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234 || AWSAR Awarded Popular Science Stories - 2019
can be used as nutraceuticals in the health industry, can be used as a highly nutritious feed source for aquaculture, its extracts are used in cosmetics and last but not the least, and it is a great source of alternative biofuels, which can replace the “harmful gases emitting- conventional fossil fuels”.
Microalgal products have a huge industry base to flourish in the coming decades, generating employment and alternative solutions to many existing products. It offers a solution in terms of food, fuel, employment, as well as cash flow. Most developed and developing countries like the US, Germany, the Netherlands and China have already established basic research units and pilot plants for microalgal cultivation and its downstream processing for its valuable products. However, India is far behind in terms of research as well as establishment of pilot plants. Thus, we need to make extra effort to stay at par with the world.
For use as a source of
biofuel, many universities and
research organizations are
working on a variety of easy-
to-manipulate microalgae, for
increased lipid production. Our
research work was focussed
on improving the various steps
involved in microalgal biofuel
production and, thereby,
enhancing the productivity.
Microalgal biofuel production
consists of four major steps:
cultivation, harvesting, lipid
extraction and transesterification. Each of these four steps, have their share of challenges. Harvesting being the bottleneck of the entire process. Microalgae’s small size makes the harvesting rather difficult by all existing methods. Most methods are highly expensive and not feasible for large volumes of culture media, like centrifugation, whereas
methods like filtration cannot be used due to clogging and fouling of filters. New, micro and nanotechnology methods have been applied to harvest microalgae to make the process easier, simpler and faster. Our work was based on similar lines using nanotechnological methods to enhance harvesting and increasing lipid productivity by manipulating carbon-nitrogen ratio of the culture volume.
The process begins with culturing two microalgal species separately in small amounts of about 200 ml BG 11 medium in 500 ml/1 L conical flasks for 12 to 14 days under constant luminous light with occasional shaking at ambienttemperature.Toharvestthefull-grown microalgae, iron oxide nanoparticles (IONPs) were synthesized using iron chloride salts by chemical co-precipitation. Using the chemical co-precipitation method, the iron chloride salts are transformed into absolute nano- sized particles increasing its surface area
tremendously. The synthesis process takes merely 60 minutes and is easy, fast and very simple to perform. The process takes place in a simple four-necked glass apparatus at a specific temperature under inert conditions. Upon successful synthesis, the nanoparticles are dried and stored. These are characterized by fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, vibrating sample magnetometry
and zeta potential, which authenticate the IONPs.
The full-grown microalgae are known to possess an overall negative surface charge over an entire pH range, whereas the synthesized nanoparticles can have varying pH across different pH. Hence the nanoparticles are used in an acidic environment for harvesting,
Microalgae grows faster than plants and trees, captures harmful carbon dioxide from the environment, can be grown on sewage and marshy waters, helps in reducing the harmful chemical load from the wastewater.