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Expanding the use of tropical biomass wastes for nitrogen-limited fermentation was investigated, specifically, the production of medium chain length polyhydroxyalkanoates. Comprehensive central composite design was conducted to assess pH, temperature, biomass solid loading, cellulase loading and amylase loading and their impact on the hydrolysis of palm, coconut and cassava wastes. Glucose yields of 33.3, 31.7 and 79.0% wt. with respect to total glucose were found for palm, coconut and cassava, respectively. Importantly, the impact on the total nitrogen derived during enzymatic hydrolysis of these tropical biomass was described for the first time. The level of nitrogen needs to be properly controlled as high nitrogen would result in low carbon to nitrogen ratio leading to low polyhydroxyalkanoates accumulation, but low nitrogen would hinder growth of the biopolymer producer. Maximum hydrolysate nitrogen, were 1.80, 1.55 and 0.871 g/l for palm, coconut and cassava, respectively. Using the surface responses, biomass media designed for high carbon-to-nitrogen were produced and validated using Pseudomonas putida. Low glucose-carbon to nitrogen were found for palm and coconut after scale-up, leading to the majority of their polyhydroxyalkanoates not being biomass-derived. However, cassava-derived biopolymers were successfully accumulated at 9.01 and 7.13% wt. for total medium chain length polyhydroxyalkanoates and 10-carbon polyhydroxyalkanoates, respectively. This study provides an important foundation for the expansion of tropical biomass wastes for biopolymer production and other nitrogen-limited applications in general.

In this work, refined bleached deodorised palm oil (RPO) and palm kernel oil (PKO) obtained from palm oil refinery, were used as feedstocks to investigate the production of bio-hydrogenated kerosene (BHK) via hydrocracking reaction. A statistical tool of box-behnken design (BBD) was applied to consider the effects of reaction temperature, pressure and liquid hourly space velocity (LHSV) on biofuel production from RPO. The results revealed that the temperature was strongly significant effect on the yield and the optimal condition was found at 477 °C, 5.6 MPa and 1.5 h−1 of LHSV. Subsequently, crude biofuel was separated by fractional distillation, the biofuel yield was obtained at approximately 90% and providing 49.59% kerosene selectivity. Curiously, another feedstock of PKO which has lauric acid as the main composition whereas RPO contained palmitic and oleic acids, was used to produce BHK by using operating condition based-on RPO optimal condition. The biofuel yield derived from PKO reached at the same quantity. On the other hand, kerosene selectivity obtained was higher than in case of RPO (55.35%). However, high oxygen content was found in PKO-derived BHK, and this affected to freezing point and total acid number.

The alternative approach to the production of biodiesel from sludge palm oil (SPO) via two steps of extraction and enzymatic esterification was performed. Free fatty acids (FFAs) from SPO were obtained through saponification reaction and subsequent extraction. The FFAs were further converted to biodiesel (fatty acids methyl esters) via esterification reaction catalysed by immobilised Rhizopus oryzae lipase on alginate-polyvinyl alcohol (PVA) beads. The esterification reaction was investigated by variations of temperature (30–50 °C), molar ratio of methanol to FFAs (1:1 to 5:1), agitation rate (100–300 rpm) and for 4 h. The results were revealed that optimal condition for biodiesel production reached at reaction temperature of 40 °C, methanol to FFAs molar ratio of 3:1 and agitation rate of 200 rpm. Under the optimum condition, the highest biodiesel yield of 91.30% was achieved. Successfully, biodiesel production from SPO gave high conversion rate. In addition, the biocatalyst also showed in high catalytic efficiency and stability up to 15 cycles. The process cost could be reduced cost effectively for biodiesel production when a low cost substrate of SPO as well as the capable biocatalyst were used.

Prior to biodiesel production of a high free fatty acid (FFA) oil, esterification of the oil is recommended to reduce the FFA to less than 1%. In this work, dual frequency ultrasound-assisted esterification with three different techniques was investigated. Three wave applying techniques have been proposed with the same energy used during the process. Firstly, for technique A, 28 kHz (100 W) and 40 kHz (100 W) waves were concurrently applied for a total time of T min. Secondly, for technique B, 28 kHz (200 W) waves were firstly applied for a total time of T/2 min and followed by 40 kHz (200 W) for a total time of T/2 min. Lastly, for technique C, 28 kHz (200 W) and 40 kHz (200 W) waves were concurrently applied for a total time of T/2 min. Pertinent parameters, i.e., methanol to oil molar ratio, catalyst loading, and reaction time, were investigated. Response surface methodology (RSM) was used as a tool for optimization. The amount of final FFA and energy used during the process were the key indices to optimize the most suitable condition. The results revealed that technique C* gave the highest FFA conversion of 99.40% with specific energy consumption of 23.73 Wh/% for methanol to oil (M/O) molar ratio of 12:1, catalyst loading of 2.2%wt., and 40 min reaction time. However, when considering both final FFA less than 1% and least energy used, it was suggested that M/O ratio 15:1, catalyst loading of 1.5%wt., and 22.5 min reaction time could give as high as 94.5% conversion yield with 14 Wh/% for technique C.

In this work, water hyacinths, bagasse and rice straw were valorized to produce an innovative biopolymer. Serial steps of extraction, bleaching and conversion of cellulose to be carboxymethylcellulose (CMC) as well as the last steps of blending and molding were performed. The CMC was mixed with tapioca starch solution by a ratio of 9:18, and a plastic sizer of glycerol was varied at 2%, 4% and 6% by volume. In addition, bioplastic sheets were further determined in their properties and biodegradation. The results revealed that bioplastics with 6% glycerol showed a high moisture content of 23% and water solubility was increased by about 47.94% over 24 h. The effect of temperature on bioplastic stability was found in the ranges of 146.28–169.25 °C. Furthermore, bioplastic sheets with 2% glycerol could maintain their shape. Moreover, for texture analysis, the highest elastic texture in the range of 33.74–38.68% with 6% glycerol was used. Moreover, bioplastics were then tested for their biodegradation by landfill method. Under natural conditions, they degraded at about 10.75% by weight over 24 h after burying in 10 cm soil depth. After 144 h, bioplastics were completely decomposed. Successfully, the application of water, weed and agricultural wastes as raw materials to produce innovative bioplastic showed maximum benefits for an environmentally friendly product, which could also be a guideline for an alternative to replace synthetic plastics derived from petroleum.

An integrated cleaner biocatalyst process was performed for biodiesel production from crude palm oil (CPO) and refined palm oil (RPO). It was evaluated on process efficiency in terms of high purity of biodiesel as well as by-products without purification, less wastewater, less time consuming, and a simple downstream process. A first saponification step was carried out in both f CPO and RPO, a high purity of glycerol (86.25% and 87.5%) was achieved, respectively, while free fatty acids (FFASs) in soap were obtained after hexane extraction. High yields of FFASs were obtained from both CPO and RPO (98.83% and 90.94%). Subsequently, the FFAs were esterified to biodiesel by a biocatalyst of immobilized lipase. The highest biodiesel yields achieved were of 92.14% and 92.58% (CPO and RPO). Remarkably, biodiesel yields obtained from CPO and RPO achieved satisfactory values and the biocatalyst used could be reused for more than 16–17 cycles.

Palm oil mill effluent (POME), wastewater discharged from the palm oil refinery industry, is classified as an environmental pollutant. In this work, a heterogeneous catalytic process for biojet fuel or green kerosene production was investigated. The enzymatic hydrolysis of POME was firstly performed in order to obtain hydrolysed POME (HPOME) rich in free fatty acid (FFA) content. The variations of the water content (30 to 50), temperature (30 to 60 &deg, C) and agitation speed (150 to 250 rpm) were evaluated. The optimal condition for the POME hydrolysis reaction was obtained at a 50% v/v water content, 40 &deg, C and 200 rpm. The highest FFA yield (Y FA) of 90% was obtained. Subsequently, FFA in HPOME was converted into hydrocarbon fuels via a hydrocracking reaction catalysed by Pd/Al2O3 at 400 &deg, C, 10 bars H2 for 1 h under a high pressure autoclave reactor (HPAR). The refined-biofuel yield (94%) and the biojet selectivity (57.44%) were achieved. In this study, we are the first group to successfully demonstrate the POME waste valorisation towards renewable biojet fuel production based on biochemical and thermochemical routes. The process can be applied for the sustainable management of POME waste. It promises to be a high value-added product parallel to the alleviation of wastewater environmental issues.

A new application of biocomposite hydrogels named gelatin-alginate (GA) and pectin alginate (PA) enables the use of the hydrogels as carriers for lipase entrapment during biodiesel production. Waste frying acid oil (WFAO), a raw material, was converted to biodiesel via an esterification reaction catalysed by two different immobilised biocatalysts: gelatin-alginate lipase (GAL) and pectin-alginate lipase (PAL). The highest immobilisation yield of GAL and PAL beads was achieved at 97.61% and 98.30%, respectively. Both of them gave biodiesel yields in the range of 75&ndash, 78.33%. Furthermore, capability and reusability of biocatalysts were improved such that they could be reused up to 7 cycles. Moreover, the predicted biodiesel properties met the European biodiesel standard (EN14214). Interestingly, entrapped lipase on composite hydrogels can be used as an alternative catalyst choice for replacing the chemical catalyst during the biodiesel production.

Graphical abstract, Typically, sludge palm oil (SPO) which discharged from the palm oil refining process, is a low cost material of potential value, due to its high free fatty acid content. Accordingly, there is potential for upgrading low grade oil into valuable biofuel. In this work, we present a novel method for biodiesel production from SPO. The process consists of two steps (i) free fatty acid (FFA) extraction (ii) enzymatic esterification. Firstly, SPO was saponified by hydroalcoholic solution into soap and glycerol. Secondly, the FFAs obtained were further converted into biodiesel via enzymatic esterification catalyzed by immobilised alginate-PVA lipase beads. • Biodiesel production from sludge palm oil could be completed. • A modified fatty acid extraction was used for SPO fatty acid preparation. • Immobilised alginate-PVA lipase beads were used as biocatalyst for esterification reaction.

In this work, two kinds of catalyst called monometallic Palladium (Pd) and a bimetallic of Pd-Iron (Fe) were synthesised using aluminum oxide (Al2O3) as the supported material via the wet impregnate method. A monometallic catalyst (0.5% Pd/Al2O3) named Pd cat was used as control. For the bimetallic catalyst, ratios of Pd to Fe were varied, and included 0.38% Pd&ndash, 0.12% Fe (PF1), 0.25% Pd&ndash, 0.25% Fe (PF2), and 0.12% Pd&ndash, 0.38% Fe (PF3). The catalysts were characterised to investigate physical properties such as the surface area, pore size, porosity, and pore size distribution including their composition by Brunauer&ndash, Emmett&ndash, Teller (BET) surface area, Scanning Electron Microscopy (SEM), and X-Ray Diffraction (XRD). Subsequently, all catalysts were applied for biofuels production in terms of green diesel/kerosene/gasoline from palm oil via a hydrocracking reaction. The results showed that the loading of Fe to Pd/Al2O3 could improve the active surface area, porosity, and pore diameter. Considering the catalytic efficiency for the hydrocracking reaction, the highest crude biofuel yield (94.00%) was obtained in the presence of PF3 catalyst, while Pd cat provided the highest refined biofuel yield (86.00%). The largest proportion of biofuel production was green diesel (50.00&ndash, 62.02%) followed by green kerosene (31.71&ndash, 43.02%) and green gasoline (6.10&ndash, 8.11%), respectively. It was clearly shown that the Pd-Fe bimetallic and Pd monometallic catalysts showed potential for use as chemical catalysts in hydrocracking reactions for biofuel production.

Palm oil soap stock (POSS) was recycled from bio-waste to bio-fuel. Firstly, POSS was converted through acidification to be acidified POSS (APOSS) coupled with solvent extraction. APOSS with a high content of free fatty acids (FFAs) (90.94%) was obtained. Subsequently, the FFAs in APOSS were converted to biodiesel via esterification, catalyzed by immobilized alginate-polyvinyl alcohol (ALG-PVA) lipase. The key factors affecting the reaction, such as the temperature (30–50 °C), methanol to FFA molar ratio (2:1 to 4:1), and agitation rate (150–250 rpm) were optimized by statistical response surface methodology (RSM). The highest biodiesel yield was achieved with a reaction temperature of 40 °C, methanol/FFA molar ratio of 3:1, and 200 rpm agitation rate, as the optimal conditions. Furthermore, the biocatalyst can be reused up to 16 cycles. Interestingly, the alternative biodiesel production process reported herein promotes zero waste from the palm oil refinery process.

The green microalga, Scenedesmus incrassulatus PPAY1 was cultivated in vertical tubular photobioreactor under batch/fed-batch modes. Biodiesel derived glycerol waste (BDGW) was applied as a cheap main nutrient source. For batch cultivation (BC), maximum biomass concentration was reached at 2.83 gL-1when 20 gL-1 BGW was used. In contrast, in the case of fed-batch cultivation (FBC), the maximum algae and lipid contents were achieved at 5.65 gL-1 and 58.27%, respectively when 30 and 20 gL-1 BDGW were applied. The highest lipid yield of 2.94 gL-1was found at 30 gL-1 BDGW. The analysis of the fatty acid content revealed that palmitic acid-, oleic acid- and linoleic acid- were mainly found in both BC and FBC conditions. As expected, FBC was in a better culture strategy than BC. BDGW could be used directly without any pretreatment in both algal biomass growth and microalgal oil accumulation which simplifies cultivation and reduces operating costs during biodiesel production.

Polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is mixed with natural rubber latex to make better mechanical properties of PHBV. The various ratios between PHBV and natural rubber latex are examined to improve their mechanical properties. The PHBV are solid, easily broken, while natural rubber is excessive elastic materials. Concentrations of the employed PHBV solution are 1, 2, and 3 (%w/v). The mixtures of this solution to natural rubber latex are fabricated the biofilms in three different ratios, 4:6, 5:5, and 6:4, respectively. The films are characterized by electron microscope, universal testing machine, and differential scanning calorimetry (DSC). The electron micrographs of the mixed films and unmixed PHBV yield the lowest void distributions in 3%w/v PHBV. For mechanical properties, the averaged elastic moduli of 1, 2, and 3 (%w/v PHBV) mixed films are 773, 955 and 1,008 kPa, respectively. Their tensile strengths increase with increasing the PHBV concentrations. A similar trend is also found in elastic modulus. The crystallization and melting behavior of pure PHBV and the mixed films are examined by DSC. Melting transition temperatures of pure PHBV exhibit two melting peaks at 154°C and 173°C. In addition, the melting peaks of the mixed films remain in the range of 152-156°C and 168-171°C, respectively. According to their morphology, void distributions reduce twice, compared to the unmixed PHBV. Mechanical properties and thermal analysis indicate that the mixed PHBV can be improved their properties with more resilient and wide range temperature than usual.

In this work, the effect of catalysts, temperatures and different types of vegetable oil on the production of synthetic bio-fuel via a hydro-processing process called as a hydro-cracking reaction by high pressure pack bed reactor is investigated. Firstly, H2gas (95% purity) was fed into the reactor together with palm oil under two different catalysts (Pd/Al2O3and Pt/Al2O3) separately packed in the reactor. The effect of different temperatures (500°C and 530°C) was investigated and the pressure was applied and maintained at 5 MPa for both temperatures. The results revealed that, when the Pd/Al2O3catalyst was used the highest bio-fuel (approximately 90% at 500°C) after distillation can be produced. Then, palm oil and soybean oil were used to compare in the efficiency of kerosene fuel production. The reaction was operated at 500°C, 5 MPa under H2pressure on the presence of 0.5% Pd/Al2O3. The bio-fuel achieved the highest yields at about 88% and 69% in cases of palm oil and soybean oil. It was also classified as kerosene yield approximately 70% when palm oil was used as a feed stock and at about 55% for soybean oil. Some properties of the kerosene product were characterised. The viscosities were obtained at 1.75 and 1.84 mm2/s and provided 43.06 and 45.85 MJ/kg of heating combustion values when palm oil and soybean oil were used. In addition, the carbon distribution of the synthetic kerosene produced from palm oil was clearly shown to be in the range of C11-C13which is similar to kerosene fuel obtained from petroleum.

Biodegradable polymers of polyhydroxyalkanoates (PHAs) are produced and accumulated in various microorganisms, especially in bacteria. In this work, a cheap agricultural sugar cane juice (SCJ) was used as a carbon source by Alcaligenes latus during its growth coupled with the production of PHAs via batch/ repeated batch fermentation processes. In batch fermentation, the maximum PHAs and PHAs content of 2.20 ± 0.14 g/L and 53.65 % were obtained within 24 h while in the case of four cycles of repeated batch fermentation, the PHAs productivity was reached at about 0.21 g/L·h that was 2.33 fold when compared to the first batch fermentation (0.09 g/L·h). Interestingly, the duration in each cycle or in batch operation during repeated batch fermentation was shorter than that found in the batch fermentation and PHAs productivity was also improved. After PHAs recovery, the physicochemical properties of nuclear magnetic resonance (NMR) and a fourier transform infrared (FTIR) spectrogram were characterized and revealed to be in full agreement with the standard polymer of polyhydroxybutyrate (PHB).

This work revealed for the first time the possible use of a newly isolated Bacillus aryabhattai PKV01 for poly-β-hydroxyalkanoates (PHAs) production from fermentative sweet sorghum juice. Its growth and PHA production were investigated under different pH and nitrogen sources. Medium composition was optimized using statistical tools. The highest biomass and PHA content were reached at pH 6.5 with the use of urea. Plackett-Burman design was then applied to test the relative importance of medium components and process variables on cell growth and PHA production. Cell growth and PHAs production were affected by total sugar and urea and were subjected to optimize the sorghum juice medium using response surface methodology (RSM) via central composite design (CCD). The predicted optimal culture composition was achieved. Maximum dry cell weight and PHAs were obtained using a flask and almost double the amount was achieved using a bioreactor. After PHA recovery, the structure and thermal properties were characterised and revealed to be similar to the standard of poly-β-hydroxybutyrate (PHB).

Biopolymers of hard, brittle and low flexible polyhydroxyalkanoates (PHAs) and a soft and high elastic natural-latex rubber are blended at room temperature by using a combination technique. Concentrations of the PHAs solution are constituted at 1%, 2% and 3% w/v and mingled with fresh natural latex in different ratios (PHAs : Latex Rubber = 0:10, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1 and 10:0). After vigorous blending, forming polymeric sheets leave a dried-film pattern. Only the best 3 different ratios (4:6, 5:5 and 6:4) are selected by evaluating morphological-based information. These lead to actually define and characterize for their morphological and mechanical properties. The morphological attributes are exemplified by polarized optical microscopy and X-ray diffractometry (XRD) while the thermal characterization is determined by differential scanning calorimetry (DSC). Morphological analysis for the criterion of blending achievement indicated that there is a significant relationship among porosity, texture and shrinkage. The porosity shows obviously low to high for gradually increasing PHAs and decreasing the latex. Thus, dense texture and shrinkage relate to blending compositions between PHAs and latex. The XRD and DSC reveal certain aspects of decreasing crystallinity arising from enhancing of the latex content. A high degree of crystallinity and melting temperature relates to greater PHAs ratio. The mechanical investigations have revealed complex localization patterns of tensile strength and elastic modulus. The more PHAs concentration at 2% w/v indicates the greater elastic modulus than 3% and 1% w/v. Significant differences are found on polymeric composites of mechanical analyses between PHAs and natural latex. The constituted superiority in the ratio of 5:5 significantly differs in extension to break. Additionally, both tensile strength and elastic modulus of 2% w/v PHAs present the maximum value among them.

Biodiesel is a renewable and environmental friendly energy source that can be produced via tranesterification from various oil crops such as soy bean, sunflower, palm, and algae. In this work, the microalgae Scenedesmus obliquus, S. armatus and S. bernadii, isolated from natural water basins, were enriched in modified Chu 13 medium. Only S. obliquus showed significant oil accumulation and was thus further cultivated in 3 L tubular photo-reactors under mixotrophic conditions (16:8 h light-dark cycle) at room temperature and varying CO2 (5, 10, and 15%) supply. The results indicated that S. obliquus can be grown under various CO2 concentrations. A maximum biomass of 2.3 g/L was achieved when 15% CO2 was used. The effect of salinity on oil storage was also considered, using sodium chloride (NaCl) solutions of varying concentrations (0.05, 0.2, and 0.3 M). Higher lipid contents were found in cells that were subjected to salt stress compared to those in conditions without salt stress. A maximum oil accumulation of 36% was observed within 15 days at 0.3 M NaCl. A biodiesel yield of up to 97.4% was obtained.

In this work, the separation of two types of mixtures, ethanol–water mixture and fermented sweet sorghum, was investigated using cellulose acetate supported polyvinyl alcohol composite membranes. The pervaporation (PV) performances of the two mixtures under different operating parameters (ethanol concentrations, operating times and temperatures) were studied. PV performances using sweet sorghum fermentation broth, under all operating parameters, were significantly lower compared to separating ethanol from binary mixtures. Preliminary economic analysis shows that cost of producing 1 l of ethanol from the broth is about 0.9 $/l which is about 1.1 times higher than from the pure binary system.

Biopolymers of polyhydroxyalkanoates (PHAs) are produced by pure bacterial strain of Alcaligenes eutrophus TISTR 1095 via batch fermentation using sugarcane juice as a carbon source, and yielded up to 21% (w/w) after recovery process. The PHAs are blended with bio-based materials such as tapioca and corn starch including glycerol and methanol to improve their microstructures. The combination of various plasticizers with PHAs is studied in different ratios. The PHAs and starch are mixed for 3% w/v and 30% w/v in hot chloroform, respectively. The varieties of PHAs to starch solution ratios are situated for casting as of films. The PHAs blended films are characterized by polarized light microscopy, differential scanning calorimetry (DSC) and x-ray diffractometry (XRD). The initial PHAs indicate remarkably crystalline structure with cross-polarized light on optical microscope. Macroscopic scales of their films are very brittle and flexible. However, their microscopic scales present small patches of particular components from each starch. Immiscibility of the blends is gradually increased on adding the starch portions. Additional glycerol shows more strongly interfacial adhesion between starch and PHAs, and methanol produces specifically thin films. Melting transition temperatures of blended films are slightly higher than the biosynthesized PHAs as examined by DSC. Corn starch mixture causes highly brittle films than tapioca mixtures, which indicates poor adhesion between corn starch and the PHAs. This result is correspondent to their highly crystallinity from diffractogram. Microstructural evolution of the blended films is increased slightly crystallinity by the solution casting.

Ethanol is an important renewable energy that can be produced from byproducts of agricultural products such as cassava, corn, potato, sorghum and sugar cane etc. via chemical and bio-fermentation processes. Pervaporation, an effective and economical membrane technology, has been proven to substitute distillation process for ethanol separation. In this work, the separation of two types of mixtures; ethanol–water mixture and fermented sweet sorghum were investigated using cellulose acetate membranes. The pervaporation performances of the two mixtures were carried out under various operating conditions such as ethanol concentrations (10%, 15%, 20% and 30%), operating times (15, 30, 45 and 60 min) and temperatures (50 °C, 60 °C and 70 °C). The permeate fluxes, selectivity and percent separation declined significantly under all operating conditions in the presence of sweet sorghum fermentation broth when compared to the binary mixture. Preliminary economic analysis shows that cost of producing 1 l of ethanol from the broth is about 1.0 $/l which is about 1.2 times higher than from the pure binary system and approximately 5 times higher than the minimum production cost of 0.2 $/l reported by Wasewar and Pangarkar (2006) [20].

The present work investigated microbial leaching of zinc from ore using Acidithiobacillus ferrooxidans (ATCC 14859). The ore samples, consisted of 13wt% zinc, were obtained from a gold mine in north-eastern Thailand. A shake flask study was performed on the ore samples using a rotary shaker under the following fixed conditions (250 r•min^(-1), 30°C for 16 d). The influence of various conditions, namely medium type (with and without iron), particle ore size (＜20, 20-40, 40-60, 60-100, and ＞100 mesh), ore density (20 kg•m^(-3), 50 kg•m^(-3), and 100 kg•m^(-3)), and pH of the medium (2, 2.5, 2.8, and 3), were investigated. The microbial leaching was assessed by determining the concentration of zinc in the medium and compared with the initial sample concentration. The results show that Acidithiobacillus ferrooxidans can successfully leach zinc by as much as 6 times compared with the control experiment (without Acidithiobacillus ferrooxidans ferrooxidans). The maximum efficiency (92.3%) for microbial leaching is obtained in iron-containing medium, 20-40 mesh ore sizes, 20 kg•m^(-3) ore density at pH 2.8, and the zinc content is found in the medium at about 120 mg•L^(-1).

The effects of pH and aluminium sulphate concentration on the stability of whey suspension have been investigated. The particle size and particle size distribution are examined by scanning electron microscopy and granulometric analysis, respectively. The zeta potential and residual turbidity of 0.01 wt% whey suspensions are determined over the pH range of 3–8 with aluminium sulphate as background electrolyte. The results show that the zeta potential of whey suspensions depends on pH and, to a lesser degree, aluminium sulphate concentration. The average particle size of flocs in suspension increases with decreasing zeta potentials which is accompanied by low turbidity. The degree of flocculation of whey suspension is linked to the zeta potential. The DLVO calculations are in good agreement with the observed trends indicating that the classical DLVO theory can be used to predict colloidal stability of the whey protein suspensions in the presence of higher strength electrolyte and varying pHs.

The present work considers the influence of surfactants and coagulant on the ultrafiltration (UF) of whey suspensions in ceramic membranes. The filtration performance is assessed both in terms of permeate flux and total organic carbon (TOC). Prior to filtration, the stability of whey suspensions under different conditions was characterized in terms of particle sizes and zeta potentials. Additionally, the membrane was characterized in terms of its zeta potential ( ζ ). A higher range of permeate flux was found at pH 6.2 when both particles and membrane had significant ζ -potentials. In contrast better TOC reductions were observed at pH 3.0 when the ζ -potentials of both membranes and particles were low. Generally, larger average particle sizes were obtained at pH 3.0 where the ζ -potentials of the particles were lower which encouraged aggregation. However, the presence of these larger particles did not seem to improve the filtration performance. This study demonstrates that electrokinetics can exert more influence than particle size on membrane performance.

According to the cost of carbon substrate for producing biopolymer of polyhydroxyalkanoates (PHAs) still has a barrier to extend in an industrial scale. The aim of this work was to evaluate the defined PHAs media containing the agricultural raw materials of pineapple and sugarcane to produce PHAs by Bacillus strain. Batch fermentation was carried out in flask scale to compare the efficiency of defined media using statistical methodology. The defined medium 8 of pineapple was achieved the highest PHAs concentration and productivity (1.86 g/L and 0.077 g/Lh). The effect of pH and aeration was extensively studied in a fermentor. The results were revealed that PHAs production would be increased from the condition of uncontrolled pH and at higher aeration rate. The extracted PHAs clearly showed in a homopolymer structure of poly(3-hydroxybutyrate) (PHB) with melting temperature (Tm) of 172°C 54.39% crystallinity.

A biopolymer of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is blended with bio-based materials, natural rubber latex, to improve their microstructures. The various ratios between PHBV and natural rubber latex are examined to develop their mechanical properties. In general, physical properties of PHBV are hard, brittle and low flexible while natural rubber (NR) is presented itself as high elastic materials. Concentrations of the PHBV solution are constituted at 1%, 2% and 3% (w/v). The mixtures of their PHBV solutions to natural rubber latex are produced the blended films in three different ratios of 4:6, 5:5 and 6:4, respectively. They are characterized by appearance analyses which are the scanning electron microscope (SEM), universal testing machine (UTM) and differential scanning calorimetry (DSC). The SEM photomicrographs of the blended films and the controlled PHBV can provide the void distribution in the range of 12-14% and 19-21%, respectively. For mechanical properties of the blended films, the ...

This study aims to use sweet sorghum juice (SSJ) to produce an environmentally friendly biopolymer of polyhydroxyalkanoates (PHAs) by bacteria isolated from soil. Among 18 isolates, only 3 isolates, coded as S4, S6, and S11, were chosen to produce PHA via batch fermentation compared to 3 strains of Alcaligenes eutrophus, A. latus, and Hydrogenophaga sp., respectively, under controlled conditions at pH 7, 35 °C, and 20 g/L of initial total sugar in the SSJ. The results clearly showed that the isolate S4 can produce maximum PHAs of 1.74 g/L with 57.62% dry cell weight and yield maximum hourly productivity at 0.097 g/L. S4 was further identified by full-length 16S rDNA gene sequence homology, and the findings showed that it was closely related to Bacillus aryabhattai (99.70% similarity). Interestingly, there has been as of yet no report on the use of this strain to produce an added-value biopolymer of PHA.

The aim of this study is to optimize the lipid accumulation in microalgae by using two agricultural residues of pineapple peels and sugarcane bagasse as low-cost organic carbon sources. Green microalgae Scenedesmus acutus was isolated and selected for cultivation. Effects of three initial sugar concentrations and the stage for adding sugar during cultivation on biomass and lipid production were investigated. The results clearly showed that two-stage cultivation is more suitable than one-stage. The maximum biomass concentration and productivity were obtained at 3.85 g/L and 160.42 mg/L/day when sugarcane bagasse was used. The highest lipid content and lipid yield was reached at 28.05 % and 0.93 g/L when pineapple peels were used, while in the case of sugarcane bagasse, 40.89 % and 1.24 g/L lipid content and yield were obtained. Lipid content was found in normal condition (autotrophic) at 17.71 % which was approximately 2.13-fold lower than when sugarcane bagasse was used (40.89 %). Biodiesel production via in situ transesterification was also investigated; the main fatty acids of palmitic acid and oleic acid were found. This work indicates that using agricultural residues as organic carbon sources could be able to increase lipid content and reduce the cost of biofuel production.

The world today cannot deny the prospect of 'peak oil', higher prices and depletion of petrochemical feed stocks. At the same time, there is an environmental concern of the widely used synthesized plastic from petroleum industry because of its nondegradable nature. Plastics, solid wastes, and pollutants of all kinds not only accumulate as carbon footprint, but also pose a threat to the global warming issues. If they are disposed by open air burning. The United Nation’s International Center for Science and High Technology (ICS) thus launched a program focusing on the development of degradable biopolymeric materials and plastic waste disposal in developing countries. Recycling, reuse, incineration, composting, and new technology for development of environmental friendly degradable plastics are making a highly efficient contribution to the mitigation of environmental problems. In addition, concerned researchers and the industrial sector have seen the importance of producing bio-based plastics and biopolymers from agricultural crops based on locally available biomass resources.

This work aims to investigate a potential of microalgae for utilizing industrial wastewater as a cheap nutrient for their growth and oil accumulation. Wastewater was collected from the effluent ponds of agro-industrial factories (cassava and ethanol production plants). Only 2 microalgal strains were isolated and identified as Scenedesmus quadricauda and Chlorella sp.. However, only S. quadricauda was selected to cultivate in various wastewater concentrations (10%, 20%, 40%, 60%, 80% and 100%). The highest biomass obtained at 6.6×106 and 6.27×106 cells/ml when 60% wastewater was used in flask and photo-bioreactor. The cultures gave the highest lipid content at 18.58 % and 42.86% in cases of S. quadricauda and S. obliquus. In addition, under salt stress (1.0 M NaCl), S. obliquus demonstrated the highest lipid content at 50% which was much more than the case of no NaCl adding. However, the concentration of NaCl does not affect on lipid accumulation in case of S. quadricauda., {"references":["Amin S. Review on biofuel oil and gas production processes from\nmicroalgae. Energy Conversion and Management. 2009; 50: 1834-1840.","Ramadhas A.S., Jayaraj S. and Muraleedharan, C. Biodiesel production\nfrom high FFA rubber seed oil. Fuel. 84: 335-340.","Dujjanutat, P, Kaewkannetra, P. Potential use of industrial wastewater\nin selection and cultivation of microalgae as a raw material for biodiesel\nproduction Journal of Biotechnology, 2010; 150S: 149-150.","Chinnasamy S., Bhatnagar A., Hant R.W. and Das K.C. Microalgae\ncultivation in a wastewater dominated by carpet mill effluents logy.\n2010; 101: 3097-3105.","Anderson R.A, editor. Algal Culturing Techniques. [n.p.]. Hing Yip Co;\n2005","Burdon K.L. Fatty material in bacteria and funji revealed by staining\ndried, Fixed slide preparations. Journal of Bacteriology. 52: 665-678.","Iverson S.J., Lang S.L.C. and Cooper M.H. Comparison of Bligh and\nDyer and Folch methods for total lipid determination in a broad range of\nmarine tissue. Chemistry and Material Science. 2001; 36(11): 1283-\n1287.","Enmak P., Kaewkannetra P. Influences of CO2 concentrations and\nsalinity on acceleration of microalgal oil as raw material for biodiesel\nproduction. Journal of Biotechnology. 2010; 150S:19.","Dayananda C., Sarada R., Rani M.U., Shamala T.R. and Ravishankar\nG.A. Influence of Nitrogen sources on growth, hydrocarbon and fatty\nacid production by Botryococcus braunii. Asian Journal of plant\nSciences. 2006; 5(5): 799-804.\n[10] Rattanapoltee, P. Chulalaksananukul, W., James, A.E., Kaewkannetra,\nP. Comparison of autotrophic and heterotrophic cultivations of\nmicroalgae as a raw material for biodiesel production\nJournal of Biotechnology, 2008; 36: S412\n[11] Arroyo T.H., Wei W., Ruan R. and Hu B. Mixotrophic cultivation of\nChlorella vulgaris and its potential application for the oil accumulation\nfrom non-sugar materials. Biomass and Bioenergy. 2011; 35: 2245-\n2253.\n[12] Hodaifa G., Mart├¡nez M.E. and S├ínchez S. Use of industrial wastewater\nfrom olive-oil extraction for biomass production of Scenedesmus\nobliquus. Bioresource Technology. 2008; 99: 1111-1117.\n[13] Chiu S.Y., Kao C.Y., Chen C.H., Kuan T.C., Ong S.C. and Lin C.S.\nReduction of CO2 by a high - density culture of Chlorella sp. in a\nsemicontinuous photo bioreactor. Bioresource Technology. 2008; 99:\n3389-3396.\n[14] APHA, AWWA, Standard methods of the examination of water and\nwastewater, 15th edition, Washington, D.C., USA, 1995.\n[15] Zhang H., Wang W., Li Y., Yang W. and Shen G. Mixotrophic\ncultivation of Botryococcus braunii. Biomass and Bioenergy. 2011; 35:\n1710-1715.\n[16] Kojima E. and Zhang K. Growth and hydrocarbon production of\nmicroalga Botryococcus braunii in bubble column photo-bioreactors.\nBioscience and Bioenginerring. 1999; 87: 811-815."]}

Cassava mill wastewater has a high organic and cyanide content and is an important economic product of traditional and rural low technology agro-industry in many parts of the world. However, the wastewater is toxic and can pose serious threat to the environment and aquatic life in the receiving waters. The ability of Azotobactor vinelandii TISTR 1094, a N2-fixing bacterium, to grow and remove cyanide in cassava wastewater was evaluated. Results revealed that the cells in the exponential phase reduce the level of cyanide more rapidly than when the cells are at their stationary growth phase. The rate of cyanide removal by A. vinelandii depends on the initial cyanide concentration. As the initial cyanide concentration increased, removal rate increased and cyanide removal of up to 65.3% was achieved. In the subsequent pilot scale trial involving an activated sludge system, the introduction of A. vinelandii into the system resulted in cyanide removals of up to 90%. This represented an improvement of 20% when compared to the activated sludge system which did not incorporate the strain.