摘要:

AbstractThis paper describes an extractive membrane bioreactor developed to extract and biodegrade toxic organic pollutants present in chemical industry wastewaters. The technology is applicable to wastewaters emanating in organic synthesis operations which are not treatable by conventional ‘direct’ biological treatment due to extremes of pH, high salt contents, or otherwise hostile organic compositions, and also to wastewaters that contain volatile organic compounds. A laboratory scale prototype demonstrating the technology has been operated continuously over periods of several months, using industrially produced wastewaters. No pre‐conditioning or dilution of the wastewaters is necessary prior to treatment, which removes and destroys over 99% of the toxic organics pr

ISSN:0268-2575    

DOI:10.1002/jctb.280600202

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractRotating‐disk mechanical foam‐breakers (MFRDs) were applied to the control of foaming in bubble column (BC) reactors containing complex solutions and biological media. The foaming behaviour of BCs and the foam‐breaking behaviour of MFRDs fitted to BCs were evaluated respectively from the changes in the liquid hold‐up in ascending foam, ϕb, and the required critical disk rotational speed,Nc, for foam‐breaking. The differences in ϕbandNc, reflecting the difficulty or ease of foam‐breaking among the liquids, correlated well with differences in the foaming characteristic term,FCT, of respective liquids, which could be determined on the basis of the results measured in the experimental small foaming apparatus which were different from those measured in the gas‐bubbling apparatus employed in practice. The usefulness of the empirical correlations for the prediction of ϕbandNc, which can be applied independently of the type and concentration of foaming liquid or their physical properties, was a

ISSN:0268-2575    

DOI:10.1002/jctb.280600203

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractSerratia marcescenschitinase was immobilized by covalent binding to a polymer (hydroxypropyl methylcellulose acetate succinate, AS‐L) showing reversibly soluble–insoluble characteristics with pH change. The immobilized enzyme (CHAS) was soluble above pH 5·2 and insoluble below 4·5, which offers advantages in that it can carry out hydrolysis of chitin particles in a soluble form yet be recovered after precipitation at low pH. CHAS has much higher activity than chitinase immobilized to a water‐insoluble carrier. The effects of pH and temperature on the activity and stability of CHAS, and the adsorption of CHAS to chitin were studied and compared with those of free chitinase. Following repeated pH cycles between 6·6 and 4·5, CHAS lost 30% of its enzyme activity during the first cycle due to protein release and enzyme denaturation, but substantially less activity was lost in the following cycles, with minimum enzyme denaturation. Chitin hydrolysis with CHAS could be carried out in a semi‐batch mode with intermittent enzyme precipitation and product removal, this can enhance product yield up to 1·4‐fold when co

ISSN:0268-2575    

DOI:10.1002/jctb.280600204

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe measurement of the adsorption equilibrium constants of the bases and the total mass of base adsorbed at 200°C are proposed as reproducible indices of average acidity strength and of total acidity of the solid, respectively. The adsorption of different bases (ammonia,n‐butylamine,tert‐butylamine, pyridine) in gas phase on solid acidic catalysts (silica–alumina and zeolite catalysts and a silica gel) has been studied, by applying the calorimetric method in flow regime through an isothermal bed of solid. Both the conditions under which the adsorption is exclusively chemical as well as those under which the adsorption is not limited by the internal diffusion of the base have been determined. For these acidity measurementstert‐butylamine behaves well and is an alternative base to

ISSN:0268-2575    

DOI:10.1002/jctb.280600205

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractCoconut coir pith, available in abundance especially in tropical countries, was studied as a substrate for the production of cellulase[1,4(1,3;1,4)‐β‐D‐glucan 4‐glucanohydrolase, EC 3.2.1.4] and β‐D‐glucosidase(β‐D‐glucoside glucohydrolase, EC 3.2.1.21) in solid state fermentation. The effects of fermentation time, nutrient level, substrate particle size and inoculum size have been examined for optimal production of these enzymes by the fungal strainAspergillus nigerNCIM 1005. The highest filter paper activity (FPA) of 4.11 IU g−1, carboxyl methyl cellulose (CMCase) activity of 15·55 IU g−1and cellobiase activity of 9·31 IU g−1were obtained after 7 to 8 days of fermentation. Reese and Mandel's mineral solution in the substrate to mineral solution ratio of 1:10 (w/v) supported high cellulase and cellobiase activities. An inoculum size of 20–50% (v/v) based on the volume of mineral medium and substrate average particle size of 375 μm were

ISSN:0268-2575    

DOI:10.1002/jctb.280600206

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractA simple affinity chromatography procedure for specific isolation of serine proteases is described. The procedure was tested using enzymes from five microbial and one plant source. Feather keratin, covalently bound to controlled‐pore glass, was the support and magnesium chloride was used in the elution buffers instead of zinc chloride. This enabled one‐step isolation of serine proteases present in the biological materials used. The small (15 cm × 1 cm) controlled‐pore keratin‐glass column allowed high flow rates and protected the proteases from autodigestion during the chromatography process. The serine proteases were eluted from the column with good recovery (40–84·6%) and a purification efficiency between 5 and 7. The purified proteases were homogeneous by polyacrylamide gel elec

ISSN:0268-2575    

DOI:10.1002/jctb.280600207

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe cobalt ferrite spinel oxide series, CoxFe3–xO4(0 ≤x≤ 3), has been prepared by coprecipitation. The adsorption–desorption isotherms of all the compositions calcined between 200 and 600°C have been measured using nitrogen gas at −196°C. The structural and the phase changes were characterized by TGA and XRD techniques. The results obtained revealed that the transformation of γ‐ to α‐Fe2O3was accompanied by a sharp decrease in theSBETvalues. The addition of Co2+ions into Fe2O3up to × = 0.6 led to an observable increase in theSBETvalue. This behaviour was attributed to the incorporation of Co2+ions into the Fe2O3lattice and the retardation of the phase transition of γ‐ to α‐Fe2O3. The minimumSBETvalues obtained at a lattice composition of × = 1·0 corresponded to the formation of a cobalt ferrite normal spinel which is associated with the existence of narrow pores. The increase inSBETvalues in the cobalt‐rich region, with a maximum atx= 2·6 is explained on the basis of the cationic replacement of Fe3+ions in the Co3O4lattice. Finally, calculation of pore volume distribution was carried out, in addition toVa–tplots, in order to study the nature of the surface porosity, w

ISSN:0268-2575    

DOI:10.1002/jctb.280600208

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractA comparative study of different sludges (anaerobic sewage sludge and anaerobic sewage sludge cultivated for 30 days) as the seed of UASB reactors for treatment of synthetic resin production wastewater was carried out on a laboratory scale. Significant differences in reactor performance were observed. With anaerobic sewage sludge seed, the reactor obtained a 71% COD removal efficiency and produced 2·94 dm3biogas per dm3wastewater under an organic loading rate of 4·5 kg COD m−3day−1. The sludge in the reactor was diffuse and possessed poor settling ability, which led to effluent SS as high as 1200 mg dm−3. However, with anaerobic sewage sludge cultivated with synthetic substrate for 30 days as a seed, the same reactor gave 78% COD removal efficiency and produced 3·5 dm−3biogas per dm3wastewater at the same loading rate. Moreover, the sludge in the reactor was completely granulated and possessed good settling ability, which resulted in effluent SS as low as 200 mg dm−3. The granular sludge produced less biomass per gram COD removed than the diffused sludge. Anaerobic sewage sludge cultivated for a short time could form the nuclei of granules for the reactor, allowing granulation to proceed smoothly. Therefore, sludge nuclei are a prerequisite of sludge granulation in UASB reactors for treatment of toxi

ISSN:0268-2575    

DOI:10.1002/jctb.280600209

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe adsorption of Pb2+, Cu2+, Zn2+and Cd2+from aqueous solution at 293 K by activated carbons obtained from different raw materials was studied. These carbons were prepared by water vapour pyrolysis of the raw materials—apricot stones, coconut shells and lignite coal. The influence of the solution pH on the adsorption processes has been studied. The presence of other metal ions in the solution decreases the adsorption of each of the ions. The selective adsorption of the metal ions is observed but the ones preferentially adsorbed do not completely prevent the adsorption of other ions. The chemical nature of the carbon surface and metal ions have great significance for the adsorption proces

ISSN:0268-2575    

DOI:10.1002/jctb.280600210

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractFilamentous cells ofTrichoderma reeseiwere immobilized by an adhesion method using carriers prepared by radition polymerization and the effects of the ionic properties of the carriers on cellulase productivity have been investigated. The cationic polymers were better than anionic polymers in the adhesion of the cells. Enzyme productivity was affected by the ionic property of the polymer, the concentration of the coating monomer and the hydrophobicity of the pre‐coating polyme

ISSN:0268-2575    

DOI:10.1002/jctb.280600211

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY