Effects of coal ash supplementation on aerobic granular sludge cultivated in a simultaneous fill/draw sequencing batch reactor / Efeitos da suplementação de cinzas de carvão mineral em lodo granular aeróbio cultivado em reator em batelada sequencial de alimentação/descarte simultâneos

ABSTRACT This study aimed to verify if coal ash, a residue from thermal power plants, could act as a granulation nucleus, cations source, and abrasive element to favor granules formation and stability in aerobic granular sludge (AGS) systems. Two simultaneous fill/draw sequencing batch reactors (SBRs) (R1 and R2) were operated with 6-h cycles, i.e., the filling and drawing phases occurred simultaneously, followed by the reaction and settling phases. R1 was maintained as control, while R2 was supplemented with coal ash (1 g·L-1) on the first day of operation. Granulation was achieved in both reactors, and no significant differences were observed in terms of settleability, biomass retention, morphology, resistance to shear, and composition of the EPS matrix. However, the ash addition did not change the settleability, biomass retention, granule morphology, shear resistance, and extracellular polymeric substances (EPS) content significantly. COD removal was high (≥ 90%), while nitrogen (~50%) and phosphorus (~40%) removals were low, possibly due to the presence of nitrate during the anaerobic phase. With granulation, microbial population profile was altered, mainly at the genus level. In general, the operational conditions had a more considerable influence over granulation than the ash addition. The possible reasons are because the ash supplementation was performed in a single step, the low sedimentation rate of this particular residue, and the weak interaction between the ash and the EPS formed in the granular sludge. These factors appear to have decreased or prevented the action of the ash as granulation nucleus, source of cations, and abrasive element.

RESUMO O objetivo deste estudo foi verificar se a cinza de carvão mineral, um resíduo de usinas termelétricas, poderia atuar como núcleo de granulação, fonte de cátions e elemento abrasivo em sistemas de lodo granular aeróbio (LGA) para favorecer a formação e estabilidade dos grânulos. Dois reatores em batelada sequencial (RBS) (R1 e R2) foram operados em regime de alimentação/descarte simultâneos com ciclos de 6 h, ou seja, as fases de alimentação e descarte do efluente ocorreram simultaneamente, seguidas das fases de reação e de decantação. O R1 foi mantido como controle, enquanto o R2 foi suplementado com as cinzas (1 g·L-1) no primeiro dia de operação. A granulação foi alcançada em ambos os reatores, não havendo diferenças marcantes em termos de sedimentabilidade, retenção de biomassa, morfologia do grânulo, resistência ao cisalhamento e conteúdo de substâncias poliméricas extracelulares (SPE). A remoção de DQO foi alta (≥ 90%), enquanto as remoções de nitrogênio (~50%) e fósforo (~40%) foram baixas, possivelmente pela presença de nitrato na fase anaeróbia. Após a granulação, o perfil da comunidade microbiana mudou, especialmente em termos de gênero. Globalmente, as condições operacionais tiveram maior influência sobre a granulação do que a adição das cinzas, possivelmente porque elas só foram adicionadas uma vez e possuem baixa velocidade de sedimentação, bem como devido a uma fraca interação das cinzas com a matriz de SPE formada no lodo aeróbio. Esses fatores podem ter diminuído, ou mesmo impedido, a ação das cinzas como núcleo de grânulo, fonte de cátions ou elemento abrasivo.

The Influence of Stirring Speed, Temperature and Initial Nitrogen Concentration on Specific Anammox Activity

ABSTRACT This study evaluates the influence of initial nitrogen concentration, temperature and stirring speed on specific anammox activity (SAA). The biomass was tested in single batch reactors with different initial nitrogen concentrations (Assay 1) ranging from 60 to 140 mg Ntotal/L in equimolar ratio (NO2--N/NH4+-N) and in another test to 67.3 mg NH4+-N/L and 92.2 mg NO2--N/L (close to anammox stoichiometric ratio). The anammox biomass was also tested in single batch at different temperatures (from 20 to 37° C) to determine the short-term effects on SAA (Assay 2). In the third assay the stirring speed ranged from 50 to 150 rpm in a sequencing batch reactor (SBR) at 37 ºC. SAA was affected by the stoichiometric molar ratio but not by equimolar initial concentrations. The maximum specific anammox activities were 26.2 mg NH4+-N/g VSS.h in the single batch reactor at 37 ºC with NO2--N/NH4+-N stoichiometric ratio and 33.5 mg NH4+-N/g VSS.h in the SBR at 37 ºC and 50 rpm. The NO2--N/NH4+-N molar ratio affected specific anammox activity, and SAA showed to be more hindered by low increases of stirring speed than reported in the literature.

Remocao de demanda quimica de oxigenio e nitrogenio total Kjeldahl de efluente de industria de vegetais congelados por Reator em Batelada Sequencial / Chemical Oxygen Demand and Total Kjeldahl Nitrogen removal of frozen vegetables industry wastewater by Sequential Batch Reactor

O objetivo deste trabalho foi estudar o tratamento biológico de efluente de indústria de vegetais congelados em Reator em Batelada Sequencial (RBS), verificando o efeito da concentração de Sólidos Suspensos Voláteis (SSV), Demanda Química de Oxigênio inicial (DQOi) e aeração na remoção biológica de carbono e nitrogênio, a fim de obter um efluente tratado que atenda aos padrões de lançamento recomendados pela legislação ambiental brasileira. Nesta pesquisa, o tratamento dos efluentes foi feito em um RBS, utilizando concentração de SSV variando entre 2000 mg.L-1 e 4000 mg.L-1, DQOi variando entre 300 mg.L-1 e 600 mg.L-1, e quantidade de aeração variando entre 3 L.min-1 e 6 L.min-1. Os resultados mostram que a maior eficiência de remoção para DQO foi de 88%, e para nitrogênio total Kjeldahl (NTK) foi de 74,9%. As condições otimizadas para remoção de DQO e NTK do efluente estudado foram: DQO inicial de 600 mg.L-1, aeração de 4,5 L.min-1 e concentração de SSV de 2000 mg.L-1 .

The objective of this work was to study the biological wastewater treatment from frozen vegetables industry in sequential batch reactor (SBR), verifying the effect of the volatile suspended solids (VSS) concentration, initial Chemical Oxygen Demand (iCOD) and aeration to remove organic carbon and nitrogen in order to obtain a treated wastewater that meets discharge standards recommended by the Brazilian environmental legislation. In this study, the treatment of wastewaters was done in an SBR using VSS concentration ranging from 2000 mg L-1 and 4000 mg.L-1, iCOD ranging from 300 mg.L-1 and 600 mg.L-1, and aeration ranging between 3 L.min-1 and 6 L.min-1. The results show that the major removal efficiency for COD was 88%, and for Total Kjeldahl Nitrogen (TKN) was 74,9%. The optimized conditions for COD and TKN removal of the studied wastewater were: initial COD of 600 mg.L-1, aeration of 4.5 L.min-1 and VSS concentration of 2000 mg.L-1 .

Tratabilidad del efluente de una tenería con presencia de cromo usando un reactor por carga secuencial / Tratability of Tannery Wastewater in the Presence of Chromium Usinga Sequencing Batch Reactor

Los efluentes industriales de las tenerías son altamente contaminantes por las elevadas concentraciones de materia orgánica, nitrógeno y metales pesados como el cromo que contienen. Los sistemas biológicos no convencionales, en especial los que usan reactores por carga secuencial (SBR) han demostrado ser una buena opción de tratamiento de estos efluentes por su flexibilidad y eficiencia en presencia de sustancias inhibidoras, tales como el cromo. El objetivo de esta investigación fue evaluar la eficiencia de un SBR en cuanto a la remoción de materia orgánica, nutrientes y metales pesados utilizando una mezcla de dos de las fracciones de los vertidos de una tenería (curtido con cromo y teñido). Se compararon las eficiencias de remoción obtenidas al alimentar el reactor con afluentes diluidos y concentrados, variando el tiempo de residencia hidráulica en 8 y 12 horas. Durante el tiempo de reacción se combinaron fases anóxicas y óxicas. Se obtuvo que las remociones de contaminantes fueron estadísticamente mayores cuando se usaron afluentes diluidos (DQO£1000 mg/L y [Cr3+]£10 mg/L), independientemente del tiempo de retención utilizado, lográndose la mayor eliminación durante la fase anóxica. Las remociones no mostraron diferencia estadística entre ellas, oscilando para los tratamientos con afluentes diluidos entre 82,5 y 84,2% para la DQO; 58,0 y 73,9% para P-PO4(3-) y 51,2 y 53,9% para el Cr. La eliminación de nitrógeno se realizó por asimilación debido a que los microorganismos nitrificantes fueron más sensibles e inhibieron su actividad frente a la presencia del cromo y altas concentraciones de materia orgánica. La remoción de cromo se logró por precipitación y/o adsorción en el lodo, por lo que fue fundamental controlar el pH en los reactores entre 7,5 y 8,5 unidades.

Tannery wastewater are highly pollutant for the high concentrations of organic matter, nitrogen and heavy metals as chrome that they contain. Sequential batch reactors (SBR) have demonstrated to be a good option of treatment of these effluents due to their flexibility and efficiency in presence of inhibiting substances (chrome). The aim of this investigation was to determine the best conditions for removal of organic matter, nutrients and heavy metals of the residual water of a tannery using a SBR fed on a mixture of tanning-dyeing effluent. The efficiencies of removal were compared when using dilute and concentrated influents, under 8 and 12 hour of hydraulic residence time. During the reaction phases anoxics and oxics phases were combined. The removal of pollutants were significantly higher when dilute influent was used (DQO£1000 mg/L and [Cr3+]£10 mg/L), independently of the retention time, being achieved the major elimination during the anoxic phase. The removals fluctuated between 82.5 and 84.45% of DQO, 58.0 and 73.9% of P-PO4(3-) and 51.2 and 53.9% of Cr. The elimination of nitrogen was achieved by assimilation, due to the fact that nitrifying bacteria were more sensitive and their activity was inhibited by the presence of chrome and high concentrations of organic matter. The removal of chrome was achieved by precipitation and/or adsorption on the sludge, being necessary to control the pH between 7.5 - 8.5 in the reactors.

Tratabilidad del efluente de una tenería usando un reactor por carga secuencial / Tratability of tannery wastewater using a sequencing batch reactor

El curtido de pieles es uno de los procesos más contaminantes de la industria por la serie de tratamientos químicos que involucra y el abundante volumen de agua residual que produce. Los efluentes de las tenerías son ricos en materia orgánica, nitrógeno, sólidos suspendidos, sales y otras sustancias inhibidoras que afectan los procesos de nitrificación y desnitrificación. Los reactores por carga secuencial (SBR) han demostrado ser una buena opción de tratamiento de estos efluentes por su flexibilidad y capacidad de soportar altas cargas de alimentación. En este trabajo se evaluó la eficiencia de un SBR alimentado con una mezcla de las fracciones del efluente de una tenería provenientes de los procesos de pelambre y teñido. El funcionamiento del sistema fue evaluado para dos tiempos de residencia hidráulico (8 y 12 horas) y para dos niveles de concentración del afluente (diluido con DQO máxima de 2.700 mg/L y concentrado con DQO mínima de 25.000 mg/L). Durante el tiempo de reacción se combinaron fases anóxicas y óxicas. Se obtuvo que sólo la concentración del afluente fue el factor que presentó diferencia estadística en los cuatro tratamientos aplicados, siendo mayores las remociones de contaminantes cuando se usaron afluentes diluidos (DQO£2.700 mg/L), lográndose la mayor eliminación durante la fase anóxica. Las remociones estuvieron en el rango de 83,3-85,0% para DQO; 59,6-73,0% para P-PO4(3-) y 83,9-84% para Cr. La eliminación de nitrógeno se realizó presumiblemente por asimilación debido a que los microorganismos nitrificantes mostraron ser los más sensibles cuando se modificaron las condiciones de funcionamiento del reactor.

The leather tanning is one of the most pollutant processes in the industry for the series of chemical treatments that involves and the abundant volume of residual water produced. Tanneries wastewaters are rich in organic matter, nitrogen, solid suspended, salts and other inhibiting substances that affect the processes of nitrificación and desnitrificación. Sequential batch reactors (SBR) have demonstrated to be a good option for treatment of this effluent because they have flexibility and manage high load charges. The objetive of this work was evaluated the efficiency of a SBR fed on a mixture of two fractions of the tannery wastewater, soak liquour and dyeing effluent. The functioning of the system was evaluated for two hydraulic residence time (8 and 12 hours) and for two levels of concentration of the influent (diluted with maximum DQO of 2700 mg/L and concentrate with minimal DQO of 25000 mg/L). During the reaction two phases were combined: anoxic and oxic. There was obtained that only the concentration of the influent was the factor that presented statistical difference in the four treatments tested, being major removals of pollutants when influents were diluted (DQO£2700 mg/L), the major elimination were achieved during the anoxic phase. The removals were in the range of 83.3-85.0% for DQO; 59.6-73.0% for P-PO4(3-) and 83.9-84.0% for Cr. The elimination of nitrogen was achived presumably by assimilation, due to the fact that nitrifying bacteria were more sensitive when operation conditions were modified in the reactor.

Dimensionamento do volume do reator seqüencial em batelada (RSB) com enchimento estático / Sizing of the sequential batch reactor (SBR) with static filling

Este trabalho teve como objetivo propor uma metodologia de dimensionamento para o volume do RSB. O desenvolvimento do modelo matemático para calcular o volume do reator foi realizado a partir da modelagem fenomenológica do comportamento do lodo. A metodologia ora proposta foi aplicada em estudo de caso para comparação com metodologias já consolidadas no dimensionamento do sistema de lodos ativados em batelada. A partir da metodologia apresentada neste trabalho, a determinação do volume do reator e do ciclo operacional mostrou que é possível contribuir para o dimensionamento do RSB sem transgredir o conhecimento da ação do lodo sobre a matéria orgânica e sem admitir fluxo contínuo no comportamento hidráulico do reator.

The purpose of this study was to propose a methodology for sizing SBR volumes. The mathematical model to calculate reactor volume was developed by modeling sludge behavior phenomena. The methodology proposed here was applied to a case study in order to compare it to already consolidated methods used to size the activated sludge batch system. The reactor volume and operational cycle were determined based on the method presented here, showing that it is possible to help size the SBR without challenging knowledge regarding the action of sludge on organic matter, and without allowing continuous flow into the hydraulic compartment of the reactor.

Eficiência do reator seqüencial em batelada (RSB) na remoção de nitrogênio no tratamento de esgoto doméstico com DQO baixa / The sequencing batch reactor (SBR) efficiency in the removal of nitrogen on the treatment of domestic sewage with low COD

Este trabalho tem como objetivo avaliar a eficiência e a estabilidade do RSB na remoção de nitrogênio no tratamento de esgoto doméstico com DQO baixa. O reator utilizado no experimento possui volume de trabalho de 600 L e trata 1200 L/d de esgoto bruto em três bateladas de oito horas. A partir dos dados obtidos na pesquisa, observou-se que o reator seqüencial em bateladapossibilitou a remoção média de nitrogênio total igual a 88 % no tratamento de esgoto doméstico com DQO média de 257 mg/L. A remoção de DQO foi de 90 %, a média da alcalinidade total no efluente foi 72 mgCaCO3/L e o índice volumétrico de lodo médio ficou em 86 mL/g. Estes resultados indicam que é possível utilizar RSB para o tratamento de esgoto doméstico com matéria orgânica reduzida sem comprometer a qualidade do efluente, a remoção de nitrogênio e a estabilidade operacional do sistema.

This work had the objective of evaluating the SBR efficiency and stability in the removal of nitrogen on the treatment of domestic sewage with low COD. The reactor used in the experiment has a working volume of 600 L, and treats 1200 L/d of raw sewage in three 8-hour cycles. From the data gathered during the research, itwas realized that the SBR fostered an average removal of total nitrogen equal to 88% in the treatment of a domestic sewage with an average COD of 257 mg/L. The COD removal was 90%, the final effluent total alkalinity was 72 mgCaCO3/L, and the sludge volumetricindex was 86 mL/g. The results indicate that is possible to use SBR for the treatment of domestic sewage with low organic matter without compromising the final effluent quality, the nitrogen removal ability, and the stability of the system.

Study on Treatment of Dyeing Wastewater in the Combination Process of ABR and SBR / 微生物学通报

A laboratory scale combination process of anaerobic baffled reactor(ABR) with sequencing batch reactor(SBR) for treatment of real dyeing wastewater was studied.The effects of operational conditions were investigated.The results demonstrated that removal rates of COD,colour and aniline were 32%~95%,89%~99% and 50%~98%,respectively,the effluents of COD were 30.0 ~97.1mg/L,colour were 8 ~40 times dilution ratio,concentration of aniline were 0.20 ~0.95 mg/L,which could meet the National Discharge Criteria(GradeⅠ) under the operational conditions of HRTs of 24~36 h,organic loading rates of 0.43 ~2.46 kg COD/(m~(3)?d),the influent pH values of 6.5~8.0,ambient temperatures of 20℃~35℃ at the ABR stage and DOs of 2 mg/L,reaction times of 3~10h,settle times of 2 h at the SBR stage.