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Journal ArticleDOI

Bioaugmentation and anaerobic treatment of pharmaceutical effluent in fluidized bed reactor.

TL;DR: The start-up of an anaerobic fluidized bed reactor was carried out using a single inoculum and later on with multiple inoculum to achieve a faster start- up and the effect of hydraulic retention time (HRT) on COD removal (%) and biogas production was studied.
Abstract: The start-up of an anaerobic fluidized bed reactor was carried out using a single inoculum (supernatant of anaerobic digester) and later on with multiple inoculum (a mixture of supernatant of anaerobic digester and volatile fatty acid (VFA)) to achieve a faster start-up. Then regular experiments were carried out to study the effect of hydraulic retention time (HRT) on COD removal (%) and biogas production. The pharmaceutical effluent with COD of 2000 to 4000 mg/L was treated in a fluidized bed reactor using an enricher-reactor concept with a hydraulic retention times of 3 (Uf = 6 Umf) to 24 (Uf = 1.5 Umf) hr. The maximum COD removal (%) of 91.2 and a maximum biogas production of 5.62 L/d were obtained at 24 hr HRT for a maximum COD concentration of 4000 mg/L corresponding to a fluidization velocity (Uf) of 20 m/hr (1.5 Umf) using a granular activated carbon bed of average size 700 microns.
Citations
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18 Sep 2012
TL;DR: It was hypothesized that through routine bioaugmentation with cellulolytic microorganisms, a microbial population better suited for degradation of lignocellulosic material could be achieved and maintained, thereby increasing the rate of hydrolysis and ultimately increasing the rates of methane production.
Abstract: In this study, two methods for improving anaerobic digestion processes were investigated. The first method was routine bioaugmentation and the second was alkaline pretreatment. Both of these methods were applied to a two-phase anaerobic digestion process for treating the residuals from sweet corn processing, which have a significant lignocellulosic fraction as well as some starch from the base of the kernels. The two-phase anaerobic digestion process was proposed as one component of a larger integrated anaerobic/aerobic waste treatment process in which four co-products would be generated namely, methane-rich biogas, fertilizer, single cell protein, and algal biomass. The first objective of this study was to determine whether bioaugmentation with a cellulolytic bioculture would result in increased methane production compared to a non-bioaugmented control condition. Batch tests were conducted to compare the biogas potential of sweet corn processing residues with and without bioaugmentation using a proprietary cellulolytic bioculture. The results indicated that bioaugmentation was beneficial to digestion performance, increasing the average methane production by 34% compared to non-bioaugmented controls (265 versus 199 ml/g VSadded). The average rate of methane production was also increased in the bioaugmented condition compared to non-bioaugmented controls. However, the observed total methane production was relatively low in comparison to the maximum theoretical production (415 ml CH4/g VSadded), suggesting there to be room for further improving digestion efficiency. The second objective of this study was to verify whether routine bioaugmentation with cellulolytic microorganisms benefited substrate hydrolysis and subsequent methane production compared to one-time bioaugmentation. It was hypothesized that through routine bioaugmentation with cellulolytic microorganisms, a microbial population better suited for degradation of lignocellulosic material could be achieved and maintained, thereby increasing the rate of hydrolysis and ultimately increasing the rate of methane production. Pursuant to this objective, a two-phase sequencing/semi batch experiment was conducted in which routine bioaugmentation with two sources of cellulolytic microorganisms was compared to one-time bioaugmented and non-bioaugmented conditions. Neutral detergent fiber (NDF) analysis and net soluble chemical oxygen demand (sCOD) generation suggested that routine bioaugmentation improved substrate hydrolysis by 22-25% in comparison to one-time bioaugmentation after 14 days of operation. Methane yields from routine bioaugmented conditions using a proprietary cellulolytic bioculture also showed 15% higher methane production was achieved in comparison to one-time bioaugmentation after 36 days of digestion. In this experiment, bioaugmentation with a proprietary cellulolytic bioculture was compared to bioaugmentation with dairy cattle rumen fluid. The rumen bioaugmentation culture produced higher methane yields than the proprietary bioculture (16-34%).…

10 citations

Journal ArticleDOI
TL;DR: Feedstock sterilization through thermal pretreatment strongly impacted anaerobic digestion process stability, due to feedstock inoculation and compositional modification.
Abstract: Strategies to enhance process performance of anaerobic digestion remain of key importance to promote wider usage of this technology for integrated resource recovery from organic waste streams. Continuous inoculation of the microbial community in the digester via the feedstock could be such a cost-effective strategy. Here, anaerobic digestion of fresh waste activated sludge (WAS) was compared with sterilized WAS in response to two common process disturbances, i.e. organic overloading and increasing levels of salts, to determine the importance of feedstock inoculation. A pulse in the organic loading rate severely impacted process stability of the digesters fed sterile WAS, with a 92 +/- 45% decrease in methane production, compared to a 42 +/- 31% increase in the digesters fed fresh WAS, relative to methane production before the pulse. Increasing salt pulses did not show a clear difference in process stability between the digesters fed fresh and sterile WAS, and process recovery was obtained even at the highest salt pulse of 25 g Na+ L-1. Feedstock sterilization through thermal pretreatment strongly impacted the microbial community in the digesters. In conclusion, feedstock thermal pretreatment strongly impacted anaerobic digestion process stability, due to feedstock inoculation and compositional modification.

6 citations

Patent
04 Apr 2011
TL;DR: In this article, methods for improving performance of an anaerobic digester system are presented. The methods typically include adding a culture comprising hydrogenotrophic methanogens to the system, otherwise referred to as bioaugmentation.
Abstract: Disclosed herein are methods for improving performance of an anaerobic digester system. The methods typically include adding a culture comprising hydrogenotrophic methanogens to the system, otherwise referred to as bioaugmentation.

6 citations

01 Jan 2010
TL;DR: Results indicated that there was a relation between SMA and methanogenic community compositions studied, and bioaugmentation helped restore the microbial communities of overloaded digesters to their original undisturbed state.
Abstract: BIOAUGMENTATION FOR RECOVERY OF ANAEROBIC DIGESTERS SUBJECTED TO ORGANIC OVERLOAD Vaibhav P. Tale, B.Tech., M.Tech. Marquette University, 2010 Anaerobic digester upset due to organic overload is common and methods to reduce recovery time would be beneficial. One potential method is bioaugmentation, adding an external culture for performance improvement. Methanogenic community structure differs from digester to digester and there may exist a relation between specific methanogenic activity (SMA) and microbial community composition. The research presented herein tested whether there is a relationship between SMA and community structure. Also, the effectiveness of bioaugmentation was tested by hypothesizing that bioaugmenting with a methanogenic, propionate-degrading culture acclimated to small oxygen doses will help rapid recovery of organically overloaded digesters. Fourteen different anaerobic cultures were tested for SMA and microbial community using the mcrA gene and DGGE to establish a relationship between SMA and community structure. The culture with the highest SMA was enriched by feeding 0.17g propionate/L-day and different oxygen doses. The enrichment cultures were used to bioaugment organically overloaded anaerobic digesters. Microbial communities present in bioaugmented, non-bioaugmented control and undisturbed control digesters as well as the bioaugmentation culture were analyzed using 16S rDNA. A statistically significant relationship between SMA and community structure could not be established highlighting the difficulty in establishing activity/community structure relationships. However, the results indicated that there was a relation between SMA and methanogenic community compositions studied. Enriching a culture for 25mgO2/L-day increased its SMA by 29.7%, but higher oxygen doses yielded lower SMA values. Bioaugmentation with this enrichment culture reduced the time required for upset digester effluent to decrease below 1000mgSCOD/L by 108 days (10.8 SRTs) and the time required to reach 25mLCH4/day by 37 days (3.7 SRTs) respectively. Bioaugmented digesters consistently produced lower effluent SCOD and more methane than non-bioaugmented controls. Bioaugmentation is a promising approach for speeding up recovery of organically overloaded digesters. Bacterial and archaeal communities of the bioaugmented and undisturbed control digesters had similar phylogenetic tree structures (p>0.3), whereas the tree structures of non-bioaugmented and undisturbed control digesters differed significantly (p<0.01). Bioaugmentation helped restore the microbial communities of overloaded digesters to their original undisturbed state. Higher relative abundance of clones related to Methanospirillum hungatei may have caused better performance of bioaugmented

5 citations


Cites background from "Bioaugmentation and anaerobic treat..."

  • ...73 Saravanane et al. (2001) bioaugmented fluidized bed reactors with a cephalexin- enriched anaerobic culture to evaluate cephalexin-degrading behavior of the reactor....

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Journal ArticleDOI
TL;DR: In this article , the adverse effects of antibiotics on biogas yield and COD removal in anaerobic reactor technologies for antibiotic wastewater treatment have been discussed and perspectives have been given for understanding the fate and elimination of antibiotics from AD.

5 citations

References
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Journal ArticleDOI
TL;DR: The metabolism of toluene, phenol, and p-cresol by GS-15 provides a model for how aromatic hydrocarbons and phenols may be oxidized with the reduction of Fe(III) in contaminated aquifers and petroleum-containing sediments.
Abstract: The dissimilatory Fe(III) reducer, GS-15, is the first microorganism known to couple the oxidation of aromatic compounds to the reduction of Fe(III) and the first example of a pure culture of any kind known to anaerobically oxidize an aromatic hydrocarbon, toluene. In this study, the metabolism of toluene, phenol, and p-cresol by GS-15 was investigated in more detail. GS-15 grew in an anaerobic medium with toluene as the sole electron donor and Fe(III) oxide as the electron acceptor. Growth coincided with Fe(III) reduction. [ring-14C]toluene was oxidized to 14CO2, and the stoichiometry of 14CO2 production and Fe(III) reduction indicated that GS-15 completely oxidized toluene to carbon dioxide with Fe(III) as the electron acceptor. Magnetite was the primary iron end product during toluene oxidation. Phenol and p-cresol were also completely oxidized to carbon dioxide with Fe(III) as the sole electron acceptor, and GS-15 could obtain energy to support growth by oxidizing either of these compounds as the sole electron donor. p-Hydroxybenzoate was a transitory extracellular intermediate of phenol and p-cresol metabolism but not of toluene metabolism. GS-15 oxidized potential aromatic intermediates in the oxidation of toluene (benzylalcohol and benzaldehyde) and p-cresol (p-hydroxybenzylalcohol and p-hydroxybenzaldehyde). The metabolism described here provides a model for how aromatic hydrocarbons and phenols may be oxidized with the reduction of Fe(III) in contaminated aquifers and petroleum-containing sediments. Images

463 citations


"Bioaugmentation and anaerobic treat..." refers methods in this paper

  • ...Anaerobic degradation of different constituents of antibiotic and synthetic drug based effluents were recently been carried out, using methanogenic organisms [6–9], sulphate reducing organisms [7, 10–12], nitrate reducing organisms [13–14] and iron reducing organisms [15]....

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Journal ArticleDOI
TL;DR: Preliminary evidence is presented that the first reaction in anaerobic phenol oxidation is phenol carboxylation to 4-hydroxybenzoate.
Abstract: From various oxic or anoxic habitats several strains of bacteria were isolated which in the absence of molecular oxygen oxidized phenol to CO2 with nitrate as the terminal electron acceptor. All strains grew in defined mineral salts medium; two of them were further characterized. The bacteria were facultatively anaerobic Gram-negative rods; metabolism was strictly oxidative with molecular oxygen, nitrate, or nitrite as electron acceptor. The isolates were tentatively identified as pseudomonads. Besides phenol many other benzene derivatives like cresols or aromatic acids were anaerobically oxidized in the presence of nitrate. While benzoate or 4-hydroxybenzoate was degraded both anaerobically and aerobically, phenol was oxidized under anaerobic conditions only. Reduced alicyclic compounds were not degraded. Preliminary evidence is presented that the first reaction in anaerobic phenol oxidation is phenol carboxylation to 4-hydroxybenzoate.

273 citations

Journal ArticleDOI
TL;DR: The stoichiometry of sulfate-reduction and substrate depletion by the various enrichment cultures indicated that the parent cresol isomers were completely mineralized, which helps clarify the fate of alkylated aromatic chemicals in anoxic aquifers.
Abstract: Sulfate-reducing bacterial enrichments were obtained from a shallow anoxic aquifer for their ability to metabolize eithero-, m-, orp-cresol. GC/MS and simultaneous adaptation experiments suggested that the anaerobic decomposition ofp-cresol proceeds by the initial oxidation of the aryl methyl group to formp-hydroxybenzoic acid. This intermediate was then converted to benzoic acid. Benzoic acid and a hydroxybenzaldehyde were also found in spent culture fluids from ano-cresol-degrading enrichment culture. This result, in addition to others, suggested thato-cresol may also be anaerobically degraded by the oxidation of the methyl substituent. An alternate pathway for anaerobicm-cresol decomposition might exist. Enrichment cultures obtained with eitherp- oro-cresol degraded both of these substrates but notm-cresol. In contrast, am-cresol enrichment culture did not metabolize theortho orpara isomers. Anaerobic biodegradation in all enrichment cultures was inhibited by molybdate and oxygen, and was dependent on the presence of sulfate as a terminal electron acceptor. The stoichiometry of sulfate-reduction and substrate depletion by the various enrichment cultures indicated that the parent cresol isomers were completely mineralized. This result was confirmed by the conversion of14C-labeledp-cresol to14CO2. These results help clarify the fate of alkylated aromatic chemicals in anoxic aquifers.

54 citations

Journal ArticleDOI
TL;DR: Results suggested that CO(2) incorporation occurred because each molecule of m-cresol contained seven carbon atoms, whereas four molecules of acetate product contained a total of eight carbon atoms.
Abstract: The metabolism of m-cresol by methanogenic cultures enriched from domestic sewage sludge was investigated. In the initial studies, bromoethanesulfonic acid was used to inhibit methane production. This led to the accumulation of 4.0 ± 0.8 mol of acetate per mol of m-cresol metabolized. These results suggested that CO2 incorporation occurred because each molecule of m-cresol contained seven carbon atoms, whereas four molecules of acetate product contained a total of eight carbon atoms. To verify this, [14C]bicarbonate was added to bromoethanesulfonic acid-inhibited cultures, and those cultures yielded [14C]acetate. Of the label recovered as acetate, 89% was found in the carboxyl position. Similar cultures fed [methyl-14C]m-cresol yielded methyl-labeled acetate. A 14C-labeled transient intermediate was detected in cultures given either m-cresol and [14C]bicarbonate or bicarbonate and [methyl-14C]m-cresol. The intermediate was identified as 4-hydroxy-2-methylbenzoic acid. In addition, another metabolite was detected and identified as 2-methylbenzoic acid. This compound appeared to be produced only sporadically, and it accumulated in the medium, suggesting that the dehydroxylation of 4-hydroxy-2-methylbenzoic acid led to an apparent dead-end product.

53 citations

Journal ArticleDOI
TL;DR: In this article, anaerobic biodegradation of m-cresol was observed in anoxic aquifer slurries kept under both sulfate-reducing and nitrate reducing but not methanogenic conditions.
Abstract: The anaerobic biodegradation of m-cresol was observed in anoxic aquifer slurries kept under both sulfate-reducing and nitrate-reducing but not methanogenic conditions. More than 85% of the parent substrate (300 microM) was consumed in less than 6 days in slurries kept under the former two conditions. No appreciable loss of the compound from the corresponding autoclaved controls was measurable. A bacterial consortium was enriched from the slurries for its ability to metabolize m-cresol under sulfate-reducing conditions. Metabolism in this enrichment culture was inhibited in the presence of oxygen or molybdate (500 microM) and in the absence of sulfate but was unaffected by bromoethanesulfonic acid. The consortium consumed 3.63 mol of sulfate per mol of m-cresol degraded. This stoichiometry is about 87% of that theoretically expected and suggests that m-cresol was largely mineralized. Resting-cell experiments demonstrated that the degradation of m-cresol proceeded only in the presence of bicarbonate. 4-Hydroxy-2-methylbenzoic acid and acetate were detected as transient intermediates. Thus, the parent substrate was initially carboxylated as the primary degradative event. The sulfate-reducing consortium could also decarboxylate p- but not m-hydroxybenzoate to near stoichiometric amounts of phenol, but this reaction was not sulfate dependent. The presence of p-hydroxybenzoate in the medium temporarily inhibited m-cresol metabolism such that the former compound was metabolized prior to the latter and phenol was degraded in a sequential manner. These findings help clarify the fate of a common groundwater contaminant under sulfate-reducing conditions.

52 citations