Showing papers by "Razif Harun published in 2015"

Thermochemical conversion of microalgal biomass for biofuel production.

Abstract: Reliable and sustainable energy supply is critical to effective natural resource management, and it encompasses functioning efficiency of energy resources as well as socio-economic and environmental impact considerations. The complete reliance on fossil fuels is recognized as unsustainable throughout the world, and this is due to, amongst others, the rapid declining of fossil fuel reserves and the emission of significant quantities of greenhouse gases associated with their production and combustion. This has resulted in escalating interest in research activities aiming to develop alternative and somewhat carbon neutral energy sources. Algal biofuels, so called third generation biofuels, appear to be promising in delivering sustainable and complementary energy platforms essential to formulate a major component of the renewable and sustainable energy mix for the future. Algal biomass can be converted into various portfolios of biofuel products, such as bio-hydrogen, biodiesel, bioethanol and biogas, via two different pathways: biochemical and thermochemical pathways. Thermochemical conversion is considered as a viable method to overcome the existing problems related with biochemical conversion such as lengthy reaction time, low conversion efficiency by microbes and enzymes, and high production costs. This paper discusses process technologies for microalgae-to-biofuel production systems, focusing on thermochemical conversion technologies such as gasification, pyrolysis, and liquefaction. The benefits of exploiting upstream microalgal biomass development for bioremediation such as carbon dioxide mitigation and wastewater treatment are also discussed.

Effects of lipid inhibition on biogas production of anaerobic digestion from oily effluents and sludges: an overview.

Abstract: Anaerobic digestion of lipid effluent and sludge is becoming an interest due to its high biodegradability in producing biogas. Due to complex polymeric substances, lipid has been investigated as a potential substrate to produce biogas when digested anaerobically as compared to carbohydrate and protein. However, it is known that lipid degradation causes inhibition to biogas production with lag phase occurrence, sludge floatation and washout. Co-digestion of lipid substrates has shown enhancement to biogas production of low biodegradability substrates but the experience of slow hydrolysis due to inhibition is still occurred. Long chain fatty acids (LCFAs) produced during lipid hydrolysis is known as primary inhibitor due to its toxicant effects to cell wall adsorption by microorganisms. Currently, the study of lipid inhibition and mitigation to induce reduction of lipid toxicity has regained attention. In this overview, a detailed of previous and current literature on lipid biodegradability, inhibition effects, methods to reduce lipid inhibition in enhancing biogas production are discussed to provide a summary of available information regarding lipid inhibition and its potential in enhancing biogas production.

Optimization of the microalgae Chlorella vulgaris for syngas production using central composite design

Abstract: Gasification has emerged as an effective thermochemical conversion technology for generating syngas products from biomass. Process conditions for optimizing the productivity and quality of syngas during gasification vary with the type and composition of the biomass. With escalating research interests in the development of biofuels from microalgae, resulting from its high biomass productivity, agronomical and environmental bioremediation benefits, the current study investigates the optimization of microalgal gasification for syngas production using high temperature horizontal tubular furnace. Four response variables (H2, CO, CO2, and CH4) were optimized under varying conditions of temperature (500–900 °C), microalgal (Chlorella vulgaris) biomass loading (0.6–2.5 g), heating rate (5–25 °C min−1), and equivalent ratio (ER = 0.1–0.35). The optimization study was carried out using central composite design (CCD). Temperature was the most significant process parameter influencing H2 production, followed by microalgal biomass loading and heating rate. An optimum H2 yield of 41.75 mol% was obtained at a temperature of 703 °C, a microalgal biomass loading of 1.45 g, a heating rate of 22 °C min−1, and an ER of 0.29. Statistical analysis showed that the generated models were sufficiently in agreement with the experimental results. It was concluded that the direct gasification of microalgal biomass in the presence of air has significant potential for the commercial-scale production of syngas products.

Thermogravimetric study of Chlorella vulgaris for syngas production

Abstract: The present study investigates the thermal degradation behavior of Chlorella vulgaris using a thermogravimetric analyzer (TGA) to explore application as feedstock for syngas production. The biomass was heated continuously from room temperature to 1000 °C at different heating rates (5, 10 and 20 °C min− 1) under N2/air conditions at a constant flow rate of 25 mL min− 1. Experimental results showed that the combustion process of C. vulgaris can be divided into three major phases; (1) moisture removal, (2) devolatilization of carbohydrates, protein and lipids and (3) degradation of carbonaceous material. A degradation rate of 80% was obtained at the second phase of the combustion process in the presence of air whilst a degradation rate of 60% was obtained under N2 atmosphere at the same phase. The biomass was further gasified for syngas production using a Temperature Programmed Gasifier (TPG). The effect of three different process variables, temperature, microalgal loading, and heating rate was investigated. The maximum H2 production was found at 800 °C temperature with a biomass loading of 0.5 g. No significant effect of heating rate was observed on H2 production. The activation energy values, based on the Kissinger method, were evaluated to be 45.38 ± 0.5 kJ mol− 1 (1st stage), 61.20 ± 0.5 kJ mol− 1 (2nd stage) and 97.22 ± 0.5 kJ mol− 1 (3rd stage). The results demonstrate a significant potential for the utilization of the microalgae biomass as feedstock for large-scale production of syngas via gasification.

The Influence of Inoculum to Substrate Ratio on the Biochemical Methane Potential of Fat, Oil, and Grease in Batch Anaerobic Assays

Abstract: Anaerobic digestion is one of the potential methods widely applied for organic waste recovery to produce biogas. In this study, biodegradability of fat, oil, and grease was tested in biochemical methane potential assays and the effects of substrate to inoculum ratio ranging from 0.2–4.0 were determined. The results indicated that fat, oil, and grease is feasible to produce methane (670 mL CH4 gVS−1) and the ideal substrate to inoculum ratio range of 0.5–1.0 was determined. After 60 days of experiments, maximum methane yield for the ideal ratio was 603–741 mLgVS−1, which corresponds to 81–89% methane production. Increasing substrate to inoculum ratio showed a lag phase phenomena where methane yield may be decreased initially or started slowly, thus delaying the entire digestion process. With a higher substrate to inoculum ratio (2.0–4.0), methane yield was recorded lower than 60% and the highest methane production was 250.2 mLgVS−1.

Rethinking sustainable biofuel marketing to titivate commercial interests

Abstract: Even though considerable strides have been made in the development of effective technologies for the production of different biofuels in some commercial quantities, global consumer patronage in biofuel utilisation has been discouraging. This has triggered significant inquisitions and research into different key aspects of the biofuel supply chain some of which are; techno-economic innovations targeted at reducing production cost, product marketing and packaging, and sustainable resources for biomass generation. This paper seeks to investigate biofuel marketing modalities beyond the current scope of a majority public sector industry to aid the development and promotion of biofuels to commercial and public sectors. The need for marketing in the biofuel industry is explored to identify innovative strategies, trending capacities, and key success factors to revolutionise marketing schemes with the potential to predict future trends. Scholarly positions on effective strategies using well-known marketing paradigms are discussed to suit the need of the industry. A proposal for the application of a strategic marketing framework built on sustainability precept is put forward, concluding that sustainable marketing (green and social marketing) could be used concurrently and continuously to improve growth and development through increased sales and competitive scoping.