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A particular fermentation process produces reusable chemicals and reduces treatment costs.
Even dirty water, sometimes, can be recycled. A group of researchers has developed a new system to produce high value chemicals from glycerol and fatty acids that can be found in waste waters through an anaerobic mixed culture fermentation process. This technique was devised by the Hong Kong Polytechnic University.
Glycerol is a low value by-product in the production of bio fuels. The production ratio of glycerol from bio-diesel is 1:10. In the fermentation process, glycerol provides the electrons necessary to convert fatty acids into n-Caproic acid, which is a basic chemical in the industrial production of artificial flavours, medications, and lubricants. Its energy density is 700 times higher than that of gas methane, and 1.2 times higher than that of liquid ethanol. Its solubility level (1.1 g/100 mL at 20°C) is sufficiently low for it to be easily recovered by distillation. At the same time, another high value chemical is produced, propanediol, which is used in the production of polymers.
If replicated on an industrial scale, the system developed by the Hong Kong researchers could become an exceptional tool for the circular economy. On the one hand, it would allow to recover high value raw materials, treating them and reintegrating them in the production cycle. On the other hand, it would be an efficient system for the treatment and depuration of waste waters, reducing the costs and energy required by the sterilization process.
Concerning its applications, the ecological fermentation developed by the Hong Kong University can be used to treat municipal or industrial waste waters and can also help to solve the problems of by-product management and waste disposal.