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Use of Algae through different approaches

It seems probable that growth in human population, future climate change effects on freshwater resources, which are already stressed in some regions and eventual shortages of unutilized arable land will encourage the exploitation of microalgae based production systems for both food and fuel. Claims that the ability to utilise non-arable land and waste water resources with few competing uses make algal biofuel production systems superior to biofuels based on terrestrial biomass has created great interest in governments, NGOs, the private sector and the research community. Current initiatives clearly indicate this interest at all levels of government and the in private sector in the development of algal biofuels technologies and enterprises. Microalgae are one of the most important bioresources that are currently receiving a lot of attention due to a multiplicity of reasons. The world is faced with energy challenges in the near future and it is reported that fossil fuel reserves will be depleted in half a century . This will be an unprecedented vicissitude that will impact negatively on all anthropogenic activities most importantly agriculture, industry and commerce. With this in mind, it is crucial to explore renewable and cost-effective sources of energy for the future. It has been estimated that biomass could provide about 25% of global energy requirements and can also be a source of valuable chemicals, pharmaceuticals and food additives.

In addition, the growing of urban population poses a serious threat to the environment due to the release of copious amounts of domestic municipal wastewater. The use of microalgae is desirable since they are able to serve a many role of bioremediation of wastewater, generating biomass for biofuel production with concomitant carbon dioxide sequestration. In addition, wastewater remediation by microalgae is an eco-friendly process with no secondary pollution as long as the biomass produced is reused and allows efficient nutrient recycling. As the demand for energy continues to increase globally, fossil fuel usage will likewise continue to rise. There is still a plentiful supply of fossil fuels at reasonably low cost, although this is likely to change in the future, but more critically a rising use of fossil fuels is unlikely to be sustainable in the longer term principally due to the attributed increase in greenhouse gas (GHG) emissions from using these fuels and the environmental impact of these emissions on global warming. There is therefore significant interest in identifying alternative renewable sources of fuel that are potentially carbon neutral. Biofuels derived from the cultivation of algae have therefore been proposed as an alternative approach that does not impact on agriculture. Microalgae cultivation using sunlight energy can be carried out in open or covered ponds or closed photobioreactors, based on tubular, flat plate or other designs. Microalgae production in closed photobioreactors is highly expensive. Closed systems are much more expensive than ponds. However, the closed systems require much less light and agricultural land to grow the algae. In order to have an optimal yield, these algae need to have CO2 in large quantities in the basins or bioreactors where they grow. Thus, the basins and bioreactors need to be coupled with traditional thermal power centers producing electricity which produce CO2 at an average tenor of 13% of total flue gas emissions. The CO2 is put in the basins and is assimilated by the algae. It is thus a technology which recycles CO2 while also treating used water. Use of biodiesel from oilgae is a promising alternative to solve air pollution problems. Algae-based technologies could provide a key tool for reducing greenhouse gas emissions from coal-fired power plants and other carbon intensive industrial processes. To achieve environmental and economic sustainability, fuel production processes are required that are not only renewable, but also capable of sequestering atmospheric carbon dioxide (CO2). Second generation microalgal systems have the advantage that they can produce a wide range of feedstocks for the production of biofuels. Biodiesel is currently produced from oil synthesized by conventional fuel crops that harvest the sun’s energy and store it as chemical energy. This presents a route for renewable and carbon-neutral fuel production. However, current supplies from oil crops and animal fats account for only approximately 0.3% of the current demand for transport fuels. In 2008 the world production of biodiesel fuel was about 13.9 million ton [48-52]. In addition, these photosynthetic microorganisms are useful in bioremediation applications. The advantages of using microalgae for biodiesel production cannot be overemphasized. Biodiesel can be generated from 0306-2619/$ crops such as sugar cane, soybean, canola, rapeseed, maize, olive oil, non-edible jatropha, inter alia. However the use of food crops for biofuels has generated much debate involving food security concerns. The main advantages of using microalgae as a source of biomass for biodiesel production are: high growth rates and short generation times, minimal land requirements, high lipid content, use of wastewater stream as nutrient feed with no need for chemicals such as herbicides and pesticides.

There is several utilization of algae or microalgae by which we can sort out the environment problems like; the major problem of global warming is CO2 in the atmosphere which creates green house effects, so for the growth of microalgae the utilization of CO2 is very essential, and to generates around 1 kg algal biomass requires 1kg of CO2 which is better to sort out this problem, it can be reduce many heavy or toxic metals form waste water and this process called Phycoremediation, It can be use as biofuel to reduce the effect of our conventional fuel which is going to be finish day by day because algae have potential to produce biofuel in the form of lipid which id further processed by transesterification process get the biodiesel which has the properties same as the our conventional diesel and it can be use for the many cosmetics, food and many use in the field of pharmaceuticals.

A. Phycoremediation
Phycoremediation may be defined in a broad sense as the use of macroalgae or microalgae for the removal or biotransformation of pollutants, including nutrients and xenobiotics from wastewater and CO2 from waste air with concomitant biomass propagation. There are numerous processes of treating water, industrial effluents and solid wastes using microalgae aerobically as well as anaerobically. Remediation is generally subject to an array of regulatory requirements, and also can be based on assessments of human health and ecological risks where no legislative standards exist. Recent studies have shown that microalgae can indeed support the aerobic degradation of various hazardous contaminants. The mechanisms involved in microalgae nutrient removal from industrial wastewaters are similar to that from domestic wastewaters treatment. Phycoremediation comprises several applications: (i) nutrient removal from municipal wastewater and effluents rich in organic matter; (ii) nutrient and xenobiotic compounds removal with the aid of algae-based biosorbents; (iii) treatment of acidic and metal wastewaters; (iv) CO2 sequestration; (v) transformation and degradation of xenobiotics; and (vi) detection of toxic compounds with the aid of algae-based biosensors. Nutrient removal with the aid of microalgae compares very favourably to other conventional technologies.

The growth of microalgae is indicative of water pollution since they respond typically too many ions and toxins. Blue-green algae are ideally suited to play a dual role of treating wastewater in the process of effective utilization of different constituents essential for growth leading to enhanced biomass production. The release of free oxygen is of major significance in organically enriched wastewater, promoting aerobic degradation processes by and other microorganisms. Secondly the role of microalgae is the accumulation and conversion of wastewater nutrients to biomass and lipids.

The capability of microalgae to degrade hazardous organic pollutants is well known. Chlorella, Ankistrodesmus and Scenedesmus species have been already successfully used for the treatment of olive oil, mill wastewaters and paper industry wastewaters. One way to investigate the capability of algae to biodegrade organic pollutants in municipal waste is to encourage the cells to grow in the presence of the pollutants and findings showed that both cyanobacteria (blue-green algae) and eukaryotic microalgae were capable of biotransforming naphthalene to four major metabolites, 1-naphthol, 4-hydrox-4-tetralone, cis-naphthalene dihydrodiol and trans-naphthalene dihydrodiol at concentrations which were non-toxic. The biomass resulting from the treatment of wastewaters can be easily converted into added value products. Depending by the species used for this purpose, the resulting biomass can be applied for different aims, including the use as additives for animal feed, the extraction of added value products like carotenoids or other bio-molecules or the production of biofuel.

The mass production of algae has historically been for use as a food supplement or wastewater treatment. The technology for production of biomass from wastewater has been present since the 1950s. Microalgae are efficient in the removal of nutrients from wastewater. Thus many microalgal species proliferate in wastewater due to the abundance of carbon, nitrogen and phosphorus that act as nutrients for the algae. Unicellular algae have shown great efficiency in the uptake of nutrients and have been found to show dominance in oxidation ponds. Application of using wastewater for the production of biomass however, occurs only on a minor scale and generally in the form of waste stabilization ponds or high rate algal ponds for the treatment of wastewater. Production of biomass from wastewater requires, similar production of biomass on artificial media, depends on a number of factors. However factors of heavy metal contamination require greater attention than in conventional production from media. Park et al. has recorded the following to be desirable attributes of microalgal species for use in High rate algal ponds (HRAPs), (1) High biomass productivity when grown on wastewater, (2) tolerances to seasonal and diurnal variation in outdoor conditions, (3) form aggregates to enhance ease of harvesting, (4) accumulation of high amounts of lipid or other valuable products. This suggests the potential of lowering the cost of algal biofuels production, which is currently not economically feasible.

B. Wastewater treatment methods
An understanding of the nature of wastewater is essential in the design and operation of treatment processes. Disposing of liquid and solid waste in rivers, streams, lakes and oceans seemed convenient for mankind. The quantities of wastewater at any point may ‘‘over load’’ the bio-system disrupting the natural recycling processes such as photosynthesis, respiration, nitrogen fixation, evaporation and precipitation. Wastewater treatment is an important initiative which has to be taken more seriously for the betterment of society and our future. Wastewater treatment is a process, where contaminants are removed from wastewater including domestic wastewater, to produce waste stream or solid waste suitable for discharge or reuse. Domestic wastewater is a combination of water and other wastes originating from homes, commercial and industrial facilities, and institutions. Untreated wastewater generally contains high levels of organic material, numerous pathogenic microorganisms, as well as nutrients and toxic compounds. Disposal of municipal solid wastes (MSW) in sanitary landfills is usually associated with soil, surface water and groundwater contamination when the landfill is not properly constructed. It thus entails environmental and health hazards, consequently, must immediately be conveyed away from its generation source(s) and treated appropriately before final disposal. The ultimate goal of wastewater management is the protection of the environment in a manner commensurate with public health and socio-economic concerns. Biological treatment is an important aspect of industrial and municipal wastewater treatment and reuse processes. Wastewater treatment methods are broadly classified into three categories; there are physical, chemical and biological. Among the first treatment methods used were physical unit operations, in which mechanical forces are applied to remove contaminants. Today, they still form the basis of most process flow systems for wastewater treatment. Chemical processes used in wastewater treatment are designed to bring about some form of change by means of chemical reactions. They are always used in conjunction with physical unit operations and biological processes. In general, chemical unit processes have an inherent disadvantage compared to physical operations in that they are additive processes, since there is usually a net increase in the dissolved constituents of the wastewater. This can be a significant factor if the wastewater is to be reused.

It has been appreciated for some years now that microalgae can be potentially utilized for low cost and environmentally friendly wastewater treatment compared to other more commonly used treatment processes. The selection of microorganisms for use as alternative fuel sources requires a sustainable growth medium such as domestic wastewater streams. The majority of wastewaters contain very high concentrations of nutrients, particularly total N and total P concentration as well as toxic metals, so there is no requirement for costly chemical-based treatments. According to de la Noue et al. the concentration of total N and P can be found at values of 10–100 mg L-1 in municipal wastewater and >1000 mg L-1 in agricultural effluent. Microalgae have potential to treat wastewater by efficiently accumulating nutrients and metals from the wastewater. Sustainable low cost wastewater treatment has been strongly proven by using microalgae. Microalgae grown on wastewater for energy production have been proposed for a long time. However, in recent years, microalgae seem to be a favorite candidate for this purpose, due to their ease of cultivation and the favourable possibility of their use as an alternative biomass for bioenergy production. Increase in global warming, depletion of fossil fuel and the need for mitigation of green-house gas (GHS) emissions; make exploration of the feasibility of biological wastewater treatment .

C. Algal biofuels
Algae, particularly green unicellular microalgae have been proposed for a long time as a potential renewable fuel source. Microalgae have the potential to generate significant quantities of biomass and oil suitable for conversion to biodiesel. Microalgae have been estimated to have higher biomass productivity than plant crops in terms of land area required for cultivation, are predicted to have lower cost per yield, and have the potential to reduce GHG emissions through the replacement of fossil fuels.

As with plant-derived feedstocks, algal feedstocks can be utilized directly or processed into liquid fuels and gas by a variety of biochemical conversion or thermochemical conversion processes. Dried algal biomass may be used to generate energy by direct combustion but this is probably the least attractive use for algal biomass. Thermochemical conversion methods include gasification, pyrolysis, hydrogenation and liquefaction of the algal biomass to yield gas- or oil-based biofuels. Biochemical conversion processes include fermentation and anaerobic digestion of the biomass to yield bioethanol or methane. In addition, hydrogen can be produced from algae by bio- photolysis. Finally, lipids, principally triacylglycerol lipids can be separated and isolated from harvested microalgae and then converted to biodiesel by transesterification.

The potential for sustainable biofuel production One of the attractions of microalgae as a biofuel feedstock is that they can be effectively grown in conditions which require minimal freshwater input unlike many plant-based biofuel crops, and utilize land which is otherwise non-productive to plant crops, thus making the process potentially sustainable with regard to preserving freshwater resources. For example, microalgae could be cultivated near the sea to utilize saline or brackish water. There has therefore been significant interest in the growth of microalgae for biofuels under saline conditions. However, another potentially sustainable growth medium for algal feedstock is wastewater. It has been appreciated for some years now that microalgae can be potentially utilized for low-cost and environmentally friendly wastewater treatment compared to other more commonly used treatment processes.

D. Biodiesel from oilgae
Biodiesel is a biofuel commonly consisting of methyl esters that are derived from organic oils, plant or animal, through the process of transesterification.

An excess of methanol is used to force the reaction to favor the right side of the equation. The excess methanol is later recovered and reused. Biodiesel has received much attention in recent years. Biodiesel is the best candidate for diesel fuels in diesel engines. Biodiesel burns similarly to petroleum diesel as it concerns regulated pollutants. On the other hand biodiesel probably has better efficiency than gasoline. Biodiesel fuel has better properties than petro-diesel fuel; it is renewable, biodegradable, non-toxic, and essentially free of sulfur and aromatics. Typical raw materials of biodiesel are rapeseed oil, soybean oil, sunflower oil and palm oil. Beef and sheep tallow and chicken fat from animal sources and cooking oil are also sources of raw materials. Commonly accepted biodiesel raw materials include the oils from soy, canola, corn, rapeseed, and palm. New plant oils that are under consideration include mustard seed, peanut, sunflower, and cotton seed. The most commonly considered animal fats include those derived from poultry, beef, and pork. Serious problems face the world food supply today. Food versus fuel is the dilemma regarding the risk of diverting farmland or crops for liquid biofuels production in detriment of the food supply on a global scale. Biofuel production has increased in recent years.

E. Biofixation of carbon dioxide by microalgae
Biofixation of CO2 by microalgae mass cultures represents an advanced, climate friendly biological process that enables the direct utilization of fossil CO2 streams produced from concentrated sources. Mitigation of GHG emissions would result from the conversion of the algal biomass to renewable biofuels [56,45,52 and 69]. Fossil-fuel-fired power plants contribute approximately one third of the total human-caused emissions of CO2. Fossil fuels will remain the mainstay of energy production well into the 21st century. However, increased concentrations of CO2 due to carbon emissions are expected unless energy systems reduce the carbon emissions to the atmosphere. To stabilize and ultimately reduce concentrations of the CO2 gas, it will be necessary to employ carbon sequestration – carbon capture, separation and storage or reuse. Carbon sequestration, along with reduced carbon content of fuels and improved efficiency of energy production and use, must play major roles if the nation is to enjoy the economic and energy security benefits, which fossil fuels brings to the energy mix. The availability of a carbon dioxide fixation technology would serve as insurance in case global warming causes severe restrictions on carbon dioxide emissions. Integrated processes in wastewater treatment and aquaculture were indicated as near-term applications of this technology. Microalgae applications in greenhouse gas mitigation could come through the development of wastewater treatment and aquaculture processes that combine their waste treatment features with reduction in greenhouse gas emissions and biofuels production. The greatest potential for microalgae biofixation processes is in developing countries, which should be included in any future development of this technology. The ultimate objective of microalgae biofixation of CO2 is to operate large-scale systems that are able to convert a significant fraction of the CO2 outputs from a power plant into biofuels. Biofixation of CO2 using photosynthetic organisms has been looked at as a way to stop or slow down the effects of global warming.

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Marine algae are ecologically significant as primary producers and have been utilized economically as medicines and food for generations. Nowadays, numerous species of marine algae supply not only food but also with extracts such as agar, alginates and carrageenans. These extracts are utilized in various foods, cosmetic, pharmaceutical and industrial purposes.

Red algae (Rhodophyta)

Carrageenan is prepared from various species of red algae such as Chondrus crispus , Mastocarpus stellatus and Eucheuma. It is similar to agar, but is required in greater concentrations to form gels. It is utilized in the stabilization of ice cream, chocolates, milk, instant puddings, egg nog, sherbets, creamed soups, frostings and so on. Industrial applications of carrageenan involves its utilization in Enzyme immobilization, Air freshener gels, Tertiary oil treatment, Electrophoresis media, Cleaners, Chromatographic media etc. The pharmaceutical and medical application of it includes its utilization in Capsules and tablets, creams and lotions, Laxatives, Ulcer products, Toothpastes and shampoos.

Agar is prepared from different species of red algae such as Gracilaria, Gelidium, Ahnfeltia and Pterocladia. It is a colloidal substance that is utilized as thickening, stabilizing and suspending agent. It is also noticed for its unique capability to form thermally reversible gels at lower temperatures. The maximum utilization of agar is in association with food and in pharmaceutical industry (as an inert carrier for drug products where slower release of the drug is required or used as a laxative). It is used in mycology and bacteriology as a stiffening agent in various growth media. Agar is used sometimes as a substitute for gelatine in food, anti-drying substance in pastry, bread and also for thickening and gelling purposes. It is utilized in the manufacturing of mayonnaise, frozen dairy products, processed cheese and creams. Agar is used as an ingredient of cosmetic skin preparations, lotions and ointments and also in dental impression moulds, photographic film, shaving soaps and tanning industry.
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Brown algae (Phaeophyta)

The class phaeophyceae includes species such as Kelps (Laminaria, Macrocystis) Fucus ,Ascophyllum and Sargassum.

Alginic Acid or Alginate is a colloidal substance that is used for emulsifying, thickening, stabilizing, suspending, film-forming and gel-forming as necessary. Almost half of the alginate that is produced is utilized for making dairy products and ice-creams and the rest of it is used in various other products such as paint, rubber and also shaving creams. In textile manufacturing alginates are utilized to thicken dye pastes that are reactive to fibres and it promotes the sharpness in printed lines that conserves dyes. Dentists utilize alaginates to generate dental impressions of the teeth.

Diatoms (Bacillariophyceae)
Diatoms are unicellular microscopic algae that belong to the class Bacillariophyceae that are found in both marine and freshwater environments. Diatomite is a derivative of diatoms that is commercially important. The porous feature of the diatomaceous earth (diatomite) promotes industries to exploit this nature and utilize it as an absorbent for, noxious materials, gases, soluble fertilising agents, pasteboard, sealing wax, rubber erasers and so on. The properties of diatomite make it suitable for industrial filters. Heavier industries utilize it for stabilization and filtration of chemicals, including liquid acids and other liquid wastes. It is also utilized as filter in pharmaceuticals, serums and in various other biotechnology applications. Diatomite is also utilized in a diversity of food production applications which includes Refining sugar and sweeteners, Clarification and filtration of beer and wines, filtering fruit juices, oils and syrups. The various other significant application of diatomite can be found in area of structural materials such as sound proofing material, fire and heat resistant products, polishing substances such as Tripoli Powder, in drain pipes, porcelain materials, tiles, artificial stones and non conducting materials. The diatomite also finds its application in cosmetic products such as soap, sozodont tooth powder, toothpastes and deodorants.
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