摘要:

AbstractThe fluidized‐bed, granular activated carbon (GAC) anaerobic reactor has been shown to be an effective process for the continuous long‐term treatment of wastewaters that contain biodegradable or nonbiodegradable toxic organic compounds. With loadings of 10 g COD/kg GAC day, COD removal of 94% was achieved. The anaerobic biofilm that develops on the GAC reduces the load on the carbon by converting the biodegradable organics to methane and carbon dioxide. Approximately 50% of the COD applied to the reactor was converted to methane, thereby reducing carbon requirements. Successful operation of the system requires that a carbon replacement schedule be maintained that will keep the bulk concentrations of toxic adsorbable compounds below their toxic threshold. As long as toxic substances can be adsorbed by the carbon, they will not inhibit the anaerobic biofilm. If nonadsorbable toxic compounds are present, processing must be included to reduce these materials to concentrations below their threshold le

ISSN:0006-3592    

DOI:10.1002/bit.260330202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractWe investigated the ability of several hydrolases to catalyze reactions with an abiotic water‐insoluble substrate, carbonic acid diphenyl ester, also known as diphenyl carbonate (DPC). In single‐phase water/organic systems, turnover numbers (TN) of greater than 2 × 104min−1have been achieved for the hydrolysis of DPC. TheKmvalues for the hydrolytic reaction were measured to be 200μMand 330μMforCandida cylindracealipase andPorcineliver esterase, respectively. In addition to hydrolysis, we observed transesterification of carbonates with a wide variety of alcohol and phenol species. Transesterifications of DPC with bifunctional alcohols resulted in the synthesis of polycarbonates. We investigated the stability and transesterification activity of these enzymes in several water‐restricted environments to limit competing hydrolysis reactions. We find that, with the removal of water, hydrolysis is reduced more than four orders of magnitude while transesterification is diminished only 10‐fold (turnover numbers of 600 min−1in water‐miscible systems to 60 min−1in water‐restricted environments with pureCandidalipase). Stability of theCandidalipase in these water‐restricted environments (half‐life of longer than 3 days) is much greater than in water/organic single phase systems (5 h in 20% methanol). In addition, theCandidalipase displayed enantiomeric selectivity in transesterifications of DPC with racemic 2‐but

ISSN:0006-3592    

DOI:10.1002/bit.260330203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractA number of experimental studies on deposition and detachment of bacterial cells ofPseudomonassp. was performed in an inclined plate apparatus 2.3 m long. In each run, ca. 108cells were introduced into a layer of flowing water at Reynolds numbers of ca. 1000 and 1300. After a preset time, the flow was stopped and the position of attached cells measured. Spatial pattern of attached cells was initially aggregative and remained so for lower flow rates. For higher flow rates the pattern tended towards randomness, perhaps as a result of cell detachment. Overall sticking efficiency of cells was very small (ca. 10−5

ISSN:0006-3592    

DOI:10.1002/bit.260330204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractFor a packed‐bed biofilm reactor two reactor models are proposed. One model is for the limiting case of a biofilm with a constant biofilm thickness in which diffusion within the biofilm is shown to be negligible. The second model assumes that the thickness of the biofilm is limited by the concentration of substrate within the biofilm. The analytical solutions for these reactor models are shown to agree very well with the numerical solutions to the exact differential equation

ISSN:0006-3592    

DOI:10.1002/bit.260330205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractA novel purification technique is proposed which employs affinity‐ligand‐modified liposomes to specifically purify bioactive macromolecules from solution. This process is demonstrated with avidin as the model biomolecule and biotin as the affinity ligand. Biotin is covalently bound to the surface of small unilamellar vesicles composed of dimyristoyl phosphatidylcholine (DMPC) and dimyristoyl phosphatidylethanolamine (DMPE). The number of accessible binding sites on the liposomes is determined by titration with avidin, and the kinetics of binding are evaluated by monitoring the concentration of free avidin in solution after the addition of biotinylated liposomes. The specificity of the process is determined by following the affinity binding of avidin to biotinylated liposomes in the presence of model impurities (i.e., lysozyme and cytochrome C). Liposome‐bound avidin is separated from the impurities by ultrafiltration through a membrane which retains the lipo

ISSN:0006-3592    

DOI:10.1002/bit.260330206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractShearing experiments were conducted in a stirred tank reactor with 0.1% lipase solutions ofCandida cylindracea.Inactivation of the lipase solutions were observed at various shear rates from 50 to 150 s−1after continuous shearing for ca. 30‐240 min under optimal pH and temperature conditions. However, there was no shear stress denaturation of the lipase when it was subjected to shear stresses of 0.72‐109.2 kg/m/s2and shear rate of 100 s−1. In the presence of polypropylene glycol, the rate of denaturation of the lipase decreased by 93%. When the lipase solution was filled to the brim, the rate of denaturation of the lipase decreased by 97% compared to that when reactor was half‐filled. The rate of denaturation of the lipase decreased by 61% when probes in the fermentor were removed. There was no significant difference in the rate of denaturation of the lipase under ambient conditions compared with that in the absence of oxygen, or in the absence of free metal ions. Recovery of lipase activity from the first hour of shearing was observed at a shear rate of 150 s−1. The native lipase and the lipase which had recovered its activity showed similar pH profiles, temperature profiles, and activation energies. Temperature was found to have no effect in the rate of shear‐induced denaturation of the lipase in the range 20 to 30°C during shearing at 100 s−1and optimal pH. Above 30°C, the rate of denaturation of the lipase increased drastically as a function of temperature. The significance of the findings in the de sign of reactor systems for hydrolysis or esterification of oils by lipase

ISSN:0006-3592    

DOI:10.1002/bit.260330207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractA modified simulation procedure based on a statistical approach was investigated. The procedure predicts the time course of fed‐batch culture for glutamic acid production by a temperature‐sensitive strain ofBrevibacterium flavum.The statistical approach requires only a data base of state points obtained in experiments, and not perfect identification of fermentation models. The simulation procedure is based on regression analysis to estimate specific rate parameters of system equations using the data points selected with reference to the Euclid distance. It was modified in that the data selection procedure included the use of the Maharanobis distance as well as a modified distance defined in this study. Simulation results using the modified procedure allow reasonable prediction of the time course of fed‐batch culture for glutamic acid compared to that involving the Euclid distance

ISSN:0006-3592    

DOI:10.1002/bit.260330208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractGrowth and α‐amylase production characteristics ofBacillus amyloliquefaciensstrain F (ATCC 23350) in batch cultures are examined using glucose or maltose as the carbon source. While the cell growth is rapid when glucose is used as the carbon source, higher cell mass, higher total and specific enzyme activities, and higher enzyme production rates are obtained when maltose is used as the carbon source. The overall specific enzyme activity decreases with an increase in the initial concentration of carbon source. The oxygen requirement and carbon dioxide generation vary linearly with the maximum amount of cell mass produced. For experiments conducted using glucose as the carbon source, the kinetics of cell growth and glucose consumption are described using a special form of the Vavilin equation. For a given amount of initial carbon source, the enzyme synthesis capability is retained by the microorganism, although at a substantially reduced level, under severe oxygen limitati

ISSN:0006-3592    

DOI:10.1002/bit.260330209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe energy requirements associated with conventional mechanical size reduction of poplar and aspen wood are compared to a new method of size reduction employing a wood planer. Although the planer requires about 2.3 times less energy to achieve the same size reduction as conventional methods, large‐scale equipment to implement this approach does not currently exist. Explosive depressurization was also compared to conventional mechanical size reduction. The conventional mechanical methods require roughly 70% more energy to achieve the same size reduction as explosive depressurization. Thus, explosive depressurization appears to be the preferred method and has the added benefit of altering the chemical structure of the wood to enhance the enzymatic hydrolysis of the cellulose fractio

ISSN:0006-3592    

DOI:10.1002/bit.260330210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractInPseudomonas C, an obligate RMP‐methylotroph, externally added formic acid and multi‐carbon intermediates are co‐metabolized in the obligate presence of methanol. Cell yield and methanol‐carbon conversion to cell mass are optimal in a chemostat culture growing on a mixture of energy sources and methanol as the sole limiting carbon source. Growth on methanol as the sole, obligate energy source and an additional carbon source (e.g. pyruvate) is less efficient. Under these energy limited conditions, the cyclic oxidation pathway is predominantly o

ISSN:0006-3592    

DOI:10.1002/bit.260330211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY