulk-liquid increased when particle substrate was present. Therefore, it appears that cell-free extracellular enzymes participate in the hydrolytic mechanism for particle degradation. Biomass observed yields were calculated for the full-scale BAF using full-scale mass balances and bench-scale particle hydrolysis experiments. / Master of Science

Este trabalho fundamentou-se na concepção e operação de um sistema combinado anaeróbio-aeróbio, constituído de reator UASB e Biofiltro Aerado Submerso (BAS) Multiestágio (anaeróbio-aeróbio-anóxico). Os sistemas foram operados em escala piloto e aplicado ao tratamento de esgoto sanitário, sendo testados três meios-suporte, nomeadamente tampas e gargalos de garrafas PET (Asup=160m²/m³), pedra britada n.4 (40m²/m³) e anéis Pall 1,5’’ (130m²/m³), sendo denominados de BAS 1, 2 e 3. O trabalho foi dividido em duas fases, compondo ao todo 6 etapas experimentais: 1ª fase, onde se buscou avaliar a remoção de matéria orgânica e obtenção de nitrificação em três regimes hidráulicos (TDH total: 4h, 8h e 12h); 2ª fase, onde se buscou obter a pré-desnitrificação utilizando-se o carbono presente no efluente do reator UASB (4ª etapa) e através de carbono externo dosado no afluente dos BAS (5ª etapa); e a pós-desnitrificação através da dosagem de carbono externo na câmara anóxica (6ª etapa). Foram operados paralelamente dois sistemas de CBR, preenchidos com os meiossuporte “tampas e gargalos de garrafas PET” (CBR 1) e anéis Pall 1’’ (CBR 2), nos TDH de 1,75; 3,5 e 5,25h, equivalentes aos TDH das câmaras aeróbias dos BAS. As cargas orgânicas aplicadas variaram de 0,27 a 1,19 kgDQOt/m³.d para os BAS e de 0,63 – 2,72 kgDQOt/m³.d para os CBR. As eficiências totais (UASB+BAS ou CBR) em termos de DQO total superaram 90% para os BAS 1 e 3 e para os CBR 1 e 2 (considerando-se a DQO decantada). A conformação empregada de BAS, quando utilizados materiais com elevados índices de vazios (tampas e gargalos de garrafas PET e anéis Pall), possibilitou elevadas remoções de SS (Cefl 30mgSS/L), tornando desnecessário uso o decantador secundário. O desenvolvimento da nitrificação e remoção carbonácea em conjunto limitaram as taxas de nitrificação e exigiram elevados TDH para os BAS. A nitrificação nos CBR foi superior a 90% para TDH de 3,5h, enquanto que os BAS requereram 5,25h na câmara aeróbia (TDH total: 12h) e a aplicação de recirculação para a obtenção de resultados similares. A influência da recirculação sobre a nitrificação nos BAS foi positiva, possibilitando as melhores taxas de nitrificação superficiais para os BAS (0,61; 1,29 e 0,70gN/m².d para os BAS 1, 2 e 3 respectivamente). Não foram verificadas interferências significativas de elevadas relações C/N ( 5,0) sobre a nitrificação dos BAS e CBR. Valores de pH abaixo do neutro não influenciaram de maneira adversa a nitrificação, observando-se, no entanto, provável limitação por deficiência de alcalinidade total. Observaram-se também inibições para valores de OD inferiores a 3,5mgO2/L na câmara aeróbia dos BAS. A oxidação do nitrogênio amoniacal a nitrato de mostrou ser a etapa crítica do processo biológico e remoção de nitrogênio total. Foram obtidas eficiências de pósdesnitrificação superiores a 90% (Nefl 4,5mgNT/L), com auxílio de carbono externo, a uma relação C/N de 1,46(mol/mol). / This work was based on the conception and operation of a combined anaerobic-aerobic system, consisting of an UASB reactor and a Multi-stage Biological Aerated Filter (BAF) (anaerobic-aerobic-anoxic) in pilot-scale and applied to the treatment of sanitary wastewater. Three different biofilter’s media were tested, namely “lids and bottlenecks of PET bottles” (160m²/m³), gravel no4 (40m²/m³) and Pall rings (130m²/m³), called BAF 1, 2 and 3, respectively. The experimental work was divided in two phases, comprising 6 experimental stages: The 1st phase was carried out to evaluate the effect of Hydraulic Retention Time (4, 8 and 12h) upon the removal of organic carbon and the attainment of nitrification. The 2nd phase evaluated different strategies to promote denitrification by using internal carbon source present in the UASB’s effluent (4th stage); by dosing external carbon source (Sodium Acetate) on the influent to the BAS aiming pre-denitrification (5th stage); and dosing external carbon (Sodium Acetate) at the inlet of the anoxic chamber aiming the post-denitrification (6th stage). Two RBC systems, filled with “lids and bottlenecks of PET bottles” (RBC 1) and Pall rings with 1'' diameter (RBC 2) were operated in parallel with the BAFs, adjusting the influent flow to obtain Hydraulic Retention Time (HRT) of 1,75; 3,5 and 5,25h. These values corresponded to the HRT of the aerobic chambers of the BAFs. The applied organic loading rates varied between 0,27 and 1,19 kgCODt/m³.d for the BAS and between 0,63 – 2,72 kgCODt/m³.d for the RBC. The systems efficiencies (UASB+BAF and UASB+RBC) had surpassed 90% in terms of total COD for BAF 1 and 3 and for RBC 1 and 2 (considering decanted COD for RBC systems). The employed conformation of BAF, when using high void index media (lids and bottlenecks, Pall rings), allowed high SS removals (Cefl 30mgSS/L), making unnecessary the use of a secondary clarifier. The development of combined nitrification and organic carbon removal limited the nitrification rates and had demanded high HRT for the BAFs. The nitrification in the RBC systems was above 90% for HRT=3,5h, whereas the BAF had required TDH=5,25h in aerobic chamber (total HRT=12h) and the use of internal recirculation for the attainment of similar results. Internal recirculation in the BAF improved nitrification, making possible the best superficial nitrification rates for the BAF, reaching 0,61; 1,29 and 0,70gN/m².d for BAF 1, 2 and 3 respectively. High relations C/N ( 5,0) had no detrimental effect upon the nitrification on the BAF and the RBC. Values of pH below 7,0 had not adversely influenced the nitrification of both BAF and RBC. However, the low values of effluent alkalinity may have limited the rate of nitrification on the biological reactors. Values of Dissolved Oxygen (DO) below 3,5 mgO2/L in the aerobic chamber of the BAF clearly inhibited the nitrification rate. The ammonia nitrogen oxidation to nitrate was the critical step of the overall biological process and, as a consequence, to total nitrogen removal. Average efficiencies of post-denitrification was above 90% (Nefl 4,5 mg TN/L), when dosing external carbon source (C/N=1,46 mol/mol) to BAF 1.

Este trabalho fundamentou-se na concepção e operação de um sistema combinado anaeróbio-aeróbio, constituído de reator UASB e Biofiltro Aerado Submerso (BAS) Multiestágio (anaeróbio-aeróbio-anóxico). Os sistemas foram operados em escala piloto e aplicado ao tratamento de esgoto sanitário, sendo testados três meios-suporte, nomeadamente tampas e gargalos de garrafas PET (Asup=160m²/m³), pedra britada n.4 (40m²/m³) e anéis Pall 1,5’’ (130m²/m³), sendo denominados de BAS 1, 2 e 3. O trabalho foi dividido em duas fases, compondo ao todo 6 etapas experimentais: 1ª fase, onde se buscou avaliar a remoção de matéria orgânica e obtenção de nitrificação em três regimes hidráulicos (TDH total: 4h, 8h e 12h); 2ª fase, onde se buscou obter a pré-desnitrificação utilizando-se o carbono presente no efluente do reator UASB (4ª etapa) e através de carbono externo dosado no afluente dos BAS (5ª etapa); e a pós-desnitrificação através da dosagem de carbono externo na câmara anóxica (6ª etapa). Foram operados paralelamente dois sistemas de CBR, preenchidos com os meiossuporte “tampas e gargalos de garrafas PET” (CBR 1) e anéis Pall 1’’ (CBR 2), nos TDH de 1,75; 3,5 e 5,25h, equivalentes aos TDH das câmaras aeróbias dos BAS. As cargas orgânicas aplicadas variaram de 0,27 a 1,19 kgDQOt/m³.d para os BAS e de 0,63 – 2,72 kgDQOt/m³.d para os CBR. As eficiências totais (UASB+BAS ou CBR) em termos de DQO total superaram 90% para os BAS 1 e 3 e para os CBR 1 e 2 (considerando-se a DQO decantada). A conformação empregada de BAS, quando utilizados materiais com elevados índices de vazios (tampas e gargalos de garrafas PET e anéis Pall), possibilitou elevadas remoções de SS (Cefl 30mgSS/L), tornando desnecessário uso o decantador secundário. O desenvolvimento da nitrificação e remoção carbonácea em conjunto limitaram as taxas de nitrificação e exigiram elevados TDH para os BAS. A nitrificação nos CBR foi superior a 90% para TDH de 3,5h, enquanto que os BAS requereram 5,25h na câmara aeróbia (TDH total: 12h) e a aplicação de recirculação para a obtenção de resultados similares. A influência da recirculação sobre a nitrificação nos BAS foi positiva, possibilitando as melhores taxas de nitrificação superficiais para os BAS (0,61; 1,29 e 0,70gN/m².d para os BAS 1, 2 e 3 respectivamente). Não foram verificadas interferências significativas de elevadas relações C/N ( 5,0) sobre a nitrificação dos BAS e CBR. Valores de pH abaixo do neutro não influenciaram de maneira adversa a nitrificação, observando-se, no entanto, provável limitação por deficiência de alcalinidade total. Observaram-se também inibições para valores de OD inferiores a 3,5mgO2/L na câmara aeróbia dos BAS. A oxidação do nitrogênio amoniacal a nitrato de mostrou ser a etapa crítica do processo biológico e remoção de nitrogênio total. Foram obtidas eficiências de pósdesnitrificação superiores a 90% (Nefl 4,5mgNT/L), com auxílio de carbono externo, a uma relação C/N de 1,46(mol/mol). / This work was based on the conception and operation of a combined anaerobic-aerobic system, consisting of an UASB reactor and a Multi-stage Biological Aerated Filter (BAF) (anaerobic-aerobic-anoxic) in pilot-scale and applied to the treatment of sanitary wastewater. Three different biofilter’s media were tested, namely “lids and bottlenecks of PET bottles” (160m²/m³), gravel no4 (40m²/m³) and Pall rings (130m²/m³), called BAF 1, 2 and 3, respectively. The experimental work was divided in two phases, comprising 6 experimental stages: The 1st phase was carried out to evaluate the effect of Hydraulic Retention Time (4, 8 and 12h) upon the removal of organic carbon and the attainment of nitrification. The 2nd phase evaluated different strategies to promote denitrification by using internal carbon source present in the UASB’s effluent (4th stage); by dosing external carbon source (Sodium Acetate) on the influent to the BAS aiming pre-denitrification (5th stage); and dosing external carbon (Sodium Acetate) at the inlet of the anoxic chamber aiming the post-denitrification (6th stage). Two RBC systems, filled with “lids and bottlenecks of PET bottles” (RBC 1) and Pall rings with 1'' diameter (RBC 2) were operated in parallel with the BAFs, adjusting the influent flow to obtain Hydraulic Retention Time (HRT) of 1,75; 3,5 and 5,25h. These values corresponded to the HRT of the aerobic chambers of the BAFs. The applied organic loading rates varied between 0,27 and 1,19 kgCODt/m³.d for the BAS and between 0,63 – 2,72 kgCODt/m³.d for the RBC. The systems efficiencies (UASB+BAF and UASB+RBC) had surpassed 90% in terms of total COD for BAF 1 and 3 and for RBC 1 and 2 (considering decanted COD for RBC systems). The employed conformation of BAF, when using high void index media (lids and bottlenecks, Pall rings), allowed high SS removals (Cefl 30mgSS/L), making unnecessary the use of a secondary clarifier. The development of combined nitrification and organic carbon removal limited the nitrification rates and had demanded high HRT for the BAFs. The nitrification in the RBC systems was above 90% for HRT=3,5h, whereas the BAF had required TDH=5,25h in aerobic chamber (total HRT=12h) and the use of internal recirculation for the attainment of similar results. Internal recirculation in the BAF improved nitrification, making possible the best superficial nitrification rates for the BAF, reaching 0,61; 1,29 and 0,70gN/m².d for BAF 1, 2 and 3 respectively. High relations C/N ( 5,0) had no detrimental effect upon the nitrification on the BAF and the RBC. Values of pH below 7,0 had not adversely influenced the nitrification of both BAF and RBC. However, the low values of effluent alkalinity may have limited the rate of nitrification on the biological reactors. Values of Dissolved Oxygen (DO) below 3,5 mgO2/L in the aerobic chamber of the BAF clearly inhibited the nitrification rate. The ammonia nitrogen oxidation to nitrate was the critical step of the overall biological process and, as a consequence, to total nitrogen removal. Average efficiencies of post-denitrification was above 90% (Nefl 4,5 mg TN/L), when dosing external carbon source (C/N=1,46 mol/mol) to BAF 1.

Este trabalho fundamentou-se na concepção e operação de um sistema combinado anaeróbio-aeróbio, constituído de reator UASB e Biofiltro Aerado Submerso (BAS) Multiestágio (anaeróbio-aeróbio-anóxico). Os sistemas foram operados em escala piloto e aplicado ao tratamento de esgoto sanitário, sendo testados três meios-suporte, nomeadamente tampas e gargalos de garrafas PET (Asup=160m²/m³), pedra britada n.4 (40m²/m³) e anéis Pall 1,5’’ (130m²/m³), sendo denominados de BAS 1, 2 e 3. O trabalho foi dividido em duas fases, compondo ao todo 6 etapas experimentais: 1ª fase, onde se buscou avaliar a remoção de matéria orgânica e obtenção de nitrificação em três regimes hidráulicos (TDH total: 4h, 8h e 12h); 2ª fase, onde se buscou obter a pré-desnitrificação utilizando-se o carbono presente no efluente do reator UASB (4ª etapa) e através de carbono externo dosado no afluente dos BAS (5ª etapa); e a pós-desnitrificação através da dosagem de carbono externo na câmara anóxica (6ª etapa). Foram operados paralelamente dois sistemas de CBR, preenchidos com os meiossuporte “tampas e gargalos de garrafas PET” (CBR 1) e anéis Pall 1’’ (CBR 2), nos TDH de 1,75; 3,5 e 5,25h, equivalentes aos TDH das câmaras aeróbias dos BAS. As cargas orgânicas aplicadas variaram de 0,27 a 1,19 kgDQOt/m³.d para os BAS e de 0,63 – 2,72 kgDQOt/m³.d para os CBR. As eficiências totais (UASB+BAS ou CBR) em termos de DQO total superaram 90% para os BAS 1 e 3 e para os CBR 1 e 2 (considerando-se a DQO decantada). A conformação empregada de BAS, quando utilizados materiais com elevados índices de vazios (tampas e gargalos de garrafas PET e anéis Pall), possibilitou elevadas remoções de SS (Cefl 30mgSS/L), tornando desnecessário uso o decantador secundário. O desenvolvimento da nitrificação e remoção carbonácea em conjunto limitaram as taxas de nitrificação e exigiram elevados TDH para os BAS. A nitrificação nos CBR foi superior a 90% para TDH de 3,5h, enquanto que os BAS requereram 5,25h na câmara aeróbia (TDH total: 12h) e a aplicação de recirculação para a obtenção de resultados similares. A influência da recirculação sobre a nitrificação nos BAS foi positiva, possibilitando as melhores taxas de nitrificação superficiais para os BAS (0,61; 1,29 e 0,70gN/m².d para os BAS 1, 2 e 3 respectivamente). Não foram verificadas interferências significativas de elevadas relações C/N ( 5,0) sobre a nitrificação dos BAS e CBR. Valores de pH abaixo do neutro não influenciaram de maneira adversa a nitrificação, observando-se, no entanto, provável limitação por deficiência de alcalinidade total. Observaram-se também inibições para valores de OD inferiores a 3,5mgO2/L na câmara aeróbia dos BAS. A oxidação do nitrogênio amoniacal a nitrato de mostrou ser a etapa crítica do processo biológico e remoção de nitrogênio total. Foram obtidas eficiências de pósdesnitrificação superiores a 90% (Nefl 4,5mgNT/L), com auxílio de carbono externo, a uma relação C/N de 1,46(mol/mol). / This work was based on the conception and operation of a combined anaerobic-aerobic system, consisting of an UASB reactor and a Multi-stage Biological Aerated Filter (BAF) (anaerobic-aerobic-anoxic) in pilot-scale and applied to the treatment of sanitary wastewater. Three different biofilter’s media were tested, namely “lids and bottlenecks of PET bottles” (160m²/m³), gravel no4 (40m²/m³) and Pall rings (130m²/m³), called BAF 1, 2 and 3, respectively. The experimental work was divided in two phases, comprising 6 experimental stages: The 1st phase was carried out to evaluate the effect of Hydraulic Retention Time (4, 8 and 12h) upon the removal of organic carbon and the attainment of nitrification. The 2nd phase evaluated different strategies to promote denitrification by using internal carbon source present in the UASB’s effluent (4th stage); by dosing external carbon source (Sodium Acetate) on the influent to the BAS aiming pre-denitrification (5th stage); and dosing external carbon (Sodium Acetate) at the inlet of the anoxic chamber aiming the post-denitrification (6th stage). Two RBC systems, filled with “lids and bottlenecks of PET bottles” (RBC 1) and Pall rings with 1'' diameter (RBC 2) were operated in parallel with the BAFs, adjusting the influent flow to obtain Hydraulic Retention Time (HRT) of 1,75; 3,5 and 5,25h. These values corresponded to the HRT of the aerobic chambers of the BAFs. The applied organic loading rates varied between 0,27 and 1,19 kgCODt/m³.d for the BAS and between 0,63 – 2,72 kgCODt/m³.d for the RBC. The systems efficiencies (UASB+BAF and UASB+RBC) had surpassed 90% in terms of total COD for BAF 1 and 3 and for RBC 1 and 2 (considering decanted COD for RBC systems). The employed conformation of BAF, when using high void index media (lids and bottlenecks, Pall rings), allowed high SS removals (Cefl 30mgSS/L), making unnecessary the use of a secondary clarifier. The development of combined nitrification and organic carbon removal limited the nitrification rates and had demanded high HRT for the BAFs. The nitrification in the RBC systems was above 90% for HRT=3,5h, whereas the BAF had required TDH=5,25h in aerobic chamber (total HRT=12h) and the use of internal recirculation for the attainment of similar results. Internal recirculation in the BAF improved nitrification, making possible the best superficial nitrification rates for the BAF, reaching 0,61; 1,29 and 0,70gN/m².d for BAF 1, 2 and 3 respectively. High relations C/N ( 5,0) had no detrimental effect upon the nitrification on the BAF and the RBC. Values of pH below 7,0 had not adversely influenced the nitrification of both BAF and RBC. However, the low values of effluent alkalinity may have limited the rate of nitrification on the biological reactors. Values of Dissolved Oxygen (DO) below 3,5 mgO2/L in the aerobic chamber of the BAF clearly inhibited the nitrification rate. The ammonia nitrogen oxidation to nitrate was the critical step of the overall biological process and, as a consequence, to total nitrogen removal. Average efficiencies of post-denitrification was above 90% (Nefl 4,5 mg TN/L), when dosing external carbon source (C/N=1,46 mol/mol) to BAF 1.

Orientador: Edson Aparecido Abdul Nour / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-11T03:49:57Z (GMT). No. of bitstreams: 1 Castagnato_Renata_M.pdf: 1224635 bytes, checksum: 513cfc1c14b5af1159379a00e5d00297 (MD5) Previous issue date: 2006 / Resumo: O formaldeído é um composto orgânico muito utilizado em diversos setores da indústria e serviços de saúde. Em hospitais e laboratórios de anatomia, ele é empregado em solução de 8 a 10 %, que ao se tornar imprópria para uso, necessita ser disposta adequadamente para não afetar os ecossistemas presentes nos corpos d¿água ou nos processos biológicos das estações de tratamento de esgotos. Pois, dependendo da concentração que o formaldeído se encontra, pode ser extremamente tóxico. O presente estudo teve o objetivo de verificar a tratabilidade de esgoto sanitário contendo formaldeído em um sistema combinado composto de um filtro anaeróbio (FA) seguido de um biofiltro aerado submerso (BAS). O volume útil de cada reator era de 17,6 L e o tempo de detenção hidráulica de 12 h. As concentrações de formaldeído aplicadas ao esgoto sanitário afluente ao sistema foram de 50, 100, 200 e 400 mg L-1, dividas em quatro fases de operação. Durante o monitoramento do sistema, foi verificado que a eficiência de remoção de formaldeído variou de 85,0 a 99,4 %, sendo que a partir do início da segunda fase (quando a concentração aplicada era de 100 mg L-1), a média de remoção foi de 98,0 ± 1,2 %. A média de remoção de DQO, durante as quatro fases de aplicação, foi de 84,4 ± 7,3 %, apesar do formaldeído não ter sido a única fonte de carbono. O valor máximo de carga de formaldeído removida no sistema foi de 0,407 kgm-3 d-1, quando sua aplicação no esgoto bruto era de 0,411 kg m-3 d-1 (concentração de 410,8 mg L-1). Foi observado também que a maior concentração de formaldeído encontrada no efluente tratado pelo sistema foi de 5,8 mg L-1, com valor médio de 1,9 ± 1,4 mg L-1. Houve inibição do processo de nitrificação no BAS a partir de 50 mg L-1 de formaldeído presente no esgoto afluente. Verificou-se que o sistema proposto foi adequado ao tratamento de esgoto sanitário com formaldeído, pois em todas as concentrações do composto aplicado (0 a 410,8 mg L-1), o seu desempenho se manteve estável, principalmente com relação à remoção de DQO e do próprio formaldeído. Palavras-chave: Formaldeído, sistema combinado anaeróbio/aeróbio, filtro anaeróbio, biofiltro aerado submerso, nitrificação, esgoto sanitário / Abstract: Formaldehyde is an organic compound largely used in several industrial sectors and health services, for example in hospitals and anatomy laboratories in a proportion of 8 to 10 %. When it becomes inadequate to be used, this solution must be properly disposed in order not to affect the ecosystems in water streams or in the biological process in the treatment sewage works, because depending on its concentration it can be extremely toxic. This study aims to verify the treatability of domestic wastewater containing formaldehyde in a combined system formed by an Anaerobic Filter followed by a Biological Aerated Filter. Each reactor presented a volume of 17,6 l and 12 h of hydraulic retention time (HRT). This type of system aggregates the advantages of these combined processes: anaerobic and aerobic. The concentration of formaldehyde used in domestic wastewater influent in the system was divided into 4 phases of operation, which corresponded to 50, 100, 200 and 400 mg L-1. The efficacy of removal of formaldehyde in the system varied from 85,0 and 99,4 %, and it must be noted that from the beginning of the 2nd phase (100 mg L-1) the average of removal was 98,0 ± 1,2 %. The average of removal of COD, during the whole 4 phases of operation, was 84,4 ± 7,3 %. It must be said that formaldehyde was not the only carbon source. The removal rate of formaldehyde achieved a maximum of 0,407 kg m-3 d-1, when the applied rate in the system was 0,411 kg m-3 d-1. This fact happened when the concentration of aldehyde in the influent was 410,8 mg L-1. The maximum concentration verified of formaldehyde in the effluent of system was 5,8 mg L-1, with an average of 1,9 ± 1,4 mg L-1. The process of nitrification has been inhibited in the Biological Aerated Filter from 50 mg L-1 of formaldehyde present in the influent. The proposed system was adequate to the treatment of domestic wastewater plus formaldehyde because in all concentration of aldehyde applied (0 a 410,8 mg L-1) its performance was kept stable, mainly in relation to COD removal and formaldehyde itself. Key words: Formaldehyde, combined system anaerobic/aerobic, anaerobic filter, biological aerated filter, nitrification, domestic wastewater / Mestrado / Saneamento e Ambiente / Mestre em Engenharia Civil