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1.
We studied the process of conversion of microcrystalline-cellulose into fermentable glucose in the formic acid reaction system using cross polarization/magic angle spinning 13C-nuclear magnetic resonance, X-ray diffraction and Fourier transform infrared spectroscopy. The results indicated that formic acid as an active agent was able to effectively penetrate into the interior space of the cellulose molecules, thus collapsing the rigid crystalline structure and allowing hydrolysis to occur easily in the amorphous zone as well as in the crystalline zone. The microcrystalline-cellulose was hydrolyzed using formic acid and 4% hydrochloric acid under mild conditions. The effects of hydrochloric acid concentration, the ratio of solid to liquid, temperature (55–75 °C) and retention time (0–9 h), and the concentration of glucose were analyzed. The hydrolysis velocities of microcrystalline-cellulose were 6.14 × 10− 3 h− 1 at 55 °C, 2.94 × 10− 2 h− 1 at 65 °C, and 6.84 × 10− 2 h− 1 at 75 °C. The degradation velocities of glucose were 0.01 h− 1 at 55 °C, 0.14 h− 1 at 65 °C, 0.34 h− 1 at 75 °C. The activation energy of microcrystalline-cellulose hydrolysis was 105.61 kJ/mol, and the activation energy of glucose degradation was 131.37 kJ/mol.  相似文献   

2.
The net production of dissolved organic matter (DOM) and dissolved combined and free amino acids (DCAA and DFAA, respectively) by the hermatypic coral Acropora pulchra was measured in the submerged condition, and the production rates were normalized to the coral surface area, tissue biomass, and net photosynthetic rates by zooxanthellae. When normalized to the unit surface area, the production rates of dissolved organic carbon and nitrogen (DOC and DON, respectively) were 37 and 4.4 nmol cm− 2 h− 1, respectively. Comparing with the photosynthetic rate by zooxanthellae, which was measured by 13C-tracer accumulation in the soft tissue of the coral colony, the release rate of DOC corresponded to 5.4% of the daily net photosynthetic production. The tissue biomass of the coral colony was 178 µmol C cm− 2 and 23 µmol N cm− 2, indicating that the release of DOC and DON accounted for 0.021% h− 1 and 0.019% h− 1 of the tissue C and N, respectively. The C:N ratios of the released DOM (average 8.4) were not significantly different from those of the soft tissue of the coral colonies (average 7.7). While DFAA did almost not accumulate in the incubated seawater, DCAA was considerably released by the coral colonies at the rate of 2.1 nmol cm− 2 h− 1 on average. Calculating C and N contents of the hydrolyzable DCAA, it was revealed that about 20% and 50%–60% of the released bulk DOC and DON, respectively, were composed of DCAA.  相似文献   

3.
This study compared the mass-specific routine metabolic rate (RMR) of similar sized mulloway (Argyrosomus japonicus), a sedentary species, and yellowtail kingfish (Seriola lalandi), a highly active species, acclimated at one of several temperatures ranging from 10–35 °C. Respirometry was carried out in an open-top static system and RMR corrected for seawater–atmosphere O2 exchange using mass-balance equations. For both species RMR increased linearly with increasing temperature (T). RMR for mulloway was 5.78T − 29.0 mg O2 kg− 0.8 h− 1 and for yellowtail kingfish was 12.11T − 39.40 mg O2 kg− 0.8 h− 1. The factorial difference in RMR between mulloway and yellowtail kingfish ranged from 2.8 to 2.2 depending on temperature. The energetic cost of routine activity can be described as a function of temperature for mulloway as 1.93T − 9.68 kJ kg− 0.8 day− 1 and for yellowtail kingfish as 4.04T − 13.14 kJ kg− 0.8 day− 1. Over the full range of temperatures tested Q10 values were approximately 2 for both species while Q10 responses at each temperature increment varied considerably with mulloway and yellowtail kingfish displaying thermosensitivities indicative of each species respective niche habitat. RMR for mulloway was least thermally dependent at 28.5 °C and for yellowtail kingfish at 22.8 °C. Activation energies (Ea) calculated from Arrhenius plots were not significantly different between mulloway (47.6 kJ mol− 1) and yellowtail kingfish (44.1 kJ mol− 1).  相似文献   

4.
Two bed media were tested (gravel and Filtralite) in shallow horizontal subsurface flow (HSSF) constructed wetlands in order to evaluate the removal of ammonia and nitrate for different types of wastewater (acetate-based and domestic wastewater) and different COD/N ratios. The use of Filtralite allowed both higher mass removal rates (1.1 g NH4–N m−2 d−1 and 3 g NO3–N m−2 d−1) and removal efficiencies (>62% for ammonia, 90–100% for nitrate), in less than 2 weeks, when compared to the ones observed with gravel. The COD/N ratio seems to have no significant influence on nitrate removal and the removal of both ammonia and nitrate seems to have involved not only the conventional pathways of nitrification–denitrification. The nitrogen loading rate of both ammonia (0.8–2.4 g NH4–N m−2 d−1) and nitrate (0.6–3.2 g NO3–N m−2 d−1) seem to have influenced the respective removal rates.  相似文献   

5.
The primary objective of this study was to evaluate the performance of a 20 l lab scale anaerobic hybrid reactor (AHR) combining sludge blanket in the lower part and filter in the upper part under varying organic loading rates (OLRs) in order to study biodegradation of olive mill effluent (OME). For this purpose, some parameters, such as total phenols, effluent chemical oxygen demand (COD), suspended solids (SS), volatile fatty acids (VFAs), and pH in the influent and effluent, and removal efficiencies for those parameters (except pH) were continuously monitored throughout the experimental period of 477 days. Eleven different organic loadings between 0.45 and 32 kg COD m−3 day−1 were imposed by either varying influent COD or hydraulic retention time (HRT). The results demonstrated that the AHR reactor could tolerate high influent COD concentrations. Removal efficiencies for the studied pollution parameters were found to be as follows: COD, 50–94%; total phenol, 39–80%; color, 0–54%; and suspended solids, 19–87%. The levels of VFAs in the effluent, which was principally acetate, butyrate, iso-butyrate, and propionate, varied between 10 and 2005 mg l−1 depending upon OLRs. A COD removal efficiency of 90% could be achieved as long as OLR is kept at a level of less than 10 kg COD m−3 day−1. However, a secondary treatment unit for polishing purposes is necessary to comply with receiving media discharge standards.  相似文献   

6.
Oxygen and shear stress are the key factors for enhanced glucan production with Schizophyllum commune. During batch cultivation control of or (specific oxygen uptake rate) was achieved by variation of the impeller speed. Biomass was modelled by using the carbon and oxygen balance derived from exhaust data. At mycel growth a of 0.042 h–1 presents just the border before oxygen limitation arises and is simultaneously the optimum operation condition for maximum glucan formation. Related to an overall cultivation time of 72 h a maximum of both productivity (4.3 kg m–3 d–1) and yield (13 kg m–3) were obtained.List of Symbols C kg m–3 concentration - k L a h –1 volume related oxygen transfer coefficient - K s mol m–3 substrate saturation constant - N rpm impeller speed - % oxygen partial pressure of the liquid phase - kg m–3h–1 oxygen uptake rate - h–1 specific oxygen uptake rate, kg O2 (kg biomass h)–1 - t h time - yield coefficient (biomass formed/oxygen consumed) Greek Symbols h–1 specific growth rate Indices O 2 oxygen - X biomass - L liquid phase - * gas/liquid interface - S substrate (glucose) Dedicated to the 65th birthday of Professor Fritz Wagner.This work was kindly supported in parts by B. Braun Biotech International. The authors are grateful to Prof. Dr. Fritz Wagner for scientific support and appreciate the technical assistance of Detlev Rasch  相似文献   

7.
We measured nitrous oxide (N2O), dinitrogen (N2), methane (CH4), and carbon dioxide (CO2) fluxes in horizontal and vertical flow constructed wetlands (CW) and in a riparian alder stand in southern Estonia using the closed chamber method in the period from October 2001 to November 2003. The replicates’ average values of N2O, N2, CH4 and CO2 fluxes from the riparian gray alder stand varied from −0.4 to 58 μg N2O-N m−2 h−1, 0.02–17.4 mg N2-N m−2 h−1, 0.1–265 μg CH4-C m−2 h−1 and 55–61 mg CO2-C m−2 h−1, respectively. In horizontal subsurface flow (HSSF) beds of CWs, the average N2 emission varied from 0.17 to 130 and from 0.33 to 119 mg N2-N m−2 h−1 in the vertical subsurface flow (VSSF) beds. The average N2O-N emission from the microsites above the inflow pipes of the HSSF CWs was 6.4–31 μg N2O-N m−2 h−1, whereas the outflow microsites emitted 2.4–8 μg N2O-N m−2 h−1. In VSSF beds, the same value was 35.6–44.7 μg N2O-N m−2 h−1. The average CH4 emission from the inflow and outflow microsites in the HSSF CWs differed significantly, ranging from 640 to 9715 and from 30 to 770 μg CH4-C m−2 h−1, respectively. The average CO2 emission was somewhat higher in VSSF beds (140–291 mg CO2-C m−2 h−1) and at the inflow microsites of HSSF beds (61–140 mg CO2-C m−2 h−1). The global warming potential (GWP) from N2O and CH4 was comparatively high in both types of CWs (4.8 ± 9.8 and 6.8 ± 16.2 t CO2 eq ha−1 a−1 in the HSSF CW 6.5 ± 13.0 and 5.3 ± 24.7 t CO2 eq ha−1 a−1 in the hybrid CW, respectively). The GWP of the riparian alder forest from both N2O and CH4 was relatively low (0.4 ± 1.0 and 0.1 ± 0.30 t CO2 eq ha−1 a−1, respectively), whereas the CO2-C flux was remarkable (3.5 ± 3.7 t ha−1 a−1). The global influence of CWs is not significant. Even if all global domestic wastewater were treated by wetlands, their share of the trace gas emission budget would be less than 1%.  相似文献   

8.
Emissions of greenhouse gases from ponds constructed for nitrogen removal   总被引:6,自引:0,他引:6  
Methane and carbon dioxide emission from three constructed ponds were monitored during an annual cycle. Water temperature was a good predictor of methane emission in all three ponds. In the most intensively studied pond, nitrate concentration in the bottom water could further explain the amount of methane emitted. When water temperature exceeded 15 °C between 1 and 54 mg, CH4 m−2 h−1 was emitted on all occasions, while at temperatures below 10 °C, less than 0.6 mg CH4 m−2 h−1 was emitted. The flux of carbon dioxide differed between the ponds and no consistent patterns were found. In a laboratory study at 20 °C, we showed that high, but naturally occurring, nitrate concentrations (8 and 16 mg NO3–N l−1) constrained the production of methane compared to the treatment with no nitrate addition. Nitrous oxide production was positively correlated with nitrate concentration. Carbon dioxide production was highest at the highest nitrate concentration, which indicates that increased nitrate loading on ponds and wetlands will stimulate organic matter decomposition rates. Our conclusion is that these ponds constructed for nitrate removal emit greenhouse gases comparable to lakes in the temperate region.  相似文献   

9.
We investigated the solid particle flow characteristics and biomass gasification in a clapboard-type internal circulating fluidized bed reactor. The effect of fluidization velocity on particle circulation rate and pressure distribution in the bed showed that fluidization velocities in the high and low velocity zones were the main operational parameters controlling particle circulation. The maximum internal circulation rates in the low velocity zone came almost within the range of velocities in the high velocity zone, when uH/umf = 2.2–2.4 for rice husk and uH/umf = 3.5–4.5 for quartz sand. In the gasification experiment, the air equvalence ratio (ER) was the main controlling parameter. Rice husk gasification gas had a maximum heating value of around 5000 kJ/m3 when ER = 0.22–0.26, and sawdust gasification gas reached around 6000–6500 kJ/m3 when ER = 0.175–0.24. The gasification efficiency of rice husk reached a maximum of 77% at ER = 0.28, while the gasification efficiency of sawdust reached a maximum of 81% at ER = 0.25.  相似文献   

10.
Removal of toluene in waste gases using a biological trickling filter   总被引:12,自引:0,他引:12  
The removal of toluene from waste gas was studied in a trickling biofilter. A high level of water recirculation (4.7 m h–1) was maintained in order to keep the liquid phase concentration constant and to achieve a high degree of wetting. For loads in the range from 6 to 150 g m–3 h–1 the maximum volumetric removal rate (elimination capacity) was 35±10 g m–3 h–1, corresponding to a zero order removal rate of 0.11±0.03 g m–2 h–1 per unit of nominal surface area. The surface removal was zero order above the liquid phase concentrations of approximately 1.0 g m–3, corresponding to inlet gas concentrations above 0.7–0.8 g m–3. Below this concentration the surface removal was roughly of first order. The magnitude of the first order surface removal rate constant, k1A , was estimated to be 0.08–0.27 m h–1 (k1A a=24–86 h–1). Near-equilibrium conditions existed in the gas effluent, so mass transfer from gas to liquid was obviously relatively fast compared to the biological degradation. An analytical model based on a constant liquid phase concentration through the trickling filter column predicts the effluent gas concentration and the liquid phase concentration for a first and a zero order surface removal. The experimental results were in reasonable agreement with a very simple model valid for conditions with an overall removal governed by the biological degradation and independent of the gas/liquid mass transfer. The overall liquid mass transfer coefficient, KLa, was found to be a factor 6 higher in the system with biofilm compared to the system without. The difference may be explained by: 1. Difference in the wetting of the packing material, 2. Mass transfer occurring directly from the gas phase to the biofilm, and 3. Enlarged contact area between the gas phase and the biofilm due to a rough biofilm surface.  相似文献   

11.
The purpose of this study was to localize vasopressin (VP) V1a receptor in stomach and to characterize the role of VP in the regulation of gastric motility in rats. Double staining was used to locate the V1a receptor in the gastric body of the rat. The contraction of the circular muscle strips of gastric body was monitored by a polygraph. V1a receptor was expressed on the neurons of myenteric plexus of the gastric body. VP (10− 10–10− 6 M) caused a concentration-dependent contractile effect on the circular muscle strips of gastric body in vitro. V-1880 ([deamino-Pen1, O-Me-Tyr2, Arg8]-Vasopressin, 10− 7 M), a V1 receptor antagonist, inhibited the spontaneous contraction of the strips. Tetradotoxin (TTX, 10− 6 M) and V-1880 (10− 7 M) abolished the excitatory effect of VP. Atropine (10− 6 M) partially inhibited VP-induced excitatory effect on the muscle strips but hexamethonium (10− 4 M) did not influence it. These results suggest that V1a receptor was expressed on the neurons of myenteric nerves. The cholinergic nerve was involved in the excitatory effect of VP on the contraction of gastric body.  相似文献   

12.
Summary The linear growth phase in cultures limited by intracellular (conservative) substrate is represented by a flat exponential curve. Within the range of experimental errors, the presented model fits well the data from both batch and continuous cultures ofEscherichia coli, whose growth is limited in that way.List of symbols D dilution rate, h–1 - KS saturation constant, g.L–1 - S concentration of the limiting substrate, g.L–1 - Si concentration of the limiting substrate accumulated in the cells, g.g–1 - So initial concentration of the limiting substrate, g.L–1 - t time of cultivation, h - t1 time of exhaustion of the limiting substrate from medium, h - to beginning of exponential phase, h - X biomass concentration, g.L–1 - X1 biomass concentration at the time of exhaustion of the limiting substrate from the medium, g.L–1 - Xo biomass concn. at the beginning of exponential phase, g.L–1 - biomass concn. at steady-state, g.L–1 - Y growth yield coefficient (biomass/substrate) - specific growth rate, h–1 - m maximum specific growth rate, h–1  相似文献   

13.
We measured Na+/K+ ATPase activity in homogenates of gill tissue prepared from field caught, winter and summer acclimatized yellow perch, Perca flavescens. Water temperatures were 2–4°C in winter and 19–22°C in summer. Na+/K+ ATPase activity was measured at 8, 17, 25, and 37°C. Vmax values for winter fish increased from 0.48±0.07 μmol P mg−1 protein h−1 at 8°C to 7.21±0.79 μmol P mg−1 protein h−1 at 37°C. In summer fish it ranged from 0.46±0.08 (8°C) to 3.86±0.50 (37°C) μmol P mg−1 protein h−1. The Km for ATP and for Na+ at 8°C was ≈1.6 and 10 mM, respectively and did not vary significantly with assay temperature in homogenates from summer fish. The activation energy for Na+/K+ ATPase from summer fish was 10 309 (μmol P mg−1 h−1) K−1. In winter fish, the Km for ATP and Na+ increased from 0.59±0.08 mM and 9.56±1.18 mM at 8°C to 1.49±0.11 and 17.88±2.64 mM at 17°C. The Km values for ATP and Na did not vary from 17 to 37°C. A single activation energy could not be calculated for Na/K ATPase from winter fish. The observed differences in enzyme activities and affinities could be due to seasonal changes in membrane lipids, differences in the amount of enzyme, or changes in isozyme expression.  相似文献   

14.
Protein synthesis is an essential growth process in all animals. Little information is available on post-prandial protein synthesis and even less where different protein sources are compared. Protein synthesis was measured at 4 and 24 h after feeding juvenile barramundi in order to determine the effect of using lupin as a partial protein replacement for fish meal on the post-prandial protein metabolism. Juvenile barramundi (4.3 ±0.6 g) were held in a recirculation system (27 °C, salinity 10‰ and 24 h light) for 15 days. Fish were fed one of two isonitrogenous isoenergetic diets (40% crude protein, 16% lipid and 18.5 GE MJ kg− 1). One diet was formulated with 100% fish meal as the protein source while the other had 45% of the protein replaced with lupin ingredients (lupin kernel meal (Lupinus angustifolius) and lupin protein concentrate). All fish were fed a ration of 6%·d− 1 and feed intake was not significantly different between the two diets. Specific growth rate (SGR) and growth efficiency (in relation to protein (PPV) and energy (PEV)) were 6.5 ± 0.14%·d− 1, 43.8 ± 2.72% and 38.31 ± 1.56%, respectively, and were not significantly different between the two diets. There was no significant difference in protein synthesis between the two diets at 4 and 24 h after feeding, however protein synthesis was significantly higher 4 h after feeding than at 24 h (p = 0.02). Neither growth performance nor protein metabolism was altered by replacing 45% of the protein with lupin protein and indicated this to be a suitable protein source for barramundi feeds.  相似文献   

15.
Total contribution of six recently discovered submerged coral reefs in northern Australia to Holocene neritic CaCO3 and CO2 is assessed to address a gap in global budgets. CaCO3 production for the reef framework and inter-reefal deposits is 0.26–0.28 Mt. Holocene CO2 production is 0.14–0.16 Mt. Coral and coralline algae are the dominant sources of Holocene CaCO3 although foraminifers and molluscs are the dominant constituents of inter-reefal deposits. The total amount of Holocene neritic CaCO3 produced by the six submerged coral reefs is several orders of magnitude smaller than that calculated using accepted CaCO3 production values because of very low production, a ‘give-up’ growth history, and presumed significant dissolution and exports. The contribution of submerged coral reefs to global Holocene neritic CaCO3 is estimated to be 0.26–0.62 Gt, which yields 0.15–0.37 Gt of CO2. This amount of CO2 is 0.02–0.05% of the 780 Gt added to the atmosphere since 18 kyr BP. Contributions from Australian submerged coral reefs are estimated to be 0.05 Gt CaCO3 and 0.03 Gt CO2 for an emergent reef area of 47.9 × 103 km2. Based on the growth history of the submerged coral reefs in the Gulf of Carpentaria, maximum global Holocene CaCO3 fluxes could have attained 0.3 Gt yr− 1 between 11 and 7 ka BP. This additional CaCO3 would have culminated in a maximum CaCO3 production from all (emergent and submerged) coral reefs of 1.2 Gt yr− 1 and neritic CaCO3 production of 2.75 Gt yr− 1. The dilemma remains that the global area and CaCO3 mass of submerged coral reefs are currently unknown. It is inevitable that many more submerged coral reefs will be found. Our findings imply that submerged coral reefs are a small but fundamental source of Holocene neritic CaCO3 and CO2.  相似文献   

16.
Phosphorus uptake and release by periphyton mats were quantified in the Everglades Nutrient Removal Project (ENRP) to evaluate the potential for periphyton P removal. Short-term P uptake rates were determined by incubating cyanobacteria (Oscillatoria princeps and Shizothrix calcicola) and Chlorophycean (primarily Rhizoclonium spp.) algal mat samples for 0.5–2 h under ambient conditions in BOD bottles spiked with soluble reactive P (SRP). Cyanobacterial mats removed P more than twice as fast (80–164 μg P h−1 g−1 AFDM) as Chlorophycean mats (33–61 μg P h−1 g−1 AFDM) during these incubations. In a longer term study, fiberglass cylinders were used to enclose 1.8 m2 plots within the wetland and were dosed weekly for 7 weeks with: (1) no nutrients; (2) SRP (0.25 g P m−2 week−1); or (3) SRP plus nitrate (0.42 g N m−2 week−1) and ammonium (0.83 g N m−2 week−1). Phosphorus uptake rates by this periphyton assemblage, which was dominated by the chlorophytes Stigeoclonium spp. and Oedogonium spp., were measured weekly and were similar among nutrient treatments on most dates, indicating that the algal storage compartment for P was not saturated despite repeated P additions. Decomposition rates and P loss by cyanobacteria and Chlorophycean mats were determined by measuring biomass loss and SRP release in darkened BOD bottles over 28–42 day periods under anaerobic and aerobic conditions. First-order aerobic and anaerobic decomposition rates for cyanobacterial mats (k = 0.1095 and 0.1408 day−1, respectively) were 4–20-fold higher than rates for Chlorophycean mats (k = 0.0066 and 0.0250 day−1, respectively) and cyanobacteria released considerably more P back to the water column. Our findings suggest that periphyton can be an important short-term sink for P in treatment wetlands and that retention is strongly affected by the taxonomic composition of the periphyton assemblage.  相似文献   

17.
Conclusions Except for the pronounced adaptation-hysteresis effect, the pulse experiments exhibited the expected trend: deviation from the steady feed reference curve was greatest at lowest dilution rates. Under conditions of lowest glucose level the effect of pulsing would be expected to cause the largest fluctuations in glucose, causing a certain fraction of the cells to ferment. Generally over the entire dilution rate range the biomass production was decreased and the ethanol was increased by pulsing the feed stream. There is, however, some evidence that pulse feeding can trigger quite unexpected results. Point (6) at D=0.3 h–1 in Fig. 1 exhibit a biomass productivity which was about 20% greater than the continuous feeding reference value (DX=3.6 kg m–3 h–1 as compared with 3.0 kg m–3 h–1). Such performance would be of significant commercial value, but the poor reproducibility due to adaptation, as seen here, certainly would preclude its application.The results obtained should also be applicable to fed batch operation at the corresponding glucose level. Further experiments including the variation of the glucose feeding period would be necessary to obtain a conclusive picture. The observed phenomena are likely to occur in other fermentations and could eventually explain some of the problems existing with scale up of fermentation processes.Symbols D dilution rate h–1 - P product (ethanol) concentration kg m–3 - QO2 specific oxygen uptake rate mol kg–1 s–1 - QCO2 specific CO2 production rate mol kg–1 s–1 - S substrate (glucose) concentration kg m–3 - X biomass concentration kg m–3 - YP/S yield of ethanol from glucose kg kg–1 - YX/S yield of biomass from glucose kg kg–1  相似文献   

18.
High strength milk permeate derived from ultra-filtration based cheese making process was treated in an anaerobic moving bed biofilm reactor (AMBBR) under mesophilic (35 °C) condition. Total chemical oxygen demand (TCOD) removal efficiencies of 86.3–73.2% were achieved at organic loading rates (OLR) of 2.0–20.0 g TCOD L−1 d−1. A mass balance model gave values of methane yield coefficient (YG/S) and cell maintenance coefficient (km) of 0.341 L CH4 g−1 TCODremoved and 0.1808 g TCODremoved g−1 VSS d−1, respectively. The maximum substrate utilization rate Umax was determined as 89.3 g TCOD L−1 d−1 by a modified Stover–Kincannon model. Volumetric methane production rates (VMPR) were shown to correlate with the biodegradable TCOD concentration through a Michaelis–Menten type equation. Moreover, based on VMPR and OLR removed from the reactor, the sludge production yield was determined as 0.0794 g VSS g−1 TCODremoved.  相似文献   

19.
Summary The influence of temperature on the growth of the theromophilic Bacillus caldotenax was investigated using chemostat techniques and a chemically defined minimal medium. All determined growth constants, that is maximal specific growth rate, yield and maintenance, were temperature dependent. It was striking that the very large maintenance requirement was about 10 times higher than for mesophilic cells under equivalent conditions. A death rate, which was very substantial at optimal and supraoptimal growth temperatures, was estimated by comparing the maintenance for substrate and oxygen. There was no indication for a thermoadaptation as postulated by Haberstich and Zuber (1974).Symbols D Dilution rate (h–1) - Dc=max Critical dilution rate (h–1) - E Temperature characteristic (J mol–1) - k Organism constant - kd Death rate coefficient (h–1) - km Maintenance substrate coefficient estimated from MO (h–1) - MO Maintenance respiration, mmol O2 per g dry biomass and h (mmol g–1h–1) - MO Maintenance respiration, taking kd into account - mS Maintenance substrate coefficient, g glucose per g dry biomass and h (h–1) - OD Optical density at 546 nm - QO2 Specific O2-uptake rate (mmol g–1h–1) - Q O2 V Specific O2-uptake rate for viable portion of biomass (mmol g–1 h–1) - QS Specific glucose uptake rate (h–1) - Q S V Specific glucose uptake rate for viable portion of biomass (h–1) - R Gas constant 8.28 J mol–1K–1 - S Substrate concentration in reactor (g l–1) - SO Influent substrate concentration (g l–1) - Tmax Maximal growth temperature (°C) - Tmin Minimal growth temperature (°C) - X Dry biomass (g l–1) - XtOt=X Dry biomass containing dead and viable cells - Xv Viable portion of biomass - Y O m Potential yield for O2 corrected for maintenance respiration (g mol–1) - Y S m Potential yield for substrate corrected for maintenance requirement, g biomass per g glucose (–) - Specific growth rate (h–1) - max Maximal specific growth rate (h–1)  相似文献   

20.
Laboratory investigation of the potential use of Penicillium sp. as biosorbent for the removal of acid violet dye from aqueous solution was studied with respect to pH, temperature, biosorbent, initial dye concentrations. Penicillium sp. decolourizes acid violet (30 mg l−1) within 12 h agitation of 150 rpm at pH 5.7 and temperature of 35 °C. The pellets exhibited a high dye adsorption capacity (5.88 mg g−1) for acid violet dye over a pH range (4–9); the maximum adsorption was obtained at pH 5.7. The increase of temperature favored biosorption for acid violet, but the optimum temperature was 35 °C. Adsorption kinetic data were tested using pseudo-first-order, pseudo-second-order and kinetic studies showed that the biosorption process follows pseudo-first-order rate kinetics with an average rate constant of 0.312 min−1. Isotherm experiments were conducted to determine the sorbent–desorption behavior of examined dye from aqueous solutions using Langmuir and Freundlich equations. Langmuir parameter indicated a maximum adsorption capacity of 4.32 mg g−1 for acid violet and RL value of 0.377. Linear plot of log qe vs log Ce shows that applicability of Freundlich adsorption isotherm model. These results suggest that this fungus can be used in biotreatment process as biosorbent for acid dyes.  相似文献   

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