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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.

AbstractThe 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.

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Citations
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Journal ArticleDOI
TL;DR: The findings further demonstrate the strong influence of ammonia on the methane-producing consortia and on the representative methanization pathway in mesophilic biogas reactors.
Abstract: The importance of syntrophic acetate oxidation for process stability in methanogenic systems operating at high ammonia concentrations has previously been emphasized. In this study we investigated bioaugmentation of syntrophic acetate-oxidizing (SAO) cultures as a possible method for decreasing the adaptation period of biogas reactors operating at gradually increased ammonia concentrations (1.5 to 11 g NH4+-N/liter). Whole stillage and cattle manure were codigested semicontinuously for about 460 days in four mesophilic anaerobic laboratory-scale reactors, and a fixed volume of SAO culture was added daily to two of the reactors. Reactor performance was evaluated in terms of biogas productivity, methane content, pH, alkalinity, and volatile fatty acid (VFA) content. The decomposition pathway of acetate was analyzed by isotopic tracer experiments, and population dynamics were monitored by quantitative PCR analyses. A shift in dominance from aceticlastic methanogenesis to SAO occurred simultaneously in all reactors, indicating no influence by bioaugmentation on the prevailing pathway. Higher abundances of Clostridium ultunense and Tepidanaerobacter acetatoxydans were associated with bioaugmentation, but no influence on Syntrophaceticus schinkii or the methanogenic population was distinguished. Overloading or accumulation of VFA did not cause notable dynamic effects on the population. Instead, the ammonia concentration had a substantial impact on the abundance level of the microorganisms surveyed. The addition of SAO culture did not affect process performance or stability against ammonia inhibition, and all four reactors deteriorated at high ammonia concentrations. Consequently, these findings further demonstrate the strong influence of ammonia on the methane-producing consortia and on the representative methanization pathway in mesophilic biogas reactors.

163 citations


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

  • ...Bioaugmentation, in terms of adding specific microorganisms or enriched consortia to anaerobic processes to enhance a desired activity, has been reported to lead to improvements in degradation of specific organic compounds (9, 13, 16), such as cellulose-containing biomass (6) and manure (25), start-up of new reactors (28), odor...

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Journal ArticleDOI
01 Jan 2015
TL;DR: More work is required to realize robust, quantitative relationships between microbial community structure and functions such as methane production rate and resilience after perturbations and to describe microbial communities in digester function.
Abstract: Anaerobic digestion (AD) involves a consortium of microorganisms that convert substrates into biogas containing methane for renewable energy. The technology has suffered from the perception of being periodically unstable due to limited understanding of the relationship between microbial community structure and function. The emphasis of this review is to describe microbial communities in digesters and quantitative and qualitative relationships between community structure and digester function. Progress has been made in the past few decades to identify key microorganisms influencing AD. Yet, more work is required to realize robust, quantitative relationships between microbial community structure and functions such as methane production rate and resilience after perturbations. Other promising areas of research for improved AD may include methods to increase/control (1) hydrolysis rate, (2) direct interspecies electron transfer to methanogens, (3) community structure–function relationships of methanogens, (4) methanogenesis via acetate oxidation, and (5) bioaugmentation to study community–activity relationships or improve engineered bioprocesses.

136 citations

Journal ArticleDOI
TL;DR: In conclusion, bioaugmentation with an H(2)-utilizing culture is a potential tool to decrease the recovery period, decrease propionate concentration, and increase biogas production of some anaerobic digesters after a toxic event.
Abstract: Bioaugmentation was investigated as a method to decrease the recovery period of anaerobic digesters exposed to a transient toxic event Two sets of laboratory-scale digesters (SRT = 10 days, OLR = 2 g COD/L-day), started with inoculum from a digester stabilizing synthetic municipal wastewater solids (MW) and synthetic industrial wastewater (WW), respectively, were transiently exposed to the model toxicant, oxygen Bioaugmented digesters received 12 g VSS/L-day of an H2-utilizing culture for which the archaeal community was analyzed Soon after oxygen exposure, the bioaugmented digesters produced 25–60% more methane than non-bioaugmented controls (p < 005) One set of digesters produced lingering high propionate concentrations, and bioaugmentation resulted in significantly shorter recovery periods The second set of digesters did not display lingering propionate, and bioaugmented digesters recovered at the same time as non-bioaugmented controls The difference in the effect of bioaugmentation on recovery may be due to differences between microbial communities of the digester inocula originally employed In conclusion, bioaugmentation with an H2-utilizing culture is a potential tool to decrease the recovery period, decrease propionate concentration, and increase biogas production of some anaerobic digesters after a toxic event Digesters already containing rapidly adaptable microbial communities may not benefit from bioaugmentation, whereas other digesters with poorly adaptable microbial communities may benefit greatly

105 citations


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

  • ...For anaerobic processes, bioaugmentation has been investigated at laboratory scale to improve start-up of new digesters (Saravanane et al., 2001a,b), odor reduction (Duran et al., 2006; Tepe et al., 2008), and recovery after organic overload (Lynch et al., 1987)....

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Journal ArticleDOI
TL;DR: Fluorescence in situ hybridization indicated that probably an archaeal population shift was responsible for the observed stimulations and an addition of compost induced a methanogenic community change towards hydrogenotrophic methanogens.
Abstract: The influence of compost as inoculum during continuous anaerobic digestion of fodder beet silage was studied over 330 days. Two simultaneously driven mesophilic fermentors (Inoc-1/Inoc-2) were inoculated with manure and sewage sludge. Only the digester Inoc-2 was inoculated additionally with compost. After 160 days fermentor Inoc-2 reached a hydraulic retention time (HRT) around 15 days whereas Inoc-1 remained at a HRT of 40d. After changing the substrate feed from one to three times a day both digesters stabilised at a shorter HRT; Inoc-2 at 10 days and Inoc-1 around 20 days. An additional inoculation of fermentor Inoc-1 by compost shortened the HRT to 10 days and revealed a minor increased gas production of about 6%. Fluorescence in situ hybridization indicated that probably an archaeal population shift was responsible for the observed stimulations. An addition of compost induced a methanogenic community change towards hydrogenotrophic methanogens.

33 citations

04 Mar 2011
TL;DR: Changing in the organic loading affected the treatment performance of the anaerobic reactor, and at high OLRs, it was not able to withstand the short HRT, probably due to the complexity of pharmaceutical wastewater.
Abstract: The wastewater generated from pharmaceutical industry generally contain high organic load and the treatment is primarily carried out using two major types of biological methods; aerobic and anaerobic. However, due to high strength, it is infeasible to treat some pharmaceutical wastewater using aerobic biological processes. As an alternative, an anaerobic process is preferred to remove high strength organic matter. Anaerobic wastewater treatment is considered as the most cost effective solution for organically polluted industrial waste streams. In particular the development of high rate systems, in which hydraulic retention times (HRT) are uncoupled from solids retention times (SRT), has led to a worldwide acceptance of anaerobic wastewater treatment. In this paper, literature on anaerobic digestion, anaerobic reactor technology and existing anaerobic treatment of pharmaceutical wastewater are presented. In addition, fate of pharmaceuticals in the environment was also discussed in brief. A case study of a laboratory investigation into the treatment of pharmaceutical wastewater containing the antibiotic Tylosin in an anaerobic reactor was also given. Specifically, it was determined whether the anaerobic reactor could be used as a pre-treatment system at an existing pharmaceutical production plant. The performance of the reactor treating real pharmaceutical wastewater at various organic loading rate (OLR) was investigated and showed efficient substrate removal at low OLRs (0.43 - 1.86 kg COD.m -3 .d -1 ) by promoting efficient chemical oxygen demand (COD) reduction (70 - 75%). Under these conditions, an average of 95% Tylosin reduction was achieved in the UASR. However, increasing the OLRs to 3.73 kg COD.m -3 .d -1 by reducing the hydraulic retention time (HRT) (4 - 2 d) reduced the COD removal efficiency (45%). Changes in the organic loading affected the treatment performance of the anaerobic reactor, and at high OLRs, it was not able to withstand the short HRT, probably due to the complexity of pharmaceutical wastewater.

19 citations


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

  • ...Furthermore, they also adventured into studying on bioaugmentation and treatment of Cephalexin drug based pharmaceutical effluent in an up-flow anaerobic fluidized bed (UAFB) system [28]....

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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

452 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.

272 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: 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.

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