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A laboratory-scale study was carried out to produce lignin peroxidase (ligninase) by white rot fungus (Phanerochaete chrysosporium) using sewage-treatment-plant (STP) sludge as the major substrate. The optimization was done using full-factorial design (FFD) with agitation and aeration as the two parameters. Nine experiments indicated by the FFD were fermented in a stirred-tank bioreactor for 3 days. A second-order quadratic model was developed using the regression analysis of the experimental results with the linear, quadratic, and interaction effects of the parameters. Analysis of variance (ANOVA) showed a high coefficient of determination (R (2)) value of 0.972, thus indicating a satisfactory fit of the quadratic model with the experimental data. Using statistical analysis, the optimum aeration and agitation rates were determined to be 2.0 vvm and 200 rpm, respectively, with a maximum activity of 225 U l(-1) in the first 3 days of fermentation. The validation experiment showed the maximum activity of lignin peroxidase was 744 U l(-1) after 5 days of fermentation. The results for the tests of the stability of lignin peroxidase showed that the activity was more than 80% of the maximum for the first 12 h of incubation at an optimum pH of 5 and temperature of 55 degrees C.

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Phenolic compounds are aromatic compounds known for their bioactive substances which can be found in plants. It has been widely used in various applications due to its antibiotics, anti-inflammatory, anti-allergic, and other benefits. There are various methods to extract the phenolic compounds from plants including ionic liquid, liquid-liquid extraction as well as supercritical extraction. However, all of these methods requires energy extensive, laborious processes, advanced technology, and generate toxic waste. Therefore, there is a growing need to find an alternative green extraction method to reduce the environmental impact while improving the efficiency of the extraction process. Thus, natural deep eutectic solvents (NADES), a combination of two or more components that comes from primary metabolites like organic acids, choline chloride, or sugar, are able to form liquids upon mixing with lower melting point of individual constituents due to hydrogen bond interactions were proposed as alternatives to conventional extraction methods. Therefore, this research determined the suitable combination of NADES solvents (hydrogen bond acceptor/donor ratio) for extraction of phenolic compounds from biomass waste which included young and mature coconut shells and coconut husk, banana peel, empty fruit bunch, and palm oil fruit husk. The extracted compound was analysed using fourier-transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) to identify the functional groups and type of phenolic compounds present. The best biomass waste was coconut shell and the best NADES combination was choline chloride and ascorbic acid at 1:2 molar ratio. The FTIR analysis of coconut shell extracted by NADES showed peaks at 3404 cm−1 and 3523 cm−1 indicating OH stretching followed by 2915 cm−1, 1388 cm−1 to 1473 cm−1, and 1674 cm−1 showing C-H stretching, sp3 C-H band and C=C stretch respectively. As for GC-MS analysis, 26 compounds were detected and four phenolic compounds were identified at peaks 2, 13, 22, and 25. The research was successful in determining the best biomass waste and NADES combination for highest total phenol. The use of NADES was able to extract more phenolic compound from coconut shell than water due to the hydrogen bond between the choline chloride and ascorbic acid.

Palm oil mill effluent (POME) contains approximately 6% fiber. The effectiveness of pre-treatment on POME can serve a very good feedstock for hydrogen production in fermentation process. In this research, the effectiveness of pre-treatment methods on POME treated using acid and base were analysed based total carbohydrate and reducing sugar content. By using 1M NaOH with heat treatment, 26.12% carbon source converted to reducing sugar while by using 1M H2SO4 with heat treatment, over 32.09% carbon source converted to reducing sugar. The highest increment of total carbohydrate where from acid-heat treatment with 26.1% increment from initial concentration. At the initial pH (5.5) with fermentation temperature 37°C, the highest hydrogen production rate given by acid-heat treatment was 0.5mL H2/mL POME. Different for initial pH 7.0 with the same temperature, the highest hydrogen produced rate was given by base-heat treatment with 0.59 mL H2/mL POME. The production of hydrogen in 2L bioreactor given much higher hydrogen production compare to production in serum bottle. This fermentation was run in batch mode with initial pH 7 and control at 5.5. The maximum hydrogen produce was 4304 mL H2/ L POME from acid-heat treatment.

The world's most economically developed countries are facing an energy crisis caused by geopolitical instability, rising energy costs, global stock disruptions, and a shift towards lowcarbon energy sources that has yet to be fully realized. Electrification of the transportation industry offers the advantages of increased energy efficiency and reduced local pollutants. Electric Vehicles (EVs) are environmentally friendly because they reduce fossil fuels usage even zero consumption, need fewer maintenance requirements, and lower operating costs than the vehicles powered by gasoline or diesel. However, this study focuses on comparing various energy management strategies (EMS) for a backup energy supply system for EVs. The hybrid power system (HPS) considered in this study includes DC-DC and DC-AC synchronous converters, as well as supercapacitors, batteries, and fuel cells. The EMS analyzed includes state machine control, classical proportional-integral control, equivalent consumption minimization, frequency decoupling, rule-based fuzzy logic, and fuzzy logic control. The HPS's efficiency, hydrogen fuel, supercapacitor or battery state of charge levels, and overall performance are evaluated as primary efficiency criteria. Additionally, the HPS not only increases system energy but also reduces the number of pack batteries required. This study designs and constructs the combined power systems to enhance EV power schemes with rechargeable battery power supplies. The results show that a 6-kW fuel cell hybrid increases the power system capacity to 408 kWh. Moreover, a novel method based on wavelet transforms of the instantaneous power of each energy source is used to quantify the stressors on each energy source that impact its life cycle. To validate all analyses and performance, a simulation model and an experimental test bench are created. Finally, simulation results demonstrate a synchronous converter with a 6-kW output power and 96% efficiency, validating the optimization results.

Aims: Biofilm is a complex structure that provides protection towards the bacteria within the barrier. Enhanced biogas production from Palm Oil Mill Effluent (POME) can be achieved by applying biofilm based anaerobic digestion system. Methodology and results: Bacteria that produces biofilm were isolated and tested on its hydrolytic enzyme secretion. The biofilm produced were also characterized. Out of 120 strains isolated from POME, PKC and food waste compost, only 33 strains were producing biofilm and only 11 of them exhibited significant amount of biofilm produced at optical density of wavelength 595 nm (>0.01). In hydrolysis enzyme assay test, all strains were not able to secrete protease enzyme. The biofilms were extracted and characterized to show similar characteristic for all strains. Strain numbers of 11, 9C, 23C and 30C showed positive result for cellulase, amylase and lipase enzymes, to be tested as single strain bacteria and also mixed with other isolated bacterium for prospect research on effective hydrolysis towards enhanced biogas production. The composition of biofilms from different bacteria mixture also similar under the same incubation condition. Conclusion, significance and impact of study: Bacteria producing biofilm are very limited and does not secrete the same hydrolytic enzymes. Utilization of these bacteria may eliminate the problem of microbial instability in a system.