[show abstract][hide abstract] ABSTRACT: The role of anaerobic digestion (AD) on the decontamination and biomethanization of a PCB-spiked sludge obtained from a Membrane Biological Reactor (MBR) pilot plant was investigated throughout a 10-month batch experiment. The study was carried out under mesophilic (35°C) and thermophilic (55°C) conditions and was monitored by means of an integrated chemical, microbiological and molecular biology strategy. Remarkable PCB depletions (higher than 50% of the overall spiked PCBs) and dechlorinations were achieved under methanogenic conditions. The process was not affected by yeast extract addition. Both acetoclastic and hydrogenotrophic methanogens, together with some fermentative eubacteria, were found to persist in all PCB biodegrading microcosms. This finding, together with those obtained from parallel microcosms where specific populations were selectively inhibited, suggested that native methanogens played a key role in the biodegradation and dechlorination of the spiked PCBs. Taken together, the results of this study indicate that AD is a feasible option for the decontamination and the efficient disposal (with the production of a CH(4)-rich biogas) of contaminated MBR sludge, which can be then employed as a fertilizer for agricultural purposes.
Journal of hazardous materials 02/2011; 186(2-3):2060-7. · 4.14 Impact Factor
[show abstract][hide abstract] ABSTRACT: The recovery of polyphenols from olive mill wastewaters (OMWs) decreases the toxicity of the effluent and permits the obtainment of high-added value natural antioxidants. Solid phase extraction (SPE) represents a valuable approach to obtain polyphenols from OMWs, since it relies on simple, cheap and environmental friendly procedures and agents. In this work, five resins with different physical properties, namely Amberlite XAD4, XAD7, XAD16, IRA96 and Isolute ENV+, were tested in parallel for their adsorption and desorption features towards an aqueous solution of ten target phenolic compounds typically occurring in OMWs. Water, methanol and ethanol, also under basic and acidified conditions, were tested as possible desorbing agents. Adsorption isotherms related to the mixture of all phenols and to each single phenol were determined. Experimental data well fitted with Langmuir isotherm model. The highest phenol adsorption (76%) was achieved with IRA96 polar resin. Conversely, non-polar adsorbents allowed higher desorption ratios. Almost 60% of the overall phenols originally occurring in the applied mixture were recovered by employing ENV+ and ethanol as the desorbing phase. Lower performances were achieved with the other recovery and desorption agents. The compound polarity generally influenced the adsorption ratios (the sorption capacities of non-polar resins increased by decreasing the compound polarity, and vice versa), while the desorption ones were not always affected by such a compound feature. These findings are of special interest in the perspective of developing an effective SPE procedure for the recovery of natural phenols from real OMWs.
Chemical Engineering Journal. 01/2011; 166(3):994-1001.
[show abstract][hide abstract] ABSTRACT: The recovery of polyphenols from olive mill wastewaters (OMWs) provides the double opportunity to obtain high-added value biomolecules and to reduce the phytotoxicity of the effluent. In this work, a solid phase extraction procedure for the recovery of OMW phenolic compounds recently developed on water solutions was applied and assessed on two different actual site OMWs. To this aim, the four most promising resins employed in the previous work, namely Amberlite XAD7, XAD16, IRA96 and Isolute ENV+, were tested and compared for their adsorption and desorption features towards the natural phenols occurring in the two real OMWs. Water, methanol and ethanol, also acidified with HCl 0.5 ml/100 mL, were tested as possible desorbing agents. Adsorption isotherms related to total phenols and to hydroxytyrosol, i.e., the most abundant (about 0.6 g L−1) and valuable phenolic compound detected in the employed OMWs, were determined. Generally, all experimental data were well fitted with Freundlich isotherm model. The highest total phenols adsorption was achieved with ENV+ resin, which adsorbed almost completely the OMW hydroxytyrosol. The highest desorption ratios were generally obtained with acidified ethanol, which mobilized almost all polyphenols adsorbed onto resins ENV+, XAD7 and XAD16. Considering the integrated adsorption–desorption processes, ENV+ allowed to achieve (a) the highest recovery of total phenols when elution was done with acidified ethanol and (b) the highest specific recovery of hydroxytyrosol when non-acidified ethanol was used as the desorbing phase.Highlights► We assessed a solid phase extraction procedure for the recovery of natural polyphenols from olive mill wastewaters. ► Comparison among the adsorption/desorption performances of four commercially available resins was done. ► Isolute ENV+ resin allowed the highest overall phenol recovery. ► The chemical features of olive mill wastewaters can affect the process productivities.
Chemical Engineering Journal. 01/2011; 171(3):1287-1293.
[show abstract][hide abstract] ABSTRACT: Four identically configured anaerobic packed bed biofilm reactors were developed and employed in the continuous acidogenic digestion of olive mill wastewaters to produce volatile fatty acids (VFAs), which can be exploited in the biotechnological production of polyhydroxyalkanoates. Ceramic porous cubes or granular activated carbon were used as biofilm supports. Aside packing material, the role of temperature and organic loading rate (OLR) on VFA production yield and mixture composition were also studied. The process was monitored through a chemical, microbiological and molecular biology integrated procedure. The highest wastewater acidification yield was achieved with the ceramic-based technology at 25 degrees C, with an inlet COD and an OLR of about 17 g/L and 13 g/L/day, respectively. Under these conditions, about the 66% of the influent COD (not including its VFA content) was converted into VFAs, whose final amount represented more than 82% of the influent COD. In particular, acetic, propionic and butyric acids were the main VFAs by composing the 55.7, 21.5 and 14.4%, respectively, of the whole VFA mixture. Importantly, the relative concentrations of acetate and propionate were affected by the OLR parameter. The nature of the packing material remarkable influenced the process performances, by greatly affecting the biofilm bacterial community structure. In particular, ceramic cubes favoured the immobilization of Firmicutes of the genera Bacillus, Paenibacillus and Clostridium, which were probably involved in the VFA producing process.
Water Research 08/2010; 44(15):4537-49. · 4.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: Xenobiotic compounds accumulate in activated sludge resulting from wastewater treatment plants serving both civil and industrial areas. The opportunity to use anaerobic digestion for the decontamination and beneficial disposal of a contaminated activated sludge was investigated in mesophilic and thermophilic microcosms monitored through an integrated chemical, microbiological and ecotoxicological procedure. The 10 months anaerobic sludge incubation at 35 degrees C resulted in an extensive production of a methane-rich biogas, a marked reduction of pathogenic cultivable bacteria and, importantly, a marked biodegradation of the sludge-carried organic pollutants, including some polychlorinated biphenyls and polycyclic aromatic hydrocarbons, along with a relevant sludge detoxification. The sludge decontamination seemed to occur mostly under methanogenic conditions and was not significantly affected by the addition of yeast extract or molasses. Lower bioremediation and biomethanization yields were observed under thermophilic conditions.
Water Research 07/2007; 41(11):2407-16. · 4.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: The opportunity to apply an immobilized-cell biotechnological process in the remediation of polyethoxylated nonylphenol (NPnEO) contaminated water was studied in this work. To this purpose, three identically configured aerobic column reactors packed with different materials (silica beads, granular activated carbon, or glass spheres) were developed, inoculated with the NPnEO-degrading Pseudomonas sp. strain BCb 12/3, and compared for their ability to biodegrade the two NPnEO industrial mixtures Igepal CO-520 and CO-210 fed in synthetic wastewater at concentrations in the range 30−90 mg/L. The three biofilm reactors, tested under batch conditions, showed comparable degradation capabilities and specificities, being able to remove from 77 to 99% of the total Igepal mixtures supplied after 9 days of batch treatment. NPnEOs were mostly removed through biodegradation, as suggested by the accumulation of two metabolites typical of NPnEO aerobic biodegradation, such as phenol and 4-nonylphenol, and by the low NPnEO amounts recovered from the reactors at the end of the study. Fluorescent in situ hybridization and DAPI staining performed at the end of the study showed that the bacterial biofilm was well and homogenously developed on the packed beds of the three reactors and that it was mostly composed by bacteria belonging to Gammaproteobacteria, i.e., the Proteobacteria class which includes the genus Pseudomonas.
Industrial & Engineering Chemistry Research - IND ENG CHEM RES. 03/2007; 46(21).
[show abstract][hide abstract] ABSTRACT: Surfactant-aided soil washing is often proposed for the restoration of aged organic pollutant-contaminated soils. As many of commercial surfactants have been found to be toxic and recalcitrant, the opportunity to use in this process cheap, non-toxic, and biodegradable pollutant-mobilizing agents, such as deoxycholic acid (DA), bovine bile (BB), and the residue resulting from DA extraction from BB (BBR), was studied in this work. A soil historically contaminated by chlorinated anilines and benzenes, thiophenes, and several polycyclic aromatic hydrocarbons was suspended at 15% w/v and washed in water or water amended at 1.0% (w/v) with DA, BB, BBR, or Triton X-100 (TX). The resulting effluents were supplemented with nutrients and subjected to aerobic bioremediation. The biogenic agents enhanced the water pollutant elution potential by 230/440%. TX enhanced the same parameter by about 540%; however, it mediated a lower depletion of the initial soil ecotoxicity and a more extensive mobilization of soil constituents with respect to the biogenic agents. Furthermore, TX adversely affected the biotreatability of resulting effluents, by adversely affecting the growth of cultivable bacterial biomass and the structure of eubacterial community of the effluent. On the contrary, the biogenic agents, and in particular DA and BB, enhanced the effluents bioremediation, by sustaining the growth and increasing the complexity of the effluent eubacterial communities. Thus, DA and BB are very promising additives for an effective and environmental friendly soil washing treatment of aged (chloro)organics contaminated soils.
Biotechnology and Bioengineering 04/2006; 93(4):761-70. · 3.65 Impact Factor
[show abstract][hide abstract] ABSTRACT: Olive mill wastewater (OMW) is the aqueous effluent of olive oil producing processes. Given its high COD and content of phenols, it has to be decontaminated before being discharged. Anaerobic digestion is one of the most promising treatment process for such an effluent, as it combines high decontamination efficiency with methane production. The large scale anaerobic digestion of OMWs is normally conducted in dispersed-growth reactors, where however are generally achieved unsatisfactory COD removal and methane production yields. The possibility of intensifying the performance of the process using a packed bed biofilm reactor, as anaerobic treatment alternative, was demonstrated. Even in this case, however, a post-treatment step is required to further reduce the COD. In this work, a biological post-treatment, consisting of an aerobic biological "Manville" silica bead-packed bed aerobic reactor, was developed, tested for its ability to complete COD removal from the anaerobic digestion effluents, and characterized biologically through molecular tools.
The aerobic post-treatment was assessed through a 2 month-continuous feeding with the digested effluent at 50.42 and 2.04 gl(-1)day(-1) of COD and phenol loading rates, respectively. It was found to be a stable process, able to remove 24 and 39% of such organic loads, respectively, and to account for 1/4 of the overall decontamination efficiency displayed by the anaerobic-aerobic integrated system when fed with an amended OMW at 31.74 and 1.70 gl(-1)day(-1) of COD and phenol loading rates, respectively. Analysis of 16S rRNA gene sequences of biomass samples from the aerobic reactor biofilm revealed that it was colonized by Rhodobacterales, Bacteroidales, Pseudomonadales, Enterobacteriales, Rhodocyclales and genera incertae sedis TM7. Some taxons occurring in the influent were not detected in the biofilm, whereas others, such as Paracoccus, Pseudomonas, Acinetobacter and Enterobacter, enriched significantly in the biofilter throughout the treatment.
The silica-bead packed bed biofilm reactor developed and characterized in this study was able to significantly decontaminate anaerobically digested OMWs. Therefore, the application of an integrated anaerobic-aerobic process resulted in an improved system for valorization and decontamination of OMWs.
[show abstract][hide abstract] ABSTRACT: Two laboratory scale biofilm bioreactors of identical configuration were set up and tested for the continuous treatment of waters artificially contaminated with simple or complex mixtures of low chlorinated biphenyls (PCBs) and chlorobenzoic acids (CBAs). Frosted glass beads and polyurethane foam cubes were employed as immobilization supports. A three-membered aerobic bacterial co-culture, that was previously shown to have a high degradation and dechlorination activity towards PCBs in fixed bed batch bioreactors, was used to inoculate both biofilm reactors. The two bioreactors developed, operating in a continuous mode, were both capable of degrading and stoichiometrically dechlorinating the PCBs and CBAs present in the influent. The PCB degradation and dechlorination efficiency of the reactors did not decrease by increasing the organic load or by changing the influent composition, thus indicating a good stability and versatility of the developed process.
Process Biochemistry - PROCESS BIOCHEM. 01/2006; 41(4):935-940.
[show abstract][hide abstract] ABSTRACT: The occurrence of reductive dechlorination processes towards pre-existing PCBs and five exogenous coplanar PCBs were investigated
in a contaminated sediment of Porto Marghera (Venice Lagoon, Italy) suspended, under strictly anaerobic conditions, in water
collected from the same site. PCB dechlorination started after five months of incubation, when sulfate initially occurring
in the microcosms was completely depleted and methanogenesis was in progress. It was ascribed to sulfate-reducing bacteria.
Several pre-existing hexa-, penta- and tetra-chlorinated biphenyls were slowly bioconverted into tri- and di-, ortho-substituted PCBs from the 5th to the 16th month of experiment. Spiked coplanar PCBs, i.e., 3,3′,4,4′-tetrachlorobiphenyl,
3,3′,4,4′,5- and 2,3′,4,4′,5-pentachlorobiphenyls, 3,3′,4,4′,5,5′- and 2,3,3′,4,4′,5-hexachlorobiphenyls, were extensively
transformed (by about 90%) into lower chlorinated congeners, such as 3,3′,5,5′-/2,3′,4,4′-tetrachlorobiphenyl, 3,3′,5-, 2,4,4′-,
2,3′,4- and 2,3′,5-trichlorobiphenyl, 3,4-/3,4′- and 3,3′-dichlorobiphenyl and 2-chlorobiphenyl. The reductive dechlorination
of spiked PCBs did not influence significantly the biotransformation rate and extent of pre-existing PCBs.
[show abstract][hide abstract] ABSTRACT: The high hydrophobicity of polycyclic aromatic hydrocarbons (PAHs) strongly reduces their bioavailability in aged contaminated soils, thus limiting their bioremediation. The biodegradation of PAHs in soils can be enhanced by employing surface-active agents. However, chemical surfactants are often recalcitrant and exert toxic effects in the amended soils. The effects of two biogenic materials as pollutant-mobilizing agents on the aerobic bioremediation of an aged-contaminated soil were investigated here. A soil historically contaminated by about 13 g kg(-1) of a large variety of PAHs, was amended with soya lecithin (SL) or humic substances (HS) at 1.5% w/w and incubated in aerobic solid-phase and slurry-phase reactors for 150 days. A slow and only partial biodegradation of low-molecular weight PAHs, along with a moderate depletion of the initial soil ecotoxicity, was observed in the control reactors. The overall removal of PAHs in the presence of SL or HS was faster and more extensive and accompanied by a larger soil detoxification, especially under slurry-phase conditions. The SL and HS could be metabolized by soil aerobic microorganisms and enhanced the occurrence of both soil PAHs and indigenous aerobic PAH-degrading bacteria in the reactor water phase. These results indicate that SL and HS are biodegradable and efficiently enhance PAH bioavailability in soil. These natural surfactants significantly intensified the aerobic bioremediation of a historically PAH-contaminated soil under treatment conditions similar to those commonly employed in large-scale soil bioremediation.
Biotechnology and Bioengineering 11/2004; 88(2):214-23. · 3.65 Impact Factor
[show abstract][hide abstract] ABSTRACT: Anaerobic digestion is one of the most promising technologies for disposing olive mill wastewaters (OMWs). The process is generally carried out in the conventional contact bioreactors, which however are often unable to efficiently remove OMW phenolic compounds, that therefore occur in the effluents. The possibility of mitigating this problem by employing an anaerobic OMW-digesting microbial consortium passively immobilized in column reactors packed with granular activated carbon (GAC) or "Manville" silica beads (SB) was here investigated. Under batch conditions, both GAC- and SB-packed-bed biofilm reactors exhibited OMW COD and phenolic compound removal efficiencies markedly higher (from 60% to 250%) than those attained in a parallel anaerobic dispersed growth reactor developed with the same inoculum; GAC-reactor exhibited COD and phenolic compound depletion yields higher by 62% and 78%, respectively, than those achieved with the identically configured SB-biofilm reactor. Both biofilm reactors also mediated an extensive OMW remediation under continuous conditions, where GAC-reactor was much more effective than the corresponding SB-one, and showed a tolerance to high and variable organic loads along with a volumetric productivity in terms of COD and phenolic compound removal significantly higher than those averagely displayed by most of the conventional and packed-bed laboratory-scale reactors previously proposed for the OMW digestion.
Water Research 01/2004; 38(14-15):3167-78. · 4.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: The biological removal of polychlorinated biphenyls (PCBs) from contaminatedsoils is adversely affected by the poor bioavailability of these pollutants. Twodifferent aged-contaminated soils containing about 890 and 8500 mg/kg of PCBswere supplemented with biphenyl and treated in slurry- and solid-phase aerobic0.5 litre-microcosms in the presence of RAMEB at 0, 0.5, 1.0, 3.0% (w/w). RAMEB,which was non-toxic and slowly biodegraded by the soil microorganisms, significantlyenhanced the bioavailability (from 30 to 50%) and the biological degradation (from 15to 55%) and dechlorination of PCBs in both soils and treatment conditions. RAMEBeffects were dependent on the concentration at which it was applied, the soil featuresand the treatment conditions. RAMEB enhanced PCB biodegradation by increasingboth the PCB bioavailability and the availability of biodegrading bacteria in themicrocosms. RAMEB appears a promising bioavailability enhancing agent for thetreatment of PCB-contaminated soils, not only for its positive effects on the PCBsbiodegradation, but also for its biodegradability, non-toxicity and relatively low cost.
Journal of Inclusion Phenomena 11/2002; 44(1):417-421. · 1.40 Impact Factor
[show abstract][hide abstract] ABSTRACT: Seven aerobic bacterial strains capable of degrading several of the monocyclic aromatic compounds occurring in the phenolic fraction of olive-mill wastewaters (OMWs) were isolated from an Italian OMW. The results of the 16S rDNA restriction analysis evidenced that these strains are distributed among four different groups. One strain of each group was taxonomically characterized by sequencing the amplified 16S rDNA, and the four strains were assigned to the genera Comamonas (strain AV1A), Ralstonia (strain AV5BG), Pseudomonas (strain AV2A) and Sphingomonas (strain AV6C). The four strains, when checked for the ability to degrade nine monocyclic aromatic compounds abundant in OMWs, were found to significantly metabolize five to eight of them, both as resting cells and growing cells. Specific enzyme analyses of the same selected strains showed: (1) the occurrence of O-demethylating activities towards four methoxylated mono-aromatic acids in three of the four studied strains (strains AV1A, AV5BG and AV6C), (2) ring-cleavage activity towards protocatechuic acid in all of the strains, and (3) a ring-cleavage activity towards catechol in strain AV6C. The isolates described here exhibit a biodegradation potential towards monocyclic aromatic compounds of OMWs that is markedly broader and higher than that displayed by other aerobic bacteria described previously. These features make them excellent candidates for removing the low-molecular-weight phenolic compounds persisting in the effluent following anaerobic digestion of OMWs.
Archives of Microbiology 10/2002; 178(3):208-17. · 1.91 Impact Factor
[show abstract][hide abstract] ABSTRACT: Two bacterial strains, Ralstonia sp. LD35 and Pseudomonas putida DSM 1868, were assayed for their ability to degrade the monocyclic aromatic compounds commonly found in olive mill wastewaters (OMWs). The goal was to study the possibility of employing the two strains in the removal of these recalcitrant and toxic compounds from the effluents of anaerobic treatment plants fed with OMWs. At first, the two strains were separately assayed for their ability to degrade a synthetic mixture of nine aromatic acids present in OMWs, both in growing- and resting-cell conditions. Then, due to the complementary activity exhibited by the two strains, a co-culture of the two bacteria was tested under growing-cell conditions for degradation of the same synthetic mixture. Finally, the degradation activity of the co-culture on two fractions was studied. Both fractions one deriving from natural OMWs through reverse osmosis treatment and containing low-molecular weight organic molecules, and the other obtained from an anaerobic lab-scale treatment plant fed with OMWs, were rich in monocyclic aromatic compounds. The co-culture of the two strains was able to biodegrade seven of the nine components of the tested synthetic mix (2, 6-dihydroxybenzoic acid and 3, 4, 5-trimethoxybenzoic acid were the two undegraded compounds). In addition, an efficient biodegrading activity towards several aromatic molecules present in the two natural fractions was demonstrated.
Applied Microbiology and Biotechnology 06/2001; 55(5):619-26. · 3.69 Impact Factor
[show abstract][hide abstract] ABSTRACT: Two aerobic bacterial strains, a chlorophenol-degrading bacterium characterized in this work as a Ralstonia sp. LD35 on the basis of the sequence of the gene encoding for 16S ribosomal RNA, and Pseudomonas putida DSM 1868, capable of metabolizing 4-methoxybenzoic acid, were tested for their capacity to degrade monocyclic aromatic acids responsible for the toxicity of olive mill wastewaters (OMWs). Both strains possess interesting and complementary degradation capabilities in resting cell conditions: Ralstonia sp. LD35 was found to metabolize 4-hydroxybenzoic, 4-hydroxyphenylacetic, 3,4-dihydroxycinnamic and cinnamic acid, whereas DSM 1868 was capable of metabolizing 4-hydroxy-3-methoxybenzoic, 3,4-dimethoxybenzoic and 4-hydroxy-3,5-dimethoxybenzoic acid, as well as 4-hydroxybenzoic and 4-hydroxyphenylacetic acid. The kinetic parameters describing the growth of the two strains on the same compounds were determined in growing-cell batch conditions, and showed that both strains presented high affinity and high specific growth rates towards all assayed substrates. In addition, the two strains were capable of growing on and extensively biodegrading a mixture of monocyclic aromatic acids commonly found at high concentrations in OMWs, and of growing on a 20% dilution of a natural OMW. All these features make the two strains attractive candidates for the development of a biotechnological process for the biodegradation of aromatic compounds found in OMWs.
Research in Microbiology 01/2001; 152(1):83-93. · 2.89 Impact Factor
[show abstract][hide abstract] ABSTRACT: The biotreatability of a xenobiotic contaminated soil is frequently determined through a bioslurry treatment usually performed in lab-scale shaken baffled flasks. In this study, a 3-1 unconventional stirred tank reactor was developed and tested in the slurry-phase treatment of a soil heavily contaminated by polychlorobiphenyls (PCBs) derived from an Italian dump site, in the absence and in the presence of biphenyl and of the exogenous PCB aerobically dechlorinating co-culture ECO3. The data obtained were compared with those obtained on the same soil in experiments performed in parallel in 3-1 baffled shaken flask reactors. Considerably higher PCB removal and soil detoxification yields (determined through the Lepidium sativum germination test and the Collembola mortality test) were attained in the stirred tank reactors, which generally displayed a higher slurry-phase homogeneity and a higher availability of biphenyl- and chlorobenzoic acid-degrading bacteria compared to the corresponding shaken flask reactors. Moreover, enhanced soil PCB biodegradation and detoxification yields were observed when the developed reactor was supplemented with biphenyl and the exogenous ECO3 bacteria. In conclusion, the results of the soil biotreatability experiments commonly performed in bioslurry lab-scale reactors are significantly influenced by the reactor configuration; the use of the unconventional stirred tank reactor system developed in this work is recommended.
Applied Microbiology and Biotechnology 03/2000; 53(2):243-8. · 3.69 Impact Factor