Optimization of solid state fermentation parameters for bioethanol production from waste glycerol using immobilized escherichia coli

The rapid industrial and economic development runs on fossil fuels and other energy sources. Limited oil reserves, environmental issues, and high transportation costs lead towards carbon unbiased renewable and sustainable fuel. Compared to other carbon-based fuels, biodiesel is attracted worldwide as a biofuel to reduce global dependence on fossil fuels and the greenhouse effect. During biodiesel production, approximately 10% of glycerol is formed as byproduct. Malaysia is one of the largest producers of palm oil in the global market; thus, palm oil is used as the primary source for biodiesel production. In Malaysia, 480 million liters of biodiesel was produced in 2017 and is expected to reach 815 million liters in 2027, showing a 66% increase. Valorizing industrial waste is a big challenge to provide a significant economic advantage through the sustainable approach. Hence, there is an urgent need to find a compromising way to balance the environmental protection and sustainable reuse of the glycerol residue from the biodiesel industry. Our present work aims to produce bioethanol from biodiesel waste using immobilized Escherichia coli cells by solid-state fermentation. Hence, glycerol waste from the biodiesel industry is used as the carbon source for bioconversion to ethanol without primary treatment using Escherichia coli. Escherichia coli cells were immobilized using Na alginate. The stability, leakage and recycling of immobilized cells were studied for solid-state fermentation. High-performance liquid chromatography was used to analyze the concentration of glycerol and ethanol. Fourier transform infrared spectroscopy was used to analyze the functional group of glycerol and ethanol. Ethanol that has been produced was optimized by Response Surface Methodology. The important bio-process parameters such as inoculum (20%), mass substrate (20 g) and time (12 h) optimized to achieve maximal ethanol production of 10.0 g/L by immobilized E.coli cells. The kinetic study of free cells and immobilized cells were studied. The results obtained for maximum specific growth rate μmax was 0.028 h-1 and KS 6.23 g obtained for immobilized cells, while for the free cells, maximum growth rate μmax was 0.025 h-1 and KS of 5.11g. This study successfully used the biodiesel byproduct waste glycerol as the carbon source for the fermentation, using immobilized E.coli cells to produce ethanol

Opportunities of biodiesel industry waste conversion into value-added products

The global attention for the alternative fuel to decrease the dependence on carbon-biased fossil fuels and reduce the carbon footprint led to biodiesel production. Crude glycerol generated as a major by-product of the biodiesel industry. The vast amounts of crude glycerol pose an environmental threat. Valorisation of industrial waste is the big challenge to provide a significant economic advantage by the sustainable approach. Hence the crude glycerol needs to be valorised through the biotechnology process into value-added products and gives biodiesel producers more revenue. The biodiesel industrial by-product glycerol waste serves as raw material to convert into several products like citric acid, succinic acid, 1,3-propanediol, butanol, and ethanol. The present manuscript focuses on the significance of crude glycerol from the biodiesel industry as a stable feedstock that undergoes biotransformation to value-added products by microorganisms

The crashworthiness performance of the energy-absorbing composite structure—A review

The improved energy absorption capacity of composite materials will upgrade people’s safety in accidents. Several parameters affect energy absorption such as fibre type, matrix type, fibre architecture, specimen geometry, processing conditions, fibre volume fraction, and test speed. These parameters influence the composite material-specific energy absorption. The distinct characteristic properties of composites play an essential role in a variety of industries. Automotive applications have attracted worldwide attention due to their rapid use and are expected to increase. This review focuses on understanding the effect of a particular parameter on the energy absorption capability of composites, an analysis of the energy absorption properties of polymer composites. The data from the various researchers are collected and categorised in the field of energy absorption of composites. Many testing methods and refraction types for composites are described

Bioconversion of glycerol waste to ethanol by Escherichia coli and optimisation of process parameters

Biofuel is one of the best ways to reduce our dependence on fossil fuels. Ever since commercial biodiesel production began, waste glycerol, the biodiesel byproduct, has gained researchers’ interest, especially its recycling. Here, we explored using glycerol residue (carbon source) as a substrate in the fermentation process for ethanol production by Escherichia coli K12 in anaerobic conditions. The factors affecting the ethanol production was optimised by response surface methodology (RSM). Significant variables that impact the ethanol concentration were pH, temperature and the substrate, with a statistically significant effect (P <0.05) on ethanol formation. The significant factor was analyzed by the Box-Behnken design. The optimum conditions for bioethanol formation using glycerol as substrate was obtained at pH 7 and temperature 37°C. The ethanol productivity was 0.77 g/L/h. The ethanol concentration of 9.2 g/L achieved from glycerol residue was close to the theoretical value with the fermentation achieved at optimised terms

Growth profile study of Escherichia Coli K12 by optical density measurement

Bioconversion by microorganisms plays an important role worldwide over chemical transformation. Thus, microbial fermentation offers a significant advantage in producing valueadded products. The biodiesel industry's primary by-product is crude glycerol. The glycerol waste from the biodiesel industry was used as the carbon source for the fermentation process. The biodiesel industry will benefit from the bioconversion of glycerol into valuable chemicals because it is a widely accepted renewable fuel. For the fermentation process for conversion of valuable product, bacteria's stability and growth conditions were monitored using the glycerol as a substrate. Therefore the growth of E.coli cells were required so bacterial growth are commonly analysed using optical density measurements in microbiology. Hence, in the present research focussed on the growth profile study of Escherichia coli K12 by optical density measurement using the spectrophotometer

Bioconversion of glycerol waste to ethanol by Escherichia coli and optimisation of process parameters

Biofuel is one of the best ways to reduce our dependence on fossil fuels. Ever since commercial biodiesel production began, waste glycerol, the biodiesel byproduct, has gained researchers’ interest, especially its recycling. Here, we explored using glycerol residue (carbon source) as a substrate in the fermentation process for ethanol production by Escherichia coli K12 in anaerobic conditions. The factors affecting the ethanol production was optimised by response surface methodology (RSM). Significant variables that impact the ethanol concentration were pH, temperature and the substrate, with a statistically significant effect (P <0.05) on ethanol formation. The significant factor was analyzed by the Box-Behnken design. The optimum conditions for bioethanol formation using glycerol as substrate was obtained at pH 7 and temperature 37°C. The ethanol productivity was 0.77 g/L/h. The ethanol concentration of 9.2 g/L achieved from glycerol residue was close to the theoretical value with the fermentation achieved at optimised terms

Glycerol Waste to Bio-Ethanol: Optimization of Fermentation Parameters by the Taguchi Method

Global attention caused by pollutants and greenhouse gas emissions leads to alternative fuels that decrease the dependence on fossil fuels and reduce the carbon footprint that preceded the development of biodiesel production. Glycerol residue is generated more significantly from the biodiesel industry as a byproduct and is left as waste. In this study, we utilized glycerol residue from the biodiesel industry as an excellent opportunity to convert ethanol by bioconversion. The waste glycerol was used as a good and cheap carbon source as a substrate to synthesize ethanol by immobilizing E. coli cells. The screening of parameters such as mass substrate, temperature, inoculum size, and fermentation time was carried out using the one-factor-at-a-time (OFAT) technique. The Taguchi model employed optimization of fermentation parameters. The process parameters showed the mass substrate glycerol of 20 g with an inoculum size of 20%, and 12 hours yielded the ethanol concentration of 10.0 g/L

Facile manufacture of oxide-free Cu particles coated with oleic acid by electrical discharge machining

Particle synthesis has seen significant advances in current trends. However, the synthesis of metal particles without oxidation is a challenge for researchers. The current study presents a straightforward, convenient, and convincing approach for manufacturing copper (Cu) particles free of surface oxide. The die-sink Electrical Discharge Machine (EDM) of copper alloys with oleic acid resulted in the formation of Cu particles with diameters between 10 to 20 µm. X-ray diffraction (XRD) was used for particle examination after cleaning and sonication with distilled water. Cu particles with oleic acid coating retained a Cu phase without oxidation after synthesis. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to determine the size and morphology of generated particles. Fourier transforms infrared (FT-IR) analysis revealed the oleic acid-coated Cu surface bonded with an oxygen atom. Also, the agglomeration and change of size involving Cu particles with increasing voltages in the pulse supply in EDM were reported

Experimental investigation on magnetorheological finishing process parameters

Magneto-rheological polishing (MRP) fluid was developed by MR fluid using a magnetic field, non-magnetic abrasives such as SiC and Al2O3, and carrier medium like oil. A magnetic polishing tool was developed using a super-strong permanent neodymium magnet (Nd2Fe14B) with 0.5-tesla magnetic intensity. This polishing tool was assembled to the vertical milling machine for the finishing workpieces. In the present research, magnetic materials (steel material) and non-ferromagnetic (copper) content were finishing using a developed MRP setup for experimental investigation. This research also investigated the parametric dependencies of different abrasives on the magneto-rheological finishing process. It determined the effect of magnetic particle concentration and abrasives on the surface roughness of ferromagnetic (stainless steel) and non-ferromagnetic material (copper). The final surface roughness value has reached 30 nm from its initial surface roughness of 800 nm for non-ferromagnetic (copper). For the magnetic material (stainless steel), the value is 50 nm from 1300 nm

Bioconversion of Glycerol into Biofuels—Opportunities and Challenges

Rising pollutants and greenhouse gas emissions from fossil fuels are serious environmental concerns that led to a tremendous focus of scientific research. The use of renewable resources as feedstock to produce fuels could help preserve the environment and offer economic and social sustainability. This preceded the development of alternative fuels such as biodiesel, and bioethanol. Over the last decade, the substantial expansion of biodiesel production indicates stoichiometrically increased crude glycerol co-production. Due to the surplus availability of the crude glycerol (as it does not find any potential application for complete utilisation), its market value has fallen and is even seen as a waste stream instead of a lucrative co-product. While high-purity glycerol is used in cosmetics, food, paints, and pharmaceutical industries for medicines, crude glycerol is an attractive organic carbon substrate to produce value-added products through microbial fermentation or physicochemical processing. The review discussed the recent developments in glycerol to produce fuels such as bioethanol, hydrogen, and methanol. Besides, it highlights the opportunities and challenges in utilising crude/waste glycerol generated from the biodiesel industry