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In this study, three anaerobic digestion reactors using up‐flow anaerobic sludge blanket (UASB), anaerobic sequencing batch reactor (AnSBR), and anaerobic membrane bioreactor (AnMBR) were studied. The chemical oxygen demand (COD), gas production, sludge performance, and microbial characteristics of the anaerobic digestion process were assessed. The results showed that the average COD removal efficiencies reached 86%, 83%, and 85%, with corresponding removed rates of 2.49, 0.48, and 0.79 kg COD m−3 d−1 in UASB, AnSBR, and AnMBR, respectively. After the reactors attained stable operation, both extracellular polymeric substances and soluble microbial products decreased in all the reactors compared with the seed sludge. Methanothrix was the dominant archaea for methane production in the UASB, the relative abundance of which increased from 58.3% to 83.4%. These results identify UASB as the most suitable reactor for anaerobic digestion when treating wastewater with low carbon. Such reactors are important for the application and development of the energy self‐sufficiency in sewage treatment. Practitioner Points: UASB, SBR, and MBR were adopted to treat low‐carbon wastewater using anaerobic digestion process.UASB performed the highest COD removal from low‐carbon wastewater.The main microorganisms in UASB were Methanothrix, Methanomassiliicoccus, and Methanobacterium. [ABSTRACT FROM AUTHOR]

BACKGROUND The baker's yeast industry is a major market and due to the intensified production large quantities of waste are generated. Wastewater from the baker's yeast industry with high content of molasses was treated anaerobically in an upflow anaerobic sludge blanket ( UASB) reactor for the production of methane ( CH4). RESULTS The molasses wastewater obtained from industry had a high pH value around 8.0 ± 0.5, which remained constant during the experimental period. The system was operated at an organic loading rate ( OLR) of 2.4-7.65 g of volatile solids per liter per day (g VS L−1 d−1) and the best results were observed at 4 g VS L−1 d−1, where methane production exceeded 350 L CH4 kg−1 VS. Anaerobic chemical oxygen demand removal was also examined and it was found that for the latter conditions of optimum OLR, it was more than 35%. VFA analysis revealed that acetic acid concentration in the reactor was more than 25 mmol L−1 even under optimum conditions. CONCLUSIONS The tested hydraulic retention time ( HRT) values did not affect methane production, unlike the OLR. The increased acetic acid concentration in the UASB reactor and the high pH were credited to the inhibition of aceticlastic microorganisms. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Effects of hydraulic retention time (HRT) and nitrogen loading rate (NLR) on performance of anammox UASBs amended with spherical plastic and bamboo charcoal carriers were investigated. During the experimental period, the performance of reactors was continuously evaluated by monitoring ammonium-N, nitrite-N, and nitrate-N at HRT of 48, 36, 24, and 12 hours. With HRTs between 24 and 48 hours, the ammonium-N and nitrite-N removal efficiency was higher than 99%, while the total nitrogen (TN) removal efficiency was almost higher than 90%. When HRT decreased to 12 hours with NLR increasing to 0.16 kg N m-3 d-1, ammonium-N, and TN removal efficiency decreased to 87 and 80%, respectively. Moreover, phylogenetic analysis revealed anammox community still existed at the HRT of 12 hours and was most closely related to C. Brocadia sp.40. In addition, different types of carriers had no significant influence on the anammox community. [ABSTRACT FROM AUTHOR]

Biohydrogen generation using anaerobic sludge from a sewage treatment plant is a promising strategy for converting waste into renewable energy. The porous foam SiC ceramic structured packing was used as a support in the up-flow anaerobic sludge blanket (UASB) reactor to enhance the biohydrogen yield. Using glucose as the major carbon source, the SiC-UASB reactor was continuously operated under the organic loading rates (OLR) between 30 and 90 gglucose/L · d at a hydraulic retention time (HRT) of 4 h. The maximum hydrogen production rate (5.24 L/L · d) and hydrogen content (50 %) were obtained at 60 gglucose/L · d OLR. It demonstrated that the reaction of fermentation was predominated by the butyric acid pathway. The employment of SiC packings resulted in quick startup (∼5 days) and high efficiency of hydrogen production. The buffering capacity and the cell culture immobilization ability of the UASB reactor were obviously improved by the application of SiC packings, which increased the feasibility of scale-up of the continuous biohydrogen production system. [ABSTRACT FROM AUTHOR]

ABSTRACT BACKGROUND Chemical thermo-mechanical pulp ( CTMP) mills holds a large biomethane potential in their wastewater. Their broadened market has involved increased bleaching and utilization of different raw materials. Therefore, the main aim of this study was to obtain and maintain a well-functioning anaerobic digestion ( AD) process, with a high methane yield and total organic carbon ( TOC) reduction, when digesting CTMP wastewater, from different production protocols including shifts in raw material and bleaching. A lab-scale upflow anaerobic sludge bed ( UASB) reactor was used for the tests. RESULTS The variations in raw material (spruce, birch and aspen) and consequently in TOC-loading (3.6-6.6 kg TOC m−3 and day−1) did not affect the UASB process negatively. Methane production values from 360 to 500 NmL g−1 TOC were obtained, with the highest yield for wastewater from the production of birch- followed by aspen- and spruce pulp. The acetic acid and filtered- TOC ( fTOC) reduction ranged from 90 to 95% and 61 to 73%, respectively. CONCLUSIONS A well-functioning process maintained during shifts in raw material for pulp production which shows that AD is feasible for CTMP mills with a diversified product portfolio. Furthermore, the increased use of hardwood and bleaching will most likely increase their potential as a biomethane producer. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Algae grown in wastewater treatment lagoons are a potentially important substrate for biofuel production. The feasibility of using upflow anaerobic sludge blanket (UASB) reactors in anaerobic digestion of algae to produce methane was investigated. A favorable carbon to nitrogen (C/N) weight ratio of 21/1 was determined in batch reactor experiments in which the ratio was adjusted by blending algal biomass with sodium acetate as a carbon source. This blend of algae and acetate was used in the feedstock applied to the UASB reactors. Duplicate, 34-L, UASB reactors initially received an organic loading rate (OLR) of 0.9 g chemical oxygen demand (COD)/L'd at a 7.2-day hydraulic retention time (HRT). The OLR was gradually increased to 5.4 g/L'd and the HRT was decreased to 5.5 days resulting in a methane production increase from 247 to 298 mL/g COD biodegraded. The COD removal efficiency was 80% with a biogas methane composition of 90%. [ABSTRACT FROM AUTHOR]

ABSTRACT Granules are large, self-supporting biofilms that form naturally in high-rate anaerobic treatment systems and are extremely important to reactor functionality. Granules exhibit functional and phylogenetic layering, interesting to both scientists and technologists. Until now, it has only been possible to analyze layering through sectioning and microscopic analysis with fluorescent in situ hybridization, or to analyze the whole granule through DNA extraction and microbial community profiling methods. This means different functional and spatial layers cannot be analyzed separately, including next generation sequencing techniques, such as pyrotag sequencing. In this work, we describe a method to remove microbes selectively from successive spatial layers through hydraulic shearing and demonstrate its application on anaerobic granules of three different types (VFA-, carbohydrate-, protein-fed) in size ranges 0.6-2 mm. Outer layers in particular could be selectively sheared as confirmed by FISH. TRFLP was used as an example bulk DNA method on selectively sheared fractions. A shift in dominant population was found from presumptive acidogens (such as Bacteroidetes and Anaerolinea) in outer layers to syntrophs (such as Syntrophomonas and Geobacter) in inner layers, with progressive changes through the depth. The strength of the shear-bulk molecular method over FISH was that a deeper phylogenetic profile could be obtained, even with TRFLP, and that prior knowledge of the community is not required. Biotechnol. Bioeng. 2013;110: 2600-2605. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The anaerobic processes literature review contains a comprehensive discussion of articles published in 2011, including both original research and review articles. Specific attention is paid to studies on design and optimization of systems using anaerobic processes, as well as characterizing the microflora involved in such processes. This year's anaerobic processes literature review is divided into the following sections: biogas treatment and use, integrated approaches, modeling advances, process technology, hydrogen production, microbiology, anammox, treatability studies, and toxicity. [ABSTRACT FROM AUTHOR]

The anaerobic processes literature review contains a comprehensive discussion of articles published in 2010 with emphasis on biological wastewater treatment processes that exploit an environment devoid of oxygen. Anaerobic systems, like the upflow anaerobic sludge blanket (UASB) reactor and the anaerobic filter (AF), represent the traditional emphasis of anaerobic processes literature review. Anaerobic hydrogen production and anaerobic ammonia oxidation (anammox) have been incorporated more recently into this chapter of the literature review. This year's anaerobic processes literature review is divided into the following sections: integrated approaches, modeling advances, process technology, hydrogen production, microbiology, anammox, treatability studies, and inhibition of the anaerobic process. [ABSTRACT FROM AUTHOR]

A combined upflow anaerobic sludge blanket (UASB) and CO-stripping system was evaluated for its capacity to simultaneously remove organic compounds and calcium from linerboard mill wastewater. A continuous-flow UASB has significant potential to remove organic compounds, and its removal efficiency is closely related to volumetric organic loading. After the UASB process, a gradual decrease of pH was observed and CO-stripping indicated the formation of acid/methane and carbonate. The high concentration of carbonate that was generated from the elevated pH of the CO stripper easily reacted with calcium in the wastewater to form a solid-phase calcium carbonate. The significant amount of methane that was produced during the UASB process implies that methane-producing bacteria dominate the microbial composition of the reactor. In the CO stripper system, calcium removal and alkalinity consumption rose simultaneously with increasing solution pHs. This result suggests that the combined activity of the UASB reactor and the CO stripper system is a powerful tool for removing organic compounds and calcium from linerboard wastewater. Such a system would allow water from the linerboard production process to be reused and be discharged with fewer toxic compounds. © 2010 American Institute of Chemical Engineers Environ Prog, 2011 [ABSTRACT FROM AUTHOR]

In this study, the membrane filtration process was proposed as a post-treatment process to treat the upflow anaerobic sludge blanket (UASB) effluent. The flat-sheet membrane modules were submerged into the UASB reactor to retain the suspended solids in the UASB effluent under intermittent permeation and air sparging conditions. The results indicated that intermittent permeation enhanced the sustainability of the submerged membrane and an idle time of 4 min with a 10-min filtration was optimal for reducing membrane fouling under the experimental conditions. Air sparging could also alleviate membrane fouling, and the lowest transmembrane pressure (TMP) change rate (dTMP/d t) was achieved at the moderate aeration rate of 2 L/min. It appears to be effective to alleviate membrane fouling and achieve high effluent production at a flux of 25 L/m2 h and an idle time of 4 min with a 10-min filtration considering the energy consumption. [ABSTRACT FROM AUTHOR]

The removal performance of typical refractory organic compounds in landfill leachate was investigated during the electrochemical (EC) oxidation and anaerobic process combined treatment system in this paper. The results indicated that the treatment of landfill leachate by the combined system was highly effective. The toxicity of leachate was notably decreased after the electrochemical oxidation process and the biodegradability was improved. The concentration of the organic acid with low molecular weight in the leachate increased from 28% to 90% based on the biodegradability assays after the EC oxidation process. The anaerobic digestion could further remove the residual organic compounds. At a hydraulic retention time (HRT) of 16 hours and an organic loading rate (OLR) of 8 kg COD/m³d, the concentration of COD, SS, ALK, VA, N-TKN, N-NH4+ and P-PO3- in UASB effluent were 532, 12, 6744, 400, 540, 455 and 11.6 mg/L, respectively, with approximately 90% removal efficiency of COD. The organic compounds in the landfill leachate revealed different degradation characteristics in the combined system. p-chloroaniline, bisphenol A, 6-methyl-2-phenyl-quinoline, dimethylnaphthaline and N′-(2-methyl-4-chlorophenyl)-N-cyclohexyformamidine, classified into the first group in this paper, were completely removed by the EC oxidation and did not reappear in the effluent of the UASB reactor. Phenylacetic acid, 3-methyl-indole and N-cyclohexyl-acetamide, called the second group, were completely removed, but reappeared in the UASB reactor. 4-methyl-phenol, 3,4-dihydroisoquinoline, 2(3H)-benzothiazolone, exo-2-hydroxycineole and benzothiazole, the third group, were degraded little in the EC oxidation process, but extensively removed by the anaerobic process. Benzoic acid, benzenepropanoic acid and 2-cyano-3,5-dimethyl-1-hydroxypyrrole, the fourth group, concentration obviously increased in the EC process, but was completely removed in the UASB reactor. The content of volatile fatty acids (VFAs) markedly increased from 0.68% in the leachate to 16.18% in the effluent from the electrochemical oxidation process (ECeffl). In addition, the degradation rate of organic compounds from the landfill leachate was different in the EC oxidation and anaerobic process. [ABSTRACT FROM AUTHOR]

Studies an aneorobic process for treating waste beer. Key features of the process; Analysis of pertinent topics and relevant issues; Implications on chemical engineering and environmental management.

SummaryA mesophilic 50-L upflow anaerobic sludge bed bioreactor (UASB) design was evaluated for the treatment of a sugar rich effluent from the canning industry. The UASB was inoculated with 1670 g anaerobic granules to give a granule bed height of 141 mm. After the system had stabilized the hydraulic retention time (HRT) was set at 24 h, the bioreactor substrate pH poised at 7.5 to prevent rapid acidification and the chemical oxygen demand (COD) increased to a full strength of 4000 mg.L–1. In the first experimental study (I) the organic loading rate (OLR) was increased by shortening the HRT from 24 to 8 h to give an OLR increase from 4.0 to 9.2 kgCOD.m–3.d–1 with an average COD removal of 81–84% and removal rate of 7.5 kgCOD.m–3.d–1. A HRT of 10 h was taken as the optimum operational HRT, as the recovery rate of the system at HRTs lower than 10 h were found to be longer than at longer HRTs. However, the data clearly showed that the bioreactor had not reached its optimal loading capacity, which was confirmed by the constant increase in the granule bed height. Since neutralization costs would influence the economic aspects of the process, the influence of lower pH values was investigated and the pH of the canning effluent was reduced from 7.5 to 5.0. At the lower pH, the COD removal remained fairly constant between 79 and 82%, with an alkalinity level of 700 mg.L–1 and a bioreactor effluent pH value of 6.5. It was clear from the low effluent pH that the lower end of the operational pH had been reached and further lowering of the substrate pH would lead to system failure. An increase of 144% in the granule bed height was found over the whole study period and the diameter of the granules obtained varied from below 1.0 mm to about 4.0 mm. The data from this study showed that the UASB system could successfully be used to treat canning effluents at short... [ABSTRACT FROM AUTHOR]