Influence Of Yeast On Anaerobic Fermentation Of Kitchen Waste For Producing Acetic Acid

Kitchen waste is an important component of the municipal solid waste account for about 40%. If we can use it reasonable, it will be a valuable resource, because of its huge production and high content of organic matter. Landfill, composting, anaerobic digestion and producing animal feeds are generally used at home and abroad for the treatment and reclamation of kitchen waste . Among them, the anaerobic digestion has been widely used for the producing energy and organic fertilizer materials. Compared with aerobic treatment, anaerobic digestion dose not need aerate to supply oxygen, so it consumes less power. As well as anaerobic digestion can produce a lot of clean energy. From the utilization of regenerated energy and environmental protection, anaerobic digestion of kitchen waste endowed with promising future.It will produce a large number of short-chain fatty acids in the process of kitchen waste anaerobic digestion, acetic acid is the dominant, followed by propionic acid, butyric acid and iso-butyric acid and other volatile fatty acids. The use of acetic acid is the widest, it was widely used in medicine, chemical industry, textile industry as raw materials or solvents. The purpose of this subject is to maximize the generation of acid in kitchen waste fermentation process.There are a number of factors have impact on kitchen waste anaerobic fermentation , one of these is functional microbial community . Yeast is the most widely used microbial, it has the characteristics of osmosis resistance, acid resistane and metabolism efficient etc. It can degradation cellulose eazily. In this experiment, yeast was inoculated in the anaerobic fermentation actor, rate of waste hydrolysis, volatile organic acids (VFA) production and acetic acid production were studied to research the influence of yeast on anaerobic fermentation of kitchen waste for producing acetic acid.In this paper, yeast can promote hydrolysis of garbage was found in the feasibility experiment. The rate of hydrolysis of the anaerobic digestion process is the rate-limiting step. Yeast can accelerate Hydrolysis of kitchen waste, accelerate the rate of organic things dissolve in liquide, and provide more degradable substrate for following response. When the amount of yeast added in a certain range, the SCOD of fermentation liquor increased as volume of yeast increased; but when too much yeast was added, the extra strain would be consumed by organisms to generate their own material for reproduction, it will reflected in a decline of the concentration of SCOD. The acid production rate of anaerobic digestion increased with yeast, and the time shortened accordingly. Yeast with micro-organisms in the garbage would generate more acid in a shorter time, the reaction stops at the 9th day ,and a lot of acid can be produced.The optimum technological condition was determined. When the pH = 7.5, adding 0.100g yeast in 1g dry refuse, conversion rate of ethanol turn to acetic acid is the highest, acetic acid production could reach to 7264mg·L^-1.At last, the bacterial community and diversity in the kitchen waste anaerobic fermentation system were studied by using Polymerase Chain Reaction-denaturing gradient gel e1ectrophoresis(PCR-DGGE).Adding in yeast have a huge impact on anaerobic digestive system, especially lactic acid bacteria will be inhibited. It can be seen from changes of SCOD concentration that organic matter been hydrolysised continuously, organic matter that can be used by yeast in the system gradually reduced, and it makes the number of yeast decreasing.