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1
Wang, Jing, Jian An Hao, Ai Jun Zhang, Bo Yang, Tian Xiang Jiang, Xiu Zhi Zhang, Xiao Qing Zhang, and Yu Shan Zhang. "Startup of Seawater Anaerobic Ammonia Oxidation Reactor." Advanced Materials Research 884-885 (January 2014): 582–85. http://dx.doi.org/10.4028/www.scientific.net/amr.884-885.582.
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Muds and water samples collected from the Bohai Sea were selected to build seawater anaerobic ammonia oxidation reactor. The reaction volume was 18 L. The startup of reactor was divided into two stages. The first stage lasted five months and hydraulic retention time was 18L/7 d. The second stage lasted a month and hydraulic retention time was 18L/14 d. Ammonia and nitrite of influent and effluent were monitored. During the first stage, the removal rate of ammonia nitrogen was around 50% and the nitrite nitrogen increased by 50%. During the second stage, the removal rate of ammonia nitrogen reached more than 75% and the removal rate of nitrite nitrogen reached more than 90%. The removal ratio of ammonia nitrogen and nitrate nitrogen was about 1:1.17. These results suggested reactor start-up successful. Microbial community in reactor was monitored by polymerase chain reaction. Once the reactor started, specific bands of anaerobic ammonia oxidation microorganisms were found.
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Deswaef, S., T. Salmon, S. Hiligsmann, X. Taillieu, N. Milande, Ph Thonart, and M. Crine. "Treatment of gypsum waste in a two stage anaerobic reactor." Water Science and Technology 34, no. 5-6 (September 1, 1996): 367–74. http://dx.doi.org/10.2166/wst.1996.0572.
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The reduction of high concentrations of gypsum (up to 110 kg/m3) is investigated in a two stage immobilised cell bioreactor. The first stage is mainly colonised by a consortium of acidogenic bacteria and sulphate reducing bacteria oxidising volatile fatty acids with more than 2 carbons (mainly, butyrate and propionate). The gypsum consumption rate is rather high (11 kg/m3.day). Most of acetate remains unconverted in this first stage. It is partially converted in the second stage (residence time : 12 days) which is predominantly colonised by acetate oxidising bacteria. The gypsum consumption rate is much lower than in the first stage: 3 kg/m3.day. With both stages, it is possible to reach an almost complete conversion of gypsum with an overall capacity of 6.1 kg gypsum/m3.day. We propose also a very simple model to describe the different transformation rates. It allows us to clearly identify the activity levels of the different types of sulphate reducing bacteria in both stages.
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RodrÃguez-Pimentel, R., F. RamÃrez-Vives, A. De Jesús-Rojas, F. J. MartÃnez-Valdez, S. RodrÃguez-Pérez, and O. Monroy-Hermosillo. "Two-Phase Anaerobic Digestion of Municipal Organic Solid Wastes." JOURNAL OF ADVANCES IN BIOTECHNOLOGY 3, no. 2 (July 30, 2013): 210–18. http://dx.doi.org/10.24297/jbt.v3i2.1681.
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Two stages anaerobic digestion of the organic fraction of municipal solid wastes (OFMSW) is proposed using a batch anaerobic trickling bed (BATB) reactor in the first hydrolysis and acidogenesis stage. At total solids loading of 135 g/L and reaction times around 30 days, total solids (ηTS) and chemical oxygen demand (ηCOD) removal efficiencies above 46% were obtained independently of pH (between 4.1 and 6.4). Dependent on pH were methane production, four times more at pH 6.4 than at 4.8 and four times more volatile fatty acids (VFA) production at 6.4 than at 4.1 and twice than at 4.8. Leachates generated in the BATB reactor were diluted with municipal wastewater and fed to an upflow anaerobic sludge blanket (UASB) reactor at volumetric organic loading rates from 11 to 28 g/L.d where 90% COD removal efficiencies (ηCOD) and 11.4 g CODCH4./L.d were obtained. Two stages anaerobic digestion results in high rates of solids removal and methane production (0.63 kWhr/kg TS fed).
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Ráduly, B., L. Gyenge, Sz Szilveszter, A. Kedves, and S. Crognale. "Treatment of corn ethanol distillery wastewater using two-stage anaerobic digestion." Water Science and Technology 74, no. 2 (May 5, 2016): 431–37. http://dx.doi.org/10.2166/wst.2016.185.
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In this study the mesophilic two-stage anaerobic digestion (AD) of corn bioethanol distillery wastewater is investigated in laboratory-scale reactors. Two-stage AD technology separates the different sub-processes of the AD in two distinct reactors, enabling the use of optimal conditions for the different microbial consortia involved in the different process phases, and thus allowing for higher applicable organic loading rates (OLRs), shorter hydraulic retention times (HRTs) and better conversion rates of the organic matter, as well as higher methane content of the produced biogas. In our experiments the reactors have been operated in semi-continuous phase-separated mode. A specific methane production of 1,092 mL/(L·d) has been reached at an OLR of 6.5 g TCOD/(L·d) (TCOD: total chemical oxygen demand) and a total HRT of 21 days (5.7 days in the first-stage, and 15.3 days in the second-stage reactor). Nonetheless the methane concentration in the second-stage reactor was very high (78.9%); the two-stage AD outperformed the reference single-stage AD (conducted at the same reactor loading rate and retention time) by only a small margin in terms of volumetric methane production rate. This makes questionable whether the higher methane content of the biogas counterbalances the added complexity of the two-stage digestion.
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Damayanti, Sri Ismiyati, Dian Fitriani Astiti, Chandra Wahyu Purnomo, Sarto Sarto, and Wiratni Budhijanto. "Inoculum Selection and Micro-Aeration for Biogas Production in Two-Stage Anaerobic Digestion of Palm Oil Mill Effluent (POME)." Jurnal Bahan Alam Terbarukan 8, no. 1 (July 24, 2019): 14–21. http://dx.doi.org/10.15294/jbat.v8i1.16318.
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Two-stage anaerobic fluidized bed is an innovation in anaerobic digestion technology intended to handle liquid waste with high organic loading and complex substrate. The process is based on separation between acidogenic/acetogenic and methanogenic processes. The first stage is anaerobic process to convert substrate (represented as soluble chemical oxygen demand/sCOD) into volatile fatty acids (VFA). The second stage is methanogenic process to convert VFA into biogas. This study aimed to separate acidogenic/acetogenic and methanogenic processes by means of limited injection of air (micro-aeration) and inoculum selection. Micro-aeration was introduced in acidogenic/acetogenic stage because the relevant microbes were facultative so that the obligate anaerobic methanogens will be suppressed. On the other hand, the methanogenic reactor was kept completely anaerobic to ensure methanogenic dominance over acidogenic/acetogenic ones. Two sources of inoculums were used in this study, i.e. anaerobically digested biodiesel waste and anaerobically digested cow manure. Both inoculums were taken from active biogas reactor treating biodiesel waste and cow manure, respectively. Experiments were run in batch reactors treating palm oil mill effluent (POME) as the substrate for the acidogenic/acetogenic reactor. After the reaction in the first stage reached the minimum substrate concentration, the content of the reactor was used as the substrate for the methanogenic reactor as the second stage. Routine measurements were taken for sCOD and VFA concentrations, biogas production, and methane concentration in the biogas. Results confirmed that micro-aeration maintained good performance of acidogenic/acetogenic process, which was indicated by peaks in VFA accumulation, while suppressing methanogenic activities as no methane produced in this stage. Digested biodiesel waste was superior inoculum to be compared to digested cow manure with respect to sCOD removal. In the methanogenic stage, digested biodiesel waste also performed better as inoculum as it led to higher VFA conversion, higher biogas production rate, and higher methane content in the biogas.
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Qu, Yuan Yuan, Wan Qian Guo, Jie Ding, and Nan Qi Ren. "Feasibility of Hydrogen Production by a Continuous Two-Stage (Dark/Dark) Fermentation System." Advanced Materials Research 374-377 (October 2011): 1000–1004. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.1000.
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Anaerobic hydrogen production in a continuous two-stage fermentation system was studied. Two continuously stirred tank reactors (CSTR) were employed to evaluate performances of the system. The first stage was fed with molasses wastewater, and the effluent discharged from the first stage was subsequently fed into the second stage. The hydrogen production rate (HPR) in the second stage achieved a remarkable increase from 1.76 L/d to 6.45 L/d during the operation by re-utilizing the residual substrates from the first reactor effluent. The two stages showed a similar metabolic pathway for biohydrogen fermentation. The hydrogen production yield (HY) and acidification efficiency increased markedly by more than 70% and 50% respectively, which indicated the hydrogen recovery and anaerobic acidification of organic substrates can be improved by the combined continuous two-stage hydrogen production process.
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Mota, V. T., and M. Zaiat. "Two- vs. single-stage anaerobic reactors: evaluation of effluent quality and energy production potential using sucrose-based wastewater." Water Science and Technology 78, no. 9 (November 12, 2018): 1966–79. http://dx.doi.org/10.2166/wst.2018.470.
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Abstract Two- and single-stage anaerobic treatment systems were assessed for treatment performance and for bioenergy production from sucrose-based wastewater. In the two-stage system, a hydrogen-producing upflow anaerobic sludge blanket reactor (HU reactor) was used in the acidogenic phase. The methanogenic reactor of the two-stage system (MF reactor) and the single-stage reactor (SSF reactor) were structured fixed-bed reactors. The two-stage system showed superior performance, evidenced by lower organic acids, chemical oxygen demand (COD) and suspended solids concentrations in the effluent, and higher biogas methane content and yield. Continuous and stable H2 production was obtained in the acidogenic reactor. At the end of operation, the organic loading rates applied to the two- and single-stage systems were 6.4 and 5.2 gCOD L−1 d−1, respectively. Under these conditions, the effluent soluble COD and volatile suspended solids (VSS) concentrations were 165 and 92 mg L−1 in the two-stage system, and 256 and 244 mg L−1 in the single-stage system, respectively. The energy yield of the two-stage system was 20.69 kJ g−1CODadded, which was 34% higher than the yield of the single-stage system. The sequencing analyses showed that the archaeal distribution changed little between the inoculum and sludge from the MF reactor, in which acetoclastic Methanosaeta was predominant. However, hydrogenotrophic Methanospirillum was found most, followed by Methanosaeta, in the sludge from the SSF reactor.
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Kang, Xing Sheng, Chang Qing Liu, Li Zhu Huang, Gong Fa Chang, Zhong Qiao, Bo Zhang, and Xue Jun Bi. "The Different Metabolic Activity of Activated Sludge Samples Taken from Reversed A2/O Process and Conventional A2/O Process." Advanced Materials Research 183-185 (January 2011): 1476–80. http://dx.doi.org/10.4028/www.scientific.net/amr.183-185.1476.
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The metabolic activity of sludge samples taken from two pilot scale activated sludge reactor was studied. The two reactors were of the same size and structure. One was operated according to the reversed A2/O process (R-reactor) and another was operated according to conventional A2/O process (C-reactor). The activities of dehydrogenase (DHA) and electron transport system (ETS) and the specific oxygen uptake rate (SOUR) of sludge taken from R-reactor were 34.98%, 22.44% and 12.70% higher than those of the sludge taken from C-reactor. As for the R-reactor, the sludge undergoes aerobic condition right after anaerobic experience. Compared to entering aerobic stage from anoxic stage (C-reactor), entering aerobic stage from anaerobic stage can significantly enhance the activity of microbes, accelerate the decomposition of organics and improve the SOUR of the sludge.
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Liu, H. W., S. N. Lo, and H. C. Lavallée. "Theoretical Study on Two-Stage Anaerobic-Aerobic Biological Treatment of a CTMP Effluent: Part 2: Optimization of Treatment System." Water Quality Research Journal 31, no. 1 (February 1, 1996): 21–36. http://dx.doi.org/10.2166/wqrj.1996.002.
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Abstract A general method based upon the Monod kinetic model for optimizing the two-stage sequential anaerobic-aerobic treatment system was established. Using this method, the total treatment time required for a fixed overall treatment efficiency for a CTMP effluent was minimized with respect to the substrate removal in the anaerobic stage, and the corresponding optimal reactor volume ratio between the two stages was determined. The effects of the principal operating conditions (concentration of microorganisms and initial substrate concentration) on the minimum total treatment time and the optimal reactor volume ratio required for the two-stage treatment of the CTMP effluent were demonstrated. Procedures in consideration of both BOD5 and RFA removals for optimizing the two-stage treatment of the CTMP effluent are presented.
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Riungu, Joy, Mariska Ronteltap, and Jules B. van Lier. "Volatile fatty acids build-up and its effect on E. coli inactivation during excreta stabilisation in single-stage and two-stage systems." Journal of Water, Sanitation and Hygiene for Development 8, no. 2 (March 19, 2018): 257–67. http://dx.doi.org/10.2166/washdev.2018.160.
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Abstract Digestion and co-digestion of faecal matter collected from urine diverting dehydrating toilet faeces (UDDT-F) and mixed organic market waste (OMW) was studied in single stage pilot scale mesophilic plug-flow anaerobic reactors at UDDT-F:OMW ratios 4:1 and 1:0. Escherichia coli inactivation and volatile fatty acids (VFA) build-up was monitored at sampling points located along the reactor profile. When applying UDDT-F:OMW ratio of 4:1 at 12% total solids (TS), E. coli inactivation achieved was 2.3 log times higher than that achieved in UDDT-F:OMW ratio of 1:0. In subsequent trials, a two-stage reactor was researched, applying a UDDT-F:OMW ratio of 4:1 and 10 or 12% TS slurry concentrations. Highest VFA concentrations of 16.3 ± 1.3 g/L were obtained at a pH of 4.9 in the hydrolysis/acidogenesis reactor, applying a UDDT-F:OMW ratio of 4:1 and 12% TS, corresponding to a non-dissociated (ND)-VFA concentration of 6.9 ± 2.0 g/L. The corresponding decay rate reached a value of 1.6 per day. In the subsequent methanogenic plug-flow reactor, a decay rate of 1.1 per day was attained within the first third part of the reactor length, which declined to 0.6 per day within the last third part of the reactor length. Results show that a two-stage system is an efficient way to enhance pathogen inactivation during anaerobic digestion.
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Fahmy, M., E. Heinzle, and O. M. Kut. "Treatment of Bleaching Effluents in Aerobic/Anaerobic Fluidized Biofilm Systems." Water Science and Technology 24, no. 3-4 (August 1, 1991): 179–87. http://dx.doi.org/10.2166/wst.1991.0474.
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Biodegradation of chloroorganic compounds in real industrial bleaching effluents (chlorination and extraction), with adapted biofilm in fluidized sand bed reactors, was studied under aerobic and anaerobic conditions. The effluents were only diluted and supplied with mineral nutrients. Two reactor combinations were compared with a single stage aerobic digestor (AFB). In the anaerobic-aerobic reactors in series (AAS), the effluents were first treated anaerobically followed by an aerobic reactor in a single pass. In the anaerobic-aerobic recycle reactor (AAR), the reactor content was periodically moving back from aerobic to anaerobic fluidized beds. The reactors were running continuously for one year. The most significant differences observed were between aerobic and anaerobic single reactors. Generally anaerobiosis reduced performance in terms of global parameters (COD, NPOC, AOX). With a residence time of 18 h for each reactor, COD and AOX typically decreased by 15-32 % for each aerobic reactor system (AFB, AAS, AAR), whereas a decrease of typically 4-15 % was observed in the purely anaerobic system. From GC and GC/MS analysis it was evident that in the anaerobic reactors, 2,4,6-trichlorophenol was first converted to 2,4-dichlorophenol. In all three systems 2,4,6-trichlorophenol and dichlorophenols were almost completely removed.
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Ribarova, I., J. Topalova, I. Ivanov, D. Kozuharov, R. Dimkov, and C. Cheng. "Anaerobic sequencing batch reactor as initiating stage in complete pentachlorophenol biodegradation." Water Science and Technology 46, no. 1-2 (July 1, 2002): 565–69. http://dx.doi.org/10.2166/wst.2002.0535.
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Biodegradation of pentachlorophenol (PCP) has been studied in a sequence of two completely mixed reactors. Investigation on the first anaerobic sequencing batch reactor (AnSBR) is discussed in detail in this paper. Key technological and microbiological features were studied: two different types of adaptation process of anaerobic sludge towards PCP detoxication; the influence of the sludge concentration upon the rate of PCP biodegradation; minimum retention time for PCP degradation in dependence on the PCP concentration; modeling of the PCP degradation process; effluent COD and SS concentrations; changes in the micro- and macrostructure of the sludge during acclimatization process.
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Jahren, Sigrun J., Jukka A. Rintala, and Hallvard Ødegaard. "Anaerobic Thermophilic (55°C) Treatment of TMP Whitewater in Reactors Based on Biomass Attachment and Entrapment." Water Science and Technology 40, no. 11-12 (December 1, 1999): 67–75. http://dx.doi.org/10.2166/wst.1999.0696.
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Thermomechanical pulping (TMP) whitewater was treated in thermophilic (55°C) anaerobic laboratory-scale reactors using three different reactor configurations. In all reactors up to 70% COD removals were achieved. The anaerobic hybrid reactor, composed of an upflow anaerobic sludge blanket (UASB) and a filter, gave degradation rates up to 10 kg COD/m3d at loading rates of 15 kg COD/m3d and hydraulic retention time (HRT) of 3.1 hours. The anaerobic multi-stage reactor, consisting of three compartments, each packed with granular sludge and carrier elements, gave degradation rates up to 9 kg COD/m3d at loading rates of 15-16 kg COD/m3d, and HRT down to 2.6 hours. Clogging and short circuiting eventually became a problem in the multi-stage reactor, probably caused by too high packing of the carriers. The anaerobic moving bed biofilm reactor performed similar to the other reactors at loading rates below 1.4 kg COD/m3d, which was the highest loading rate applied. The use of carriers in the anaerobic reactors allowed short HRT with good treatment efficiencies for TMP whitewater.
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Asato, Caitlin M., Jorge Gonzalez-Estrella, Donald S. Skillings, Andrea Vargas Castaño, James J. Stone, and Patrick C. Gilcrease. "Anaerobic digestion of synthetic food waste-cardboard mixtures in a semi-continuous two-stage system." Sustainable Energy & Fuels 3, no. 12 (2019): 3582–93. http://dx.doi.org/10.1039/c9se00667b.
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A two-stage anaerobic digestion system consisting of a continuously-stirred tank reactor and upflow anaerobic sludge blanket (CSTR-UASB) in series was evaluated for semi-continuous digestion of food waste and corrugated cardboard mixtures.
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Angelidaki, I., L. Toräng, C. M. Waul, and J. E. Schmidt. "Anaerobic bioprocessing of sewage sludge, focusing on degradation of linear alkylbenzene sulfonates (LAS)." Water Science and Technology 49, no. 10 (May 1, 2004): 115–22. http://dx.doi.org/10.2166/wst.2004.0622.
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Anaerobic degradation of sludge amended with linear alkylbenzene sulfonates (LAS) was tested in a one stage continuous stirred tank reactor (CSTR) and a two stage reactor system consisting of a CSTR as first step and upflow anaerobic sludge bed (UASB) reactor as the second step. Anaerobic removal of LAS was only observed at the second step but not at the first step. Removal of LAS in the UASB reactors was approx. 80% where half was due to absorption and the other half was apparently due to biological removal as shown from the LAS mass balance. At the end of the experiment the reactors were spiked with 14C-LAS which resulted in 5.6% 14CO2 in the produced gas. Total mass balance of the radioactivity was however not achieved. In batch experiments it was found that LAS at concentrations higher than 50 mg/l is inhibitory for most microbial groups of the anaerobic process. Therefore, low initial LAS concentration is a prerequisite for successful LAS degradation. The results from the present study suggest that anaerobic degradation of LAS is possible in UASB reactors when the concentration of LAS is low enough to avoid inhibition of microorganisms active in the anaerobic process.
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Pereira, J. O., E. F. A. Mac Conell, S. Q. Silva, and C. A. L. Chernicharo. "Granular biomass selection in a double-stage biogas collection UASB reactor: effects on SMA, abundance and diversity of the methanogenic population." Water Science and Technology 66, no. 12 (December 1, 2012): 2570–77. http://dx.doi.org/10.2166/wst.2012.483.
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The present work aimed at investigating biomass selection in a pilot-scale double-stage biogas collection (DSBC) upflow anaerobic sludge bed (USAB) reactor treating domestic wastewater. Specific methanogenic activity (SMA) measurements and FISH countings were applied to sludge samples collected during 102 days of operation of the DSBC–UASB and of a control reactor. Results showed that both reactors presented similar SMA values in early stages of operation however the UASB–DSBC reactor showed much higher SMA after day 45, when the biomass was in granular stage. In terms of archaeal abundance, no statistical difference was observed between the reactors. Polymerase chain reaction–denaturing gradient gel electrophoresis (PCR–DGGE) revealed a similar composition of the archaeal communities in the two reactors and during the operational period, mainly constituted by Methanosaeta concilii. The results suggest that cell activity rather than archaeal abundance or diversity drive the methane production in the UASB reactors.
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Walker, M., C. J. Banks, and S. Heaven. "Development of a coarse membrane bioreactor for two-stage anaerobic digestion of biodegradable municipal solid waste." Water Science and Technology 59, no. 4 (February 1, 2009): 729–35. http://dx.doi.org/10.2166/wst.2009.012.
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A laboratory-scale coarse membrane bioreactor was developed to test its potential for the enhanced degradation of biodegradable municipal (solid) waste. The purpose of the mesh was to retain solid substrate and biomass in the reactor, promoting optimal degradation while also allowing intermediate soluble compounds to be removed and degraded in a second reactor. Three reactors with nylon woven mesh membranes of pore sizes 30, 100 and 140 μm were operated at a solid and liquid retention time of 20 and 1.5 days respectively and fed at an organic loading rate of 3.75 gVS l−1 d−1. Liquid effluent was fed to an anaerobic filter reactor. The total methane production for the two stage systems was very similar at 0.21–0.22 l g−1 VS added (c.f. 0.26 l g−1 VS added for BMP). The effect of increasing the pore size of the mesh was to reduce the methane production in the first stage and transfer more of this to the filter reactor, with the proportion of the total methane produced in the first stage changing from 72% to 49% between 30 and 140 μm meshes. The VS content of the first stage effluent also increased with pore size so it is likely that the mechanism for the differences in methane production is one of solids/biomass retention. The 30 μm pore size is recommended for further work since it transmitted a lower solid and soluble loading to the anaerobic filter. Solids accumulation in the second stage, although causing no problems in the 85-day operational period of this trial, could lead to blocking of the anaerobic filter, which is undesirable on a large scale.
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Lukitawesa, Rachma Wikandari, Ria Millati, Mohammad J. Taherzadeh, and Claes Niklasson. "Effect of Effluent Recirculation on Biogas Production Using Two-stage Anaerobic Digestion of Citrus Waste." Molecules 23, no. 12 (December 19, 2018): 3380. http://dx.doi.org/10.3390/molecules23123380.
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Citrus waste is a promising potential feedstock for anaerobic digestion, yet the presence of inhibitors such as d-limonene is known to limit the process. Effluent recirculation has been proven to increase methane yield in a semi-continuous process for recalcitrant material, but it has never been applied to toxic materials. This study was aimed to investigate the effect of recirculation on biogas production from citrus waste as toxic feedstock in two-stage anaerobic digestion. The first digestion was carried out in a stirred tank reactor (STR). The effluent from the first-stage was filtered using a rotary drum filter to separate the solid and the liquid phase. The solid phase, rich in hydrophobic D-limonene, was discarded, and the liquid phase containing less D-limonene was fed into the second digester in an up-flow anaerobic sludge bed (UASB) reactor. A high organic loading rate (OLR 5 g VS/(L·day)) of citrus waste was fed into the first-stage reactor every day. The effluent of the first-stage was then fed into the second-stage reactor. This experiment was run for 120 days. A reactor configuration without recirculation was used as control. The result shows that the reactor with effluent recirculation produced a higher methane yield (160–203 NmL/g·VS) compared to that without recirculation (66–113 NmL/g·VS). More stable performance was also observed in the reactor with recirculation as shown by the pH of 5–6, while without recirculation the pH dropped to the range of 3.7–4.7. The VS reduction for the reactor with recirculation was 33–35% higher than that of the control without recirculation. Recirculation might affect the hydrolysis-acidogenesis process by regulating pH in the first-stage and removing most of the D-limonene content from the substrate through filtration.
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Triovanta, Ulfa, and Ridho Rinaldi. "Two-Stage Anaerobic Co-digestion of Landfill Leachate and Starch Wastes Using Anaerobic Biofilm Reactor for Methane Production." Progress in Agricultural Engineering Sciences 15, no. 1 (December 2019): 53–70. http://dx.doi.org/10.1556/446.15.2019.1.4.
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Abstract The study aims to evaluate two-stage anaerobic co-digestion of leachate and starch waste using anaerobic biofilm bioreactor to enhance methane production. The anaerobic digestion process was operated under the mesophilic condition at 35 ± 1 °C. Hydraulic retention time (HRT) applied to the acidogenesis and methanogenesis reactors were 5 and 25 days, respectively. The organic loading rate (OLR) used in the process of acidogenesis was 2.91 gram volatile solid /L.day, while methanogenesis was 0.58 gram volatile solid (VS) per liter per day. Results showed that two-stage process using biofilm was an effective method for operating anaerobic co-digestion of starch waste and landfill leachate in which the system produced higher methane yield at 125.11 mL methane (CH4) per gram volatile solid (VS) added (mL.CH4/g.VS.added) in comparison to the single-stage process (20.57 mL CH4/g.VS.added) and two-stage process (77.60 mL CH4/g.VS.added) without using biofilm. Two-stage process using biofilm also effectively reduced organic matters in the culture in which the system reached 61% BOD removal in comparison to the single-stage process and two-stage process without biofilm that only had 27.6 and 39.3% BOD removal, respectively. This study suggested that the two-stage process using biofilm would be the preferred technique for treating starch waste and landfill leachate.
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Banks, C. J., and P. N. Humphreys. "The anaerobic treatment of a ligno-cellulosic substrate offering little natural pH buffering capacity." Water Science and Technology 38, no. 4-5 (August 1, 1998): 29–35. http://dx.doi.org/10.2166/wst.1998.0574.
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The stability and operational performance of single stage digestion with and without liquor recycle and two stage digestion were assessed using a mixture of paper and wood as the digestion substrate. Attempts to maintain stable digestion in both single stage reactors were unsuccessful due to the inherently low natural buffering capacity exhibited; this resulted in a rapid souring of the reactor due to unbuffered volatile fatty acid (VFA) accumulation. The use of lime to control pH was unsatisfactory due to interference with the carbonate/bicarbonate equilibrium resulting in wide oscillations in the control parameter. The two stage system overcame the pH stability problems allowing stable operation for a period of 200 days without any requirement for pH control; this was attributed to the rapid flushing of VFA from the first stage reactor into the second stage, where efficient conversion to methane was established. Reactor performance was judged to be satisfactory with the breakdown of 53% of influent volatile solids. It was concluded that the reactor configuration of the two stage system offers the potential for the treatment of cellulosic wastes with a sub-optimal carbon to nitrogen ratio for conventional digestion.
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Matsuura, N., M. Hatamoto, H. Sumino, K. Syutsubo, T. Yamaguchi, and A. Ohashi. "Closed DHS system to prevent dissolved methane emissions as greenhouse gas in anaerobic wastewater treatment by its recovery and biological oxidation." Water Science and Technology 61, no. 9 (May 1, 2010): 2407–15. http://dx.doi.org/10.2166/wst.2010.219.
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Anaerobic wastewater treatment has been focused on its eco-friendly nature in terms of the improved energy conservation and reduction in carbon dioxide emissions. However, the anaerobic process discharges unrecovered methane as dissolved methane. In this study, to prevent the emission of dissolved methane from up-flow anaerobic sludge blanket (UASB) reactors used to treat sewage and to recover it as useful gas, we employed a two-stage down-flow hanging sponge (DHS) reactor as a post-treatment of the UASB reactor. The closed DHS reactor in the first stage was intended for the recovery of dissolved methane from the UASB reactor effluent; the reactor could successfully recover an average of 76.8% of the influent dissolved methane as useful gas (containing methane over 30%) with hydraulic retention time of 2 h. During the experimental period, it was possible to maintain the recovered methane concentrations greater than 30% by adjusting the air supply rate. The remaining dissolved methane after the first stage was treated by the next step. The second closed DHS reactor was operated for oxidation of the residual methane and polishing of the remaining organic carbons. The reactor had a high performance and the influent dissolved methane was mostly eliminated to approximately 0.01 mgCOD L−1. The dissolved methane from the UASB reactor was completely eliminated—by more than 99%—by the post-treatment after the two-stage closed DHS system.
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Nuansawan, Nararatchporn, Kwannate Sombatsompop, and Chayanid Witthayaphirom. "Evaluation of Greenhouse Gas Emission from Municipal Solid Waste Leachate by two-stage Sequencing Batch Reactor." Global Journal of Engineering and Technology Review Vol.4 (2) April-June. 2019 4, no. 2 (June 30, 2019): 35–42. http://dx.doi.org/10.35609/gjetr.2019.4.2(3).
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This work investigated greenhouse gas emission during the treatment of municipal solid waste leachate by two-stage Sequencing Batch Reactor (SBR). The SBR was carried out by anaerobic reactor followed by aerobic reactor. The system was operated at hydraulic retention times (HRT) of 4 and 2 days during 130 operating days. At steady state, the organic removal efficiencies were found to be 67.0% and 62.7% for 4 and 2 days of HRT. The organic carbon and nitrogen were mainly removed in aerobic reactor. The surface emission rates of methane in anaerobic reactor were 0.181 and 0.292 g/m2.d under HRT of 4 and 2 days, respectively. The emission factors of CH4 at HRT 4 and 2 days were 0.297 and 0.238 gCH4/gCOD, respectively while those of N2O were 0.25 and 0.19 gN2O/gN for HRT of 4 and 2 days, respectively. The PCR technique confirmed that the microbial group was methonogenic bacteria which corresponded to the emission of greenhouse gas. Type of Paper: Empirical Keywords: Greenhouse gas; leachate; methane emission; microbial communities; sequencing batch reactor
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Reis, M. A. M., L. M. D. Gonçalves, and M. J. T. Carrondo. "Sulfate Reduction in Acidogenic Phase Anaerobic Digestion." Water Science and Technology 20, no. 11-12 (November 1, 1988): 345–51. http://dx.doi.org/10.2166/wst.1988.0305.
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The acidogenic phase of a two-stage anaerobic digestion process using distillery molasses slops effluent with high sulfate concentrations (4.2-5.1 g/l) was investigated. Removal of sulfate was studied at pH 5.8, 6.2, 6.6 and in two different reactors: continuous stirred tank reactor and an upflow fixed film fixed bed reactor. Batch experiments were carried out to obtain the maximum specific growth rates of sulfate reducing bacteria (SRB) at the above mentioned pH values. The biological sulfate removal increased with pH and so did the acetic acid production from the fermentative bacteria and SRB. For the same pH and hydraulic retention time the sulfate reduction was more efficient in the fixed film reactor than in the CSTR. The soluble sulfides from the sulfate reduction presented at the acidogenic reactor effluent were precipitated before the methanogenic phase to avoid biogas contamination and methanogenic bacteria inhibition; under such conditions, sulfide concentrations in the biogas thus produced were very low and high methane volumetric rates of production were achieved.
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Wang, J. Y., H. L. Xu, and J. H. Tay. "A hybrid two-phase system for anaerobic digestion of food waste." Water Science and Technology 45, no. 12 (June 1, 2002): 159–65. http://dx.doi.org/10.2166/wst.2002.0422.
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A hybrid two-phase system, consisting of a solid waste reactor as the acidification reactor and a wastewater reactor, i.e. an upflow anaerobic sludge blanket (UASB) reactor, as the methanogenic reactor, for anaerobic digestion of food waste was investigated. After the pre-acidification stage, COD and total VFA removals in the methanogenic phase were in the ranges of 74-93% and 77-100%, respectively, while leachate COD and total VFA concentrations in the acidification phase decreased by 95% and 97-99%, respectively. Some 99% of the total CH4 generated was from the methanogenic phase with the CH4 content of 68-70%. About 77-79% of TOC, 57-60% of volatile solids and 79-80% of total COD were removed. The results of this laboratory-scale study show that the hybrid two-phase anaerobic batch reactor system is suitable for effective conversion of food waste into CH4 and CO2. The hybrid two-phase system can be further developed into an effective and efficient way to enhance waste stabilization in operating bioreactor landfills.
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Çiftçi, T., and I. Öztürk. "Anaerobic Treatment of the High Strength Wastes from the Yeast Industry." Water Science and Technology 28, no. 2 (July 1, 1993): 199–209. http://dx.doi.org/10.2166/wst.1993.0104.
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This paper presents the full-scale anaerobic treatment results from a fermentation plant producing baker's yeast from sugar beet molasses. The process of baker's yeast production generates high strength industrial effluents with a chemical oxygen demand (GOD) of 10 000-30 000 mg/liter. In addition to the sugar containing substances sulphur and nitrogen containing substances are added to the batch processes to promote cell growth and to control pH. This results in rather high concentrations of sulphate 0000-2700 mg/l) and ammonia (400-900 mg/l) in the wastewater. The treatment plant at Pakmaya Izmit Factory has two different processes: anaerobic first-stage treatment and aerobic second stage treatment. The anaerobic first-stage treatment system includes a buffer tank, an acid reactor, two methane reactors, lamella separators, a gas storage tank and gas burning facilities. The anaerobic reactors were constructed as upflow anaerobic sludge blanket reactors (UASBR) with internal sludge recirculation facilities. The anaerobic reactors have been operating in series mode at mesophilic temperature ranges. Long term Organic Loading Rates (OLR) in the acid, the first and the second stage methane reactors have been averaging 9.8, 8.6 and 3 kg COD/m3·d respectively. Average COD removal is 75 percent in the anaerobic pretreatment stage. Average biogas production is 8000 m3/d, corresponding to a biogas conversion yield of 0.6 m3 per kg COD removed and it is equivalent to a netbioenergy recovery of 40 000 kWh/d.
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Li, Ming, Shuai Wang, De Chen Shan, Li Wei, and Wen Jia Yin. "Study on Treatment of Wastewater with High-Concentration Sulfate by IC Anaerobic Reactor." Applied Mechanics and Materials 737 (March 2015): 649–52. http://dx.doi.org/10.4028/www.scientific.net/amm.737.649.
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In this study, IC anaerobic reactor was made to deal with the wastewater with high-concentration sulfate, the sludge from sewage treatment plant was put into two cells of IC reactor to domesticate sulfur-reducing bacteria (SRB), artificial water was made to simulate the wastewater with high-concentration SO42−. In order to remove the SO42− efficiently, two stages were designed in this study: sludge domestication stage and concentration strengthening stage. In sludge domestication stage, SRB could grow normally, the removal rate of SO42− was between 34.14% and 36.2%;in concentration strengthening stage, removal rate of SO42− was between 26% and 26.86%,demonstrating that SRB could grow and remove SO42− in such high-concentration SO42−( 38000 mg/L ) wastewater.
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Harper, Stephen R., and Frederick G. Pohland. "Microbial consortia selection in anaerobic filters operated in different reactor configurations." Water Science and Technology 36, no. 6-7 (September 1, 1997): 33–39. http://dx.doi.org/10.2166/wst.1997.0572.
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The selection and morphology of anaerobic cultures grown in anaerobic packed-bed reactors, with soft-drink wastewater serving as the primary substrate, are compared for four types of laboratory-scale reactors/flow regimes: upflow, downflow, and a pair of two-stage systems. Results were obtained from scanning electron micrographs of cultures withdrawn from sampling ports located in the top, middle, and bottom of each reactor. Samples were compared with respect to the distribution of rod-like, coccoid, and filamentous microbes.
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Ma, Xueyan, Xiaoning Liu, Bangdong Xiang, and Wenjie Zhang. "Effect of Hydraulic Retention Time on Carbon Sequestration during the Two-Stage Anammox Process." Processes 7, no. 10 (October 9, 2019): 717. http://dx.doi.org/10.3390/pr7100717.
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In a biological treatment process, hydraulic retention time (HRT) has a certain effect on the operation of the reactor. This study investigated the effect of HRT on carbon sequestration in a two-stage anaerobic ammonium oxidation (anammox) process using a partial nitrification reactor and anammox reactor to determine the optimal carbon sequestration operating conditions. Molecular biotechnology was used to analyze the sludge in the reactor in order to explore the denitrification performance and to determine the carbon sequestration pathway of the microorganisms. The results show that the partial nitrification stage had the highest carbon sequestration rate (0.319 mg/mg·N) when the nitrogen loading rate (NLR) was 0.44 kg·N/m3/d. The NLR of the anammox stage was 0.13 kg·N/m3/d. When the HRT was 33.4 h, the carbon sequestration of the anammox reaction was at its highest, reaching 0.183 mg/mg·N. The results of microbial analysis show that the carbon-fixing gene cbbLR1 was present in the sludge samples during the anammox and partial nitrification stages, and that there was a Calvin cycle carbon sequestration pathway during the growth process. However, the existence of a gene for reducing and immobilizing CO2 by the acetyl-CoA pathway was not detected; further research is thus needed.
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Hawkes, F. R., A. Rozzi, K. Black, A. Guwy, and D. L. Hawkes. "The Stability of Anaerobic Digesters Operating on a Food-Processing Wastewater." Water Science and Technology 25, no. 7 (April 1, 1992): 73–82. http://dx.doi.org/10.2166/wst.1992.0140.
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The response to step overloads of laboratory-scale contact process and UASB reactors and a pilot-scale anaerobic filter is examined. The reactors were operated on ice-cream waste water and changes in operational parameters including VFA levels and COD reduction were monitored. In the laboratory-scale experiments, feed strength was increased from 4500 to 22,000 mg [O] per litre for periods of 2 to 12 hours in contact process and one and two-stage UASB reactors. UASB stability was improved by supplementing with trace metals. Two-stage UASB's gave better COD removals under shock loading than single-stage UASB's or contact process reactors. In an 8 hour step overload experiment on the pilot-scale reactor, bicarbonate alkalinity was shown to be a good indicator of instability.
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Borzacconi, Liliana, Iván López, and Carlos Anido. "Hydrolysis constant and VFA inhibition in acidogenic phase of MSW anaerobic degradation." Water Science and Technology 36, no. 6-7 (September 1, 1997): 479–84. http://dx.doi.org/10.2166/wst.1997.0626.
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The most significant parameters of a model that simulates the hydraulic and biological behaviour of a sanitary landfill were determined. These parameters were particulate matter, hydrolysis constant, initial waste polluting potential, and waste porosity. Based on experimental data collected from two reactors, the acidogenic stage was characterized. There was an inhibition due to the accumulation of VFA in the reactor fed with a higher than usual content of easily biodegradable matter. In such reactors the methanogenic stage was never reached. The COD and VFA curves of the reactor where the methanogenic stage was attained, showed a maximum around the 200th day. After 500 days, a noticeable methane production started. Based on first order kinetics, the value of the particulate matter hydrolysis constant was determined to be 0.8×10−3d−1.
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Rai, H. S., S. Singh, P. P. S. Cheema, T. K. Bansal, and U. C. Banerjee. "Decolorization of triphenylmethane dye-bath effluent in an integrated two-stage anaerobic reactor." Journal of Environmental Management 83, no. 3 (May 2007): 290–97. http://dx.doi.org/10.1016/j.jenvman.2006.03.003.
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Ramadhani, Laily Isna, Sri Ismiyati Damayanti, Hanifrahmawan Sudibyo, Muhammad Mufti Azis, and Wiratni Budhijanto. "The Impact of Hydraulic Retention Time on the Biomethane Production from Palm Oil Mill Effluent (POME) in Two-Stage Anaerobic Fluidized Bed Reactor." International Journal of Renewable Energy Development 10, no. 1 (February 1, 2020): 11–16. http://dx.doi.org/10.14710/ijred.2021.20639.
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Indonesia is currently the most significant crude palm oil (CPO) producer in the world. In the production ofCPO, 0.7m3 of Palm Oil Mill Effluent (POME) is emitted as the wastewater for every ton of fresh fruit bunches processed in the palm oil mill.With the increasing amount of CPO production, an effective POME treatment system is urgently required to prevent severe environmental damage. The high organic content in the POME is a potential substrate forbio-methane production. The biomethane production is carried out by two groups of microbes, i.e., acidogenic and methanogenic microbes. Each group of bacteria performs optimally at different optimum conditions. To optimize the biomethane production, POME was treated sequentially by separating the acidogenic and methanogenic microbes into two stages of anaerobic fluidized bed reactors (AFBR). The steps were optimized differently according to the favorable conditions of each group of bacteria. Although perfect separation cannot be achieved, this study showed that pH control could split the domination of the bacteria, i.e., the first stage (maintained at pH 4-5) was dominated by the acidogenic microbes and the second stage (kept neutral) was governed by methanogens. In addition to the pH control, natural zeolitewas added as microbial immobilization media in the AFBR to improve the performance of the microorganisms, especially in preventing microbial wash out at short hydraulic retention time (HRT). This study was focused on the understanding of the effect of HRT on the performance of steady-state continuous AFBR. The first stage as the acidogenic reactorwas rununder acidic conditions (pH 4-5) at five different HRTs. In comparison, the second stage as the methanogenic reactorwasrun under the neutral condition at four different HRTs. In this work,short HRT (5 days) resulted in better performance in both acidogenic AFBR and methanogenic AFBR. The immobilization media was hence essential to reduce the risk of washout at such a short HRT. The two-stage system also resulted in quite a high percentage of soluble chemical oxygen demand (sCOD) removal, which was as much as 96.06%sCOD.
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Sayed, S. K. I., H. van der Spoel, and G. J. P. Truijen. "A Complete Treatment of Slaughterhouse Wastewater Combined with Sludge Stabilization Using Two Stage High Rate UASB Process." Water Science and Technology 27, no. 9 (May 1, 1993): 83–90. http://dx.doi.org/10.2166/wst.1993.0181.
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The main objectives of the present investigations were to assess the feasibility of two stage high rate UASB-reactors for complete treatment of slaughterhouse wastewater which contains approximately 55 % insoluble coarse suspended COD. The study presented in this paper addresses the maximum loading rates (hydraulic and organic) the extent of sludge stabilization (i.e. conversion into methane) and the length of the sludge stabilization period (i.e. digestion time). The experiments were performed in two stage high rate anaerobic sludge UASB-reactors. The wastewater treatment experiments were performed at an operational temperature of 18 °C, while the sludge stabilization experiments were performed at a process temperature of 30 °C. Two different types of anaerobic sludge were used in this experiment: flocculent sludge for the first stage and granular for the second stage of the system. The first stage of the reactor system consists of 2 reactors which are used alternately. In the second stage, one reactor is in operation permanently. The results of the present study indicate that the system can satisfactorily handle organic space loads up to 15 kg COD m−3.day−1 at a liquid retention time of 4 h and 1.5 h. for the first and second stage of the system, respectively. For the whole system a treatment efficiency up to 90 % on CODtotal basis, 95 % on CODcoarse suspended solids basis, 80 % on CODcolloidal basis and 80% on CODsoluble basis was achieved. The maximum extent of sludge stabilization (i.e. conversion into methane) at 30 °C was approximately 50 % for the accumulated coarse suspended solids and colloidal fractions in the reactors of the first stage of the system. The length of the sludge stabilization period (i.e. digestion time) was 14 days.
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Donoso-Bravo, Andrés, Francisca Rosenkranz, Viviana Valdivia, Michel Torrijos, Gonzalo Ruiz-Filippi, and Rolando Chamy. "Anaerobic sequencing batch reactor as an alternative for the biological treatment of wine distillery effluents." Water Science and Technology 60, no. 5 (May 1, 2009): 1155–60. http://dx.doi.org/10.2166/wst.2009.565.
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The goal of this study was to assess the effect of different modes of operation and configurations of Anaerobic Sequencing Batch Reactors (ASBRs) treating phenolic wastewater. Several lab-scale reactors were used in the mesophilic range. The reactors were fed with synthetic wastewater with a COD of 5 g/L using phenol as a carbon source (variable concentration) and glucose as a co-substrate. One and two-phase (hydrolytic/acidogenic–methanogenic) systems in batch and fed-batch operation were evaluated. The one-stage reactor operated by the fed batch (which was the only configuration using phenol as a sole carbon source), presented better results for the removal of phenol, reaching 100% removal in 10 days at a concentration of 210 mg/L. The two-stage configuration had removal percentages near 100%, but the methanogenic reactor presented greater degradation of the remaining phenol not removed in the hydrolytic/acidogenic reactor. ASBRs might be a feasible alternative to treat this type of effluent due to their operational flexibility.
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Danesh, Shahnaz, and Jan A. Oleszkiewicz. "Use of a new anaerobic-aerobic sequencing batch reactor system to enhance biological phosphorus removal." Water Science and Technology 35, no. 1 (January 1, 1997): 137–44. http://dx.doi.org/10.2166/wst.1997.0031.
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A two-stage anaerobic-aerobic sequencing batch reactor (SBR) system (PAF-SBR) was developed to enhance biological phosphorus removal in the sequencing batch reactors. The system performance was evaluated against a conventional SBR system in parallel lab-scale reactors at room temperature, using the degritted raw wastewater as the feed. The SRT for the anaerobic SBR which is named PAF (Primary Acid Fermenter) was 12 days, and for both the BNR reactors was 10 days. All reactors were run at 3 cycles per day. A significant difference (P=0.01) was observed between the performances of the two systems. The Ortho-P concentration in the effluent from the PAF-SBR was mostly below 0.5 mg/L while in the conventional SBR was generally above 1.5 mg/L. Lack of availability of carbon (mean VFA/PSol.=1.1) and long anoxic/anaerobic period were the major causes of inefficient removal of phosphorus in the conventional SBR system. The use of anaerobic stage however increased the mean VFA/PSol. to 11.3 which enhanced Bio-P removal in the PAF-SBR system. Prefermentation also improved the sludge consistency and settleability in the following SBR unit. The results indicated that by using the perfermentation step, the anoxic/anaerobic period in the BNR-SBR could be controlled and reduced to less than 50 minutes, which would reduce the total cycle time from 8 hr to 6 hr.
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Sayed, S. K. I., and M. A. A. Fergala. "Two-stage UASB concept for treatment of domestic sewage including sludge stabilization process." Water Science and Technology 32, no. 11 (December 1, 1995): 55–63. http://dx.doi.org/10.2166/wst.1995.0402.
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A multi-target study was conducted to assess the feasibility of the UASB-reactor system for the anaerobic treatment of raw domestic sewage (low-strength complex wastewater; CODtot=200-700 mg/l and CODss=45-55% of CODtot) combined with sludge stabilization process under a moderate temperature of 18-20 °C. The study has produced a design of a modified Three-Phase Separator (TPS) to control the sludge retention inside the UASB reactors as well as the determination of design parameters of the treatment process viz. the hydraulic retention time (HRT), the potential period of loading the UASB reactors and the most convenient digestion time required for advanced sludge stabilization. The study was performed in a Two-Stage Flocculent-Granular-Sludge UASB-reactor system. The first stage consisted of two identical UASB reactors seeded with flocculent sludge and operated alternately (i.e. one reactor was fed while the other was unfed for the stabilization of the sludge). The second stage consisted of one UASB reactor seeded with granular sludge and was operated continuously. The feed period and the corresponding feedless period of the first stage were two days. The results study have shown that the removal efficiency of the COD increases considerably with the decrease of the HRT, as a treatment efficiency of 75% was achieved at HRT=10 h (8 h for Stage I and 2 h for Stage II), while the treatment efficiency was 84% at HRT=6 h (4 h for Stage I and 2 h for Stage II). In contrast to the above the extent of sludge stabilization (i.e. conversion into methane) for the first stage of the system was directly proportional to the HRT as 41% of the removed CODtot was converted into methane at HRT=8 h, the conversion ratio decreased to 28% at HRT=4 h. For the granular sludge (the second stage of the system), the conversion ratio of the removed CODtot into methane was almost stable in the range of 17-20%. The percentages CODpaper-filtered of the CODtot were 85-90% and 92-97% for the effluents of the first and second stages respectively with the conclusion that the modified Three-Phase Separator (TPS) has a satisfactory operational potential.
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Aydin, S., B. Ince, Z. Cetecioglu, E. G. Ozbayram, A. Shahi, O. Okay, O. Arikan, and O. Ince. "Performance of anaerobic sequencing batch reactor in the treatment of pharmaceutical wastewater containing erythromycin and sulfamethoxazole mixture." Water Science and Technology 70, no. 10 (October 16, 2014): 1625–32. http://dx.doi.org/10.2166/wst.2014.418.
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This study evaluates the joint effects of erythromycin–sulfamethoxazole (ES) combinations on anaerobic treatment efficiency and the potential for antibiotic degradation during anaerobic sequencing batch reactor operation. The experiments involved two identical anaerobic sequencing batch reactors. One reactor, as control unit, was fed with synthetic wastewater while the other reactor (ES) was fed with a synthetic substrate mixture including ES antibiotic combinations. The influence of ES antibiotic mixtures on chemical oxygen demand (COD) removal, volatile fatty acid production, antibiotic degradation, biogas production, and composition were investigated. The influent antibiotic concentration was gradually increased over 10 stages, until the metabolic collapse of the reactors, which occurred at 360 days for the ES reactor. The results suggest that substrate/COD utilization and biogas/methane generation affect performance of the anaerobic reactors at higher concentration. In addition, an average of 40% erythromycin and 37% sulfamethoxazole reduction was achieved in the ES reactor. These results indicated that these antibiotics were partly biodegradable in the anaerobic reactor system.
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Cacho Rivero, J. A., N. Madhavan, M. T. Suidan, P. Ginestet, and J. M. Audic. "Oxidative and thermo-oxidative co-treatment with anaerobic digestion of excess municipal sludge." Water Science and Technology 52, no. 1-2 (July 1, 2005): 237–44. http://dx.doi.org/10.2166/wst.2005.0523.
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The effect of oxidative and thermo-oxidative co-treatment of excess municipal sludge was investigated. A mixture of primary and waste activated sludge was anaerobically treated using two different configurations: i) two stages and ii) a single stage with recycling. Oxidative or thermo-oxidative co-treatment placed in between the reactor or in the recycle line was studied. A two-stage configuration with no co-treatment served as a control and resulted in 50.1% overall solids removal. Compared to the control, an increase in solids removal of 10.8 and 2.7% was observed when oxidative co-treatment was placed between reactors and in the recycle line respectively. When thermo-oxidative co-treatment was placed between the two stages or in the recycle line an increase in solids removal of 25.1 and 26.9% respectively was observed. The performances of the different configurations were also evaluated with parameters such as COD, TKN, ammonia, and fecal coliform concentration.
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Rodríguez-Pimentel, Reyna I., Suyen Rodríguez-Pérez, Oscar Monroy-Hermosillo, and Florina Ramírez-Vives. "Effect of organic loading rate on the performance of two-stage anaerobic digestion of the organic fraction of municipal solid waste (OFMSW)." Water Science and Technology 72, no. 3 (May 12, 2015): 384–90. http://dx.doi.org/10.2166/wst.2015.223.
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Two-stage anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) was carried out: hydrolysis and acidogenesis in a continuous anaerobic hydrolytic leach bed (AHLB) reactor loaded at different rates (Bv = 3.8–7 gVSSL−1d−1) and methanogenesis of leachates, diluted with municipal wastewater in an upflow anaerobic sludge blanket (UASB) reactor at organic loading rates of 6.6–13 gCODLr−1d−1. In the AHLB reactor, 51–76% and 58–71% volatile solids and chemical oxygen demand (COD) removal efficiencies were obtained. During the hydrolysis and acidogenesis phases, the effluents were at pH 4.93, the leachate had a volatile fatty acids concentration of 35 g/L and the biogas was composed only of CO2. The average methane production in the UASB in the load of 4.4 gVS L−1 d−1 in the AHLB was 3.32 LCH4Lr−1d−1 (yCH4 = 80%), with COD removal efficiency of 95% and methane yield 279 LCH4KgVS−1OFMSW degraded.
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Welander, T., and P. E. Andersson. "Anaerobic Treatment of Wastewater from the Production of Chemi-Thermomechanical Pulp." Water Science and Technology 17, no. 1 (January 1, 1985): 103–11. http://dx.doi.org/10.2166/wst.1985.0008.
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The anaerobic treatment of waste water from the production of peroxide-bleached chemi-thermomechanical pulp was studied. Hydrogen peroxide had to be removed from the waste water before treatment in a methane producing reactor was possible. Peroxide in concentrations up to 200 mg/1 could be removed from the waste water by means of degradation in an acidogenic reactor, the first stage in an anaerobic two-stage process. A system consisting of a prestage and a subsequent acidogenic reactor could successfully remove peroxide in a concentration of 1200 mg/l from the waste water. The prestage was continuously fed with sludge from the acidogenic reactor. The redox potential in the acidogenic stage of a two-stage process proved to be a valuable control parameter when treating waste water containing peroxide. Adaptation of the methanogenic microflora to inhibitory compounds in the waste water was possible. Treatment of the waste water in a pilot plant at low loading rates gave a COD reduction of 50-60% and a methane yield of 0.3 Nm3/kg COD reduced.
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Lettinga, Gatze, Salih Rebac, Sofia Parshina, Alla Nozhevnikova, Jules B. van Lier, and Alfons J. M. Stams. "High-Rate Anaerobic Treatment of Wastewater at Low Temperatures." Applied and Environmental Microbiology 65, no. 4 (April 1, 1999): 1696–702. http://dx.doi.org/10.1128/aem.65.4.1696-1702.1999.
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ABSTRACT Anaerobic treatment of a volatile fatty acid (VFA) mixture was investigated under psychrophilic (3 to 8°C) conditions in two laboratory-scale expanded granular sludge bed reactor stages in series. The reactor system was seeded with mesophilic methanogenic granular sludge and fed with a mixture of VFAs. Good removal of fatty acids was achieved in the two-stage system. Relative high levels of propionate were present in the effluent of the first stage, but propionate was efficiently removed in the second stage, where a low hydrogen partial pressure and a low acetate concentration were advantageous for propionate oxidation. The specific VFA-degrading activities of the sludge in each of the modules doubled during system operation for 150 days, indicating a good enrichment of methanogens and proton-reducing acetogenic bacteria at such low temperatures. The specific degradation rates of butyrate, propionate, and the VFA mixture amounted to 0.139, 0.110, and 0.214 g of chemical oxygen demand g of volatile suspended solids−1 day−1, respectively. The biomass which was obtained after 1.5 years still had a temperature optimum of between 30 and 40°C.
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Nkemka, Valentine Nkongndem, Jorge Arenales-Rivera, and Marika Murto. "Two-Stage Dry Anaerobic Digestion of Beach Cast Seaweed and Its Codigestion with Cow Manure." Journal of Waste Management 2014 (July 17, 2014): 1–9. http://dx.doi.org/10.1155/2014/325341.
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Two-stage, dry anaerobic codigestion of seaweed and solid cow manure was studied on a laboratory scale. A methane yield of 0.14 L/g VSadded was obtained when digesting solid cow manure in a leach bed process and a methane yield of 0.16 L/g VSadded and 0.11 L/g VSadded was obtained from seaweed and seaweed/solid manure in a two-stage anaerobic process, respectively. The results showed that it was beneficial to operate the second stage methane reactor for the digestion of seaweed, which produced 83% of the methane, while the remainder was produced in the first leach bed reactor. Also, the two-stage system was more stable for the codigestion for seaweed and manure when compared to their separate digestion. In addition, the initial ammonia inhibition observed for manure digestion and the acidification of the leach bed reactor in seaweed digestion were both avoided when the materials were codigested. The seaweed had a higher Cd content of 0.2 mg Cd/kg TS than the manure, 0.04 mg Cd/kg TS, and presents a risk of surpassing limit values set for fertiliser quality of seaweed digestate. Evaluation of the heavy metal content of seaweed or a mixture of seaweed and manure digestate is recommended before farmland application.
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Urbinati, Estevão, Rose M. Duda, and Roberto A. de Oliveira. "Performance of UASB reactors in two stages under different HRT and OLR treating residual waters of swine farming." Engenharia Agrícola 33, no. 2 (April 2013): 367–78. http://dx.doi.org/10.1590/s0100-69162013000200015.
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In this study it was evaluated the effects of hydraulic retention time (HRT) and Organic Loading Rate (OLR) on the performance of UASB (Upflow Anaerobic Sludge Blanket) reactors in two stages treating residual waters of swine farming. The system consisted of two UASB reactors in pilot scale, installed in series, with volumes of 908 and 188 L, for the first and second stages (R1 and R2), respectively. The HRT applied in the system of anaerobic treatment in two stages (R1 + R2) was of 19.3, 29.0 and 57.9 h. The OLR applied in the R1 ranged from 5.5 to 40.1 kg CODtotal (m³ d)-1. The average removal efficiencies of chemical oxygen demand (COD) and total suspended solids (TSS) ranged, respectively, from 66.3 to 88.2% and 62.5 to 89.3% in the R1, and from 85.5 to 95.5% and 76.4 to 96.1% in the system (R1 + R2). The volumetric production of methane in the system (R1 + R2) ranged from 0.295 to 0.721 m³CH4 (m³ reactor d)-1. It was found that the OLR applied were not limiting to obtain high efficiencies of CODtotal and TSS removal and methane production. The inclusion of the UASB reactor in the second stage contributed to increase the efficiencies of CODtotal and TSS removal, especially, when the treatment system was submitted to the lowest HRT and the highest OLR.
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Sponza, D. T., and H. Atalay. "Simultaneous toxicity and nutrient removals in simulated DEPHANOX (anaerobic/anoxic/oxic sequentials) process treating dinitrotoluene and trichlorotoluene." Water Science and Technology 49, no. 5-6 (March 1, 2004): 237–44. http://dx.doi.org/10.2166/wst.2004.0759.
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A modified DEPHANOX process including two upflow sludge blanket reactors (USB) (anaerobic-upflow sludge blanket -UASB and anoxic-upflow anoxic sludge blanket -UANSB) and one completely stirred tank reactor (CSTR system was simulated in order to detect the simultaneous removal of dinitrotoulene (DNT), trichlorotoluene (TCT), and nutrients. The phosphorus uptake and nitrification was excessively determined in aerobic CSTR reactor. Influent DNT was transformed to toluene, NH4-N and total aromatic amines (TAA) while TCT was transformed to toluene and dichlorotoluene (DCT) under anaerobic and anoxic conditions. Increasing the volumetric loading rate of DNT and TCT from 18 mg/L.day and 0.35 g/L.day to 60 mg/l.day and 1.2 g/L.day, respectively, resulted in higher COD conversion (70-80%) rates and methane productions (250-300 ml/day) in anaerobic reactor. 90% NO3-N and 87% PO4-P were achieved in anoxic and aerobic reactors at DNT and TCT loading rates as high as 40-60 mg/L.day and 0.8-1.2 g/L.day, respectively. The TAA produced under anaerobic and anoxic conditions were ultimately removed under the aerobic stage. The UASB and anoxic UASB reactor effluents were less toxic relative to the influent when analyzed by anaerobic toxicity tests and specific methanogenic activity tests, indicating that such anaerobic/anoxic aerobic sequential treatments could be able to reduce toxic organics together with nutrient removal.
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Sugumar, R. Wilfred, and Sandhya Sadanandan. "Combined Anaerobic-Aerobic Bacterial Degradation of Dyes." E-Journal of Chemistry 7, no. 3 (2010): 739–44. http://dx.doi.org/10.1155/2010/987362.
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Wastewaters from the dye baths of a non-formal textile-dyeing unit containing C.I. Acid Orange 7 and C.I. Reactive Red 2 were subjected to degradation in a sequential anaerobic-aerobic treatment process based on mixed culture of bacteria. The technical samples of the dyestuffs and the dye bath wastes were treated in an anaerobic reactor, using an adapted mixed culture of anaerobic microorganisms. The dyestuffs were biotransformed into colourless substituted amine metabolites in the reactor. The biotransformation was assisted by co-metabolic process. The amine metabolites did not undergo further degradation in the anaerobic reactor. The effluent from the anaerobic reactor was treated in an aerobic rotating biological contactor and the amine metabolites were found to undergo complete mineralization. This two stage treatment resulted in 94% elimination of dissolved organic carbon. In addition, 85% of organic nitrogen was converted into nitrate in the aerobic reactor during nitrification process.
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Valero, David, Carlos Rico, Raul Tapia-Tussell, and Liliana Alzate-Gaviria. "Rapid Two Stage Anaerobic Digestion of Nejayote through Microaeration and Direct Interspecies Electron Transfer." Processes 8, no. 12 (December 8, 2020): 1614. http://dx.doi.org/10.3390/pr8121614.
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Corn is one of the main food products in Mexico. The elaboration of corn-derived products generates wastewater with a high organic load (nejayote). Anaerobic digestion is an indicated treatment for wastewater with high organic loads. The results of this study show that the application of microaeration in the hydrolysis-fermentative reactor increased the percentage of volatile fatty acids (VFA) available in the medium by 62%. The addition of a conductive material, such as granulated activated carbon (GAC), promotes DIET (Direct interspecies electrons transfer) in the methanogenic UASB reactor increasing the methane yield by 55%. Likewise, a great diversity of exoelectrogenic bacteria, with the ability to donate electrons DIET mechanisms, were developed in the GAC biofilm, though interestingly, Peptoclostridium and Clostridium (17.3% and 12.75%, respectively) were detected with a great abundance in the GAC biofilm. Peptoclostridium has not been previously reported as a participant in DIET process.
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Keller, J., M. Romli, P. L. Lee, and P. F. Greenfield. "Dynamic Model Simulation and Verification of a Two-Stage High-Rate Anaerobic Treatment Process with Recycle." Water Science and Technology 28, no. 11-12 (December 1, 1993): 197–207. http://dx.doi.org/10.2166/wst.1993.0659.
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The effect of overload on a two-phase high rate anaerobic wastewater treatment system with recycle was determined experimentally and simulated dynamically using a structured model. The experimental system consisted of a well mixed continuous reactor, controlled at pH 6 by sodium hydroxide addition, as the acidification stage and a fluidized bed reactor for the methanogenic stage, with an additional recycle connection from the second to the first reactor. Step changes in the feed concentration as well as in the feed flow rate were investigated and compared to simulation predictions. Operation without recycle was modelled accurately, with the simulation data of most process variables matching the experimental results quantitatively. The application of the same model to recycle operation showed significant discrepancy between the experimental and simulated data for the sodium hydroxide consumption rate and the gas flow rate in the acidification reactor. Although the actual values were different, the qualitative responses of the experimental and simulated step changes were similar. Other simulated variables showed good agreement with the experimental measurements. The model provides a useful tool for design and control studies in systems without recycle and, with some modification, for operation with recycle.
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Liu, Xinyuan, Ruying Li, and Min Ji. "Effects of Two-Stage Operation on Stability and Efficiency in Co-Digestion of Food Waste and Waste Activated Sludge." Energies 12, no. 14 (July 18, 2019): 2748. http://dx.doi.org/10.3390/en12142748.
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The two-stage anaerobic digestion (AD) technology attracts increasing attention due to its ability to collect both hydrogen and methane. A two-stage AD system feeding with food waste and waste activated sludge was investigated in order to achieve higher energy yield and organics removal. The two-stage process consists of a thermophilic H2-reactor and a mesophilic CH4-reactor, achieved the highest hydrogen and methane yields of 76.8 mL/g-VS and 147.6 mL/g-VS at hydraulic retention times (HRTs) of 0.8 d and 6 d, respectively. The co-digestion process in this study required much less external alkalinity to maintain the pH values than sole food waste digestion in the literature. Compared with the single-stage mesophilic methane AD process, the two-stage AD system had better performance on operation stability, biogas and energy yields, organics removal and chemical oxygen demand (COD) conversion at high organic loading rates (OLRs). According to the TA-cloning analysis, the dominant bacteria in H2-reactor was closely related to Clostridium sp. strain Z6 and species Thermoanaerobacterium thermosaccharolyticum. The dominant methanogens in two-stage and single-stage CH4-reactor were recognized as acetotrophic methanogens and hydrogenotrophic methanogens, respectively. The presence of the genus Nitrososphaera in the two CH4-reactors might contribute to the low NH4+-N concentration in digestate and low CO2 content in biogas.
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YAZAR, Emre, Kevser CIRIK, Şebnem ÖZDEMIR, Dilek AKMAN, Yakup CUCİ, and Özer ÇINAR. "Optimization of Two-Stage and Single-Stage Anaerobic Reactors Treating Cheese Whey." Kahramanmaraş Sütçü İmam Üniversitesi Mühendislik Bilimleri Dergisi 19, no. 1 (May 10, 2016): 25. http://dx.doi.org/10.17780/ksujes.18309.
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Davel, J., M. T. Suidan, and N. Adrian. "Biodegradation of the energetic compound TNT through a multiple-stage treatment approach." Water Science and Technology 47, no. 9 (May 1, 2003): 129–35. http://dx.doi.org/10.2166/wst.2003.0509.
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Biodegradation of the energetic compound 2,4,6-trinitrotoluene (TNT) and its intermediate 2,4,6-triaminotoluene (TAT) was investigated in this study. From previous investigations, a relationship between the biological utilization of ethanol as co-substrate for the reduction of TNT under anaerobic conditions was proposed using an anaerobic fluidized-bed reactor (AFBR). In this study, the theoretical co-substrate requirement for reduction of TNT to TAT was further investigated through the systematic lowering of the ethanol loading to the reactor. Near complete reduction to TAT was observed up to a critical ethanol loading point, as well as the production of methane from the limited excess available ethanol. Once ethanol deficient loading conditions were established, the increased presence of incompletely reduced degradation intermediates, such as 2,4-diamino-6-nitrotoluene, and even TNT, was observed. The cessation of methanogenesis confirmed that no excess ethanol was available. Degradation of the TAT intermediate in the reactor effluent was investigated using two second-stage reactors under oxidizing conditions. The first was an aerobic activated sludge reactor, and the second was a denitrifying fluidized-bed reactor (DenFBR). The aerobic reactor was successful in lowering the chemical oxygen demand (COD), but complete removal of TAT was not accomplished. Because of TAT polymerization and auto-oxidation under aerobic conditions, it was difficult to confirm to what extent of TAT removal was biological. In the DenFBR, incompletely reduced TNT intermediates were not successfully degraded, but strong evidence existed for the degradation of TAT. This is the first known report of second stage degradation of TAT under denitrifying conditions.