Effects of temperatures and organic loading rates on biomethanation of acidic petrochemical wastewater using an anaerobic upflow fixed-film reactor

The effect of temperature and organic loading rate on the rate of methane production from acidic petrochemical wastewater without neutralization was investigated by continuously feeding an anaerobic upflow fixed-film reactor. The temperatures selected for the studies were 25, 37, 45 and 55 degrees C. Organic loading rate (OLR) for each temperature was varied from 3.6 to 21.7 kg COD m(-3) d(-1). Best performance with respect to COD and BOD reduction, total gas production and methane yield was obtained with the reactor operating at 37 degrees C. OLR could be increased to a maximum of 21.7 kg COD m(-3) d(-1) with 90-95% COD and BOD reduction and methane yield of 0.450 m3 kg(-1) COD d(-1) added. The reactor operating at 55 degrees C gave the highest methane yield of 0.666 m3 kg(-1) COD d(-1) at an OLR of 6 kg COD m(-3) d(-1). This decreased to 0.110 m3 kg(-1) COD d(-1) when the OLR was increased to 18.1 kg COD m(-3) d(-1). The reactor operating at 45 degrees C gave a maximum methane yield of 0.416 m3 kg(-1) COD d(-1) added at an OLR of 6 kg COD m(-3) d(-1). On further increasing the OLR to 9 kg COD m(-3) d(-1), COD reduction was 89%, however, methane yield decreased to 0.333 m3 kg(-1) COD d(-1) added. The highest methane yield of 0.333 m3 kg(-1) COD d(-1) added at an OLR of 6 kg COD m(-3) d(-1) was obtained with reactors operating at 25 degrees C. These studies indicate potential rates of methane production from acidic petrochemical wastewater under different temperatures. This provides a guideline for various kinetic analyses and economic evaluation of the potential feasibility of fermenting acidic wastewater to methane.     

Performance of a horizontal-flow anaerobic immobilized biomass (HAIB) reactor and dynamics of the microbial community during degradation of pentachlorophenol (PCP)

The anaerobic biological treatment of pentachlorophenol (PCP) and methanol as the main carbon source was investigated in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor at 30+/-1 degrees C, during a 220-day trial period. The reactor biomass was developed as an attached biofilm on polyurethane foam particles, with 24h of hydraulic retention time. The PCP concentrations, which ranged from 2.0 to 13.0 mg/L, were controlled by adding synthetic substrate. The HAIB reactor reduced 97% of COD and removed 99% of PCP. The microbial biofilm communities of the HAIB reactor amended with PCP, without previous acclimatization, were characterized by polymerase chain reaction (PCR) and amplified ribosomal DNA restriction analysis (ARDRA) with specific Archaea oligonucleotide primers. The ARDRA technique provided an adequate analysis of the community, revealing the profile of the selected population along the reactor. The biomass activities in the HAIB reactor at the end of the experiments indicated the development of PCP degraders and the maintenance of the population of methanogenic Archaea, ensuring the high efficiency of the system treating PCP with added methanol as the cosubstrate. The use of the simplified ARDRA method enabled us to monitor the microbial population with the addition of high concentrations of toxic compounds and highlighting a selection of microorganisms in the biofilm.     

Cold-Hardiness and Supercooling Capacity in Diapausing and Nondiapausing Stages of the Cabbage Root Fly Delia radicum

Supercooling point (SCP) values and cold-hardiness were measured in individual ontogenetic stages of Delia radicum (Diptera:Anthomyiidae) in various physiological states (winter diapause, summer quiescence, and normal development). Winter diapause-destined mature third-instar larvae had a lower SCP (-9.9 degrees C) than their nondiapause counterparts (-5.2 degrees C), and more of them survived exposure to -10 degrees C for 5 h to pupariation and adult emergence. Values of SCPs were equal in both diapause and nondiapause states of prepupal and pupal stages. The lowest SCP (ca. -20 degrees C) was found in the stage of phanerocephalic pupa (PCP) regardless of the physiological state. The cold-hardiness of PCP corresponded with a low SCP value only in diapausing pupae stored for 80 days at 3 degrees C and in pupae which had terminated their diapause and whose further development was inhibited by storage at low temperatures (3 degrees C). Such pupae survived exposure to temperatures close to their SCP (14 days at -17 degrees C). However, this high cold-hardiness was only acquired after some time and/or exposure to 3 degrees C, as the PCP at the beginning of diapause showed significantly impaired cold-hardiness despite the fact that their SCP was low. The cold-hardiness of nondiapausing PCP did not correspond at all to that of low SCP, as no pupa survived the exposure to -17 degrees C for 1 day; survival rates at temperatures of -13.5 and -10 degrees C were also remarkably lower than those in diapausing pupae. Cold-hardiness in D. radicum was closely connected with the diapause syndrome but the changes in SCP value corresponded rather with the ontogeny of this insect. Copyright 1993, 1999 Academic Press.     

Performance of anaerobic granules for degradation of pentachlorophenol.

Anaerobic granules degrading pentachlorophenol (PCP) with specific PCP removal activity up to 14.6 mg/g of volatile suspended solids per day were developed in a laboratory-scale anaerobic upflow sludge blanket reactor at 28 degrees C, by using a mixture of acetate, propionate, butyrate, and methanol as the carbon source. The reactor was able to treat synthetic wastewater containing 40 to 60 mg of PCP per liter at a volumetric loading rate of up to 90 mg/liter of reactor volume per day, with a hydraulic retention time of 10.8 to 15 h. PCP removal of more than 99% was achieved. Results of adsorption of PCP by granular biomass indicated that the PCP removal by the granules was due to biodegradation rather than adsorption. A radiotracer assay demonstrated that the PCP-degrading granules mineralized [14C]PCP to 14CH4 and 14CO2. Toxicity test results indicated that syntrophic propionate degraders and acetate-utilizing methanogens were more sensitive to PCP than syntrophic butyrate degraders. The PCP-degrading granules also exhibited a higher tolerance to the inhibition caused by PCP for methane production and degradation of acetate, propionate, and butyrate, compared with anaerobic granules unadapted to PCP.     

Activated carbon from olive kernels in a two-stage process: industrial improvement

Activated carbons have been prepared from olive kernels and their adsorptive characteristics were investigated. A two stage process of pyrolysis-activation has been tested in two scales: (a) laboratory scale pyrolysis and chemical activation with KOH and (b) pilot/bench scale pyrolysis and physical activation with H(2)O-CO(2). In the second case, olive kernels were first pyrolysed at 800 degrees C, during 45 min under an inert atmosphere in an industrial pyrolyser with a throughput of 1t/h (Compact Power Ltd., Bristol, UK). The resulting chars were subsequently activated with steam and carbon dioxide mixtures at 970 degrees C in a batch pilot monohearth reactor at NESA facility (Louvain-la Neuve, Belgium). The active carbons obtained from both scales were characterized by N(2) adsorption at 77 K, methyl-blue adsorption (MB adsorption) at room temperature and SEM analysis. Surface area and MB adsorption were found to increase with the degree of burn-off. The maximum BET surface area was found to be around 1000-1200 m(2)/g for active carbons produced at industrial scale with physical activation, and 3049 m(2)/g for active carbons produced at laboratory with KOH activation. The pores of the produced carbons were composed of micropores at the early stages of activation and both micropores and mesopores at the late stages. Methylene blue removal capacity appeared to be comparable to that of commercial carbons and even higher at high degrees of activation.     

A novel process configuration for anaerobic digestion of source-sorted household waste using hyper-thermophilic post-treatment

A novel reactor configuration was investigated for anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW). An anaerobic hyper-thermophilic (68 degrees C) reactor R68 was implemented as a post-treatment step for the effluent of a thermophilic reactor R1 (55 degrees C) in order to enhance hydrolysis of recalcitrant organic matter, improve sanitation and ease the stripping of ammonia from the reactor. The efficiency of the combined system was studied in terms of methane yield, volatile solids (VS) reduction, and volatile fatty acid (VFA) production at different hydraulic retention times (HRT). A single-stage thermophilic (55 degrees C) reactor R2 was used as control. VS reduction and biogas yield of the combined system was 78-89% and 640-790 mL/g VS, respectively. While the VS reduction in the combined system was up to 7% higher than in the single-stage treatment, no increase in methane yield was observed. Shifting the HRT of the hyper-thermophilic reactor from 5 days to 3 days resulted in a drop in the methanogenic activity in the hydrolysis reactor to a minimum. Operation of R68 at HRTs of 24-48 h was sufficient to achieve high VS conversion into VFAs. Removal of pathogens was enhanced by the hyper-thermophilic post-treatment. 7% of the ammonia load was removed in the hyper-thermophilic reactor with a flow of headspace gas through the reactor equivalent to four times the biogas flow produced in reactor R1.     

Sensitivity of Escherichia coli O157:H7 to commercially available alkaline cleaners and subsequent resistance to heat and sanitizers

The effects of seven commercially available alkaline cleaners used in the food processing industry, 0.025 M NaOH, and 0.025 M KOH on viability of wild-type (EDL 933) and rpoS-deficient (FRIK 816-3) strains of Escherichia coli O157:H7 in logarithmic and stationary phases of growth were determined. Cells were treated at 4 or 23 degrees C for 2, 10, or 30 min. Cleaners 2, 4, 6, and 7, which contained hypochlorite and <11% NaOH and/or KOH (pH 11.2 to 11.7), killed significantly higher numbers of cells than treatment with cleaner 3, containing sodium metasilicate (pH 11.4) and <10% KOH, and cleaner 5, containing ethylene glycol monobutyl ether (pH 10.4). There were no differences in the sensitivities of logarithmic and stationary-phase cells to the alkaline cleaners. Treatment with KOH or NaOH (pH 12.2) was not as effective as four out of seven commercial cleaners in killing E. coli O157:H7, indicating that chlorine and other cleaner components have bactericidal activity at high pH. Stationary-phase cells of strain EDL 933 that had been exposed to cleaner 7 at 4 or 23 degrees C and strain FRIK 816-3 exposed to cleaner 7 at 23 degrees C had significantly higher D(55 degrees C) (decimal reduction time, minutes at 55 degrees C) values than control cells or cells exposed to cleaner 5, indicating that exposure to cleaner 7 confers cross-protection to heat. Cells of EDL 933 treated with cleaner 7 at 12 degrees C showed significantly higher D(55 degrees C) values than cells of FRIK 816-3, indicating that rpoS may play a role in cross-protection. Stationary-phase cells treated with cleaner 5 or cleaner 7 at 4 or 12 degrees C were not cross-protected against subsequent exposure to sanitizers containing quaternary ammonium compounds or sodium hypochlorite, or to cetylpyridinium chloride and benzalkonium chloride.     

Influence of a supplemental carbon source on anaerobic dechlorination of pentachlorophenol in granular sludge.

Anaerobic dechlorination of pentachlorophenol (PCP) was studied in two upflow anaerobic sludge blanket reactors. One reactor received glucose (0.9 g liter-1) as an additional carbon source; the other one served as a control. The concentration of PCP in the medium was 4.5 and 3.0 mg liter-1 in the experimental and control reactors, respectively. The reactors were inoculated with granular sludge previously grown on sugar-containing wastewater. After 10 months of continuous operation, the removal of PCP was 99% in the glucose-amended reactor, whereas the removal in the control reactor varied between 32 and 77%. Furthermore, 94% of the PCP was completely dechlorinated in the glucose reactor compared with a maximum of 20% in the control reactor. In the same period, the amount of biomass in the glucose reactor had increased by approximately 150% compared with that in the control reactor, where no growth of the sludge bed occurred. Batch culture activity tests showed that the addition of glucose had a stimulatory effect on the dechlorination rate of PCP per gram of volatile solids. This indicated that the better performance of the glucose-amended reactor was due to a higher concentration of biomass and a direct stimulatory effect of glucose on the dechlorination rate. The pattern of dechlorination of PCP showed that an initial para cleavage was followed by two ortho cleavages.     

Influence of a supplemental carbon source on anaerobic dechlorination of pentachlorophenol in granular sludge.

Anaerobic dechlorination of pentachlorophenol (PCP) was studied in two upflow anaerobic sludge blanket reactors. One reactor received glucose (0.9 g liter-1) as an additional carbon source; the other one served as a control. The concentration of PCP in the medium was 4.5 and 3.0 mg liter-1 in the experimental and control reactors, respectively. The reactors were inoculated with granular sludge previously grown on sugar-containing wastewater. After 10 months of continuous operation, the removal of PCP was 99% in the glucose-amended reactor, whereas the removal in the control reactor varied between 32 and 77%. Furthermore, 94% of the PCP was completely dechlorinated in the glucose reactor compared with a maximum of 20% in the control reactor. In the same period, the amount of biomass in the glucose reactor had increased by approximately 150% compared with that in the control reactor, where no growth of the sludge bed occurred. Batch culture activity tests showed that the addition of glucose had a stimulatory effect on the dechlorination rate of PCP per gram of volatile solids. This indicated that the better performance of the glucose-amended reactor was due to a higher concentration of biomass and a direct stimulatory effect of glucose on the dechlorination rate. The pattern of dechlorination of PCP showed that an initial para cleavage was followed by two ortho cleavages.     

Sunflower shells utilization for energetic purposes in an integrated approach of energy crops: laboratory study pyrolysis and kinetics

Sunflower is a traditional crop which can be used for the production of bioenergy and liquid biofuels. A study of the pyrolytic behaviour of sunflower residues at temperatures from 300 to 600 degrees C has been carried out. The experiments were performed in a captive sample reactor under atmospheric pressure and helium as sweeping gas. The yields of the derived pyrolysis products were determined in relation to temperature, with constant sweeping gas flow of 50 cm3 min(-1) and heating rate of 40 degrees Cs(-1). The maximum gas yield of around 53 wt.% was obtained at 500 degrees C, whereas maximum oil yield of about 21 wt.% was obtained at 400 degrees C. A simple first order kinetic model has been applied for the devolatilization of biomass. Kinetic constants have been estimated: E=78.15 kJ mol(-1); k(0)=1.03 x 10(3)s(-1).     

Olive bagasse (Olea europea L.) pyrolysis

Olive bagasse (Olea europea L.) was pyrolysed in a fixed-bed reactor. The effects of pyrolysis temperature, heating rate, particle size and sweep gas flow rates on the yields of the products were investigated. Pyrolysis runs were performed using pyrolysis temperatures between 350 and 550 degrees C with heating rates of 10 and 50 degrees C min(-1). The particle size and sweep gas flow rate varied in the ranges 0.224-1.8mm and 50-200 cm3 min(-1), respectively. The bio-oil obtained at 500 degrees C was analysed and at this temperature the liquid product yield was the maximum. The various characteristics of bio-oil obtained under these conditions were identified on the basis of standard test methods. The empirical formula of the bio-oil with heating value of 31.8 MJ kg(-1) was established as CH(1.65)O(0.25)N(0.03). The chemical characterization showed that the bio-oil obtained from olive bagasse may be potentially valuable as a fuel and chemical feedstock.     

Development of a sensitive radiorespiration method for detecting microbial activity at subzero temperatures

We have developed a simple and sensitive method to detect microbial respiration at subzero temperatures. Microbial activity was detected by measuring (14)CO(2) evolved during the microbial-mediated mineralization of [1-(14)C] acetic acid or [2-(14)C] glucose in microcosm assays using modified (14)CO(2) traps. Various (14)CO(2) traps, designed to withstand freezing at subzero temperatures, were tested for their quench characteristics during liquid scintillation spectrometry and their ability to trap (14)CO(2). Solutions consisting of 1 M KOH supplemented with 20% or 30% v/v ethylene glycol did not freeze at temperatures above -20 degrees C and had a minor quenching effect on liquid scintillation spectrometry. Addition of ethylene glycol did have an effect on the efficiency of (14)CO(2) trapping, as the cumulative recovery of (14)CO(2) was reduced by 14% and 32% in the 1 M KOH+20% ethylene glycol and 1 M KOH+30% ethylene glycol solutions, respectively. Using the modified (14)CO(2) traps, microbial activity in representative Canadian high Arctic environmental samples was detected at temperatures as low as -15 degrees C. This simple method allows for sensitive, specific, and reliable detection of microbial activity occurring at subzero temperatures and is readily adaptable for studies in other cryoenvironments.     

Comparison of two-stage thermophilic (68 degrees C/55 degrees C) anaerobic digestion with one-stage thermophilic (55 degrees C) digestion of cattle manure

A two-stage 68 degrees C/55 degrees C anaerobic degradation process for treatment of cattle manure was studied. In batch experiments, an increase of the specific methane yield, ranging from 24% to 56%, was obtained when cattle manure and its fractions (fibers and liquid) were pretreated at 68 degrees C for periods of 36, 108, and 168 h, and subsequently digested at 55 degrees C. In a lab-scale experiment, the performance of a two-stage reactor system, consisting of a digester operating at 68 degrees C with a hydraulic retention time (HRT) of 3 days, connected to a 55 degrees C reactor with 12-day HRT, was compared with a conventional single-stage reactor running at 55 degrees C with 15-days HRT. When an organic loading of 3 g volatile solids (VS) per liter per day was applied, the two-stage setup had a 6% to 8% higher specific methane yield and a 9% more effective VS-removal than the conventional single-stage reactor. The 68 degrees C reactor generated 7% to 9% of the total amount of methane of the two-stage system and maintained a volatile fatty acids (VFA) concentration of 4.0 to 4.4 g acetate per liter. Population size and activity of aceticlastic methanogens, syntrophic bacteria, and hydrolytic/fermentative bacteria were significantly lower in the 68 degrees C reactor than in the 55 degrees C reactors. The density levels of methanogens utilizing H2/CO2 or formate were, however, in the same range for all reactors, although the degradation of these substrates was significantly lower in the 68 degrees C reactor than in the 55 degrees C reactors. Temporal temperature gradient electrophoresis profiles (TTGE) of the 68 degrees C reactor demonstrated a stable bacterial community along with a less divergent community of archaeal species.     

Effect of long-term cobalt deprivation on methanol degradation in a methanogenic granular sludge bioreactor

The effect of the trace metal cobalt on the conversion of methanol in an upflow anaerobic sludge bed (UASB) reactor was investigated by studying the effect of cobalt deprivation from the influent on the reactor efficiency and the sludge characteristics. A UASB reactor (30 degrees C; pH 7) was operated for 261 days at a 12-h hydraulic retention time (HRT). The loading rate was increased stepwise from 2.6 g chemical oxygen demand (COD) x L reactor(-1) x d(-1) to 7.8 g COD x L reactor(-1) x d(-1). Cobalt deprivation had a strong impact on the methanogenic activity of the sludge. In batch tests, the methanogenic activity of the sludge with methanol as the substrate increased 5.3 (day 28) and 2.1 (day 257) times by addition of 840 nM of cobalt. The sludge had an apparent K(m) for cobalt of 948 nM after 28 days of operation and 442 nM at the end of the run. Cobalt deprivation during 54 days of operation led to a methanol conversion efficiency of only 55%. Continuous addition of cobalt (330 nM) for 33 days improved the methanol removal efficiency to 100%. In this period of cobalt dosing, the cobalt concentration in the sludge increased 2.7 times up to 32 microg x g TSS(-1). Upon omission of the cobalt addition, cobalt washed-out at a stable rate of 0.1 microg x g VSS(-1) x d(-1). At the end of the run, the cobalt concentration of the sludge was similar to that of the seed sludge.     

Potential for thermophilic (50 degrees C) anaerobic dechlorination of pentachlorophenol in different ecosystems

Thermophilic (50 degrees C) anaerobic biodegradation of pentachlorophenol (PCP) was investigated by using different inocula from natural ecosystems and anaerobic digesters. The inocula tested were three freshwater sediments, four anaerobic sewage sludge samples from digesters treating sludge from wastewater plants with various industrial inputs, and digested manure from an anaerobic reactor. Only one digested-sludge sample and the manure sample were from thermophilic environments. The initial PCP concentration was 7.5 or 37.5 microM. After 8 months, PCP had disappeared from the sediment samples and various, less chlorinated intermediates were present. Additions of extra PCP were degraded within 4 weeks, and a maximal observed dechlorination rate of 1.61 mumol/liter/day in the vials with addition of 7.5 microM PCP and 7.50 mumol/liter/day in the vials with addition of 37.5 microM PCP were measured for a freshwater sediment. In contrast, only 2.8 to 17.5% of the initial PCP added had disappeared from the sludge samples after 8 months of incubation. The complex pattern of intermediates formed indicated that the dechlorination of PCP proceeded via different pathways, involving at least two different populations in the dechlorination processes.     

Potential for thermophilic (50 degrees C) anaerobic dechlorination of pentachlorophenol in different ecosystems.

Thermophilic (50 degrees C) anaerobic biodegradation of pentachlorophenol (PCP) was investigated by using different inocula from natural ecosystems and anaerobic digesters. The inocula tested were three freshwater sediments, four anaerobic sewage sludge samples from digesters treating sludge from wastewater plants with various industrial inputs, and digested manure from an anaerobic reactor. Only one digested-sludge sample and the manure sample were from thermophilic environments. The initial PCP concentration was 7.5 or 37.5 microM. After 8 months, PCP had disappeared from the sediment samples and various, less chlorinated intermediates were present. Additions of extra PCP were degraded within 4 weeks, and a maximal observed dechlorination rate of 1.61 mumol/liter/day in the vials with addition of 7.5 microM PCP and 7.50 mumol/liter/day in the vials with addition of 37.5 microM PCP were measured for a freshwater sediment. In contrast, only 2.8 to 17.5% of the initial PCP added had disappeared from the sludge samples after 8 months of incubation. The complex pattern of intermediates formed indicated that the dechlorination of PCP proceeded via different pathways, involving at least two different populations in the dechlorination processes.     

Microbial sulfate reduction with acetate: process performance and composition of the bacterial communities in the reactor at different salinity levels

Microbial sulfate reduction with acetate as carbon source and electron donor was investigated at salinity levels between 0.53 and 1.48%. The experiment was carried out in a 2.3-1 upflow anaerobic sludge blanket reactor inoculated with granular methanogenic sludge. A pH of 8.3, a temperature of 32 +/- 1 degrees C and a chemical oxygen demand (COD)/SO4(2-)-S ratio of 2 were maintained in the reactor throughout the experiment. Sulfate reduction and the composition of the dominant bacterial communities in the reactor were monitored. The results showed that a maximal conversion rate for SO4(2-)-S of 14 g l(-1) day(-1) and a conversion efficiency of more than 90% were obtained at a salinity level of 1.26-1.39%. A further increase in the salinity level led to reactor instability. Denaturant gradient gel electrophoresis of 16S rDNA fragments amplified by PCR from total bacterial DNA extracted from the inoculum and reactor sludge showed that salinity level had an impact on the composition of the bacterial communities in the reactor. However, no clear relationship was found between reactor performance and the composition of the dominant bacterial communities in the reactor.     

Desulfitobacterium hafniense is present in a high proportion within the biofilms of a high-performance pentachlorophenol-degrading, methanogenic fixed-film reactor

We developed a pentachlorophenol (PCP)-degrading, methanogenic fixed-film reactor by using broken granular sludge from an upflow anaerobic sludge blanket reactor. This methanogenic consortium was acclimated with increasing concentrations of PCP. After 225 days of acclimation, the reactor was performing at a high level, with a PCP removal rate of 1,173 muM day(-1), a PCP removal efficiency of up to 99%, a degradation efficiency of approximately 60%, and 3-chlorophenol as the main chlorophenol residual intermediate. Analyses by PCR-denaturing gradient gel electrophoresis (DGGE) showed that Bacteria and Archaea in the reactor stabilized in the biofilms after 56 days of operation. Important modifications in the profiles of Bacteria between the original granular sludge and the reactor occurred, as less than one-third of the sludge DGGE bands were still present in the reactor. Fluorescence in situ hybridization experiments with probes for Archaea or Bacteria revealed that the biofilms were composed mostly of Bacteria, which accounted for 70% of the cells. With PCR species-specific primers, the presence of the halorespiring bacterium Desulfitobacterium hafniense in the biofilm was detected very early during the reactor acclimation period. D. hafniense cells were scattered in the biofilm and accounted for 19% of the community. These results suggest that the presence of PCP-dehalogenating D. hafniense in the biofilm was crucial for the performance of the reactor.     

Production and characterization of pyrolysis liquids from sunflower-pressed bagasse

Pyrolysis experiments on sunflower (Helianthus annus L.)-pressed bagasse were performed in a fixed-bed tubular reactor. The effects of nitrogen flow rate and final pyrolysis temperature on the pyrolysis product yields and chemical compositions were investigated. The maximum bio-oil yield of 52.10 wt.% was obtained in a nitrogen atmosphere with flow rate of 50 ml min(-1) and at a pyrolysis temperature of 550 degrees C with a heating rate of 5 degrees C s(-1). The chemical characterization results showed that the oil obtained from sunflower-pressed bagasse may be a potentially valuable source as fuel or chemical feedstocks.     

Bioaugmentation of a two-stage thermophilic (68 degrees C/55 degrees C) anaerobic digestion concept for improvement of the methane yield from cattle manure

The possibility of improving a two-stage (68 degrees C/55 degrees C) anaerobic digestion concept for treatment of cattle manure was studied. In batch experiments, a 10-24% increase of the specific methane yield from cattle manure and its fractions was obtained, when the substrates were inoculated with bacteria of the genus Caldicellusiruptor and Dictyoglomus. In a reactor experiment inoculation of a 68 degrees C pretreatment reactor with Caldicellusiruptor resulted in a 93% increase in the methane yield of the pretreatment reactor for a period of 18 days, but gave only a slight increase in the overall methane yield of the two-stage setup.