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http://link.springer.com/content/pdf/10.1007/BF01976688.pdf

Soil enzymes: Kuprevich, V. F. & Shcherbakova, T. A.: Translated from the Russian edition (1966), published by the Indian National Scientific Documentation Centre, New Delhi 1971. 392 pp., offset printing from type script, paper cover. Obtainable from U.S. Department of Commerce, National Technical Information Service, Springfield, Va. 22151

The demand for petroleum has been rising rapidly due to increasing industrialization and modernization. This economic development has led to a huge demand for energy, most of which is derived from fossil fuel. However, the limited reserve of fossil fuel has led many researchers to look for alternative fuels which can be produced from renewable feedstock. Increasing fossil fuel prices have prompted the global oil industry to look at biodiesel, which is from renewable energy sources. Biodiesel is produced from animal fats and vegetable oils and has become more attractive because it is more environmentally friendly and is obtained from renewable sources. Glycerol is the main by-product of biodiesel production; about 10% of the weight of biodiesel is generated in glycerol. The large amount of glycerol generated may become an environmental problem, since it cannot be disposed of in the environment. In this paper, an attempt has been made to review the different approaches and techniques used to produce glycerol (hydrolysis, transesterification, refining crude glycerol). The world biodiesel/glycerol production and consumption market, the current world glycerin and glycerol prices as well as the news trends for the use of glycerol mainly in Brazil market are analyzed. The technological production and physicochemical properties of glycerol are described, as is the characterization of crude glycerol obtained from different seed oil feedstock. Finally, a simple way to use glycerol in large amounts is combustion, which is an advantageous method as it does not require any purification. However, the combustion process of crude glycerol is not easy and there are technological difficulties. The news and mainly research about the combustion of glycerol was also addressed in this review.

Glycerol: Production, consumption, prices, characterization and new trends in combustion

In recent years, biodiesel has attracted significant attention from researchers, governments, and industries as a renewable, biodegradable, and non-toxic fuel. However, several feedstocks have been proven impractical or infeasible because of their extremely high cost due to their usage primarily as food resources. Waste cooking oil (WCO) is considered the most promising biodiesel feedstock despite its drawbacks, such as its high free fatty acid (FFA) and water contents. This review paper provides a comprehensive overview of the pre-treatment and the usage of WCO for the production of biodiesel using several methods, different types of reactors, and various types and amounts of alcohol and catalysts. The most common process in the production of biodiesel is transesterification, and using a methanol–ethanol mixture will combine the advantages of both alcohols in biodiesel production. In addition, this paper highlights the purification and analysis of the produced biodiesel, operating parameters that highly affect the biodiesel yield, and several economic studies. This review suggests that WCO is a promising feedstock in biodiesel production.

Overview of the production of biodiesel from Waste cooking oil

As major part of the phytoplankton, microalgae are pivotal for the global food chain. Their exceptional capacity for CO2-fixation illustrates their indispensable significance to sustain earth's ecosystems. Further, they play a still underestimated role in eliminating contaminants from various environments. In addition to ecological benefit, many microalgal species exhibit high nutritional value and, at the same time, generate valued bio-products: Pigments, lipids, bioactive compounds, certain polysaccharides, bio-hydrogen and even biopolyesters with plastic-like properties have the potential for successful market penetration. Three substantial pigment groups, namely chlorophylls, carotenoids, and phycobilins, are essential for light harvesting and CO2 fixation. Those pigments will most likely undergo quick commercial success in “functional food”, cosmetics, aquaculture, pharmaceuticals, or food technology. Due to often high contents of polyunsaturated fatty acids essential for human metabolism, microalgal oils can be commercialized as health food and in the pharmaceutical and therapeutic field, creating much higher value than by converting them to biofuel. Finally, algal biomass remaining as residue after product recovery can be used as forage, biogas feedstock or biofertilizer. This utilization is needed for balancing the material- and energy cycles of the entire process. Thus, technology platforms following the principles of bio-refineries shall be established to enable the design of sustainable and economically feasible production of marketable microalgal products.

A.F. Chica

Papers

Use of municipal solid waste compost (MSWC) as a growing medium in the nursery production of tomato plants

Biomethanization of orange peel waste

Impact of ammonia and sulphate concentration on thermophilic anaerobic digestion.

Anaerobic co-digestion of glycerol and wastewater derived from biodiesel manufacturing

Purification of biodiesel from used cooking oils