Biodiesel Production from Microalgae

The use of fossil fuels is now widely accepted as unsustainable due to depleting resources and the accumulation of greenhouse gases in the environment. Therefore, renewable and carbon neutral biofuels are necessary for environmental and economic sustainability. The feasibility or the first generation biofuels production is however uncertain because of the conflict with food supply. Microalgal biofuels are promising alternative for energy demand especially for biodiesel production. The oil productivity of many potential microalgae exceeds the best producing oil crops. Hence microalgae is consider as promising feedstock for various biodiesel production.The present review highlight various aspects of algae and potential assessment of microalgal oil for biodiesel production.

The Industrial Revolution of past centuries have brought innovations not accompanied by a far-sighted vision of the consequences that are manifesting in the twenty-first century, particularly with an increase in energy demand and global warming. The emerging biotechnology revolution, which applies technology to biological systems, could solve these problems if driven by sustainable development. Research and development institutes, subsidized by governments, are looking for renewable energy resources and sustainable that would replace polluting fossil fuels nearly depleted. Recently the investigation of marine microalgae's potential in biotechnological application is increasing by realization that the ocean is a relatively untapped source of energy biomass and novel biomolecules. Microalgae mainly represent the last generation suitable feedstock for the transport sector, but due to their biochemical versatility are useful also for many other industrial fields such as medical, pharmaceutical, food and cosmetic. Nowadays, biofuel production form microalgae biomass is still in progress; the efficiency of each step during the whole process, from culturing to refining, needs to be improved to get yield economically reasonable. Coupling each other different industrial application could lead to overcome the substantial investments with proper earning making, hopefully in the next future, this living energy lucrative, therefore commercially feasible. In the last decades, researcher are focusing their attention on Diatoms, a taxon of microalgae characterized by silica walls derived from secondary endosymbiosis. Diatoms are affected by seasonal exponential growth called blooms that place them at the base of the ocean food chain, permit 40% of atmospheric CO 2 fixation and significant influence the biogeochemical cycle of the macronutrients: silicon (Si), nitrogen (N), phosphorous (P). This microalgae's group is a promising candidate for biodiesel production because of their great lipid accumulation like reserve storage compound mainly in form of triacylglycerols (TAG), converted into biodiesel through a reaction of trans-esterification. The aim of this thesis were evaluated the growth curves, level and composition lipids, carbohydrates and proteins in the marine diatom Cyclotella Cryptica grown in 2L batch system under two different nutritional conditions in f/2 medium. The growth curves were obtained by monitoring daily the celllar density (cell/mL) with an optical microscope combined with a Bürker chamber. The biological macromlecules' quantification was obtained by chemical methods coupled with Nuclear Magneti Resonance (NMR) techniques. Experimental Data show that a daily supply of nutrients induce high cell density (2250000 ±77567 cells/mL) and biomass dry weight (797.82±37.7 mg/L) tht mainly consist of proteins and lipid fraction is predominantly composed by phospholipids (PL). Conversely, administering the nutrients only the first day let the diatoms in a starvation condition defined by a little cell density (165772±11034 cells/mL) and biomass dry weight (150.9±22.24 mg/ mL) with a significant increase in the relative amount of storage compounds, i.e. lipids, predominantly in the form of triacylglycerols (TAG). Furthermore, a recent protocol for lipid extraction halogenate solvent-free based on methyl-t-butyl ether as solvent was successfully applied to algal pellets to obtain reliable organic extract with high recovery rate.

The upsurge in the concerning issues like global warming, environmental pollution and depletion of fossil fuel resources led to the thrust on third generation biofuels. Algal research has gained a lot of importance in the recent years. Effective utilization of algal biomass in a single step is necessary as it can produce Bio-oil (BO), gases and in addition to a variety of valuable products, along with nutrient recovery. Hydrothermal liquefaction technology does not require the energy intensive drying steps and is an attractive approach for the conversion of algae to liquid fuels. This study investigates direct hydrothermal liquefaction (HTL) of microalgae (Algal bio-mass) to produce bio-oil using a high-pressure batch reactor under subcritical water conditions. Three different micro algae samples namely, Chlorella vulgaris, Botryococcus braunii and Scenedesmus quadricauda have been examined under hydrothermal liquefaction with different water concentrations (1:6, 1:7, 1:8, 1:9 & 1:10 ratio) at certain temperature range (200-320 °C), pressure (60 bars) and reaction time (30 min). Through liquefaction, the highest BO yield achieved with S. quadricauda was 18 wt% at 1:9 ratio. The chemical components of the obtained bio-oil were analyzed via gas chromatography and the results indicated that the algal BO was composed of furan, phenol, acid, and ester derivatives. Moreover, it was found that by increasing the temperatures, the BO yields increased. This was due to the polymerization reactions that converted the small biomass components into heavier molecules. FTIR spectra showed high percentage of Aliphatic, Phenolic, alcoholic, Carboxylic and Hydroxyl groups for solid residues.

Biodiesel is a promising liquid fuel that is mainly derived from triglycerides and is utilized in diesel engines directly or after blending with conventional gasoline. Triglycerides comprise fatty acid methyl esters (FAME), which are generated from plant or animal based sources. Biodiesel generated from vegetable oils is expensive than petroleum-based diesel and has concerns with food vs. fuels debate. Therefore, biodiesel from renewable sources such as non-food feedstocks has attained a considerable interest in last two decades. This paper aims to examine the biodiesel generation from the non-food feedstocks available in the Kingdom of Saudi Arabia (KSA) as a source of renewable energy and valueadded products along with and a solution to current waste disposal problems. In KSA, non-food feedstocks such as animal fats, waste cooking oil (WCO), agricultural wastes, sewage sludge, and microalgae are promising sources for biodiesel production. These feedstocks are relatively cheap, easily available, portable, and renewable in nature. A case study of waste to biodiesel refinery is presented for KSA under three different scenarios, including (1) KSA population in 2017, (2) KSA population and pilgrims in 2017, and (3) KSA population and pilgrims by 2030. It was assessed that around 482, 488 and 627 MW of electricity on a continuous basis could be generated every year for scenarios 1, 2 and 3 respectively if using the fat fraction of municipal solid waste in waste to biodiesel refineries in KSA. Similarly, a total net savings of US$ 272, 275.2 and 353.9 million can be achieved from scenarios 1, 2 and 3 respectively. However, there are many challenges in commercializing the waste to biodiesel refinery in KSA such as collection of feedstocks, separation of lipids, products separation, soap formation, preserving products, and adequate regulations.

Ethanol fuel or ethyl alcohol is an alternative to gasoline; it can be used as additive to gasoline, and also as a feed chemical in the transesterification process for biodiesel. A number of bio feed stocks are currently being experimented for biofuel production; algae have emerged as one of the most promising sources for biofuel production. The locally isolated microalga chlorella vulgaris was used in the current study to test their ability to production bioethanol through stimulated in different nitrogen concentration treatments (0, 4, 8, 12 g/l), and effect of nitrogen concentrations on the content of primary products (carbohydrate and protein), also the yield of bioethanol. The growth curves of C. vulgaris were different among the treatments. The stationary phase was identified as day 5, 9, 12 and 14 in treatments 0, 4, 8 and 12 g/l nitrogen respectively. The growth rate (K) increased from 0.14 to 0.20 for the treatments 8 g/l and 0 g/l respectively. The shortest doubling time (...

One of the main challenges for the successful production
and use of microalgae for biodiesel production is to
obtain a satisfactory level of fatty acid methyl esters (FAME).
The aims of this study are to identify the best method of lipid
extraction and provide high FAME levels and to evaluate their
fatty acid profiles. Six lipid extraction methodologies in three
microalgae species were tested in comparison with the direct
transesterification (DT) of microalgal biomass method. The
choice of extraction method affected both the oily extract yield
and the FAME composition of the microalgae and consequently
may affect the properties of biodiesel. The efficiency of different lipid extraction methods is affected by the solvent polarity, which extracts different target compounds from lipid matrix. Dichloromethane/methanol extraction and Folch extraction produced the largest oil extract yields, but extraction with hexane/ethanol resulted in the best ester profile and levels. Performing DT reduces the volume of extractor solvent, the time and cost of FA composition analysis, as well as, presents less steps for fatty acid quantification. DT provided biomass FAME levels of 50.2, 636.4, and 258.2 mg.g−1 in Nannochlorophisis oculata, Chaetoceros muelleri, and Chlorella sp., respectively. On the basis of an analysis of the fatty acids profiles of different species,
C. muelleri is a promising microalga for biodiesel production.
Depending on the extraction method, Chlorella sp. and N. oculata can be considered as an alternative in obtaining
arachidonic (Aa) and eicosapentaenoic (EPA) acids.

Microalgae are considered to be the world’s future energy reservoir and various aspects have
been followed for optimizing the algae growth for large scale production of biodiesel. For
the same, selection and screening of microalgae strain for its lipid productivity is much more
important. Fourier transform infrared (FTIR) spectroscopy was used in this study for the
analysis of lipid extract from natural isolate of Chlorella vulgaris. In order to evaluate the
strain productivity the reference strain was obtained. Both the cultures were grown in a
chemically-defined media under photoautotrophic culture conditions. Lipid extraction
procedures were standardized for both strains based on Fourier transform infrared (FTIR)
spectroscopy .The extracted lipid samples were analyzed. This study reveals that the natural
isolate identified as Chlorella vulgaris strain is suitable for further optimization procedures
and found with high percentage of residual lipid proportions. Also the results show that
FTIR technique can be applied for determination of single cell biomass composition from
phytoplankton communities.

Sustainable production of renewable energy is being hotly debated globally since it is increasingly understood that first generation biofuels, primarily produced from food crops and mostly oil seeds are limited in their ability to achieve targets for biofuel production, climate change mitigation and economic growth. These concerns have increased the interest in developing second generation biofuels produced from non-food feedstocks such as microalgae, which potentially offer greatest opportunities in the longer term. This paper reviews the current status of microalgae use for biodiesel production, including their cultivation, harvesting, and processing. The microalgae species most used for biodiesel production are presented and their main advantages described in comparison with other available biodiesel feedstocks. The various aspects associated with the design of microalgae production units are described, giving an overview of the current state of development of algae cultivation systems (photo-bioreactors and open ponds). Other potential applications and products from microalgae are also presented such as for biological sequestration of CO2, wastewater treatment, in human health, as food additive, and for aquaculture.

Microalgae are a potential source for various valuable chemicals for commercial applications ranging from
nutraceuticals to fuels. Objective in a biorefinery is to utilize biomass ingredients efficiently similarly to petroleum
refineries in which oil is fractionated in fuels and a variety of products with higher value. Downstream
processes in microalgae biorefineries consist of different steps whereof cell disruption is the most
crucial part. To maintain the functionality of algae biochemicals during cell disruption while obtaining
high disruption yields is an important challenge. Despite this need, studies on mild disruption ofmicroalgae
cells are limited. This review article focuses on the evaluation of conventional and emerging cell disruption
technologies, and a comparison thereof with respect to their potential for the future microalgae
biorefineries. The discussed techniques are bead milling, high pressure homogenization, high speed homogenization,
ultrasonication, microwave treatment, pulsed electric field treatment, non-mechanical cell
disruption and some emerging technologies.

Global climate change and atmospheric CO 2 levels are increasing in the last decades mainly due to the rise in anthropogenic emissions. Point source emissions of CO 2 from power plants during industrialized process accounts much for this increase. An attractive approach for offsetting emissions is direct biofixation of CO 2 from flue gas through microalgae. Flue gas is fully utilized as resource to cultivate microalgae in order to moderate anthropogenic effect on our climate and for steer microalgal resource management towards innovative applications of microalgal biomass compounds. Treated and untreated flue gas into current discharge standard contains CO 2 , NO x , SO x , particulate matter, halogen acids and heavy metals. All these compounds are considered to better steer and engineered flue gas-fed microalgal cultures. This review gives an overview of effect on photochemical, physiochemical and hydrodynamic process on the performance of microalgal-CO 2 fixation and biomass production. It is important to select suitable microalgae strains having a high growth rate, high CO 2 fixation ability and being easily cultivated on large scale to gain high biomass yield and valuable by-products to offset the costs of carbon mitigation.

Microalgae are recognized as one of the most powerful biotechnology platforms for many value added products including biofuels, bioactive compounds, animal and aquaculture feed etc. However, large scale production of microalgal biomass poses challenges due to the requirements of large amounts of water and nutrients for cultivation. Using wastewater for microalgal cultivation has emerged as a potential cost effective strategy for large scale microalgal biomass production. This approach also offers an efficient means to remove nutrients and metals from wastewater making wastewater treatment sustainable and energy efficient. Therefore, much research has been conducted in the recent years on utilizing various wastewater streams for microalgae cultivation. This review identifies and discusses the opportunities and challenges of different wastewater streams for microalgal cultivation. Many alternative routes for microalgal cultivation have been proposed to tackle some of the challenges that occur during microalgal cultivation in wastewater such as nutrient deficiency, substrate inhibition, toxicity etc. Scope and challenges of microalgal biomass grown on wastewater for various applications are also discussed along with the biorefinery approach.

Background: Microalgae have been experimented as a potential feedstock for biofuel generation in current era owing to its’ rich energy content, inflated growth rate, inexpensive culture approaches, the notable capacity of CO2 fixation, and O2 addition to the environment. Currently, research is ongoing towards the advancement of microalgalbiofuel technologies. The nano-additive application has been appeared as a prominent innovation to meet this phenomenon.
Main text: The main objective of this study was to delineate the synergistic impact of microalgal biofuel integrated with nano-additive applications. Numerous nano-additives such as nano-fibres, nano-particles, nano-tubes, nanosheets, nano-droplets, and other nano-structures’ applications have been reviewed in this study to facilitate microalgae growth to biofuel utilization. The present paper was intended to comprehensively review the nano-particles preparing techniques for microalgae cultivation and harvesting, biofuel extraction, and application of microalgae-biofuel nano-particles blends. Prospects of solid nano-additives and nano-fluid applications in the future on microalgae
production, microalgae biomass conversion to biofuels as well as enhancement of biofuel combustion for revolutionary
advancement in biofuel technology have been demonstrated elaborately by this review. This study also highlighted the potential biofuels from microalgae, numerous technologies, and conversion processes. Along with that, the study recounted suitability of potential microalgae candidates with an integrated design generating value-added
co-products besides biofuel production.
Conclusions: Nano-additive applications at different stages from microalgae culture to end-product utilization presented strong possibility in mercantile approach as well as positive impact on the environment along with valuable co-products generation into the near future.

Under the Biofuels Obligation Scheme in Ireland, the biofuels penetration rate target for 2013 was set at 6% by volume from a previous 4% from 2010. In 2012 the fuel blend reached 3%, with approximately 70 million L of biodiesel and 56 million L of ethanol blended with diesel and gasoline, respectively. Up to and including April 2013, the current blend rate in Ireland for biodiesel was 2.3% and for bioethanol was 3.7% which equates to approximately 37.5 million L of biofuel for the first four months of 2013. The target of 10% by 2020 remains, which equates to approximately 420 million L yr−1. Achieving the biofuels target would require 345 ktoe by 2020 (14,400 TJ). Utilizing the indigenous biofuels in Ireland such as tallow, used cooking oil and oil seed rape leaves a shortfall of approximately 12,000 TJ or 350 million L (achieving only 17% of the 10% target) that must be either be imported or met by other renewables. Other solutions seem to suggest that microalgae (for biodiesel) and macroalgae (for bioethanol) could meet this shortfall for indigenous Irish production. This paper aims to review the characteristics of algae for biofuel production based on oil yields, cultivation, harvesting, processing and finally in terms of the European Union (EU) biofuels sustainability criteria, where, up to 2017, a 35% greenhouse gas (GHG) emissions reduction is required compared to fossil fuels. From 2017 onwards, a 50% GHG reduction is required for existing installations and from 2018, a 60% reduction for new installations is required.

Algae have long been investigated as a plausible reserve of several biofuel and bioactive compounds attributed to their fast-growing characteristics, shorter doubling time, and capability of accumulating lipids. Compounds extracted from algae are being studied in various sectors namely, pharmaceutical, cosmetics, cancer biology, nanoscience, food industry, etc. In view of the rich potentials of algae, this present review is aimed to highlight the significance of different cultivation aspects of microalgae like open pond and photobioreactor and advantages and disadvantages thereof. This state-of-the-art review provides the limitations of energy (biodiesel, bioethanol, biohydrogen, biomethane) products obtained from the algae in a perspective of shifting lab-scale into a field scale. In addition to the cultivation systems and biofuels, several non-energy products or value-added products obtained from algae were critically compared and presented. Data from plethora literatures discussing the advanced methods for the extraction of omega-3, omega-6 fatty acids, vitamins and nanoparticles from algae have been discussed extensively. Further, bioactive compounds extracted from several algal strains were listed. Considering the health benefits, anti-angiogenic, and anti-cancer properties of algal bioactive compounds were described along with other industrial applications. Overall, this comprehensive review will help in understanding status of algal biofuel, cultivation systems, metabolites and their application for the betterment of the human society.

Societal developments are hinged on the energy supplied by fossil fuels. However, the supply of these fuels is finite in the foreseeable future. This is aside the associated environmental degradation and economic sustainability of these fuels. These negative consequences and challenges spurred the search for sustainable energy sources such as biofuels. However, affordable feedstocks and efficient synthesis for renewable fuels remain indispensable and yet challenging line of research. Therefore, breakthroughs in plant biotechnology and mass production are essential prerequisites for ensuring the sustainability of biofuels as alternatives to petroleum-based energy. Conversely, public outcry concerning the foodfor-fuel conflicts and land-use change hinder the popularity of such biofuel energy sources. Therefore, this paper reviewed the prospects of biogasoline production as sustainable alternative to ethanol and a compliment to biodiesel. Apart from reduction in greenhouse gas emissions, biogasoline promises to be cheaper and more environmental friendly. Further, inedible feedstocks such as microalgae and rubber seed oil would ensure higher net energy gain. Consequently, these will help resolve the food-for-fuel conflicts and land-use competitions. However, achieving the biofuel central policy depends on advances in processing the renewable energy sources.

Biorefinery has emerged as a new concept to derive more than one utility product from biomass. The products from biorefinery include one or more biofuels (biodiesel, bioethanol, biomethane, and biohydrogen) along with other energy sources (syngas and bio-oil), pharmaceutical products, and commercially important chemicals. Biorefineries, thus could simultaneously produce biofuels, bio-based chemicals, heat, and power. The biomass production and its utilization as biofuel has a higher water footprint (WF) than fossil derived fuel. The biorefinery approach has the potential to bring down the WF. Similarly, biorefinery approach has the potential to bring down the carbon footprint. The value added product derived from biorefinery basket includes pigments, nutraceuticals, and bioactive compounds. The use of industrial refusals for biomass production includes wastewater as nutrient medium and utilization of flue gases (CO2) as the carbon source for culture of microalgae. These processes ha...

Homogeneous acid catalysts received wide acceptability because of their fast reaction rates. However, postproduction costs incurred from aqueous quenching, wastewater and loss of catalysts led to the search for alternatives. Until recently, heterogeneous base catalyzed-biodiesel production also gained the attention of most researchers. This was because the process minimized the problems of homogeneous catalysis in terms of catalyst regeneration and recycling in continuous processes. However, despite these advances, the ultimate aim of producing biodiesel at affordable cost is yet to be realized. Further, the process requires refined feedstocks which account for as high as 88% of the final production costs. Thus, the focus of many research efforts is towards the rational design and development of solid acid catalysts aimed at reducing biodiesel production costs. Therefore, this study reviewed current literature on the activities and advantages of solid acid catalysts used in biodiesel production. It discussed in details how the preparation method and prevailing reaction conditions affect the catalytic activity of the catalyst. The review concluded by suggesting way forward from the traditional trial-and-error method to a rational means of determining catalytic activities.

Over the past few decades, the upcoming scientific scenario of the ever growing area of biotechnology finds a successful application of some eco-diversified microorganisms which are employed for the recovery of metals from ores and other industrial wastes. A lot of mineral oxidizers and reducers are found in natural environments which involve a different mode of action for mineral oxidation and reduction. Mineral oxidizers are found in natural leaching environments
such as acid mine drainage, dump disposal sites, tailing ponds and are mostly aerobic in nature while the reducers are found in environments under facultative anerobic or strictly anerobic conditions. Mineral Biotechnology is primarily aimed at the application of such mineral metal oxidizers and reducers for the development and advancement of a sustainable biotechnological industry in the mineral processing sector. Analyzing several aspects, the leaching microbes have a
number of features in common that make them especially suitable for their role in mineral solubilization. This particular review focuses on such mineral oxidizing and reducing microorganisms, their mode of action and area of application towards development and growth of mineral biotechnological industry.

The potential of an inorganic fertilizer as an alternative
nutrient source for the cultivation of
Scenedesmus sp. IMMTCC-6 was investigated.
With a preliminary study at a shake-flask scale, the
microalgae cultivation was scaled up in a
photobioreactor containing an inorganic fertilizer
medium. Microalgae cultured in a shake flask containing
0.1 g L–1 of urea and 1.0 g L–1 of NPK (Nitrogen:
Phosphorus: Potassium) fertilizers showed
a promising result in biomass productivity. During
the scale-up study in a photobioreactor the specific
growth rate (μ d–1), biomass yield (g L–1), and total
biomass productivity (mg L–1 d–1), was found to be
0.265, 1.19 and 66.1, respectively. The lipid yield
(%) as per dry cell weight (DCW) and lipid productivity
(mg L–1 d–1) was found to be a maximum
of 28.55 and 18.87, respectively, in a stationary
phase of the microalgae growth. The fatty acids
methyl ester profile was proven to be desirable for
biodiesel production.

Biodiesel is one of the potential alternative energy sources that can be derived from renewable and low-grade origin through different processes. One of the processes is alcoholysis or transesterification in the presence of a suitable catalyst. The catalyst can be either homogeneous or heterogeneous. This article reviews various catalysts used for biodiesel production to date, presents the state of the art of types of catalysts, and compares their suitability and associated challenges in the transesterification process. Biodiesel production using homogeneous and heterogeneous catalysis has been studied extensively, and novel heterogeneous catalysts are being continuously investigated. Homogeneous catalysts are generally efficient in converting biodiesel with low free fatty acid (FFA) and water containing single-origin feedstock. Heterogeneous catalysts, on the other hand, provide superior activity, range of selectivity, good FFA, and water adaptability. The quantity and strengths of active acid or basic sites control these properties. Some of the heterogeneous catalysts such as zirconia and zeolite-based catalysts can be used as both basic and acidic catalyst by suitable alteration. Heterogeneous catalysts from waste and biocatalysts play an essential role in attaining a sustainable alternative to traditional homogeneous catalysts for biodiesel production. Recently, high catalytic efficiency at mild operating conditions has drawn attention to nanocatalysts. This review evaluates state of the art and perspectives for catalytic biodiesel production and assesses the critical operational variables that influence biodiesel production along with the technological solutions for sustainable implementation of the process.

Abstrak—Lipid mikroalga adalah minyak masa depan untuk produksi biodiesel yang berkelanjutan. Salah satu keputusan penting dalam memperoleh minyak dari mikroalga adalah pemilihan spesies. Oleh karena itu pada penelitian ini dilakukan isolasi dan karakterisasi mikroalga dari Wonorejo melalui seleksi terhadap kandungan lipid secara kualitatif untuk mengetahui jenis mikroalga yang berpotensi sebagai bahan baku biodiesel. Pengambilan sampel mikroalga dilakukan di 3 stasiun muara Wonorejo. Parameter perairan yang diukur yaitu suhu, DO, pH, salinitas, kecerahan, kandungan ammonia, nitrit, nitrat dan fosfat. Isolasi mikroalga dilakukan dengan menggunakan metode pengenceran bertingkat dan streak plate. Analisis kualitatif kandungan lipid dilakukan dengan pewarnaan Nile red dan diamati dibawah mikroskop fluorescence dengan panjang gelombang 450-490 nm. Hasil penelitian menunjukkan bahwa kelimpahan total mikroalga di muara Wonorejo berkisar antara 1355,53-1605,10 ind/l. Hasil isolasi didapatkan sebanyak 5 genus yaitu Nitzschia, Navicula, Oscillatoria, Chlorococcum dan Nannochloropsis. Mikroalga Chlorococcum memiliki kandungan lipid yang paling tinggi serta berpotensi untuk dikembangkan lebih lanjut sebagai bahan baku biodiesel. Kata Kunci—biodiesel, isolasi, mikroalga, kandungan lipid.

Cultivation of microalgae utilizing wastewater substrate could form a sustainable biorefinery with double benefit of biomass generation and nutrient remediation. In this study potential of aquaculture wastewater is evaluated for cultivation of Chlorella sorokiniana in heterotrophic mode for generation of high value biomass. Nutrient removal potential is also assessed. Aquaculture wastewater with 400 mgL −1 sodium nitrate supplementation resulted in biomass productivity of 498.14 mgL −1 d −1. The biomass generated showed lipid productivity of 150.19 mgL −1 d −1 , carbohydrate productivity of 172.91 mgL −1 d −1 and protein productivity of 141.57 mgL −1 d −1. The nutrient removal efficiencies were 75.56% for ammonium, 84.51% for nitrates, 73.35% for phosphates and 71.88% for COD (chemical oxygen demand). The findings of this study underline the potential of aquaculture wastewater for production of valuable microalgal biomass which can be utilized for biofuels or feed application. This biorefinery concept also polished aquaculture wastewater which can be effectively reused.

– Biodiesel fuel has capability to avoid the shortage of transportation fuel energy sources. A diesel engine combustion and emission characteristics are mainly dependant on the ignition delay (ID). This review represents the parameters affecting the ignition of the different biodiesel fuel. The analysis comparative study between various biodiesel and diesel is described. The comparative results show that the combustion of biodiesel in engine is slightly different from the engine running with petroleum diesel. The survey results show that combustion characteristics of biofuels are slightly different from an engine operating with different biodiesels. Many researchers reported that biodiesel has early start of combustion and shorter ignition delay as compared to diesel. Higher cetane number (CN), lower compressibility and fatty acid composition of biodiesel have been observed as the main parameters for early start of combustion and shorter ignition delay. In addition, it is also revealed that the heat release rate (HRR) of biodiesel is less than pure diesel due to the less lower heating value, less volatility, higher viscosity and shorter ignition delay.

Most modern searches are directed to alternative fuels because the buffer stock from the petroleum oils reduces with time and the fossil fuels are worst impact on environmental pollution. Biodiesel is derived from oil crops is a potentially renewable and carbon neutral alternative to petroleum fuels. Biodiesel is defined as a transesterified renewable fuel derived from vegetable oils or animal fats with properties similar or better than diesel fuel. In present work, Calophyllum inophyllum seeds were used to produce biodiesel. The transesterification process has been used to produce Calophyllum Inophyllum Methyl Ester (CIME) from raw Calophyllum oil. The properties of fuel are found such as viscosity, flash point, fire point and calorific value. Hence the effect of injector opening pressure (IOP) on the performance of compression ignition (CI) engine fuelled with biodiesel blends (B10, B20 and B30) with diesel fuel is evaluated. The effect of injection pressure on the performance and emission was studied at three different test pressures. From the experimental results optimum IOP is found on the comparison of Brake Thermal Efficiency and Brake specific fuel consumption (BSFC). Performance and emission characteristics are considered to find the optimality of the biodiesel blends.

First of all, I wish to express my deepest appreciation and thanks to my supervisor, Dr. Shaza Eva Mohamad for her professional guidance and help throughout the research project. Thank you also for her patience and as well as encouragement that really help me in putting everything together perfectly.

Algae were grown in a photobioreactor with wastewater centrate as the feed source. Multivalent metal salts and cationic polymers were capable of >91% recovery. There is a tradeoff between the environmental impacts and costs of coagulants. Belt presses are recommended for algae dewatering prior to oil extraction. a b s t r a c t The costs and life cycle impacts of microalgae harvesting for biofuel production were investigated. Algae were grown in semi-continuous culture in pilot-scale photobioreactors under natural light with anaero-bic digester centrate as the feed source. Algae suspensions were collected and the optimal coagulant dosages for metal salts (alum, ferric chloride), cationic polymer (Zetag 8819), anionic polymer (E-38) and natural coagulants (Moringa Oleifera and Opuntia ficus-indica cactus) were determined using jar tests. The relative dewaterability of the algae cake was estimated by centrifugation. Alum, ferric chloride and cationic polymer could all achieve >91% algae recovery at optimal dosages. Life cycle assessment (LCA) and cost analysis results revealed that cationic polymer had the lowest cost but the highest environmental impacts, while ferric chloride had the highest cost and lowest environmental impacts. Based on the LCA results, belt presses are the recommended algae dewatering technology prior to oil extraction.

This research investigates the effect of reaction variables that strongly affect the cost of biodiesel production from non-edible Spirulina-Platensis microalgae lipids, and use the acid-catalyzed in situ transesterification process. Experiments were designed to determine how variations in volume of reacting methanol, the concentration of an acid catalyst, time, temperature and stirring affected the biodiesel yield. The total lipid content of Spirulina-Platensis microalgae was obtained to be 0.1095 g/g biomass. The weight of the by-product glycerol obtained was used to predict the percentage yield conversion of microalgae oil biodiesel. Best results (84.7%), a yield of fatty acid methyl ester (FAME), were obtained at 100% (wt./wt.oil) catalyst concentration, 80 ml methanol volumes, 8 h reaction time and 65˚C reaction temperature with continuous stirring at 650 rpm. Properties of the produced biodiesel were measured according to EN 14214 standards.

Microwave and sonication techniques are compared for efficient lipid extraction. Qualitative lipid variation caused by cell disruption and drying methods is studied. Energy consumption calculated for drying and lipid extraction processes. Lipid quality has been assessed for its suitability for biodiesel production. Sun drying with efficient microwave extraction could be possible processing step. a b s t r a c t Downstream processing of microalgal biomass presents a significant challenge to large scale biodiesel production. Scenedesmus sp. which is known to be a potential feedstock for biodiesel production was cultivated in an open circular pond. The biomass productivity peaked at day 21 with a yield of 1.16 g L À1 . Biomass was harvested by gravitational settling followed by centrifugation. Harvested biomass was dried using the freeze drying, oven drying and sun drying processes followed by lipid extraction which yielded 29.65%, 28.63% and 28.33% lipid g À1 DCW (dry cell weight) respectively. Lipids were extracted from microalgal biomass dried by selected drying techniques using microwave and sonication for cell disruption in the presence of mixture of chloroform and ethanol (1:1). Microwave assisted extraction of sun dried biomass yielded 28.33% lipid g À1 DCW, as compared to 18.9% lipid g À1 DCW achieved by sonication assisted extraction. The saponification and acid values of the lipid obtained from Scenedesmus sp. dried by selected drying techniques showed high saponification and acid value indicating presence of high free fatty acid content. Effect of different drying and cell disruption technique on fatty acid profile of lipids extracted from Scenedesmus sp. biomass was also studied. These values indicate promising potential of the oil produced for conversion into biodiesel.

Biodiesel is a long-chain fatty acid ester made from renewed and biological raw materials such as used cooking, animal fat, vegetable oil, and algae. Biodiesel is a renewable and clean fuel as it reduces carbon monoxide, carbon dioxide, hydrocarbons, and particulate matter emissions compared with petroleum-based diesel fuel. Production of biodiesel from renewable resources is done through the transesterification reaction at which the organic group (alkyl) of alcohol is substituted with the organic group of a triglyceride-the main component of the feedstock-producing fatty acid alkyl ester (biodiesel) and crude glycerol. Biodiesel can be used in pure form (B100) or may be blended with petroleum diesel at any concentration if its specifications is identical to the international standard specifications provided by American standard for testing materials (ASTM) or EN14214 in the European Union for alternative fuels. In this paper, the different types of biodiesel feedstocks, feedstocks treatment methods, and biodiesel production technologies are reviewed and discussed.

Microwave energy based chemical synthesis has several merits and is important from both scientific and
engineering standpoints. Microwaves have been applied in numerous inorganic and organic chemical syntheses;
perhaps, from the time their ability to work as heat source was discovered. Recent laboratory scale microwave
applications in biodiesel production proved the potential of the technology to achieve superior results over
conventional techniques. Short reaction time, cleaner reaction products, and reduced separation-purification times
are the key observations reported by many researchers. Energy utilization and specific energy requirements for
microwave based biodiesel synthesis are reportedly better than conventional techniques. Microwaves can be very
well utilized in feedstock preparation, extraction and transesterification stages of the biodiesel production process.
Although microwave technology has advanced in other food, pharmaceutical and polymer chemistry related
research and industry, it has yet to prove its potential in the biodiesel industry at large scale applications. This paper
reviews principles and practices of microwave energy technology as applied in biodiesel feedstock preparation and
processing. Analysis of laboratory scale studies, potential design and operation challenges for developing large scale
biodiesel production systems are discussed in detail.