Articles de revues : « Granular biomasses »

1

Zhang, Xiufang, Yongqiang Liu, Jun Li, Zhuo Wei, Wenyan Duan et Fangyuan Chen. « Enhancing Effects of Sludge Biochar on Aerobic Granular Sludge for Wastewater Treatment ». Processes 10, n^o 11 (14 novembre 2022) : 2385. http://dx.doi.org/10.3390/pr10112385.

Texte intégral

Résumé :

Sludge biochar can be used as bio-carrier to enhance aerobic granular sludge, however, its impact on the formation and especially long-term stability of aerobic granules has not been fully investigated. In this paper, aerobic granular sludge was cultivated in two parallel sequencing batch reactors (SBRs), R1 and R2, with and without sludge biochar addition in the activated sludge inoculum, respectively. The sludge characteristics, wastewater treatment performance, and microbial community structure of granular sludge were examined on a 240-day operation, during which aerobic granular sludge in the two reactors experienced dynamic changes including granule formation, maturation, breakage, filamentous proliferation, and recovery. Aerobic granules in R1 with biochar formed two weeks earlier than that in R2, presenting a larger mean size, and higher settling ability and biomass retention in the granule maturation period. Concurrently, aerobic granules in R1 showed higher denitrification ability with over 80% removal efficiency throughout the whole operation period. During the maturation period, the ratio of food to biomass (F/M) in R1 was below 0.5 gCOD/gVSS d while it ranged between 0.5 and 1.0 gCOD/gVSS d in R2 due to lower biomass retention. The elemental analysis showed more Ca and P accumulation in aerobic granular sludge from R1, with 3% Ca and 2.75% P in sludge from R1 and 0.91% Ca and 0.75% P in sludge from R2, respectively. The microbial community in R1 had higher richness, diversity, excretion of extracellular polymer substances (EPSs) and abundance of denitrifying genera than that in R2, supporting its higher stability and denitrification performance. These results demonstrated that aerobic granular sludge formed by using sludge biochar as a carrier for granulation can speed up granule formation, improve denitrification performance, and enhance the long-term stability of aerobic granules. The findings disclosed the enhancing effects of biochar for wastewater treatment by aerobic granular sludge, suggesting the potential of practical application of biochar in aerobic granular sludge-based reactors.

Styles APA, Harvard, Vancouver, ISO, etc.

2

Vlaeminck, S. E., L. F. F. Cloetens, M. Carballa, N. Boon et W. Verstraete. « Granular biomass capable of partial nitritation and anammox ». Water Science and Technology 58, n^o 5 (1 septembre 2008) : 1113–20. http://dx.doi.org/10.2166/wst.2008.731.

Texte intégral

Résumé :

A novel and efficient way of removing nitrogen from wastewater poor in biodegradable organic carbon, is the combination of partial nitritation and anoxic ammonium oxidation (anammox), as in the one-stage oxygen-limited autotrophic nitrification/denitrification (OLAND) process. Since anoxic ammonium-oxidizing bacteria grow very slowly, maximum biomass retention in the reactor is required. In this study, a lab-scale sequencing batch reactor (SBR) was used to develop granular, rapidly settling biomass. With SBR cycles of one hour and a minimum biomass settling velocity of 0.7 m/h, OLAND granules were formed in 1.5 months and the nitrogen removal rate increased from 50 to 450 mg N L−1 d−1 in 2 months. The granules had a mean diameter of 1.8 mm and their aerobic and anoxic ammonium-oxidizing activities were well equilibrated to perform the OLAND reaction. Fluorescent in-situ hybridization (FISH) demonstrated the presence of both β-proteobacterial aerobic ammonium oxidizers and planctomycetes (among which anoxic ammonium oxidizers) in the granules. The presented results show the applicability of rapidly settling granular biomass for one-stage partial nitritation and anammox.

Styles APA, Harvard, Vancouver, ISO, etc.

3

Nor-Anuar, A., Z. Ujang, M. C. M. van Loosdrecht, M. K. de Kreuk et G. Olsson. « Strength characteristics of aerobic granular sludge ». Water Science and Technology 65, n^o 2 (1 janvier 2012) : 309–16. http://dx.doi.org/10.2166/wst.2012.837.

Texte intégral

Résumé :

Aerobic granular sludge has a number of advantages over conventional activated sludge flocs, such as cohesive and strong matrix, fast settling characteristic, high biomass retention and ability to withstand high organic loadings, all aspects leading towards a compact reactor system. Still there are very few studies on the strength of aerobic granules. A procedure that has been used previously for anaerobic granular sludge strength analysis was adapted and used in this study. A new coefficient was introduced, called a stability coefficient (S), to quantify the strength of the aerobic granules. Indicators were also developed based on the strength analysis results, in order to categorize aerobic granules into three levels of strength, i.e. very strong (very stable), strong (stable) and not strong (not stable). The results indicated that aerobic granules grown on acetate were stronger (high density: >150 g T SSL−1 and low S value: 5%) than granules developed on sewage as influent. A lower value of S indicates a higher stability of the granules.

Styles APA, Harvard, Vancouver, ISO, etc.

4

Zhou, Jun, Hongyu Wang, Kai Yang, Fang Ma et Bin Lv. « Optimization of operation conditions for preventing sludge bulking and enhancing the stability of aerobic granular sludge in sequencing batch reactors ». Water Science and Technology 70, n^o 9 (24 septembre 2014) : 1519–25. http://dx.doi.org/10.2166/wst.2014.406.

Texte intégral

Résumé :

Sludge bulking caused by loss of stability is a major problem in aerobic granular sludge systems. This study investigated the feasibility of preventing sludge bulking and enhancing the stability of aerobic granular sludge in a sequencing batch reactor by optimizing operation conditions. Five operation parameters have been studied with the aim to understand their impact on sludge bulking. Increasing dissolved oxygen (DO) by raising aeration rates contributed to granule stability due to the competition advantage of non-filamentous bacteria and permeation of oxygen at high DO concentration. The ratio of polysaccharides to proteins was observed to increase as the hydraulic shear force increased. When provided with high/low organic loading rate (OLR) alternately, large and fluffy granules disintegrated, while denser round-shape granules formed. An increase of biomass concentration followed a decrease at the beginning, and stability of granules was improved. This indicated that aerobic granular sludge had the resistance of OLR. Synthetic wastewater combined highly and slowly biodegradable substrates, creating a high gradient, which inhibited the growth of filamentous bacteria and prevented granular sludge bulking. A lower chemical oxygen demand/N favored the hydrophobicity of granular sludge, which promoted with granule stability because of the lower diffusion rate of ammonia. The influence of temperature indicated a relatively low temperature was more suitable.

Styles APA, Harvard, Vancouver, ISO, etc.

5

Nguyen, Phuong Thi Thanh, Phuoc Van Nguyen et Anh Cam Thieu. « Study on aerobic granular sludge formation in sequencing batch reactors for tapioca wastewater treatment ». Science and Technology Development Journal 16, n^o 1 (31 mars 2013) : 40–48. http://dx.doi.org/10.32508/stdj.v16i1.1386.

Texte intégral

Résumé :

Aerobic granular sludge has attracted extensive interest of researchers since the 90s due to the advantages of aerobic granules such as good settling ability, high biomass accumulation, being resistant to high loads and being less affected by toxic substances. Studies, however, which have mainly been carried out on synthetic wastewater, cannot fully evaluate the actual ability of aerobic granules. Study on aerobic granular sludge was performed in sequencing batch reactors, using seeding sludge taken from anaerobic sludge and tapioca wastewater as a substrates. After 11 weeks of operation, the granules reached the stable diameter of 2- 3 mm at 3.7 kgCOD/m3.day organic loading rate. At high organic loads, in range of 1.6 - 5 kgCOD/m3.day, granules could treat effectively COD, N, P with performance of 93 – 97%; 65 – 79% and 80 – 95%, respectively.

Styles APA, Harvard, Vancouver, ISO, etc.

6

Dong, Chun Juan, Qing Ye Pan, Hong Yu Lu et Ya Quan Sun. « Rapidly Start-Up and Performance of the EGSB Reactor Treating Actual Coking Wastewater when Seeded with Digestion Sludge ». Advanced Materials Research 726-731 (août 2013) : 2567–71. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.2567.

Texte intégral

Résumé :

To accomplish rapidly the granulation process of digestion sludge for the treatment of actual coking wastewater and meanwhile achieve high COD, phenol, SCN- and CN- removal, the EGSB reactor was employed with two operation stages. StageI: Granular sludge was formed from digestion sludge using brewery wastewater as substrate in the anaerobic way (meanwhile adding little granules, which were 1/7 of the total biomass). StageII: Granular sludge was acclimatized with the actual coking wastewater through continuous micro-oxygenation way. The experimental results showed that the granular sludge could quickly form in 10d in the EGSB reactor seeded with digestion sludge and little loose granules. It took only about 6 months for the successful micro-aerobic acclimating of the granular sludge by the actual coking wastewater. The removal efficiencies of COD, phenol, SCN- and CN- were 72.9, 99.5, 95.7 and 97.5%, respectively, at 12.1h hydraulic retention time (HRT) and for 631-922, 12.8-37.7, 66.7-232.7 and 0.3-57.8mg.L-1 influent COD, phenol, SCN- and CN- concentration.

Styles APA, Harvard, Vancouver, ISO, etc.

7

Zahra, S. A., L. D. A. Purba et N. Abdullah. « Development and characteristics of microalgae-bacteria aerobic granules treating low strength municipal wastewater ». IOP Conference Series : Earth and Environmental Science 1091, n^o 1 (1 novembre 2022) : 012052. http://dx.doi.org/10.1088/1755-1315/1091/1/012052.

Texte intégral

Résumé :

Abstract This study aims to assess the feasibility of cultivating microalgae-bacteria aerobic granular sludge using low-strength municipal wastewater (<200 mg COD/L) as a substrate. A laboratory-scale photo-sequencing batch reactor was inoculated with activated sludge and fed with municipal wastewater. The development and characteristics of microalgae-bacteria aerobic granular sludge were observed for 90 days. The average COD removal efficiency of this system was 71%. The granulation process was observed to occur on day 28, indicated by a high biomass accumulation and decreasing sludge volume index (SVI). After 90 days of cultivation, MLSS value was found to be 3.7 g/L and SVI30 at 18.9 mL/g. In addition, the diameter of the granules was significantly increased. Mature microalgae-bacteria aerobic granules were developed with an average and a maximum diameter of 0.65 mm and 6 mm, respectively. Moreover, cocci-shaped bacteria and microalgae cells were observed to reside on the granular surface during observation using field emission scanning electron microscopy (FESEM). The granules exhibited an excellent settling velocity at 80 m/h. The findings suggest the possibility of using low-strength wastewater to develop microalgae-bacteria aerobic granular sludge.

Styles APA, Harvard, Vancouver, ISO, etc.

8

Pedrouso, A., A. Val del Río, J. L. Campos, R. Méndez et A. Mosquera-Corral. « Biomass aggregation influences NaN3 short-term effects on anammox bacteria activity ». Water Science and Technology 75, n^o 5 (15 décembre 2016) : 1007–13. http://dx.doi.org/10.2166/wst.2016.587.

Texte intégral

Résumé :

The main bottleneck to maintain the long-term stability of the partial nitritation-anammox processes, especially those operated at low temperatures and nitrogen concentrations, is the undesirable development of nitrite oxidizing bacteria (NOB). When this occurs, the punctual addition of compounds with the capacity to specifically inhibit NOB without affecting the process efficiency might be of interest. Sodium azide (NaN3) is an already known NOB inhibitor which at low concentrations does not significantly affect the ammonia oxidizing bacteria (AOB) activity. However, studies about its influence on anammox bacteria are unavailable. For this reason, the objective of the present study was to evaluate the effect of NaN3 on the anammox activity. Three different types of anammox biomass were used: granular biomass comprising AOB and anammox bacteria (G1), anammox enriched granules (G2) and previous anammox granules disaggregated (F1). No inhibitory effect of NaN3 was measured on G1 sludge. However, the anammox activity decreased in the case of G2 and F1. Granular biomass activity was less affected (IC50 90 mg/L, G2) than flocculent one (IC50 5 mg/L, F1). Summing up, not only does the granular structure protect the anammox bacteria from the NaN3 inhibitory effect, but also the AOB act as a barrier decreasing the inhibition.

Styles APA, Harvard, Vancouver, ISO, etc.

9

Li, J., K. Garny, T. Neu, M. He, C. Lindenblatt et H. Horn. « Comparison of some characteristics of aerobic granules and sludge flocs from sequencing batch reactors ». Water Science and Technology 55, n^o 8-9 (1 avril 2007) : 403–11. http://dx.doi.org/10.2166/wst.2007.284.

Texte intégral

Résumé :

Physical, chemical and biological characteristics were investigated for aerobic granules and sludge flocs from three laboratory-scale sequencing batch reactors (SBRs). One reactor was operated as normal SBR (N-SBR) and two reactors were operated as granular SBRs (G-SBR1 and G-SBR2). G-SBR1 was inoculated with activated sludge and G-SBR2 with granules from the municipal wastewater plant in Garching (Germany). The following major parameters and functions were measured and compared between the three reactors: morphology, settling velocity, specific gravity (SG), sludge volume index (SVI), specific oxygen uptake rate (SOUR), distribution of the volume fraction of extracellular polymeric substances (EPS) and bacteria, organic carbon and nitrogen removal. Compared with sludge flocs, granular sludge had excellent settling properties, good solid–liquid separation, high biomass concentration, simultaneous nitrification and denitrification. Aerobic granular sludge does not have a higher microbial activity and there are some problems including higher effluent suspended solids, lower ratio of VSS/SS and no nitrification at the beginning of cultivation. Measurement with CLSM and additional image analysis showed that EPS glycoconjugates build one main fraction inside the granules. The aerobic granules from G-SBR1 prove to be heavier, smaller and have a higher microbial activity compared with G-SBR2. Furthermore, the granules were more compact, with lower SVI and less filamentous bacteria.

Styles APA, Harvard, Vancouver, ISO, etc.

10

Tarre, S., R. Armon, G. Shelef et M. Green. « Effects of water characteristics on granular sludge formation in a USB reactor for denitrification of drinking water ». Water Science and Technology 30, n^o 9 (1 novembre 1994) : 141–47. http://dx.doi.org/10.2166/wst.1994.0463.

Texte intégral

Résumé :

The effects of water chemical composition on granular sludge formation in a denitrifying USB reactor was studied. The mineral fraction and sludge volume index (SVI) of the granular sludge in the reactor were found to be closely related to the composition of the influent water. Groundwater and simulated ‘hard’ water produced granules with good settling characteristics and high reactor VSS concentrations. Sludge granules from the reactor fed with surface water, which had lower concentrations of calcium and alkalinity, had a low mineral content and high SVI values resulting in biomass washout and reactor instability. The mineralization process, as expressed by the sludge's ash content (mainly CaCO3), is due to an increase in the pH and alkalinity during denitrification thereby changing the reactor's precipitation potential.

Styles APA, Harvard, Vancouver, ISO, etc.

11

Nancharaiah, Y. V., C. Dodge, V. P. Venugopalan, S. V. Narasimhan et A. J. Francis. « Immobilization of Cr(VI) and Its Reduction to Cr(III) Phosphate by Granular Biofilms Comprising a Mixture of Microbes ». Applied and Environmental Microbiology 76, n^o 8 (19 février 2010) : 2433–38. http://dx.doi.org/10.1128/aem.02792-09.

Texte intégral

Résumé :

ABSTRACT We assessed the potential of mixed microbial consortia, in the form of granular biofilms, to reduce chromate and remove it from synthetic minimal medium. In batch experiments, acetate-fed granular biofilms incubated aerobically reduced 0.2 mM Cr(VI) from a minimal medium at 0.15 mM day−1 g−1, with reduction of 0.17 mM day−1 g−1 under anaerobic conditions. There was negligible removal of Cr(VI) (i) without granular biofilms, (ii) with lyophilized granular biofilms, and (iii) with granules in the absence of an electron donor. Analyses by X-ray absorption near edge spectroscopy (XANES) of the granular biofilms revealed the conversion of soluble Cr(VI) to Cr(III). Extended X-ray absorption fine-structure (EXAFS) analysis of the Cr-laden granular biofilms demonstrated similarity to Cr(III) phosphate, indicating that Cr(III) was immobilized with phosphate on the biomass subsequent to microbial reduction. The sustained reduction of Cr(VI) by granular biofilms was confirmed in fed-batch experiments. Our study demonstrates the promise of granular-biofilm-based systems in treating Cr(VI)-containing effluents and wastewater.

Styles APA, Harvard, Vancouver, ISO, etc.

12

Harun, Hasnida, Hazren A. Hamid, Norshuhaila Mohamed Sunar, Faridah Hanim Ahmad, Aznah Nor Anuar, Noor Hasyimah Rosman et Inawati Othman. « Performance of Aerobic Granular Sludge in Treating Soy Sauce Wastewater at Different Hydraulic Retention Time ». International Journal of Engineering & ; Technology 7, n^o 4.35 (30 novembre 2018) : 564. http://dx.doi.org/10.14419/ijet.v7i4.35.22910.

Texte intégral

Résumé :

Aerobic granular sludge had shown its capability in treating soy sauce wastewater, but its reactor performance, granules properties and biokinetics in different hydraulic retention times (HRT) is still unknown. To ensure the reactor is performed in optimum condition, a judicially selection of HRT is important. The study was conducted in a high and slender column operated according to a sequential batch reactor (SBR) with a sequence of aerobic and anaerobic/anoxic reaction phases. Three different HRTs (8, 16, 24 h) and different anaerobic and aerobic reaction time were evaluated. In the study demonstrated the increase in HRT could reduce the organic loading rate (OLR) as well as biomass yield (Yobs, Y), endogenous decay rate (kd) and overall specific biomass growth rate (µoverall). It was observed a slight increase in the mixed liquor suspended solid (MLSS) and the granules mean size as the OLR decreased. Meanwhile, in the lowest HRT reactor, a narrow diameter range of aerobic granule from 3 to 100 µm was observed due to the development of small and dense granules. The HRT of 24h with aerobic and anaerobic/anoxic reaction time of 3.88 and 7.77h respectively is the SBR’s best performances due to the improvement of the aerobic granular physical properties.

Styles APA, Harvard, Vancouver, ISO, etc.

13

Díaz, E., R. Amils et J. L. Sanz. « Molecular ecology of anaerobic granular sludge grown at different conditions ». Water Science and Technology 48, n^o 6 (1 septembre 2003) : 57–64. http://dx.doi.org/10.2166/wst.2003.0357.

Texte intégral

Résumé :

Qualitative and quantitative diversity of microorganisms present in anaerobic granular sludges fed with different substrates, as well as the structure of these granules have been studied using fluorescent 16S rRNA-targeted in situ hybridization and electron microscopy. The granules showed a multi-layered structure, in which both densely packed and loose micro-colonies, channels and holes could be observed. Only bacteria were found in the outer shell of the granules, while both archaea and bacteria were detected in the inner core. Although high cell density was found in the granules (more than 1011 cells/gram, determined by DAPI-stain) only a low percentage of cells was able to hybridize with the rRNA-targeted probes. Significant quantitative and qualitative differences were observed in the composition of granules fed with different substrates (formate, acetate at high and low concentrations, propionate, sucrose, starch and peptone). Bacterial cells were mostly gram-positives. Active proteobacteria were scarce in the granules exposed to VFA. Syntrophobacteria became dominant in the propionate-grown biomass. Concerning methanogenic archaea, Methanosaeta was the predominant species using complex substrates or low acetate concentration fed granules, while Methanosarcina and members of Methanobacteriales were predominant in the granules grown at high concentration of acetate or formate, respectively. Other Methanomicrobiales and Methanococcales, have been detected in the anaerobic granular sludge in the conditions used in this work.

Styles APA, Harvard, Vancouver, ISO, etc.

14

Lima, Jéssyca De Freitas, Elivânia Vasconcelos Moraes dos Santos, Heraldo Antunes Silva Filho, José Tavares de Sousa et Adrianus Cornelius Van Haandel. « AVALIAÇÃO DA SEDIMENTABILIDADE DE BIOMASSA GRANULAR E FLOCULENTA EM SISTEMAS DE LODO ATIVADO ». HOLOS 3 (3 juillet 2014) : 319. http://dx.doi.org/10.15628/holos.2014.1916.

Texte intégral

Résumé :

A sedimentação é uma importante operação unitária no tratamento de esgotos, pois pode definir o desenvolvimento de projetos mais econômicos. A pesquisa visou avaliar a sedimentabilidade de biomassa aeróbia granular e floculenta. Foram montados dois sistemas de lodo ativado, um sistema University of Cape Town - UCT com características de lodo floculento e um reator em bateladas sequenciais com estratégias para a granulação aeróbia - RBSG. Com os resultados obtidos foi possível afirmar que o lodo granular obteve uma velocidade de sedimentação elevada (35 m/h), sendo superior à velocidade considerada ideal pela literatura especializada (faixa de 6 a 10 m/h). Já o sistema UCT teve uma média de 7,9 m/h. Foi confirmado que o lodo granular do reator intermitente além da vantagem de maior acúmulo de sólidos no sistema e menor espaço construtivo, também é capaz de tratar mais esgoto por unidade de tempo quando comparado ao sistema contínuo com lodo floculento (UCT). Isso faz com que a escolha por sistemas granulares aeróbios se torne cada vez mais atrativa para o tratamento de efluentes de diferentes naturezas.

Styles APA, Harvard, Vancouver, ISO, etc.

15

Tay, J. H., Q. S. Liu et Y. Liu. « The effect of upflow air velocity on the structure of aerobic granules cultivated in a sequencing batch reactor ». Water Science and Technology 49, n^o 11-12 (1 juin 2004) : 35–40. http://dx.doi.org/10.2166/wst.2004.0798.

Texte intégral

Résumé :

The effect of upflow air velocity on the formation and structure of aerobic granules was studied in three column sequencing batch reactors. Upflow aeration would be the major cause of hydrodynamic shear force in the column reactor. Results showed that high upflow air velocity resulted in more compact, denser, rounder, stronger and smaller aerobic granules, while high biomass retention in the reactor was achieved. It was found that high upflow air velocity could induce granular sludge to secrete more cell polysaccharides which in turn contributed to the compact and strong structure. It appears from this study that the structure of aerobic granules could be controlled by manipulating the upflow air velocity.

Styles APA, Harvard, Vancouver, ISO, etc.

16

Rojas-Z, U., C. Fajardo-O, I. Moreno-Andrade et O. Monroy. « Greywater treatment in an aerobic SBR : sludge structure and kinetics ». Water Science and Technology 76, n^o 6 (12 juin 2017) : 1535–44. http://dx.doi.org/10.2166/wst.2017.341.

Texte intégral

Résumé :

In order to have an efficient operation, sequencing batch reactors (SBR) must support granular biomass with high conversion rates, settling properties, and be able to deal with the inherent variability of the composition of real wastewaters. In this study, the effect of the influent composition and the specific organic loading rate (Bx) on the granulation process was evaluated in two SBRs, fed with greywater (GW) and a synthetic medium (SM). The feeding with SM led to the formation of compact granular biomass, with a sludge volume index (SVI) of 22.4 mL g−1, and a zone settling velocity (ZSV) of 13.1 m h−1. In contrast, feeding with GW induced the formation of filamentous granules, with lower settling properties (SVI = 165 mL g−1 and ZSV = 10 m h−1), when the system was operated at high Bx (4.4 kg COD kg VSS−1 d−1). However, the reduction of the average Bx to 2 kg COD kg VSS−1 d−1 induced an improvement in the morphology and properties of the granules (SVI = 98 mL g−1 and ZSV = 13 m h−1). Furthermore, the kinetic analysis indicated that granules cultivated with SM were formed by fast growing microorganisms with a high cell yield, whereas those cultivated in GW presented a much lower cell yield.

Styles APA, Harvard, Vancouver, ISO, etc.

17

She, Zong Lian, En Shi, Xiao Hui Fu, Jian Wu, Li Na Jiang et Liang Guo. « Acclimation of Anaerobic Granular Sludge and 2,6-DNP Removal in the Upflow Anaerobic Sludge Blanket (UASB) Reactors ». Advanced Materials Research 183-185 (janvier 2011) : 352–61. http://dx.doi.org/10.4028/www.scientific.net/amr.183-185.352.

Texte intégral

Résumé :

Characteristics of anaerobic granules before and after acclimation were studied using glucose as co-substrate. Removal efficiencies of 2,6-dinitrophenol (2,6-DNP) using two different co-substrates were investigated in two lab-scale UASB reactors. Granular sludge acclimatized to the wastewater containing 2,6-DNP through 3 months. After acclimation, SEM pictures of the granular biomass showed that Filamentous bacteria were the predominant bacteria on the surface of granules. Throughout the study of 2,6-DNP anaerobic degradation with different co-substrates, influent COD concentration was kept constant as about 2500 mg l-1. Maximum 2,6-DNP concentration was 170.0 mg l-1 and 2,6-DNP removal efficiencies were always more than 98.0% using glucose as co-substrate, keeping hydraulic retention time (HRT) as 35 h. When using sodium acetate as co-substrate and keeping HRT as 30 h, maximum 2,6-DNP concentration was up to 189.5 mg l-1 and over 99.2% 2,6-DNP removal efficiencies could be obtained.

Styles APA, Harvard, Vancouver, ISO, etc.

18

Tokutomi, T. « Operation of a nitrite-type airlift reactor at low DO concentration ». Water Science and Technology 49, n^o 5-6 (1 mars 2004) : 81–88. http://dx.doi.org/10.2166/wst.2004.0740.

Texte intégral

Résumé :

Laboratory scale experiments were performed to evaluate the feasibility and potential of nitrite-type nitrification process with an airlift reactor having aerobic granular biomass. Oxygen limitation was selected as the main control parameter for inhibiting the growth of nitrite oxidizer and thus achieving only nitritation. To enhance granule formation, seeding of methanogenic anaerobic granules was used to serve as an initial carrier material. After 90 days of operation at low DO concentration of less than 1.0 mg/l, the maximum nitrite conversion rate of 2.6 g NO2-N/L/d could be achieved. During the continuing year-long stable operation, the granular mass of nitritation granules increased to about 15 g VSS/L with an average granule size of 0.7 mm. Nitrate-N concentration was observed to be below 10 mg/L during the whole operational period. From the results of the experiments, it is concluded that a granule-type airlift reactor with DO control is feasible for achieving stable nitritation.

Styles APA, Harvard, Vancouver, ISO, etc.

19

Basri, Hazlami Fikri, Aznah Nor Anuar et Mohd Hakim Ab Halim. « Pilot scale study on characterization and performance of aerobic granular sludge to treat domestic wastewater ». Malaysian Journal of Fundamental and Applied Sciences 16, n^o 1 (2 février 2020) : 38–43. http://dx.doi.org/10.11113/mjfas.v16n1.1462.

Texte intégral

Résumé :

Aerobic granular sludge (AGS) is a wastewater treatment technology that is known for having unique advantages such as great settling ability, high biomass level, good shock resistance, and able to withstand high organic loading rate (OLR) and toxic pollutants. Since studies on AGS development are mostly conducted in laboratory scale, the detailed knowledge regarding the pilot scale study is still limited especially for hot and humid tropical climate condition. Therefore, this study focused on the characteristics and performance of AGS cultivated in a pilot-scale bioreactor for hot and humid tropical climate condition, specifically in Malaysia. The formation of AGS as well as biomass concentration were also investigated during the treatment of real domestic wastewater. From the result, it was found that the highest average diameter of the cultivated mature granules was 3.36 mm with a biomass concentration of 12.48 g L−1 after 93 days of operation. The aerobic granular sludge also achieved promising removal rates of 89 %, 75 %, 96 %, and 93 % for COD, phosphate, ammoniacal nitrogen, and total inorganic nitrogen, respectively.

Styles APA, Harvard, Vancouver, ISO, etc.

20

Hu, Jun, Lan Zhou, Qing Wei Zhou, Fang Wei, Li Li Zhang et Jian Meng Chen. « Biodegradation of Paracetamol by Aerobic Granules in a Sequencing Batch Reactor (SBR) ». Advanced Materials Research 441 (janvier 2012) : 531–35. http://dx.doi.org/10.4028/www.scientific.net/amr.441.531.

Texte intégral

Résumé :

Aerobic granules efficient at degrading paracetamol as the sole carbon and energy resource were successfully developed in a sequencing batch reactor (SBR). Aerobic granules were first observed about 220 days after reactor start-up. The images SEM showed the aerobic granules typically consisted of coccus and bacillus. Meanwhile, the size distribution of aerobic granules was analyzed on day 200. The result indicated that the granules eventually grew to become the dominant form of biomass in the reactor. The granular sludge on day 80 and 200 degraded paracetamol completely in 48 h and 28 h, respectively, indicating that granulation contributed to paracetamol degradation. The specific paracetamol degradation rate was observed to increase with increasing paracetamol initial concentration from 500 to 5000 mg/L, peaked at 1200 mg-MTBE/g-VSS·h, and declined with further increases in MTBE concentration as substrate inhibition effects became significant. This study demonstrates that paracetamol can be effectively degraded by aerobic granules and gives insight into the microorganisms potentially involved in the process.

Styles APA, Harvard, Vancouver, ISO, etc.

21

Razo-Flores, Elías, Patrick Smulders, Francesc Prenafeta-Boldú, Gatze Lettinga et Jim A. Field. « Treatment of Anthranilic Acid in an Anaerobic Expanded Granular Sludge Bed Reactor at Low Concentrations ». Water Science and Technology 40, n^o 8 (1 octobre 1999) : 187–94. http://dx.doi.org/10.2166/wst.1999.0418.

Texte intégral

Résumé :

The mineralization of anthranilic acid (2AB) as the only carbon and energy source was studied in batch and continuous conditions using methanogenic granular sludge. Under batch conditions in serum vials, 2AB (300 mg/l) was completely mineralized to methane within 55 days time. The experiment with the anaerobic continuous expanded granular sludge bed (EGSB) reactor was initially conducted at an upflow velocity (Vup) of 5 m/h, a hydraulic retention time (HRT) of 12 h and an organic loading rate (OLR) of 1.5 g chemical oxygen demand (COD)/l-d. After 102 days, 2AB was not degraded at all and the reactor operation was shifted to batch mode by recycling the effluent. After some days, 2AB was completely mineralized and accumulation of flocculent sludge was observed. Batch biodegradability assays demonstrated that this flocculent biomass had a higher specific biodegradation rate compared to the granular sludge. During EGSB reactor operation, the flocculent biomass which was not attached to the granules probably washed-out under the applied hydrodynamic conditions. When the EGSB reactor was operated at Vup of 2 m/h to favour the retention of the flocculent biomass, 2AB was mineralized even at influent concentrations as low as 140 mg COD/L. Kinetic calculations indicated that the sludge had an apparent Ks value for the mineralization of 2AB as low as 24 mg COD/l.

Styles APA, Harvard, Vancouver, ISO, etc.

22

Rosenthal, A., K. Ramalingam, K. Beckmann, A. Deur et J. Fillos. « Experimental evaluation of the nitrite sensitivity coefficient in granular anammox biomass ». Water Science and Technology 68, n^o 9 (19 octobre 2013) : 2103–10. http://dx.doi.org/10.2166/wst.2013.472.

Texte intégral

Résumé :

Nitrite is widely reported to inhibit anammox activity and growth. One modeling approach for nitrite impairment of anammox growth is the use of a nitrite sensitivity coefficient which increases the endogenous decay coefficient of anammox bacteria proportionally to nitrite concentration. The objective of this study was to measure nitrite concentration profiles within active anammox granules incubated at fixed bulk nitrite concentrations and to compare these with nitrite concentration profiles predicted by a biofilm model that incorporates the nitrite sensitivity coefficient. We developed an apparatus for the repeated measurement of nitrite concentration profiles along the radius of granular anammox biomass over a period of 6 days at fixed bulk nitrite concentrations. Granular anammox biomass was obtained from a two-stage bench-scale partial nitritation/anammox reactor system. There was no apparent effect of nitrite concentration on nitrite utilization kinetics after 6 days at exposures up to 90 mg NO2−-N/L. These findings suggest that anammox bacteria tolerate extended exposures to elevated nitrite concentrations, and in its present form, the nitrite sensitivity coefficient is not applicable for anammox growth modeling.

Styles APA, Harvard, Vancouver, ISO, etc.

23

Cha, Lijuan, Yong-Qiang Liu, Wenyan Duan, Christain E. W. Sternberg, Qiangjun Yuan et Fangyuan Chen. « Fluctuation and Re-Establishment of Aerobic Granules Properties during the Long-Term Operation Period with Low-Strength and Low C/N Ratio Wastewater ». Processes 9, n^o 8 (26 juillet 2021) : 1290. http://dx.doi.org/10.3390/pr9081290.

Texte intégral

Résumé :

Long-term structure stability of aerobic granules is critical to maintaining stable wastewater treatment performance. In this study, granulation and long-term stability of sludge-treating synthetic wastewater with a low chemical oxygen demand to nitrogen (COD/N) ratio of 4:1 and COD concentration of 400 mg/L in anoxic-oxic conditions were investigated for over 300 days. Inoculated suspended sludge gradually transformed into granules-dominant sludge on day 80. Due to the improved sludge volume index after 30 min settling (SVI30), mixed liquor suspended solids (MLSS) reached 5.2 g/L on day 140. Without any external intervention or disturbance, aerobic granules started to disintegrate from day 140, causing the increase in SVI and the decrease in biomass concentration until day 210, with the average sludge size reduced to 243 µm. From day 210, granular sludge started to be re-established by re-granulation, and the average granule size increased to 500 µm on day 302. During these disintegration and re-granulation periods, there was no obvious difference in terms of COD removal and nitrification, but microbial species were found more diverse after the re-granulation, with Thauera and Sphingomonas dominant. Although there was no external intervention, the food to microorganisms ratio (F/M) varied significantly due to the changes in biomass concentration caused by strong selective pressure and the change of sludge-settling ability in the reactor. F/M ratios should be controlled between 0.3 and 1.0 gCOD/gSS·d to maintain the stable structure of granules to minimize the fluctuation of sludge properties under the conditions used in this study. Although aerobic granular sludge is able to re-establish itself after disintegration, controlling F/M ratios in a certain range would benefit long-term stability. The findings in this study are significant to deepen the understanding of granule stability with low-strength and low COD ratio wastewater and, thus, provide guidance for maintaining the long-term stability of granules.

Styles APA, Harvard, Vancouver, ISO, etc.

24

Ivanov, V., S. T. L. Tay, Q. S. Liu, X. H. Wang, Z. W. Wang et J. H. Tay. « Formation and structure of granulated microbial aggregates used in aerobic wastewater treatment ». Water Science and Technology 52, n^o 7 (1 octobre 2005) : 13–19. http://dx.doi.org/10.2166/wst.2005.0175.

Texte intégral

Résumé :

Granular microbial aggregates are used in aerobic treatment of wastewater. The granules have diverse microbial community and complex spatial structure. The structural elements are radial sub-aggregates, concentric layers, channels, pores, polysaccharide plugs, and an anaerobic core of lysed cells. Aerobic bacteria, consisting of 69–84% of microbial biomass, were concentrated in a layer to the depth of 550 μm from the surface of the granule. Facultative anaerobic bacteria, consisting of 9–13% of microbial biomass, dominated in a layer at a depth from 550 μm to 850 μm from the surface of the granule. Obligate anaerobic bacteria, consisting of 2% of microbial biomass, dominated in a layer on the depth from 850 μm to 1,000 μm from the surface of the granule. A core of dead and lysed cells was at a depth greater than 1,000 μm from the surface of the granule. The depth of the anaerobic layer correlated with the appearance of polysaccharide plugs in the pores. Enrichment cultures of microorganisms with high cell surface hydrophobicity or self-aggregation ability can be used to facilitate the formation of microbial granules.

Styles APA, Harvard, Vancouver, ISO, etc.

25

Njoya, M., M. Basitere et S. K. O. Ntwampe. « Treatment of poultry slaughterhouse wastewater using a down-flow expanded granular bed reactor ». Water Practice and Technology 14, n^o 3 (5 juin 2019) : 549–59. http://dx.doi.org/10.2166/wpt.2019.039.

Texte intégral

Résumé :

Abstract This study evaluated the performance of a novel high rate anaerobic bioreactor system for the treatment of poultry slaughterhouse wastewater (PSW). The new system consisted of a granule-based technology operated in a down-flow configuration, with the assistance of medium-sized pumice stones used as packing materials for the retention of the anaerobic granules, to avoid challenges associated with the use of the three-phase separator of up-flow systems and the washout of the anaerobic biomass. Furthermore, a recycling stream was applied to the system to improve the mixing inside the Down-flow Expanded Granular Bed Reactor (DEGBR), i.e. the influent distribution to the granular biomass, and the implementation of intermittent fluidization when required to alleviate the effects of pressure drop in such systems. The DEGBR was operated under mesophilic conditions (30–35 °C) and achieved total chemical oxygen demand (tCOD), five-day biological oxygen demand and total suspended solids average removal percentages >95%, and a fats, oils and grease average removal percentage of 93.67% ± 4.51, for an organic loading rate varying between 1.1 to 38.9 gCOD/L.day.

Styles APA, Harvard, Vancouver, ISO, etc.

26

McSwain, B. S., R. L. Irvine, M. Hausner et P. A. Wilderer. « Composition and Distribution of Extracellular Polymeric Substances in Aerobic Flocs and Granular Sludge ». Applied and Environmental Microbiology 71, n^o 2 (février 2005) : 1051–57. http://dx.doi.org/10.1128/aem.71.2.1051-1057.2005.

Texte intégral

Résumé :

ABSTRACT Extracellular polymeric substances (EPS) were quantified in flocculent and aerobic granular sludge developed in two sequencing batch reactors with the same shear force but different settling times. Several EPS extraction methods were compared to investigate how different methods affect EPS chemical characterization, and fluorescent stains were used to visualize EPS in intact samples and 20-μm cryosections. Reactor 1 (operated with a 10-min settle) enriched predominantly flocculent sludge with a sludge volume index (SVI) of 120 ± 12 ml g−1, and reactor 2 (2-min settle time) formed compact aerobic granules with an SVI of 50 ± 2 ml g−1. EPS extraction by using a cation-exchange resin showed that proteins were more dominant than polysaccharides in all samples, and the protein content was 50% more in granular EPS than flocculent EPS. NaOH and heat extraction produced a higher protein and polysaccharide content from cell lysis. In situ EPS staining of granules showed that cells and polysaccharides were localized to the outer edge of granules, whereas the center was comprised mostly of proteins. These observations confirm the chemical extraction data and indicate that granule formation and stability are dependent on a noncellular, protein core. The comparison of EPS methods explains how significant cell lysis and contamination by dead biomass leads to different and opposing conclusions.

Styles APA, Harvard, Vancouver, ISO, etc.

27

Gonzalez-Gil, Graciela, et Christof Holliger. « Aerobic Granules : Microbial Landscape and Architecture, Stages, and Practical Implications ». Applied and Environmental Microbiology 80, n^o 11 (21 mars 2014) : 3433–41. http://dx.doi.org/10.1128/aem.00250-14.

Texte intégral

Résumé :

ABSTRACTFor the successful application of aerobic granules in wastewater treatment, granules containing an appropriate microbial assembly able to remove contaminants should be retained and propagated within the reactor. To manipulate and/or optimize this process, a good understanding of the formation and dynamic architecture of the granules is desirable. Models of granules often assume a spherical shape with an outer layer and an inner core, but limited information is available regarding the extent of deviations from such assumptions. We report on new imaging approaches to gain detailed insights into the structural characteristics of aerobic granules. Our approach stained all components of the granule to obtain a high quality contrast in the images; hence limitations due to thresholding in the image analysis were overcome. A three-dimensional reconstruction of the granular structure was obtained that revealed the mesoscopic impression of the cavernlike interior of the structure, showing channels and dead-end paths in detail. In “old” granules, large cavities allowed for the irrigation and growth of dense microbial colonies along the path of the channels. Hence, in some areas, paradoxically higher biomass content was observed in the inner part of the granule compared to the outer part. Microbial clusters “rooting” from the interior of the mature granule structure indicate that granules mainly grow via biomass outgrowth and not by aggregation of small particles. We identify and discuss phenomena contributing to the life cycle of aerobic granules. With our approach, volumetric tetrahedral grids are generated that may be used to validate complex models of granule formation.

Styles APA, Harvard, Vancouver, ISO, etc.

28

Fang, Herbert H. P., et Tin-Sang Kwong. « DEGRADATION OF STARCH PARTICULATES IN A HYBRID REACTOR ». Water Science and Technology 30, n^o 4 (1 août 1994) : 97–104. http://dx.doi.org/10.2166/wst.1994.0167.

Texte intégral

Résumé :

The study was conducted over 265 days to study the feasibility of removing starch particulates from wastewater using an 8.5 L reactor which was a hybrid between the upflow anaerobic sludge blanket (UASB) and the anaerobic filter reactors. At pH 7.2-7.5 and 37°C, the reactor was effective for the removal of chemical oxygen demand (COD) from wastewater containing starch particulates equivalent to 5000 mglL of COD with 12 hours of retention time, corresponding to a loading rate of 10 g-COD/L.d. Despite their insoluble nature, the starch particulates did not cause noticeable adverse effeels on the granulation of biomass, probably due to its easy-to-biodegrade nature and the cautious startup strategy. About 5.8% of COD in wastewater remained in the effluent, 82.5% was converted to methane, and the remaining 11.7% was converted to granular biomass with an average sludge yield of 0.09 g-VSS/g-COD. The granules exhibited a layered microstructure. The methanogenic activity of the granular biomass was 0.86 g-methane-COD/g-VSS.d in the reactor, which was considerably lower than the 1.96 g-methane-COD/ g-VSS.d measured in serum vials with an abundant supply of substrate, suggesting that further increase of loading rates was possible for the hybrid reactor.

Styles APA, Harvard, Vancouver, ISO, etc.

29

Wang, X. H., et V. Ivanov. « Microbial structure of nitrifying granules and their estrogens degradation properties ». Water Science and Technology 59, n^o 9 (1 mai 2009) : 1855–62. http://dx.doi.org/10.2166/wst.2009.218.

Texte intégral

Résumé :

It has been known that endocrine disruption compounds such as natural estrogens estrone, 17β-estradiol, estriol, and synthetic steroid 17a-ethynylestradiol can be degraded by nitrifying bacteria. The aim of this research was to test biodegradation of estrogens by microbial granules containing nitrifying bacteria. Cultivation of microbial granules was performed in sequencing batch reactor in model wastewater with carbon to nitrogen ratio of 100:30 by weight. After the system reached the steady state, the mean diameter of granules, sludge volume index of granular biomass, and biomass concentration were 0.6 mm, 22 mL g−1 and 7 g L−1, respectively. Nitrite was not detected in the effluent, and conversion of the consumed NH4+-N to NO3−-N was 93%. Specific NO3−-N production rate was 0.12 d−1 at the constant NH4+- loading late of 0.9 g L d−1. The presence of ammonium-oxidizing and nitrite-oxidizing bacteria was confirmed by fluorescence in situ hybridization with 16S rRNA-targeted oligonucleotide probes Nsm156 and Nit3. The estrogen biodegradation by the granules was conducted in batch experiments. The complete biodegradation of the mixture of estrone, 17β-estradiol, estriol, and 17a-ethynylestradiol, 100 μg L−1 each, by microbial granules was within 60 days. The order of biodegradation for estrogens by microbial granules was as follows: 17β-estradiol -> estriol -> estrone ->17a-ethynylestradiol. The degradation rate constants of estrogens by microbial granules were 0.19 d−1, 1.26 d−1, 0.14 d−1 and 0.11 d−1 for estrone, 17β-estradiol, estriol and 17a-ethynylestradiol, respectively.

Styles APA, Harvard, Vancouver, ISO, etc.

30

Grgas, Dijana, Tibela Landeka Dragičević, Anita Štrkalj, Andrijana Brozinčević, Adelina Ladavac, Tea Štefanac et Mirjana Galant. « Aerobni granulirani mulj u obradi otpadnih voda ». Hrvatski časopis za prehrambenu tehnologiju, biotehnologiju i nutricionizam 16, n^o 1-2 (1 juin 2021) : 20–27. http://dx.doi.org/10.31895/hcptbn.16.1-2.3.

Texte intégral

Résumé :

Aerobni granulirani mulj (AGS, engl. Aerobic Granular Sludge) predstavlja obećavajuću tehnologiju u obradi otpadnih voda kućanstva i industrije. Aerobne granule su samoimobilizirane mikrobne nakupine, bez nosača, a karakterizira ih kompaktna gusta struktura, visoko zadržavanje biomase, visoka učinkovitost uklanjanja onečišćenja i svojstvo brzog taloženja. Na formiranje i stabilnost aerobnog granuliranog mulja utječu brojni čimbenici, poput koncentracija otopljenog kisika, vrijeme prozračivanja, vrsta izvora ugljika, sile smicanja, period gladovanja, vrijeme taloženja. Zbog slojevite strukture granule, sa vanjskim aerobnim slojem i anoksičnim i anaerobnim zonama prema središtu granule, moguće je istovremeno uklanjanje C, N i P. AGS tehnologija ima potencijal smanjenja infrastrukture i operativnih troškova pročišćavanja otpadnih voda. Ovaj rad daje pregled najnovijih spoznaja iz literature o mehanizmu granulacije i svojstvima aerobnih granula.

Styles APA, Harvard, Vancouver, ISO, etc.

31

Mahoney, E. M., L. K. Varangu, W. L. Cairns, N. Kosaric et R. G. E. Murray. « The Effect of Calcium on Microbial Aggregation during UASB Reactor Start-Up ». Water Science and Technology 19, n^o 1-2 (1 janvier 1987) : 249–60. http://dx.doi.org/10.2166/wst.1987.0206.

Texte intégral

Résumé :

The dynamics of granule formation were studied using cells from two bench-scale UASB Reactors. The objective was to elucidate factors which influence formation and maintenance of highly active self-agglomerated microbial biomass. Simultaneous examination of biological and physical parameters was performed during the start-up of a calcium-positive (100 mg/1) reactor and a reactor without added calcium. The influence of carbon nutrients and Ca++ on the cell surface and microbial aggregation was studied. The granules formed in both reactors but were larger in the calcium-positive reactor in which they settled 3-4 times faster. A higher rate of biomass accumulation also was evident in the calcium-positive reactor and this allowed a more frequent increase in the substrate loading rate and earlier development of the granular sludge.

Styles APA, Harvard, Vancouver, ISO, etc.

32

Zhang, Hongxing, Yong-Qiang Liu, Shichao Mao, Christain E. W. Steinberg, Wenyan Duan et Fangyuan Chen. « Reproducibility of Aerobic Granules in Treating Low-Strength and Low-C/N-Ratio Wastewater and Associated Microbial Community Structure ». Processes 10, n^o 3 (23 février 2022) : 444. http://dx.doi.org/10.3390/pr10030444.

Texte intégral

Résumé :

Long-term stability of the aerobic granular sludge system is essentially based on the microbial community structure of the biomass. In this study, the physicochemical and microbial characteristics of sludge and wastewater treatment performance were investigated regarding formation, maturation, and long-term maintenance of granules in two parallel sequencing batch reactors (SBR), R1 and R2, under identical conditions. The aim was to explore the linkage between microbial community structure of the aerobic granules, their long-term stability, as well as the reproducibility of granulation and long-term stability. The two reactors were operated with a COD concentration of 400 mg/L and a chemical oxygen demand to nitrogen (COD/N) ratio of 4:1 under anoxic–oxic conditions. It was found that although SVI30, sludge size, and distributions in R1 and R2 were different, aerobic granules were formed, and they maintained long-term stability in both reactors for 320 days, implying that a certain level of randomness of granulation does not affect the long-term stability and performance for COD and N removal. In addition, a significant reduction in the richness and diversity of microbial production was observed after the sludge was converted from inoculum or flocs to granules, but this did not negatively affect the performance of wastewater treatment. Among the predominant microbial species in aerobic granules, Zoogloea was identified as the most important bacteria present during the whole operation with the highest abundance, while Thauera was the important genus in the formation and maturation of the aerobic granules, but it cannot be maintained long-term due to the low food-to-microorganisms ratio (F/M) in the system. In addition, some species from Ohtaekwangia, Chryseobacterium, Taibaiella, and Tahibacter were found to proliferate strongly during long-term maintenance of aerobic granules. They may play an important role in the long-term stability of aerobic granules. These results demonstrate the reproducibility of granulation, the small influence of granulation on long-term stability, and the robustness of aerobic granulation for the removal of COD and N. Overall, our study contributes significantly to the understanding of microbial community structure for the long-term stability of aerobic granular sludge in the treatment of low-COD and low-COD/N-ratio wastewater in practice.

Styles APA, Harvard, Vancouver, ISO, etc.

33

Wichern, M., M. Lübken et H. Horn. « Optimizing sequencing batch reactor (SBR) reactor operation for treatment of dairy wastewater with aerobic granular sludge ». Water Science and Technology 58, n^o 6 (1 octobre 2008) : 1199–206. http://dx.doi.org/10.2166/wst.2008.486.

Texte intégral

Résumé :

The biological wastewater treatment using aerobic granular sludge is a new and very promising method, which is predominantly used in SBR reactors which have higher volumetric conversion rates than methods with flocculent sludge. With suitable reactor operation, flocculent biomass will accumulate into globular aggregates, due to the creation of increased substrate gradients and high shearing power degrees. In the research project described in this paper dairy wastewater with a high particle load was treated with aerobic granular sludge in an SBR reactor. A dynamic mathematical model was developed describing COD and nitrogen removal as well as typical biofilm processes such as diffusion or substrate limitation in greater detail. The calibrated model was excellently able to reproduce the measuring data despite of strongly varying wastewater composition. In this paper scenario calculations with a calibrated biokinetic model were executed to evaluate the effect of different operation strategies for the granular SBR. Modeling results showed that the granules with an average diameter of 2.5 mm had an aerobic layer in between 65–95 μm. Density of the granules was 40 kgVSS/m3. Results revealed amongst others optimal operation conditions for nitrogen removal with oxygen concentrations below 5 gO2/m3. Lower oxygen concentrations led to thinner aerobic but thicker anoxic granular layers with higher nitrate removal efficiencies. Total SBR-cycle times should be in between 360–480 minutes. Reduction of the cycle time from 480 to 360 minutes with a 50% higher throughput resulted in an increase of peak nitrogen effluent concentrations by 40%. Considering biochemical processes the volumetric loading rate for dairy wastewater should be higher than 4.5 kgCOD/(m3*d). Higher COD input load with a COD-based volumetric loading rate of 9.0 kgCOD/(m3*d) nearly led to complete nitrogen removal. Under different operational conditions average nitrification rates up to 5 gNH/(m3*h) and denitrification rates up to 3.7 gNO/(m3*h) were achieved.

Styles APA, Harvard, Vancouver, ISO, etc.

34

Pires, Danilo Prado, Julio César Benatti et Edson Aparecido Abdul Nour. « Desenvolvimento de lodo granular aeróbio em reatores em batelada sequencial com baixa velocidade de sedimentação ». Engenharia Sanitaria e Ambiental 26, n^o 6 (décembre 2021) : 1015–24. http://dx.doi.org/10.1590/s1413-415220200180.

Texte intégral

Résumé :

RESUMO Diversos trabalhos têm mostrado a formação de lodo granular aeróbio em reatores nos quais são impostas elevadas velocidades de sedimentação, da ordem de 10 a 12 m.h−1. Aparentemente, quando a velocidade de sedimentação é inferior a 3,8 m.h−1, a fração de lodo floculado é predominante, visto que o lodo suspenso não é eliminado de forma efetiva do reator. Outros estudos, entretanto, mostram a formação de lodos granulares aeróbios para velocidades menores que essa, apontando a possibilidade da formação desse tipo de biomassa em velocidades ainda menores. Assim, este trabalho avaliou a formação desse tipo de lodo em reatores que tratam esgoto sanitário, com relação altura/diâmetro unitária, para velocidades de sedimentação de 1,8 e 1,2 m.h−1, verificando as eficiências de remoção de matéria orgânica e nitrogênio. Os resultados obtidos indicaram que é possível formar lodo aeróbio granular para a faixa de velocidade de estudo, porém com baixa estabilidade estrutural para diâmetros de 1,2 mm ou mais. Essa instabilidade dos grânulos contribui para a baixa eficiência de remoção de matéria orgânica e nitrogênio nos reatores.

Styles APA, Harvard, Vancouver, ISO, etc.

35

Beltrame Benatti, Julio César, Pedro Menuzzo de Almeida Prado et Edson Aparecido Abdul Nour. « Desenvolvimento de lodo granular aeróbio em reatores em batelada sequencial utilizando esgoto sanitário e baixas taxas de aeração ». Revista DAE 68, n^o 227 (21 octobre 2020) : 6–19. http://dx.doi.org/10.36659/dae.2020.078.

Texte intégral

Résumé :

Poucos estudos sobre formação de Lodos Granulares Aeróbios (LGA) utilizam efluentes reais e reatores em escala piloto, em razão de dificuldades associadas à variação nas características do substrato e à baixa concentração de matéria orgânica desses efluentes. Este trabalho vem contribuir com o entendimento dos mecanismos de formação do LGA em condições reais de operação e baixas taxas de aeração. Para tanto, foram utilizados três reatores, operados com diferentes taxas de aeração (0,15, 0,30 e 0,60 cm.s-1), tempo de ciclo de 4 h e utilizando esgoto sanitário real de baixa carga orgânica como substrato. A granulação foi induzida pela aplicação de pressão de seleção a partir da redução controlada do tempo de sedimentação. Os resultados mostram ser possível a formação do LGA utilizando-se esgoto sanitário real como substrato e baixas taxas de aeração, com a obtenção de aproximadamente 90 % de biomassa granular nos reatores e diâmetro médio dos grânulos variando entre 1,3 mm e 1,5 mm. Palavras-chave: Lodo Granular Aeróbio. Efluente Sanitário. Taxa de Aeração. Reator em Batelada Sequencial.

Styles APA, Harvard, Vancouver, ISO, etc.

36

Toja Ortega, Sara, Mario Pronk et Merle K. de Kreuk. « Anaerobic hydrolysis of complex substrates in full-scale aerobic granular sludge : enzymatic activity determined in different sludge fractions ». Applied Microbiology and Biotechnology 105, n^o 14-15 (24 juillet 2021) : 6073–86. http://dx.doi.org/10.1007/s00253-021-11443-3.

Texte intégral

Résumé :

Abstract Complex substrates, like proteins, carbohydrates, and lipids, are major components of domestic wastewater, and yet their degradation in biofilm-based wastewater treatment technologies, such as aerobic granular sludge (AGS), is not well understood. Hydrolysis is considered the rate-limiting step in the bioconversion of complex substrates, and as such, it will impact the utilization of a large wastewater COD (chemical oxygen demand) fraction by the biofilms or granules. To study the hydrolysis of complex substrates within these types of biomass, this paper investigates the anaerobic activity of major hydrolytic enzymes in the different sludge fractions of a full-scale AGS reactor. Chromogenic substrates were used under fully mixed anaerobic conditions to determine lipase, protease, α-glucosidase, and β-glucosidase activities in large granules (>1 mm in diameter), small granules (0.2–1 mm), flocculent sludge (0.045–0.2 mm), and bulk liquid. Furthermore, composition and hydrolytic activity of influent wastewater samples were determined. Our results showed an overcapacity of the sludge to hydrolyze wastewater soluble and colloidal polymeric substrates. The highest specific hydrolytic activity was associated with the flocculent sludge fraction (1.5–7.5 times that of large and smaller granules), in agreement with its large available surface area. However, the biomass in the full-scale reactor consisted of 84% large granules, making the large granules account for 55–68% of the total hydrolytic activity potential in the reactor. These observations shine a new light on the contribution of large granules to the conversion of polymeric COD and suggest that large granules can hydrolyze a significant amount of this influent fraction. The anaerobic removal of polymeric soluble and colloidal substrates could clarify the stable granule formation that is observed in full-scale installations, even when those are fed with complex wastewaters. Key points • Large and small granules contain >70% of the hydrolysis potential in an AGS reactor. • Flocculent sludge has high hydrolytic activity but constitutes <10% VS in AGS. • AGS has an overcapacity to hydrolyze complex substrates in domestic wastewater. Graphical abstract

Styles APA, Harvard, Vancouver, ISO, etc.

37

Cheng, Jun, Liang Zhang, Yandong Yang, Shujun Zhang, Xiaoyu Han et Yongzhen Peng. « Promotion of partial nitritation-anammox process by improving granule proportion ». Water Science and Technology 75, n^o 11 (4 mars 2017) : 2580–85. http://dx.doi.org/10.2166/wst.2017.104.

Texte intégral

Résumé :

For enhancing the partial nitritation-anammox (PN/A) process, the effects of granule fraction on system performance were investigated in this study. Two sequencing batch reactors (SBRs) were inoculated with PN/A biomass with a floc mass fraction of 53%. In SBR1, when the nitrogen removal rate (NRR) was stable, flocculent sludge was gradually discharged from the reactor using a screen, and the granule fraction was therefore increased. However, nitrogen removal was not improved and finally deteriorated due to the loss of nitritation activity. In SBR2, most flocculent sludge was eliminated and granular proportion was maintained at over 90% by controlling a short settling and decanting time. NRR was low initially but gradually improved to 1.23 kg N/(m3·d), which was 54% higher than SBR1. Ammonium oxidation activities of flocs and granules were respectively measured. Results suggested that the increase of nitritation activity in the granules was the main reason for the improvement of nitrogen removal in SBR2.

Styles APA, Harvard, Vancouver, ISO, etc.

38

Tkachenko, M., N. Borys et Ye Kovalenko. « The effectiveness of granular chalk use for growing winter wheat on grey forest soil ». Agrobìologìâ, n^o 1(157) (25 mai 2020) : 181–91. http://dx.doi.org/10.33245/2310-9270-2020-157-1-181-191.

Texte intégral

Résumé :

The research aims to establish the eff ectiveness of granular chalk use produced by «Slavuta-Calcium» Ltd. under growing Poliska–90 winter wheat variety, changing the physicochemical properties of grey forest soil and the wheat productivity. It also aims to establish optimal dosis of «Slavuta-Calcium» granular chalk as the meliorant and mineral fertilizer for grey forest soil in the system of winter wheat fertilization. In the temporary fi eld studies, various doses of nutrients N60–90–120P30–45–60K60–90–120 combined with «Slavuta–Calcium» granular chalk in a dose of Ca230–460–690 kg/ha of the active substance were studied against the background of secondary plowing of rotation products – soybean biomass that averaged 2.34 t/ha. Granular chalk is a modern complex highly eff ective meliorant with the content of Ca – 37.7 and Mg – 0.2 %, the mass fraction of carbonates (CaCO3 + MgCO3) makes at least 95 %. It is characterized by a high level of solubility when interacting with moisture in soil. It has a form of white granules, the mass fraction of 4.0–6.0 mm in size granules makes not less than 90 % and the one of 1.0 mm in size makes less than 5 %. Reactivity – 97 %. The granular chalk is advisable to apply on acidic soils, as a highly concentrated calcium-magnesium fertilizer, with the former as the dominant fertilizer, to optimize the physicochemical properties of the soil, as well as the plant nutrition system, in particular, increasing the availability of an element for assimilation by plants and as long-term ameliorants. The eff ectiveness of the use of mineral fertilizers, in particular acidic nitrogen on highly and medium acidic soils, after chemical reclamation is increased by 30–50 %, and slightly acidic by 15–20 %. The increase in productivity of crops from the combined eff ects of nutrients and chalk granulated is usually higher than when separately applied. The eff ectiveness of the integrated action of these elements is manifested in the growth of plant productivity and the quality of the resulting products, as well as the optimization of physical chemical properties and soil buff ering in the long term. In order to optimize the physicochemical properties of the arable layer of gray forest soil and the productive nutrition of agricultural crops, winter wheat, in particular, biogenic elements should be used in doses N60-90-120P30-45- 60K60-90-120 with granulated chalk «Slavuta-Calcium» in doses of Ca230-460-690 kg/ha of active substance. Granulated chalk obtained as a result of industrial grinding of solid sedimentary carbonate rocks of natural origin, subsequently under the infl uence of the granulation process of the starting material contains Ca and Mg carbonates of at least 95 %, dense granules which facilitates convenient mechanized application, as well as chalk suitable for accurate metered application on the quest map. Key words: granular chalk, gray forest soil, chemical reclamation, crop productivity.

Styles APA, Harvard, Vancouver, ISO, etc.

39

Torres, Keisy, Francisco Javier Álvarez-Hornos, Carmen Gabaldón et Paula Marzal. « Start-Up of Chitosan-Assisted Anaerobic Sludge Bed Reactors Treating Light Oxygenated Solvents under Intermittent Operation ». International Journal of Environmental Research and Public Health 18, n^o 9 (7 mai 2021) : 4986. http://dx.doi.org/10.3390/ijerph18094986.

Texte intégral

Résumé :

Quality of the granular sludge developed during the start-up of anaerobic up-flow sludge bed reactors is of crucial importance to ensure the process feasibility of treating industrial wastewater such as those containing solvents. In this study, the microbial granule formation from suspended-growth biomass was investigated in two chitosan-assisted reactors. These reactors operated mimicking industrial sites working with night closures treating a mixture of ethanol, ethyl acetate, and 1-ethoxy-2-propanol. Each reactor operated under different hydrodynamic regimes typical from UASB (R1: <0.15 m h−1) and EGSB (R2: 3 m h−1). High soluble COD removal efficiencies (>90%) accompanied by rapid formation of robust anaerobic granules were achieved at both up-flow velocity levels. After three weeks from the start-up, mean size diameters of 475 µm and 354 µm were achieved for R1 and R2, respectively. The performance of the process was found to be stable for the whole operational period of 106 days treating intermittent OLR up to 13 kg COD m−3 d−1. A memory dose of chitosan at day 42 was beneficial to guarantee good quality of the granules by offsetting the negative impact of intermittent water supply on the granular size. Methanocorpusculum was identified as the dominant archaea at both up-flow velocities. Acetobacterium, Geobacter and Desulfovibrio bacteria were also abundant, demonstrating its role on the degradation of light-oxygenated solvents.

Styles APA, Harvard, Vancouver, ISO, etc.

40

Hernández, A. E., L. C. Belalcazar, M. S. Rodríguez et E. Giraldo. « Retention of granular sludge at high hydraulic loading rates in an anaerobic membrane bioreactor with immersed filtration ». Water Science and Technology 45, n^o 10 (1 mai 2002) : 169–74. http://dx.doi.org/10.2166/wst.2002.0321.

Texte intégral

Résumé :

This study shows the results of an Anaerobic Membrane Bioreactor with immersed filtration cartridges for granular biomass retention working at high hydraulic loading rates. Biomass retention capabilities, granular biomass structure and activity, filtration cartridges flux and organic material degradation performance were evaluated. Four reactors with a volume of 0.005 m3 were tested. Two different filtration cartridges were used (10 and 100 μm) with effective surface area of 0.05 m2. The filtration cartridges were submerged in the reactors for suction type filtration. Three organic loading rates were tested in the first two reactors and seven in the other two. Selective biomass washout and an increment in the biomass methanogenic activity was observed in the reactors at hydraulic loading rates between 1.2 and 4.5 m/h. Analyses of biomass granulometry showed an increase of larger size granular biomass. The immersed membrane anaerobic bioreactor maintain most of the advantages without biomass activity loss.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Zoutberg, George R., et Peter de Been. « The biobed® EGSB (expanded granular sludge bed) system covers shortcomings of the upflow anaerobic sludge blanket reactor in the chemical industry ». Water Science and Technology 35, n^o 10 (1 mai 1997) : 183–88. http://dx.doi.org/10.2166/wst.1997.0381.

Texte intégral

Résumé :

In this paper a new type of anaerobic reactor is presented. The system has been developed by Biothane Systems and is marketed under the name Biobed® EGSB reactor (Expanded Granular Sludge Bed). In this reactor it is possible to grow and maintain a granular sludge under high liquid (10 m/h) and gas velocities (7 m/h). The most striking feature is the growth of biomass in a granular form, similar to the UASB granules: no carrier material is used. The process is specially suitable to treat waste water that contains compounds that are toxic in high concentrations and that only can be degraded in low concentrations (chemical industry). An example is given for a waste water originating from a chemical factory (Caldic Europoort) in the Netherlands. In this factory formaldehyde is produced from methanol. The waste water is characterised by high concentrations of these compounds (formaldehyde to 10 g/l and methanol to 20 g/l). Due to the special configuration of the anaerobic reactor it is possible to realise a removal efficiency for both compounds of more than 98%. It is also possible to operate the reactor as an ultra high loaded anaerobic reactor (to 30 kg COD/m3.day) for applications in other sectors of industry (e.g. brewery, yeast, sugar, corn ethanol production etc).

Styles APA, Harvard, Vancouver, ISO, etc.

42

Wirtz, Randall A., et Richard R. Dague. « Laboratory studies on enhancement of granulation in the anaerobic sequencing batch reactor ». Water Science and Technology 36, n^o 4 (1 août 1997) : 279–86. http://dx.doi.org/10.2166/wst.1997.0138.

Texte intégral

Résumé :

The phenomenon of granulation was studied in anaerobic sequencing batch reactors (ASBRs) treating a synthetic sucrose wastewater. The objective was to study methods of minimizing the time typically required for start-up of high rate anaerobic processes, such as the ASBR, when utilizing biomass from typical anaerobic digesters. More specifically, the goal was to develop granular biomass soon after initial start-up of the ASBR in order to decrease the overall time required to achieve high rate anaerobic treatment. Laboratory-scale ASBRs were seeded with anaerobically digested municipal biosolids and operated until granulation was observed. Granule development was measured by determination of the average particle diameter of a representative sample of biosolids from the ASBRs. Cationic polymer was added to the test ASBR to enhance rapid granule development and to aid in start-up. Cationic polymer addition reduced the time required to form granules by approximately 75 % compared to an un-enhanced control ASBR.

Styles APA, Harvard, Vancouver, ISO, etc.

43

Butkevych, T. A., М. L. Syatynya et V. P. Popovych. « TECHNOLOGICAL ASPECTS OF TABLETS CREATION BASED ON FLAMMULINA VELUTIPES BIOMASS DRY POWDER ». Фармацевтичний часопис, n^o 4 (11 décembre 2018) : 14–18. http://dx.doi.org/10.11603/2312-0967.2018.4.9690.

Texte intégral

Résumé :

The aim of the work. To study the pharmaco-technological properties of granulate and tablets based on Flammulina velutipes biomass dry powder, to develop the composition and technology of the medication. Materials and Methods. Research of granules and tablets pharmaco-technological properties (sieve analysis, bulk density, tapped density, compressibility index, Hausner ratio, flowability of tablet mass, average weight, resistance to crushing, friability and disintegration of tablets) was carried out in accordance to the requirements of State Pharmacopoeia of Ukraine 2nd edition. Results and Discussion. The determined pharmaco-technological parameters of the granulate indicate good values of the bulk density, tapped density, compressibility index, Hausner ratio and flowability. An intermediate product undergoes a tabletting process to produce a qualitative finished product of satisfactory appearance (plain, cylindrical tablets with a facet, yellowish-white color with brown inclusions, with a height of 4 mm, and diameter of 10 mm), a constant average mass (1.0 g), and strength (68 N). Conclusions. The pharmaco-technological properties of tablet mass (granulate) and Flammulina velutipes biomass dry powder tablets (sieve analysis, bulk density, tapped density, compressibility index, Hausner ratio, flowability, average weight, resistance to crushing, friability and disintegration) were studied. The composition and technology of Flammulina velutipes biomass dry powder tablets have been developed, pharmaco-technological parameters of their quality have been studied, technological block diagram of industrial production has been developed.

Styles APA, Harvard, Vancouver, ISO, etc.

44

Basitere, M., M. Njoya, S. K. O. Ntwampe et M. S. Sheldon. « Up-flow vs downflow anaerobic digester reactor configurations for treatment of fats-oil-grease laden poultry slaughterhouse wastewater : a review ». Water Practice and Technology 15, n^o 2 (20 mars 2020) : 248–60. http://dx.doi.org/10.2166/wpt.2020.023.

Texte intégral

Résumé :

Abstract The process of anaerobic digestion has been and still remains the most efficient, cost effective and environmentally benign treatment process for poultry slaughterhouse wastewater (PSW). The PSW is characterized by a high concentration in chemical oxygen demand (COD), biological oxygen demand (BOD) and fats, oil including grease (FOG). The reactor configuration influences the performance of such anaerobic systems in the treatment of such oily wastewater. The up-flow reactor configuration provided by the Up-flow Anaerobic Sludge Blanket (UASB) Bioreactor or the Expanded Granular Sludge Bioreactor (EGSB) are highly dependent on up-flow velocity, which often contributes to periodical sludge washout during the treatment of PSW with high FOG and total suspended solids (TSS) concentration, resulting in poor reactor performance in comparison with downflow reactors such as the Static Granular Bed Reactor (SGBR), which achieves high organic load removal efficiency particularly when treating PSW due to its ability to retain sludge granules and solidified residue within the reactor. The washout of the sludge results from sludge flotation, which is induced by the inhibition of the anaerobic granular biomass by the accumulation of long chain fatty acids (LCFAs) from poor hydrolysis. The aim of this review is to highlight reactor configuration deficiencies, and to elaborate on the advantages of using anaerobic digestion for the treatment of FOG-laden PSW, with a focus on reactor performance. Additionally, a comparative analysis between up-flow reactors, such as the UASB including EGSB, and downflow reactors, such as SGBR, was performed.

Styles APA, Harvard, Vancouver, ISO, etc.

45

Carucci, A., S. Milia, G. De Gioannis et M. Piredda. « Acetate-fed aerobic granular sludge for the degradation of chlorinated phenols ». Water Science and Technology 58, n^o 2 (1 août 2008) : 309–15. http://dx.doi.org/10.2166/wst.2008.394.

Texte intégral

Résumé :

In this study, the possibility to use acetate-fed aerobic granular sludge for the degradation of low chlorinated 4-mono-chlorophenol (4CP) and highly chlorinated 2,4,6-tri- chlorophenol (TCP) was investigated. A Granulated Sequencing Batch Reactor (GSBR) was used to carry out the experiments, with acetate as growth substrate. 4CP concentration in the influent ranged between 0 and 50 mg/l, while TCP concentration varied between 0 and 15 mg/l. Different operating conditions were applied in order to obtain the complete aerobic degradation of 4CP. For TCP degradation, anaerobic feeding and control of dissolved oxygen concentration in the bulk liquid were used to keep the granules core under anaerobic conditions due to diffusion limitations: the possibility to obtain TCP reductive dechlorination under aerated conditions was thus investigated. Differences in granules shape and size were observed with 4CP and TCP dosed in the influent, and the effects of such toxic compounds on acetate removal were evaluated. Aerobic granules grown on acetate as carbon source proved to be an interesting solution for the degradation of 4CP, showing good resistance to high 4CP concentrations in the influent even if unacclimated. The presence of TCP did not irreversibly inhibit biomass activity, and complete TCP degradation was achieved after acclimation.

Styles APA, Harvard, Vancouver, ISO, etc.

46

Pronk, Mario, Andreas Giesen, Andrew Thompson, Struan Robertson et Mark van Loosdrecht. « Aerobic granular biomass technology : advancements in design, applications and further developments ». Water Practice and Technology 12, n^o 4 (1 décembre 2017) : 987–96. http://dx.doi.org/10.2166/wpt.2017.101.

Texte intégral

Résumé :

Abstract Aerobic granular sludge is seen as the future standard for industrial and municipal wastewater treatment. Through a Dutch research and development program, a full-scale aerobic granular biomass technology has been developed – the Nereda® technology – which has been implemented to treat municipal and industrial wastewater. The Nereda® system is considered to be the first aerobic granular sludge technology applied at full-scale and more than 40 municipal and industrial plants are now in operation or under construction worldwide. Further plants are in the planning and design phase, including plants with capacities exceeding 1 million PE. Data from operational plants confirm the system's advantages with regard to treatment performance, energy-efficiency and cost-effectiveness. In addition, a new possibility for extracting alginate-like exopolysaccharides (ALE) from aerobic granular sludge has emerged which could provide sustainable reuse opportunities. The case is therefore made for a shift away from the ‘activated sludge approach’ towards an ‘aerobic granular approach’, which would assist in addressing the challenges facing the wastewater treatment industry in Asia and beyond.

Styles APA, Harvard, Vancouver, ISO, etc.

47

Jachimowicz, Piotr, Agnieszka Cydzik-Kwiatkowska et Patrycja Szklarz. « Effect of Aeration Mode on Microbial Structure and Efficiency of Treatment of TSS-Rich Wastewater from Meat Processing ». Applied Sciences 10, n^o 21 (22 octobre 2020) : 7414. http://dx.doi.org/10.3390/app10217414.

Texte intégral

Résumé :

The present study investigated the effect of aeration mode on microbial structure and efficiency of treatment of wastewater with a high concentration of suspended solids (TSS) from meat processing in sequencing batch reactors (R). R1 was constantly aerated, while in R2 intermittent aeration was applied. DNA was isolated from biomass and analyzed using next-generation sequencing (NGS) and real-time PCR. As a result, in R1 aerobic granular sludge was cultivated (SVI30 = 44 mL g−1 MLSS), while in R2 a very well-settling mixture of aerobic granules and activated sludge was obtained (SVI30 = 65 mL g−1 MLSS). Intermittent aeration significantly increased denitrification and phosphorus removal efficiencies (68% vs. 43%, 73% vs. 65%, respectively) but resulted in decomposition of extracellular polymeric substances and worse-settling properties of biomass. In both reactors, microbial structure significantly changed in time; an increase in relative abundances of Arenimonas sp., Rhodobacterace, Thauera sp., and Dokdonella sp. characterized the biomass of stable treatment of meat-processing wastewater. Constant aeration in R1 cycle favored growth of glycogen-accumulating Amaricoccus tamworthensis (10.9%) and resulted in 2.4 times and 1.4 times greater number of ammonia-oxidizing bacteria and full-denitrifiers genes in biomass, respectively, compared to the R2.

Styles APA, Harvard, Vancouver, ISO, etc.

48

Arcand, Yves, Claude Chavarie et Serge R. Guiot. « Dynamic modelling of the population distribution in the anaerobic granular biofilm ». Water Science and Technology 30, n^o 12 (1 décembre 1994) : 63–73. http://dx.doi.org/10.2166/wst.1994.0583.

Texte intégral

Résumé :

Significant downward gradient of glucotrophic (acidogenic) activity was experimentally observed as anaerobic granules were stripped off their surface bacteria. This indicated a clear predominance of fermentative bacteria in the external layer of the granules. This is consistent with the multilayer microstructural model evidenced by scanning electron microscopy (SEM) of cleaved granules. In contrast, acetoclastic activities were evenly distributed along the granule depth even though SEM had shown the core of granules of various sources to be almost exclusively composed of Methanosaeta-like bacteria. A detailed distributed diffusion-reaction mathematical model was developed to predict local substance and biomass concentrations at any depth within the granular biofilm. This intragranular model combines the kinetics of ten substances and eight trophic groups of microorganisms as well as physico-chemical constraints such as ionic dissociation and gas-liquid equilibrium, internal and bulk-surface interfacial diffusion mechanisms. Predicted results of this intragranular kinetic model have shown a drastic downward glucose gradient towards the centre, as a concentration of 10 μM in the bulk liquid boundary layer dropped to almost 0 at a distance less than 100 μm below the surface. In contrast, the model predicted very low to no gradients of acetate. However, the model predicted pH values 1 mm inside the granule to be over one pH unit more alkaline than in the bulk liquid. Hence this significant pH gradient could be the major factor which gives a competitive advantage for Methanosaeta-like population to proliferate in the granule core.

Styles APA, Harvard, Vancouver, ISO, etc.

49

Barros, Antônio Ricardo Mendes, Clara de Amorim de Carvalho, Silvio Luiz de Sousa Rollemberg, Ian Holanda Herbster Moura, Paulo Igor Milen Firmino et André Bezerra dos Santos. « Effects of coal ash supplementation on aerobic granular sludge cultivated in a simultaneous fill/draw sequencing batch reactor ». Engenharia Sanitaria e Ambiental 25, n^o 5 (octobre 2020) : 691–700. http://dx.doi.org/10.1590/s1413-4152202020190327.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

50

Feldman, H., X. Flores-Alsina, P. Ramin, K. Kjellberg, U. Jeppsson, D. J. Batstone et K. V. Gernaey. « Assessing the effects of intra-granule precipitation in a full-scale industrial anaerobic digester ». Water Science and Technology 79, n^o 7 (1 avril 2019) : 1327–37. http://dx.doi.org/10.2166/wst.2019.129.

Texte intégral

Résumé :

Abstract In this paper, a multi-scale model is used to assess the multiple mineral precipitation potential in a full-scale anaerobic granular sludge system. Reactor behaviour is analysed under different operational conditions (addition/no addition of reject water from dewatering of lime-stabilized biomass) and periods of time (short/long term). Model predictions suggest that a higher contribution of reject water promotes the risk of intra-granule CaCO3 formation as a result of the increased quantity of calcium arriving with that stream combined with strong pH gradients within the biofilm. The distribution of these precipitates depends on: (i) reactor height; and (ii) granule size. The study also exposes the potential undesirable effects of the long-term addition of reject water (a decrease in energy recovery of 20% over a 100-day period), caused by loss in biomass activity (due to microbial displacement), and the reduced buffer capacity. This demonstrates how both short-term and long-term operational conditions may affect the formation of precipitates within anaerobic granules, and how it may influence methane production and consequently energy recovery.

Styles APA, Harvard, Vancouver, ISO, etc.

Articles de revues sur le sujet « Granular biomasses »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres