Anaerobic Sequencing Batch Reactor Research Articles

Biogas Production from Brewer's Yeast Using an Anaerobic Sequencing Batch Reactor.

Renewable energy sources are becoming increasingly important in the beverage and food industries. In the brewing industry, a significant percentage of the used raw materials finishes the process as secondary resource or waste. The research on the anaerobic digestion of brewer's yeast has been scarce until recent years. One of the reasons for this is its use as a secondary resource in the food industry and as cattle feed. Additionally, market value of brewer's yeast is higher than its energy value. Due to the increase of energy prices, brewer's yeast has become of interest as energy substrate despite its difficult degradability in anaerobic conditions. The anaerobic co-digestion of brewer's yeast and anaerobically treated brewery wastewater was studied using a pilot-scale anaerobic sequencing batch reactor (ASBR) seeded with granular biomass. The experiments showed very good and stable operation with an organic loading rate of up to 8.0 kg/(m3·day), and with a maximum achieved organic loading rate of 13.6 kg/(m3·day) in a single cycle. A specific biogas productivity of over 0.430 m3/kg of the total chemical oxygen demand (COD) inserted, and total COD removal efficiencies of over 90% were achieved. This study suggests that the brewer's yeast can be successfully digested in an ASBR without adverse effects on the biogas production from brewer's yeast/wastewater mixtures of up to 8% (by volume). By using the brewer's yeast in the ASBR process, the biogas production from brewery wastewater could be increased by 50%.

Evaluation of Organic Carbon from Anaerobic Sequencing Batch Reactor Effluent as a Carbon Source for Denitrification

The discharge of nitrate-rich effluent has adverse effect on the receiving environment and the public health of the polluted water users. The nitrates are eliminated in a denitrification step that requires reducing power in form of organic carbon. The objective of this study was to evaluate the potential of utilizing organic carbon in effluent from the anaerobic SBR as a carbon source for denitrification. Reactors were operated for one year using meat processing wastewater. Anaerobically treated abattoir wastewater equivalent to 5, 10 and 15% of aerobic SBR hydraulic volume were added to three separate reactors. A 12 h operating cycle consisted of the following periods: (a) filling, 0.30 h; (b) settling, 11 h and (d) decanting, 0.30 h for the anoxic reactor. A comparison between different carbon loads was performed based on biological carbon, nitrogen and phosphorus removal. Sufficient denitrification was achieved with 10% (aerobic SBR hydraulic volume) of anaerobically-treated abattoir wastewater. TCOD, BOD5, TKN, N02 -N, NO3 -N, PO4 3-, TS, EC and temperature and turbidity were reduced by 78, 70, 91, 100, 98, 62, 39, 65, 71, 5 and 39% respectively, with effluent mean concentrations of 80 ± 5 mg/L, 54 ± 12 mg/L, 35 ± 4, 00 ± 0, 2 ± 1, 18 ± 1, 254 ± 12, 1.64 ± 0.01, 22.04 ± 0.02 and 738 ± 9 FAU. Organic carbon in effluent from the anaerobic SBR can be used as a carbon source for anoxic denitrification. However, the denitrification rate is affected by the organic carbon load used. Except TKN and o-PO43- mg/L, all other parameters in the denitrified effluent met discharge standards

Synchronous rapid start-up of the methanation and anammox processes in two-stage ASBRs

The “methanation + anaerobic ammonia oxidation autotrophic denitrification” method was adopted by using anaerobic sequencing batch reactors (ASBRs) and realized a satisfactory synchronous removal of chemical oxygen demand (COD) and ammonia-nitrogen (NH4+-N) in wastewater after 75 days operation. 90% of COD was removed at a COD load of 1.2 kg/(m3•d) and 90% of TN was removed at a TN load of 0.14 kg/(m3•d). The anammox reaction ratio was estimated to be 1: 1.32: 0.26. The results showed that synchronous rapid start-up of the methanation and anaerobic ammonia oxidation processes in two-stage ASBRs was feasible.

Removal of organic matter and nutrients from food waste using a combined two-phase anaerobic digester and granular sequencing batch reactor system

Removal of organic matter and nutrients from food waste using a combined two-phase anaerobic digester and granular sequencing batch reactor system

Study of Biological Methods in Landfill Leachate Treatment

Landfill leachate is mainly the result of precipitation of water into the layers of buried waste, and biochemical reactions of waste that has dangerous substances and pollutants that lead to the contamination of surface and groundwater resources. Therefore, it must be collected and treated properly. The investigation of various biological methods in leachate treatment, their advantages and disadvantages, and their effect on reduction of COD (chemical oxygen demand) are the objectives of this study. Reviewed processes include anaerobic and aerobic sequencing batch reactor, up-flow anaerobic sludge blanket, moving-bed biofilm reactor, membrane bioreactor, and aerated lagoons, lead to reduction of biodegradability pollutants in different circumstances. The present study has indicated that the most and the least reduction of COD has been through aerated lagoon (95%) and moving-bed biofilm reactor (8%), respectively.

Carbon Footprint Analyses of Wastewater Treatment Systems in Puducherry

Carbon footprint analysis is a method to quantify the life cycle Greenhouse Gases (GHGs) emissions and identify the measure to reduce climate change impacts. The Intergovernmental Panel on Climate Change (IPCC) has identified that the global warming and climate change which is one of the most important issues in the domain of environment are caused by the excessive emission of Greenhouse Gases (GHG) mainly constituting Carbon dioxide (CO2), Methane (CH4) and Nitrous oxide (N2O). The municipal wastewater treatment plant receives wastewater for treatment and finally discharges the treated effluent. The emissions of GHG during the treatment of wastewater as well as during the treatment process of sludge and also for energy generation are known to be on-site GHG emissions. Off-site GHG emissions are generated due to transportation and disposal of sludge, off-site energy and chemical production. In Puducherry, the municipal wastewater is being treated using oxidation ponds, Upflow Anaerobic Sludge Blanket (UASB) and Sequencing Batch Reactor (SBR). Wastewater treatment using Sequencing Batch Reactor (SBR) technology is one of the state-of-the art wastewater management systems. In this technology equalization, biological treatment and secondary clarification are performed in a single reactor in a time control sequence. The emissions of GHG from the Oxidation ponds of 12.5 MLD, UASB reactor of 2.5 MLD and SBR of 17 MLD were assessed based on the IPCC guidelines and the total emissions of GHG in terms of equivalent of CO2 were compared. The performance of the SBR is more efficient and the emissions of GHG are less than the emissions in the UASB as well as in oxidation ponds. The emission of GHG in SBR is about 60% of the existing treatment systems of oxidation ponds and UASB thus a reduction of 40% GHG emission could be achieved.

Consolidated bioprocessing of microalgal biomass to carboxylates by a mixed culture of cow rumen bacteria using anaerobic sequencing batch reactor (ASBR)

This study employed mixed-culture consolidated bioprocessing (CBP) to digest microalgal biomass in an anaerobic sequencing batch reactor (ASBR). The primary objectives are to evaluate the impact of hydraulic residence time (HRT) on the productivity of carboxylic acids and to characterize the bacterial community. HRT affects the production rate and patterns of carboxylic acids. For the 5-L laboratory-scale fermentation, a 12-day HRT was selected because it offered the highest productivity of carboxylic acids and it synthesized longer chains. The variability of the bacterial community increased with longer HRT (R2=0.85). In the 5-L laboratory-scale fermentor, the most common phyla were Firmicutes (58.3%), Bacteroidetes (27.4%), and Proteobacteria (11.9%). The dominant bacterial classes were Clostridia (29.8%), Bacteroidia (27.4%), Tissierella (26.2%), and Betaproteobacteria (8.9%).

Biological groundwater treatment for chromium removal at low hexavalent chromium concentrations

The objective of this work is to develop and evaluate biological groundwater treatment systems that will achieve hexavalent chromium reduction and total chromium removal from groundwater at hexavalent chromium (Cr(VI)) groundwater concentrations in the 0–200 μg/L range. Three lab-scale units operated, as sequencing batch reactors (SBR) under aerobic, anaerobic and anaerobic–aerobic conditions. All systems received groundwater with a Cr(VI) content of 200 μg/L. In order to support biological growth, groundwater was supplemented with milk, liquid cheese whey or a mixture of sugar and milk to achieve a COD concentration of 200 mg/L. The results demonstrate that a fully anaerobic system or an anaerobic–aerobic system dosed with simple or complex external organic carbon sources can lead to practically complete Cr(VI) reduction to Cr(III). The temperature dependency of maximum Cr(VI) removal rates can be described by the Arrhenius relationship. Total chromium removal in the biological treatment systems was not complete because a significant portion of Cr(III) remained in solution. An integrated system comprising of an anaerobic SBR followed by a sand filter achieved more than 95% total chromium removal thus resulting in average effluent total and dissolved chromium concentrations of 7 μg/L and 3 μg/L, respectively.

Continuous anaerobic hydrogen and methane production using water hyacinth feedstock

The water hyacinth, Eichhornia crassipes, impacts the environment in a number of ways. This study develops a continuous cultivation strategy and investigates the effect of these strategies for hydrogen production in anaerobic sequencing batch reactor (ASBR) and intermittent-continuous stirred tank reactor (I-CSTR) systems using the water hyacinth as feedstock. Glucose (10 g/L) was used as the feedstock to start-up the fermentor using pig slurry seed in a batch model. ASBR with increasing water hyacinth concentration was used as the start-up strategy for hydrogen production. However, the hydrogen performance decreased with increasing water hyacinth concentration. Finally, the metabolic pathway shifted to methane production with no hydrogen. A strategy for controlling the substrate and reaction pH and shortening the hydraulic retention time (HRT) in I-CSTR was used to enhance the hydrogen production. Low hydrogen production performance was achieved with a hydrogen production rate of 1.1 with 82.4mL/L-d methane production rate resulting from the I-CSTR operated using pH 4.0 feedstock and HRT 2days.

Reduction of the hydraulic retention time at constant high organic loading rate to reach the microbial limits of anaerobic digestion in various reactor systems

The effects of hydraulic retention time (HRT) reduction at constant high organic loading rate on the activity of hydrogen-producing bacteria and methanogens were investigated in reactors digesting thin stillage. Stable isotope fingerprinting was additionally applied to assess methanogenic pathways. Based on hydA gene transcripts, Clostridiales was the most active hydrogen-producing order in continuous stirred tank reactor (CSTR), fixed-bed reactor (FBR) and anaerobic sequencing batch reactor (ASBR), but shorter HRT stimulated the activity of Spirochaetales. Further decreasing HRT diminished Spirochaetales activity in systems with biomass retention. Based on mcrA gene transcripts, Methanoculleus and Methanosarcina were the predominantly active in CSTR and ASBR, whereas Methanosaeta and Methanospirillum activity was more significant in stably performing FBR. Isotope values indicated the predominance of aceticlastic pathway in FBR. Interestingly, an increased activity of Methanosaeta was observed during shortening HRT in CSTR and ASBR despite high organic acids concentrations, what was supported by stable isotope data.

Treating anaerobic sequencing batch reactor effluent with electrically conducting ultrafiltration and nanofiltration membranes for fouling control

The anaerobic treatment of industrial wastewater has attracted a significant amount of interest. However, excessive fouling complicates the treatment of anaerobic reactor effluent with membranes, which limits the application of membranes as a tertiary treatment. Here, we use an anaerobic sequencing batch reactor coupled to electrically conducting ultrafiltration and nanofiltration membranes to treat high-strength industrial wastewater containing high concentrations of benzyl alcohol, a commercial paint stripper. We demonstrate that an anaerobic process can be used successfully to degrade this contaminant. We also show that the application of negative electrical potential to the ultrafiltration membrane surface prevents membrane fouling and allows for higher operational fluxes during the treatment of complex wastewater streams. The application of positive potential to the membrane surface increases membrane fouling, as well as hindering the cleaning and recovery of the nanofiltration membranes. Overall, our experimental results demonstrate the feasibility of using electrically conducting membranes to prevent membrane fouling during the treatment of anaerobic reactor effluent at high operational fluxes.

Seasonal variations of microbial community in a full scale oil field produced water treatment plant.

This study investigated the microbial community in a full scale anaerobic baffled reactor and sequencing batch reactor system for oil-produced water treatment in summer and winter. The community structures of fungi and bacteria were analyzed through polymerase chain reaction–denaturing gradient gel electrophoresis and Illumina high-throughput sequencing, respectively. Chemical oxygen demand effluent concentration achieved lower than 50 mg/L level after the system in both summer and winter, however, chemical oxygen demand removal rates after anaerobic baffled reactor treatment system were significant higher in summer than that in winter, which conformed to the microbial community diversity. Saccharomycotina, Fusarium, and Aspergillus were detected in both anaerobic baffled reactor and sequencing batch reactor during summer and winter. The fungal communities in anaerobic baffled reactor and sequencing batch reactor were shaped by seasons and treatment units, while there was no correlation between abundance of fungi and chemical oxygen demand removal rates. Compared to summer, the total amount of the dominant hydrocarbon degrading bacteria decreased by 10.2% in anaerobic baffled reactor, resulting in only around 23% of chemical oxygen demand was removed in winter. Although microbial community significantly varied in the three parallel sulfide reducing bacteria, the performance of these bioreactors had no significant difference between summer and winter.

Numerical evaluation of the low Reynolds turbulent flow behaviour in a bioreactor

Bioreactors are commonly used in industry, owing to their low energy requirement. These reactors are often operated at reduced flow rates in order to maintain a high retention time, and reduce shear stress on the biomass. An important factor is the mixing between biomass and substrate, and thus the maintenance of turbulence is important. Hence, the aim of this work is the application of the CFD technique to obtain a better understanding of the turbulent behaviour in an anaerobic sequencing batch reactor, with a nominal Reynolds number of about 1,700. This study considered a single-phase approach to evaluate several turbulence models. The obtained results indicate that the flow has little influence on the regions in the transition regime for the conditions evaluated, in spite of the low Reynolds number. Moreover, comparing the use of different models, it was found that the Reynolds stress model does not require longer time for its calculations.

Biological Treatment of Meat Processing Wastewater Using Lab-Scale Anaerobic-Aerobic/Anoxic Sequencing Batch Reactors Operated in Series

In the eastern Africa sub-region, many industries discharge untreated effluents to nearby water resources, thereby polluting the environment. This is because the technologies applicable for wastewater treatment are expensive for these small-medium sized companies with low profit margins. Slaughterhouses belong to this category of industrial setup. The objective of this study was to investigate treatment of meat processing wastewater using anaerobic– aerobic/anoxic Sequencing Batch Reactors (SBRs) operated in series. Reactors were operated for one year using meat processing wastewater. Hydraulic retention time was 2 days for the anaerobic SBR, and 1 day for the aerobic/ anoxic SBR while the organic loading was 12.8 kg COD/m3/day. In the anaerobic SBR, removal efficiencies for total and soluble chemical oxygen demand (TCOD and SCOD), total suspended solids (TSS) and turbidity were 79, 76, 79, and 70%, respectively, with effluent mean concentrations of 3554 ± 58 mg/L, 762 ± 3 mg/L, 2307 ± 21, and 2800 ± 9 FAU. Conductivity, ammonia-nitrogen, ortho-phosphates and total phosphorus concentrations increased by 38, 80, 81 and 71%. Pollutant removal efficiencies in the aerobic/anoxic SBR were 98, 96, 97, 89, 74, 97, 91, 90, and 86% for TCOD, SCOD, BOD, TSS, turbidity, ammonium nitrogen (NH4 +–N), total nitrogen (TN), orthophosphorus (o-PO4 3-–P), and total phosphorus (TP), respectively. Except TKN (35 ± 4 mg/L) and o-PO4 3-–P (8 ± 1 mg/L), all other parameters in the aerobically treated effluent met national discharge standards. Thus, abattoir effluent can be treated using anaerobic–aerobic/anoxic SBR system.

Anaerobic sulfamethoxazole degradation is driven by homoacetogenesis coupled with hydrogenotrophic methanogenesis

In this study, microbial community dynamics were assessed in two lab-scale anaerobic sequencing batch reactors (ASBRs). One of the reactors was fed by synthetic pharmaceutical industry wastewater with sulfamethoxazole (SMX) as the test reactor and the other without sulfamethoxazole as the control reactor. DNA based DGGE results indicated that Clostiridum sp. became dominant in the SMX reactor while the inoculum was dominated with Firmicutes (61%) and Methanomicrobiales (28%). However their abundances in active community decreased through the last phase. Also the abundance of hydrogenotrophs was high in each phase, while acetoclastic methanogens disappeared in the last phase. Q-PCR analysis revealed that there is a significant reduction in the bacterial community approximately 84%, while methanogens increased to 97% through the operation. Additionally an increase in the expression level of bacterial and methanogenic 16S rRNA (60% and 20%, respectively) was detected. Significant correlation between microbial community and the reactor operation data was found. The study demonstrated that the microbial community maintains the system stability under high antibiotic concentration and long-term operation by homoacetogenesis coupled with hydrogenotrophic methanogenesis.

ANAMMOX-like performances for nitrogen removal from ammonium-sulfate-rich wastewater in an anaerobic sequencing batch reactor

ABSTRACTAmmonium removal by the ANaerobic AMonium OXidation (ANAMMOX) process was observed through the Sulfate-Reducing Ammonium Oxidation (SRAO) process. The same concentration of ammonium (100 mg N L−1) was applied to two anaerobic sequencing batch reactors (AnSBRs) that were inoculated with the same activated sludge from the Vermicelli wastewater treatment process, while nitrite was fed in ANAMMOX and sulfate in SRAO reactors. In SRAO-AnSBR, in substrates that were fed with a ratio of NH4+/SO42− at 1:0.4 ± 0.03, a hydraulic retention time (HRT) of 48 h and without sludge draining, the Ammonium Removal Rate (ARR) was 0.02 ± 0.01 kg N m−3.d−1. Adding specific ANAMMOX substrates to SRAO-AnSBR sludge in batch tests results in specific ammonium and nitrite removal rates of 0.198 and 0.139 g N g−1 VSS.d, respectively, indicating that the ANAMMOX activity contributes to the removal of ammonium in the SRAO process using the nitrite that is produced from SRAO. Nevertheless, the inability of ANAMMOX to utilize sulfate to oxidize ammonium was also investigated in batch tests by augmenting enriched ANAMMOX culture in SRAO-AnSBR sludge and without nitrite supply. The time course of sulfate in a 24-hour cycle of SRAO-AnSBR showed an increase in sulfate after 6 h. For enriched SRAO culture, the uptake molar ratio of NH4+/SO42− at 8 hours in a batch test was 1:0.82 lower than the value of 1:0.20 ± 0.09 as obtained in an SRAO-AnSBR effluent, while the stoichiometric ratio of 1:0.5 that includes the ANAMMOX reaction was in this range. After a longer operation of more than 2 years without sludge draining, the accumulation of sulfate and the reduction of ammonium removal were observed, probably due to the gradual increase in the sulfur denitrification rate and the competitive use of nitrite with ANAMMOX. The 16S rRNA gene PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) and PCR cloning analyses resulted in the detection of the ANAMMOX bacterium (Candidatus Brocadia sinica JPN1) Desulfacinum subterraneum belonging to the genus Desulfacinum and bacteria that are involved in sulfur metabolism (Pseudomonas aeruginosa strain SBTPe-001 and Paracoccus denitrificans strain IAM12479) in SRAO-AnSBR.

Pilot-scale landfill with leachate recirculation for enhanced stabilization

A pilot-scale landfill and a two-phase (acidogenesis and methanogenesis) anaerobic sequencing batch reactor (anSBR) system was setup to treat leachate collected from the simulated landfill cell which had leachate recirculation (at <0.3% of total waste volume/day). It was noted there was already substantial acidogenic activity in the landfill cell before the acidogenic reactor. Development of the microbial communities in the two reactors was influenced by the acidogenesis in the landfill cell. A COD half-life of 10 weeks was achieved in the pilot-scale landfill system indicating very fast organics stabilization in the landfill. It was shown that with an ex-situ anSBR augmenting treatment of the landfill leachate, rapid landfill stabilization could be achieved even when leachate recirculation was at a relatively low rate.

Effect of biomass configuration on the behavior of pilot-scale anaerobic batch reactors treating dairy wastewater

Anaerobic sequencing batch reactors applied to the treatment of dairy wastewaters have received increasing attention in bench-scale studies, particularly because dairy plants intermittently operate. This study compared two mechanically stirred, pilot-scale reactors, the Anaerobic Sequencing Batch Reactor (ASBR) and the Anaerobic Sequencing Biofilm Batch Reactor (ASBBR), in the treatment of dairy-plant wastewater. The reactors were fed with wastewater from a dairy plant and were operated with two cycle times: 48 and 24 h. The organic matter concentration in the influent, measured as chemical oxygen demand (COD), was approximately 4500 mg l−1. The ASBR exhibited highly efficient removal of organic matter (92.8 ± 5.9%), with production of bicarbonate alkalinity and low concentration of volatile fatty acids in the effluent for both cycle times. In contrast, the organic matter removal efficiency of the ASBBR decreased from 92.3 ± 16.5% to 60.5 ± 16.5% when the cycle time was changed from 48 h to 24 h. Moreover, the ASBBR also presented higher levels of instability during operation, showing lower bicarbonate alkalinity concentrations and higher concentrations of volatile fatty acids in the effluent when compared with the ASBR. The superior results exhibited by the ASBR may be related to larger changes in its microbial ecology and biomass configuration that occurred because of its better microbial selection and adaptation conditions. Granule diameters decreased greatly over time; however, this reduction did not affect settleability, assuring the performance of the ASBR.

Microbial population dynamics during long-term sludge adaptation of thermophilic and mesophilic sequencing batch digesters treating sewage fine sieved fraction at varying organic loading rates

BackgroundIn this research, the feasibility of, and population dynamics in, one-step anaerobic sequencing batch reactor systems treating the fine sieved fraction (FSF) from raw municipal wastewater was studied under thermophilic (55 °C) and mesophilic (35 °C) conditions. FSF was sequestered from raw municipal wastewater, in the Netherlands, using a rotating belt filter (mesh size 350 micron). FSF is a heterogeneous substrate that mainly consists of fibres originating from toilet paper and thus contains a high cellulosic fraction (60–80 % of total solids content), regarded as an energy-rich material.ResultsResults of the 656-day fed-batch operation clearly showed that thermophilic digestion was more stable, applying high organic loading rates (OLR) up to 22 kg COD/(m3 day). In contrast, the mesophilic digester already failed applying an OLR of 5.5 kg COD/(m3 day), indicated by a drop in pH and increase in volatile fatty acids (VFAs). The observed viscosity values of the mesophilic sludge were more than tenfold higher than the thermophilic sludge. 454-pyrosequencing of eight mesophilic and eight thermophilic biomass samples revealed that Bacteroides and aceticlastic methanogen Methanosaeta were the dominant genera in the mesophilic digester, whereas OP9 lineages, Clostridium and the hydrogenotrophic methanogen Methanothermobacter dominated the thermophilic one.ConclusionsOur study suggests that applying thermophilic conditions for FSF digestion would result in a higher biogas production rate and/or a smaller required reactor volume, comparing to mesophilic conditions.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0355-3) contains supplementary material, which is available to authorised users.

Biogas production in an anaerobic sequencing batch reactor by using tequila vinasses: effect of pH and temperature.

In recent years, anaerobic digestion has been recognized as a suitable alternative for tequila vinasses treatment due to its high energy recovery and chemical oxygen demand (COD) removal efficiency. However, key factors such as the lack of suitable monitoring schemes and the presence of load disturbances, which may induce unstable operating conditions in continuous systems, have limited its application at full scale. Therefore, the aim of this work was to evaluate the anaerobic sequencing batch reactor (AnSBR) configuration in order to provide a low cost and easy operation alternative for the treatment of these complex effluents. In particular, the AnSBR was evaluated under different pH-temperature combinations: 7 and 32 °C; 7 and 38 °C; 8 and 32 °C and 8 and 38 °C. Results showed that the AnSBR configuration was able to achieve high COD removal efficiencies (around 85%) for all the tested conditions, while the highest methane yield was obtained at pH 7 and 38 °C (0.29 L/g COD added). Furthermore, high robustness was found in all the AnSBR experiments. Therefore, the full-scale application of the AnSBR technology for the treatment of tequila vinasses is quite encouraging, in particular for small and medium size tequila industries that operate under seasonal conditions.