Furthermore, an increase in the number of membranes resulted in a drastic decrease in filtration resistance. 3.4 (a) DO profile and (b) linearized profile for determining the KLA in ABR operated under different operating conditions.
Introduction, literature review and objectives
Polyhydroxybutyrate (PHB)…
- Properties of PHB
- Applications of PHB
- PHB production pathway…
Therefore, PLA products may not be suitable for use in temperate regions (Arrieta et al., 2015). The biocompatibility of PHB bioplastics in living creatures has been established in sheep, pigs and chickens (Lizarraga-Valderrama et al., 2016).
Refused biomass source
- Bagasse
- Spent coffee bean grounds
- Coir pith
- Rice straw
- Empty oil palm fruit bunches
- Wheat straw
- Grassland refuse
- Waste date seeds and citrus biomass
In a study conducted by Davis et al. 2013), the authors used grass biomass as a feedstock for PHB production using Pseudomonas strains. In another study by Saratale et al. 2019), the use of kenaf fiber (a non-edible crop and lignocellulosic biomass) has been reported for PHB production using Ralstonia eutropha.
Closed-loop biorefinery
- Airlift reactor
- Bubble column reactor
- Two-phase partition bioreactor
Rahnama et al. 2012) used natural gas for the production of PHB using a bubble column bioreactor with Methylocystis hairs. Furthermore, in a study by García-Pérez et al. 2018), the authors used the same species and substrate as previously mentioned; however, a minor modification was made to the bubble column bioreactor by employing an internal gas recycling strategy.
Downstream processing for PHB recovery…
After separation of biomass from the culture liquid, solvent extraction for PHB recovery and purification is very successful for large-scale processes (Koller et al., 2013). Nowadays, high use of unstable solvents and toxic solvents is a regular part of PHB extraction (Table 1.4).
Polymeric nanocomposites for food packaging application
Research Gap
In addition, the incorporation of advanced nanofillers into the PHB matrix to enhance properties to realize its potential for food packaging applications is essential.
Aim and objectives
Screening of process parameters using Taguchi experimental design for biomass growth and PHB production using R. Feedstock and analysis of key components for PHB production along with the capital and annual operating costs.
Organization of thesis
Later, appropriate concentration 1–3% (w/v) of the obtained lignin was mixed into the chloroform solution (Kurosawa et al., 2015). 2.8 (c & d)) clearly shows that the decomposition temperature (thermal stability) of the PHB extracted using a varying concentration of lignin in the extractant is reduced by 3oC. Furthermore, an increase in the number of membranes resulted in a drastic reduction of the filtration resistance.
4.7(a) clearly shows an increase in cake concentration (Cc) with an increase in applied pressure, which is due to a decrease in filtration rate (calculated by taking the slope of broth flux versus time) with an increase in the applied pressure. This initial increase in resistance can be attributed to the compressible nature of the R.
A closed-loop biorefinery approach for polyhydroxybutyrate (PHB)
Introduction
In addition, PHB is well known for its biodegradability, biocompatibility and renewable nature (Arul Manikandan et al., 2019a; Khanna and Srivastava, 2005). Ralstonia eutropha and Bacillus megaterium are well known for the production of PHB in the last 50 years (Arul Manikandan et al., 2019a; Khanna and Srivastava, 2005). However, most carob pods are rejected by the industry, so they can serve as a cheap carbon source for the microbial fermentation process (Carvalho et al.
Very recently, the operation of lignin biorefinery has boomed due to the use of lignin in various fields (Hu et al., 2018). Conventionally, this recalcitrance due to lignin is removed via hydrolysis coupled to adsorption (Kosa and Ragauskas, 2013; Liu et al., 2012; Meziani et al., 2015).
Materials and methods
- Materials
- Preparation of carob pod extract
- Analysis of sugar and other constituents
- PHB production
- Characterization methods
- PHB extraction
- Characterization of PHB polymer
Protein concentration in the locust bean extract was measured according to Lowry's method as described by Hazarika et al. Carob pod extract served as the carbon source, and it was used in the range of 20 - 40 g/L for PHB production. All the experiments were continued for 60 hours, after which the biomass in the bioreactor was harvested and analyzed for its PHB content (Arul Manikandan et al., 2019).
The samples were scanned in the 2 theta range from 5 to 80o along with a scan rate of 5o min-1. The optical property of the polymer film in this study was analyzed by UV-Vis spectrophotometer (Lambda 35, PerkinElmer, Germany).
Results and discussion
- Screening of process parameters using Taguchi experimental
- Integrated downstream processing using lignin as a green solvent
- Characterization of extracted PHB
- Fourier transform infrared (FTIR) spectroscopy analysis
- Nuclear magnetic resonance (NMR) analysis
- X-ray diffraction (XRD) analysis
- Antibacterial activity
- DSC/TGA analysis
- Mechanical properties
- Optical properties
PHB extracted from bacterial biomass using different concentration of lignin in the extractant gave an inhibition zone with the microorganism S. Differences in the melting behavior of commercial PHB and PHB extracted from bacterial biomass using a different concentration were studied of lignin in the extractant. using DSC analysis, and the results are shown in Figs. This reduction in thermal stability can be attributed to the carbonizing action of lignin in the thermal degradation process of PHB (Kai et al., 2019).
Tensile testing of the polymer films was performed to determine the mechanical properties of the commercial PHB and PHB extracted from the bacterial biomass using a varying concentration of lignin in the extractant (Fig. 2.9). Furthermore, PHB extracted with 1% w/v lignin in chloroform showed antimicrobial activity due to incorporation of lignin into the PHB matrix.
Introduction
In some cases, the sharp edges and corners contributed by the flaps and impeller in such conventional stirred tank bioreactors lead to cell death and loss of PHB (Curran and Black, 2005; Follonier et al., 2012). In a more recent study, García-Pérez et al. 2018) used a novel gas recycle bubble column bioreactor as substrate to produce PHB from methane; efforts were made to increase the solubility of methane. This type of Taylor and Couette flow bioreactor has been reported for various biotechnological applications, from animal cell cultivation (Qiao et al., 2014), microalgae cultivation (Kong et al., 2013), biopolymerization (Douaire et al., 2011). for the production of biohydrogen, etc.
For example, Paule et al. 2011) used a novel annular bioreactor with Taylor and Couette flow for the development of phototrophic biofilm cultures. Furthermore, it is worth noting that unlike the conventional stirred tank bioreactor (Kalaiyezhini and Ramachandran, 2015), membrane bioreactor (Haas et al., 2017), bubble column bioreactor (García-Pérez et al., 2018a; Ghoddosi et al. , 2019), microbubble bioreactor ( Inan et al., 2016) and air bridge bioreactor (Gahlawat et al., 2012), there is no study reported in the literature on PHB production using annular bioreactor or Taylor and Couette bioreactor.
Materials and methods
- Chemicals
- Hydrodynamic studies with the ABR
- Computational dynamics (CFD) simulation
- Microroganisms
- ABR and STBR study…
- Analytical techniques
The inner cylinder of the ABR was made of aluminum-clad plywood and attached to a motor to rotate the cylinder in the range of 250-500 rpm. Then, the DO in the bioreactor solution was measured every 25 seconds using a DO probe, as previously mentioned. Both the trace element analysis and the DO measurement were performed according to the protocol reported in the literature by Ramezani et al.
In addition, the bubble size distribution in the ABR under different operating conditions was analyzed using a high-speed camera (VEO 640, Phantom, USA). CFD simulation was performed to analyze the flow pattern in the annular bioreactor (ABR) operated at an agitation speed of 500 rpm.
Results and discussions
- Hydrodynamic studies of ABR
- CFD analysis
- Performance of ABR in batch mode
- Performance of ABR in Fed-batch mode
- Characterization of PHB
3.5(b)) due to Taylor flow or increased gas retention in Taylor vortices (Ramezani et al., 2015). Images showing (a) air bubbles originating from the atomizer, (b) air bubbles on the stem of the ABR, and (c) a plot of the bubble size distribution in the ABR operating under different operating conditions. Biomass and PHB concentration at different operating conditions in serially operated (a) ABR and (b) STBR.
Furthermore, the peak observed around 1278 cm−1 was due to the C-O-C extension found in the backbone of PHB. 3.11(c) compares the XRD profiles of the PHB extracted in this study with that of pure PHB.
Summary
A novel ceramic membrane assembly for the separation of
Introduction
Polyhydroxybutyrate (PHB) is a green polymer and, unlike petroleum-based polymer, is of natural origin, mainly from microorganisms (Raza et al., 2018). Due to its biodegradable, biocompatible, thermoplastic and non-toxic nature, it serves as the best alternative to petroleum-derived polymers (Khanna and Srivastava, 2005; Raza et al., 2018). Consequently, a large amount of culture broth must be processed to recover all (intact) biomass from the broth (Elcik et al., 2016).
In general, 20-30% of the total biomass production cost is used for the separation of biomass from the broth (Pragya et al., 2013). Some of these materials include natural raw clay, dolomite, apatite powder, bauxite and kaolin (Issaoui et al., 2017).
Materials and methods
- Materials
- R. eutropha culture growth
- Membrane separation
- Experimental setup and analytical techniques
- Calculation of filtration resistance
The number of membranes in the patterns was varied from 1 to 4, as shown in Fig. The cross flow velocity (CFV) and applied pressure values chosen in the present study are in the microfiltration range as reported in the literature (Vasanth et al. ., 2011; . Vinoth Kumar et al., 2015). Initially, pure water was permeated into the outside of the membrane and the permeate was drawn from the inside of the membrane to calculate the permeate flow rate and water flux.
In fact, filtration resistance is the summary of resistance due to membrane fouling and other boundary variations in the membrane. A detailed investigation of the variation in the membrane boundaries during microfiltration is beyond the scope of this study.
Results and discussion
- R. eutropha growth and biomass size distribution analysis
- FESEM analysis
- Permeate water flowrate and water flux analysis…
- Effect of applied pressure on broth flux
- Effect of number of membranes on the broth flux
- Biomass and PHB recovery
- Relationship between recovery efficiency and broth flux
- Resistance analysis
4.7(a)), which shows that membrane fouling increased steadily with an increase in applied pressure. Fourier transform infrared (FTIR) analysis (Shimadzu, IR-affinity model 1) under attenuated total reflection (ATR) mode was performed to identify the functional groups present in the pristine PHB and PHB/Gr-NP nanocomposites . Further increasing the concentration of Gr-NPs resulted in the aggregation of Gr-NPs in the PHB matrix.
Thus, the addition of Gr-NPs to the PHB matrix increased the contact angle of pristine PHB from 62o to a maximum value of. Above this concentration, Gr-NPs were found to aggregate in the PHB matrix.
Practical application and Future perspectives…
Summary
The transparency of the pristine PHB and PHB/Gr-NPs nanocomposite films was analyzed using a UV-visible spectrophotometer (Perkin Elmer, Lambda 35 model, USA). The biodegradability of the pristine PHB and PHB/Gr-NPs nanocomposite films was analyzed using the soil burial method (Zhijiang et al., 2011). 5.3(b) shows the XRD spectra of the Gr-NPs, pristine PHB and PHB/Gr-NPs nanocomposites.
The tensile properties of pristine PHB and PHB/Gr-NP nanocomposites are shown in Figs. Results of (a) tensile strength analysis of pristine PHB and PHB/Gr-NPs nanocomposite with different concentration of Gr-NPs, and (b) FESEM analysis on elongation of PHB/Gr-NPs nanocomposite.
Preparation and characterization of environmentally safe and
Introduction
The steps followed to prepare the PHB/Gr-NPs nanocomposite were depicted in Fig. Tensile tests of the pristine PHB and PHB/Gr-NPs nanocomposite films were measured using a 5 kN Electromechanical Universal Test Machine (Z005TN model, Zwick Roell, USA). For this analysis, a comparison was made between pristine PHB and the respective PHB/Gr-NPs nanocomposites.
Transparency of pristine PHB and PHB/Gr-NPs nanocomposite with varying concentration of Gr-NPs to UV/visible lights. Cell viability of the pristine PHB, Gr-NPs and PHB/Gr-NPs is shown in Fig.
Materials and methods
- Materials
- Preparation of PHB/Gr-NPs nanocomposite
- Characterization
- Physico-chemical characteristics
- Oxygen permeability and water vapour permeability
- Shelf life (Ɵ) simulation test
- Thermal characteristics
- Transmittance and tensile characteristics…
- Cytotoxicity test
- Biodegradation test
Results and discussion
- Physico-chemical characteristics
- Dispersion analysis
- FTIR analysis
- XRD analysis
- Contact angle analysis
- Barrier properties
- Shelf life (Ɵ) simulation
- Thermal characteristics
- TGA analysis
- DSC analysis
- Transmittance and Tensile characteristics
- Transmittance analysis
- Tensile properties
- Cytotoxicity analysis
- Biodegradation experiment
Agglomeration was observed for a Gr-NPs concentration above 0.7%. w/w) dispersed in the PHB matrix with superior grade graphene. Up to a Gr-NPs concentration of 0.7 wt% in the PHB/Gr-NPs nanocomposites, the PHB peaks are found to be prominent. The decrease in elongation at break can be attributed to the brittleness due to the addition of Gr-NPs in the PHB matrix.
Since it is a biodegradable polymer, it is necessary to study the change in the biodegradability of PHB due to the addition of Gr-NPs to the PHB matrix. However, in the present study, PHB/Gr-NPs nanocomposite was prepared by following a laboratory-scale solution casting method.
Summary
Biodegradation result of pristine PHB and PHB/Gr NPs nanocomposite with varying concentration of Gr NPs (* symbol above the bars indicates that the differences in the values are statistically significant at P < 0.05 and ** symbol above the bar indicates that the differences in the values are not statistically significant at P > 0.05 (according to the Turkish test). The inset image shows the change in the surface morphology of the 0.7 wt% PHB/Gr-NPs nanocomposite during the biodegradation, as noted by FESEM analysis.
Techno-economic assessment of large scale polyhydroxybutyrate
Introduction
Methodology
- Base Cost for constructing a PHB producing plant
- Background of the study
- Cost for the raw materials requirement
- Process flow in PHB production using carob pods under SC4
- Capital and maintenance of the key components needed for PHB
- Key components involved in the preparation of carob pod
- Key elements involved in biomass-cum-PHB production
- Key elements involved in the separation of PHB rich
- Miscellaneous requirements for PHB production
Results and Discussion
- Net revenue generated by the PHB plant considering the
Summary
Conclusions and Future perspectives
Scope for future study
