08-17-2017, 12:23 AM
Bioreactor
A bioreactor may refer to any device or system that supports a biologically active environment. A bioreactor may also refer to a device or system meant to grow cells or tissues in the context of cell culture. These devices are being developed for use in tissue engineering. In one context, a bioreactor is a vessel in which is carried out a chemical process which involves organisms or biochemically active substances derived from such organisms, and the process can either be aerobic or anaerobic.These bioreactors are commonly cylindrical, ranging in size from liters to cubic meters, and are often made of stainless steel. a bioreactor may be classified as batch, fed batch or continuous (e.g. a continuous stirred-tank reactor model) on the basis of the mode of operation.
Bioreactor design
This subject comes in the purview of the discipline of biochemical engineering. The bioreactor's environmental conditions like gas (i.e., air, oxygen, nitrogen, carbon dioxide) flow rates, temperature, pH and dissolved oxygen levels, and agitation speed/circulation rate need to be closely monitored and controlled. vessels, sensors and a control system networked together are usually used. Fouling can harm the overall sterility and efficiency of the bioreactor, especially the heat exchangers and is usually avoided by making it easily cleanable and as smooth as possible (therefore the round shape).
the bioprocess is maintained at a constant temperature by the heta exchnger. Biological fermentation is a major source of heat, therefore in most cases bioreactors need refrigeration. They can be refrigerated with an external jacket or, for very large vessels, with internal coils.
optimal oxygen transfer in an aerobic process is difficult to accomplish. Oxygen is less soluble in water--even less in fermentation broths--and is relatively scarce in air (20.95%). agitation of the mix adds the oxygen, mix nutrients and keeps the fermentation homogeneous. Practical bioreactors are often pressurized, this increases the solubility of oxygen in water.
Photobioreactor
A photobioreactor (PBR) is a bioreactor which incorporates some type of light source. Virtually any translucent container could be called a PBR. Photobioreactors are used to grow small phototrophic organisms which use light through photosynthesis as their energy source. The risk of contamination with other organisms like bacteria or fungi is lower in photobioreactors.
Sewage treatment
Bioreactors are also designed to treat sewage and wastewater. Examples of these bioreactors often have separate, sequential tanks and a mechanical separator or cyclone to speed the division of water and biosolids. Aerators supply oxygen to the sewage and media further accelerating breakdown. In the process, the liquids Biochemical Oxygen Demand BOD is reduced sufficiently to render the contaminated water fit for reuse. biosolids can be collected for further processing or used as a fertilizer. Septic systems are best suited where there is sufficient landmass and the system is not subject to flooding .
For more visit:
http://en.wikipediawiki/Bioreactor
http://goldbook.iupacB00662.html
http://sciencemagcgi/content/abstract/219/4585/728
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