Bioethanol: fuel or feedstock?Rass‐Hansen, Jeppe; Falsig, Hanne; Jørgensen, Betina; Christensen, Claus H
doi: 10.1002/jctb.1665pmid: N/A
Increasing amounts of bioethanol are being produced from fermentation of biomass, mainly to counteract the continuing depletion of fossil resources and the consequential escalation of oil prices. Today, bioethanol is mainly utilized as a fuel or fuel additive in motor vehicles, but it could also be used as a versatile feedstock in the chemical industry. Currently the production of carbon‐containing commodity chemicals is dependent on fossil resources, and more than 95% of these chemicals are produced from non‐renewable carbon resources. The question is: what will be the optimal use of bioethanol in a longer perspective? Copyright © 2007 Society of Chemical Industry
Defining sustainability: a conceptual orientationVos, Robert O.
doi: 10.1002/jctb.1675pmid: N/A
Despite the ubiquity of the concept of sustainability, defining the term and construing meaning for different contexts is difficult. This paper presents several archetypes of sustainability that are useful for classifying and understanding existing definitions. Definitions that emphasize one part or another of the core concept of sustainability will be necessary at varying scales and in different contexts. This paper presents a conceptual guide that contrasts a dominant paradigm of economic growth and development with ‘thick’ and ‘thin’ versions of sustainability. Definitions of sustainability are explored in terms of their orientation to the ontology of nature, substitutability of resources, economic growth, population growth, role of technology, and social equity. Copyright © 2007 Society of Chemical Industry
Increased tolerance and conversion of inhibitors in lignocellulosic hydrolysates by Saccharomyces cerevisiaeAlmeida, João RM; Modig, Tobias; Petersson, Anneli; Hähn‐Hägerdal, Bärbel; Lidén, Gunnar; Gorwa‐Grauslund, Marie F
doi: 10.1002/jctb.1676pmid: N/A
During hydrolysis of lignocellulosic biomass, monomeric sugars and a broad range of inhibitory compounds are formed and released. These inhibitors, which can be organized around three main groups, furans, weak acids and phenolics, reduce ethanol yield and productivity by affecting the microorganism performance during the fermentation step. Among the microorganisms that have been evaluated for lignocellulosic hydrolysate ethanol fermentation, the yeast Saccharomyces cerevisiae appears to be the least sensitive. In order to overcome the effect of inhibitors, strategies that include improvement of natural tolerance of microorganism and use of fermentation control strategies have been developed. An overview of the origin, effects and mechanisms of action of known inhibitors on S. cerevisiae is given. Fermentation control strategies as well as metabolic, genetic and evolutionary engineering strategies to obtain S. cerevisiae strains with improved tolerance are discussed. Copyright © 2007 Society of Chemical Industry
Aerated and rotated mode decolorization of a textile dye solution by native and modified mycelial biomass of Trametes versicolorBinupriya, A R; Sathishkumar, M; Kavitha, D; Swaminathan, K; Yun, S E
doi: 10.1002/jctb.1668pmid: N/A
Aerated and rotated mode adsorption experiments were carried out for the removal of a textile dye (reactive blue MR) from aqueous solution using native and pre‐treated biomass of Trametes versicolor. The effect of process parameters like contact time, dosage of adsorbent and adsorbate and pH on adsorption was investigated. The higher the dye concentration, the lower was the adsorption. Increase in biomass dosage increased the adsorption. Kinetic study showed that the adsorption of dye on fungal biomass was a gradual process, and a second‐order kinetic model fitted the present experimental data well. Experimental data were analyzed using Langmuir and Temkin et seq isotherms. Acidic pH was favorable for adsorption. Studies on pH effect and desorption show that chemisorption seems to play a major role in the adsorption process. Of the native and pre‐treated biomass studied, autoclaved biomass showed a better adsorption capacity. The adsorption capacity of autoclaved biomass in aerated mode was found to be 50.51 mg g−1. Aerated mode showed a better adsorption capacity than rotated mode. Copyright © 2007 Society of Chemical Industry
Assessing chemical oxygen demand and nitrogen conversions in a multi‐stage activated sludge plant with alternating aerationLessard, Paul; Tusseau‐Vuillemin, Marie‐Hélène; Héduit, Alain; Lagarde, Fabienne
doi: 10.1002/jctb.1679pmid: N/A
This paper provides a detailed investigation of the mass transfers involved in chemical oxygen demand (COD) and N removal in an intermittent aeration activated sludge plant, as described by the widely used ASM1 model. The model was calibrated and validated on a data set obtained during three intensive sampling campaigns. The mass transfers of COD and nitrogen were calculated with the calibrated model for every biodegradable variable of the model in each tank of the biological treatment. Only by making this balance can evaluation of the contribution of each reactor (anaerobic, anoxic and intermittently aerated) to carbon and nitrogen removal be done. It was pointed out that in such a plant (activated sludge under very low organic mass loading (F/M) ratios, sludge retention time of 30 days) operating at 20 °C, the contribution of the anoxic tank in the denitrification process is very low (only 17%). The oxygen transfer in this tank was also estimated and found partly responsible for the low denitrification efficiency. Copyright © 2007 Society of Chemical Industry
Solvent extraction of lanthanides and yttrium from nitrate medium with CYANEX 925 in heptaneLi, Wei; Wang, Xianglan; Zhang, Hui; Meng, Shulan; Li, Deqian
doi: 10.1002/jctb.1680pmid: N/A
The extraction behavior of lanthanides and yttrium usinsg CYANEX 925 (mixture of branched chain alkylated phosphine oxides) in n‐heptane from nitrate medium has been studied. The effects of aqueous phase ionic strength, CYANEX 925 concentration in the organic phase, and temperature on Sm3+, Nd3+ and Y3+ extraction have been investigated. The extractability of the lanthanides and yttrium increases with increasing nitrate concentration, as well as with increasing CYANEX 925 concentration. An extraction mechanism is proposed based on slope analysis. Furthermore, the infra‐red spectra of CYANEX 925 saturated with lanthanides are employed to provide evidence of the composition of the complex. The relationship between the logarithm of the distribution ratio and lanthanide atomic number is also discussed which indicates that yttrium can be separated from light lanthanides. In addition separation of the light and heavy lanthanide groups is also possible using CYANEX 925. From the temperature dependence data, the thermodynamic parameters values (ΔH, ΔS and ΔG) are calculated. Copyright © 2007 Society of Chemical Industry
Removal of organic contaminants from water using nanosponge cyclodextrin polyurethanesMhlanga, Sabelo D; Mamba, Bhekie B; Krause, Rui W; Malefetse, Tshepo J
doi: 10.1002/jctb.1681pmid: N/A
Insoluble nanoporous cyclodextrin (CD) polymers were synthesized using bifunctional isocyanate linkers. The ability of these polymers to remove selected organic pollutants from water at varying concentrations was studied. The investigated pollutants were selected high‐priority chlorinated disinfection by‐products (DBPs) and a common odour‐causing compound in water, 2‐methylisoborneol (2‐MIB). The unpleasant musty odour imparted by 2‐MIB and geosmin in water can be detected by the human nose even at ng L−1 (parts per trillion) levels. Pre‐concentration and extraction of water samples containing low levels of pollutants was performed using solid phase extraction (SPE) and subsequently quantified by gas chromatography‐mass spectrometry (GC/MS). Here we show that the CD polymers demonstrate excellent absorption efficiency (>99%) with respect to the organic pollutants, considerably better than granular activated carbon (GAC). The recyclability efficiency of these CD polymers is also reported. Copyright © 2007 Society of Chemical Industry
Two and three‐parameter isothermal modeling for liquid‐phase sorption of Procion Blue H‐B by inactive mycelial biomass of Panus fulvusSathishkumar, Muthuswamy; Binupriya, Arthur Raj; Vijayaraghavan, Kuppusamy; Yun, Soon‐Il
doi: 10.1002/jctb.1682pmid: N/A
Procion Blue H‐B (PBHB) was used as a model reactive dye for biosorption studies onto inactive/dead mycelial biomass of Panus fulvus. Process parameters like pH, contact time and temperature were optimized. pH 2, 150 min of contact time and 35 °C were found to be more favorable for maximum biosorption. Various two‐ and three‐parameter isotherms were employed to understand the biosorption process. Among the various two‐parameter isothermal models applied, the Langmuir isotherm showed the best fit and among the three‐parameter isothermal models, the Khan, Redlich–Peterson, Sips and Toth isotherm models showed similar fits and only the Koble–Corrigan model showed a poor fit. In kinetic studies, pseudo‐first‐order model fitted better than pseudo‐second‐order model. Maximum desorption was observed in alkaline pH, which reveals the possibility of a chemisorption mechanism involved in the removal of PBHB. Among the various desorption media assessed, 70% (v/v) acetone showed complete desorption of the sorbate from the sorbent. Scanning electron microscopy images revealed the non‐fibrous nature of the adsorbent. FT‐IR studies showed the existence of amine groups in the sorbent which are the major adsorbent sites for reactive dyes. Copyright © 2007 Society of Chemical Industry
Decolourisation and treatment of pulp and paper mill effluent by lignin‐degrading Bacillus sp.Raj, Abhay; Reddy, MM Krishna; Chandra, Ram
doi: 10.1002/jctb.1683pmid: N/A
Three lignin‐degrading bacterial strains, identified as Paenibacillus sp., Aneurinibacillus aneurinilyticus and Bacillus sp. have been examined for the treatment of pulp and paper mill effluent. The results of this study revealed that all three bacterial strains effectively reduced colour (39–61%), lignin (28–53%), biochemical oxygen demand (BOD) (65–82%), chemical oxygen demand (COD) (52–78%) and total phenol (64–77%) within six days of incubation. However, the highest reduction in colour (61%), lignin (53%), BOD (82%) and COD (78%) was recorded by Bacillus sp. while, maximum reduction in total phenol (77%) was recorded with Paenibacillus sp. treatment. Significant reduction in colour and lignin content by these bacterial strains was observed after two days of incubation, indicating that bacterium initially utilized growth supportive substrates and subsequently chromophoric compounds thereby reducing lignin content and colour in the effluent. The total ion chromatograph (TIC) of compounds present in the ethyl acetate extract of control and bacterial treated samples revealed the formation of several lignin‐related aromatic compounds. The compounds identified in extracts of treated samples by Paenibacillus sp were t‐cinnamic acid and ferulic acid, while 3‐hydroxy‐4‐methoxyphenol, vanillic acid and vanillin acid by A. aneurinilyticus and gallic acid and ferulic acid by Bacillus sp. respectively indicating the degradation of lignin present in the effluent. The identified compounds obtained after different bacterial treatments were found to be strain‐specific. Among these identified compounds, ferulic acid, vanillic acid and vanillin could have immense value for their use in preservatives and in the food flavour industry. Copyright © 2007 Society of Chemical Industry