Prakash V. Chavan

Degradation of reactive orange 4 dye using hydrodynamic cavitation based hybrid techniques.

In the present work, degradation of reactive orange 4 dye (RO4) has been investigated using hydrodynamic cavitation (HC) and in combination with other AOPs. In the hybrid techniques, combination of hydrodynamic cavitation and other oxidizing agents such as H2O2 and ozone have been used to get the enhanced degradation efficiency through HC device. The hydrodynamic cavitation was first optimized in terms of different operating parameters such as operating inlet pressure, cavitation number and pH of the operating medium to get the maximum degradation of RO4. Following the optimization of HC parameters, the degradation of RO4 was carried out using the combination of HC with H2O2 and ozone. It has been found that the efficiency of the HC can be improved significantly by combining it with H2O2 and ozone. The mineralization rate of RO4 increases considerably with 14.67% mineralization taking place using HC alone increases to 31.90% by combining it with H2O2 and further increases to 76.25% through the combination of HC and ozone. The synergetic coefficient of greater than one for the hybrid processes of HC+H2O2 and HC+Ozone has suggested that the combination of HC with other oxidizing agents is better than the individual processes for the degradation of dye effluent containing RO4. The combination of HC with ozone proves to be the most energy efficient method for the degradation of RO4 as compared to HC alone and the hybrid process of HC and H2O2.

Sustainable biobutanol production from pineapple waste by using Clostridium acetobutylicum B 527: Drying kinetics study

Present investigation explores the use of pineapple peel, a food industry waste, for acetone-butanol-ethanol (ABE) production using Clostridium acetobutylicum B 527. Proximate analysis of pineapple peel shows that it contains 35% cellulose, 19% hemicellulose, and 16% lignin on dry basis. Drying experiments on pineapple peel waste were carried out in the temperature range of 60-120°C and experimental drying data was modeled using moisture diffusion control model to study its effect on ABE production. The production of ABE was further accomplished via acid hydrolysis, detoxification, and fermentation process. Maximum total sugar release obtained by using acid hydrolysis was 97g/L with 95-97% and 10-50% removal of phenolics and acetic acid, respectively during detoxification process. The maximum ABE titer obtained was 5.23g/L with 55.6% substrate consumption when samples dried at 120°C were used as a substrate (after detoxification).

Solid-liquid circulating fluidized bed: a way forward

Abstract Solid-liquid circulating fluidized beds (SLCFBs) offer several attractive features over conventional solid-liquid fluidized beds such as efficient liquid-solid contact, favorable mass and heat transfer, reduced back-mixing of phases, and integrated reactor and regenerator design. These unique features have stimulated theoretical and experimental investigations over the past two decades on transport phenomena in SLCFBs. However, there is a need to compile and analyze the published information with a coherent theme to design and develop SLCFB with sufficient degree of confidence for commercial application. Therefore, the present work reviews and analyzes the literature on hydrodynamic, mixing, heat transfer, and mass transfer characteristics of SLCFBs comprehensively. Suitable recommendations have also been made for future work in concise manner based on the knowledge gaps identified in the literature. Furthermore, a novel multistage SLCFB has been proposed to overcome the limitations of existing SLCFBs. The proposed model of SLCFB primarily consists of a single multistage column which is divided into two sections wherein both the steps of utilization viz. loading (adsorption, catalytic reaction, etc.) and regeneration of solid phase could be carried out simultaneously on a continuous mode.

Supercritical carbon dioxide extraction of astaxanthin from Paracoccus NBRC 101723: Mathematical modelling study

ABSTRACT Astaxanthin (AX) is a secondary metabolite that accumulates inside the cell during Paracoccus fermentation. The fermentation biomass was extracted using supercritical carbon dioxide (SC-CO2). The solubility parameter of AX, CO2 and entrainer solvents was calculated and validated with experimental results. The pressure and particle size of the biomass had a significant effect on the extraction of AX. A maximum recovery of 963.33 μg/g of AX was obtained after SC-CO2 extraction at 40ºC, 350 bar and a run time of 60 min with ethanol (20% v/w) as an entrainer. Further, the experimental data has been modelled using non-linear regression analysis method.

Microbial Polyamino Acids: An Overview for Commercial Attention

Abstract Although, polyamino acids are structurally similar to proteins, they are not proteins and do not have a specific sequence. Polyamino acids are polymerized from single amino acid that has molecular mass and polydispersity as similar as polysaccharides. Polyamino acid biosynthesis is considered to be an interesting example of biopolymer synthesis that is being produced by fermentation process. Furthermore, polyamino acids have a wide range of applications from food additives and biomedical agents to biodegradable and renewable resources. The materials produced from polyamino acids are environment friendly, biodegradable, and independent of oil-based resources. Three common natural polyamino acids studied extensively in the literature are, poly-e-lysine, poly-γ-glutamic acid, and cyanophycin. This chapter covers a wide-range discussion on the importance of polyamino acids including structure, biosynthesis, and biodegradation of naturally occurring poly-e-lysine, poly-γ-glutamic acid, and cyanophycin. Fermentation and biosynthetic pathway studies, along with downstream processing and characterization of these polyamino acids, are detailed extensively in the current chapter. Besides, large-scale production and challenges associated with it are also discussed. Multifarious applications of polyamino acids in the food as well as pharmaceutical industries have been summarized comprehensively. Finally, various challenges and opportunities in well-designed trials that are needed to improve the current knowledge on polyamino acids are conjectured.

Role of Trace Elements as Cofactor: An Efficient Strategy toward Enhanced Biobutanol Production

Metabolic engineering has the potential to steadily enhance product titers by inducing changes in metabolism. Especially, availability of cofactors plays a crucial role in improving efficacy of product conversion. Hence, the effect of certain trace elements was studied individually or in combinations, to enhance butanol flux during its biological production. Interestingly, nickel chloride (100 mg L–1) and sodium selenite (1 mg L–1) showed a nearly 2-fold increase in solvent titer, achieving 16.13 ± 0.24 and 12.88 ± 0.36 g L–1 total solvents with yields of 0.30 and 0.33 g g–1, respectively. Subsequently, the addition time (screened entities) was optimized (8 h) to further increase solvent production up to 18.17 ± 0.19 and 15.5 ± 0.13 g L–1 by using nickel and selenite, respectively. A significant upsurge in butanol dehydrogenase (BDH) levels was observed, which reflected in improved solvent productions. Additionally, a three-dimensional structure of BDH was also constructed using homology modeling and subsequently docked with substrate, cofactor, and metal ion to investigate proper orientation and molecular interactions.