Abstract
In order to improve the production efficiency of volatile fatty acids (VFAs) by anaerobic fermentation of food waste and reduce the cost for the production of organic deicing salt (ODS), ceramic microfiltration (MF) membrane separation was applied in the conventional food waste fermenter to build an anaerobic membrane bioreactor (AnMBR). Results showed that the maximum VFA concentration in AnMBR was up to 55.37 g/L. Due to the fact that the MF membrane could realize in situ separation of VFAs, the recovery of VFAs could reach 95.0%; 66.6% higher than that of traditional fermentation reactors. After the application of the MF membrane, more than 20.0% of soluble COD, 40.0% of proteins, and 50.0% of polysaccharides were retained and more than 90.0% of VFAs could be transferred in a timely fashion in the AnMBR system. In addition, the enrichment effect of the MF membrane enhanced enzymatic activities such as protease, α-Glucosidase and acetate kinase, and increased the abundance of some important bacteria for organic acid generation such as Amphibacter, Peptoniphilus and Halomonas, which made a significant contribution to the yield of VFAs. After concentration, evaporation and crystallization, the melting efficiency of obtained ODS can reach more than 90.0% in chloride salts, which was 112.0% of commercial calcium magnesium acetate (CMA). When compared to chloride salts and CMA, ODS was more environmentally-friendly as it can reduce the corrosion of carbon steel and concrete significantly. This study created a new way of converting food waste into a high-value organic deicing agent, realizing the resource utilization of solid waste and reducing the production cost of organic deicing agents.
Highlights
Deicing salt is one of the main methods for the quick removal of extensive snow and ice in winter and it is widely used all over the world [1]
The fermentation separation unit was composed of a fermentation tank and a MF membrane module, whose main function was the anaerobic fermentation of food waste and the solid–liquid separation of the fermentation broth
In stage II, the MF membrane was added in the conventional fermentation system, leading to the possibility of the fermentation broth and the volatile fatty acids (VFAs) being immediately separated through the MF membrane
Summary
Deicing salt is one of the main methods for the quick removal of extensive snow and ice in winter and it is widely used all over the world [1]. The most commonly-used deicing salts are sodium chloride (NaCl) and calcium chloride (CaCl2 ) as they are readily available, relatively inexpensive and efficient in melting ice and snow. The growth of plants and crops can be seriously affected by chloride deicers. Spraying solid deicing salt can contaminate the soil and groundwater after the melting of deicing salt [4]. It is crucial to develop an environmentally-friendly deicing salt, which can replace the chloride deicers to alleviate the adverse impact of deicing salts on the environment
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