Study On The Control Effect Of Adding Microorganisms And Plant Compound Deodorant On Fecal Odor Gas

Odor pollution is the main cause of public complaints at home and abroad.Odor gas has a wide range of sources and complex components,and the evaluation of main odor substances is the key factor for deodorization.At present,there are three main methods for evaluating major malodorous substances:evaluation index method,odor wheel analysis method and odor activity value（OAV）method,and most of the current literatures use OAV method.The current research on malodorous gases is mainly concentrated in landfills,livestock and poultry farming and sewage sludge treatment systems,and there is a lack of research on deodorization of human feces.The complexity of organic matter in human feces leads to higher odor than most odors Level.China’s population is calculated at 1.4 billion,and the fecal pollution generated in one year is about 65.41billion kg.Human feces is the key factor that causes odor in septic tanks,public toilets,and fecal treatment plants.In addition,viruses in feces can cause a variety of harmful diseases,which seriously affects physical and mental health.Adding deodorant for front-end treatment is considered as a promising odor gas treatment method.In this paper,the optimal deodorant ratio and stability when combined with plant deodorant are explored by screening microbial deodorant.Compare the effects of microbial combined plant deodorant and the use of microbial deodorant and plant deodorant alone on human feces,explore its mechanism,and provide directions for further deodorization research.（1）Comprehensive morphological observation and molecular biology identification,the five deodorizing strains were Bacillus megaterium,Bacillus cereus,Lactobacillus rhamnosus,Lactobacillus caseinus and Saccharomyces cerevisiae.Widely used in pharmaceutical and food industries.（2）Combining the results of antagonism experiment and surface response experiment,it was finally determined that Bacillus:lactic acid bacteria:yeast=3.6:1:4,the deodorizing effect was the best,and the intensity of odor was reduced from 4.8to 2.7.The compound bacteria with this ratio is extremely stable and hardly inhibited by the 10%Yucca extract solution.（3）By fitting the experimental data,it is found that the correlation between NH₃,H₂S,odor concentration,and odor intensity is poor.The theoretical and actual odors are analyzed by formulas.It is found that NH₃ and H₂S may not be the most important cause of odor.Characterization of volatile organic compounds,4-methylphenol and indole（containing skatole）substances accounted for 44.07%and 41.20%of the mass fraction of malodorous substances,namely 4-methylphenol and indole（containing skatole）substances It may be a key substance for fecal odor.（4）The malodor concentration is not the best index for evaluating malodor.Due to the influence of k value,the phenomenon of high malodor concentration but not strong feeling will appear.The odor intensity method is an analysis method combining the odor concentration method and the sensory attribute k value,which is the most suitable index for evaluating odor.However,China currently lacks research on the k value.The benefits are greatest when the substance is processed primarily.（5）The sensory attribute k value is the most critical factor leading to malodor.Simply put,the k value is the degree of people’s annoyance about a substance.If people are extremely bored with fecal odor,the indole,skatole,etc.,which cause the fecal odor,have a high k value.In this paper,whether the main inorganic odor substances NH₃,H₂S or the main organic odor gas 4-methylphenol,indole（including skatole）substances are analyzed.The k value of alkaline substances is significantly greater than the k value of acid substances.Therefore,lowering the p H by the compound bacterial agent is one of the important mechanisms of good deodorizing effect.（6）Comparing the deodorizing effect of compound deodorant BY,microbial deodorant B,and plant deodorant Y on human feces at different times,it was found that the compound deodorant BY has the best deodorizing effect in the whole process,because it can play simultaneously The role of microbial deodorant B and plant deodorant Y.The optimal deodorization time is 12-24h,at which time NH3 is reduced from 40ppm to 5ppm,H2S is reduced from 0.5ppm to below the detection limit,and the odor intensity OI is reduced from 5 to 2.6.（7）High-throughput sequencing of feces,analysis of its microbial community structure and prediction of functional enzymes,and monitoring of its changes from12h to 7d.In the middle of deodorization 12h-2d,the abundance of Bacillus,lactic acid bacteria and yeast is significantly higher than that of the control group.From the analysis of abundance,yeast can best adapt to the environment of feces and has strong viability,using malodorous substances or precursor As the carbon skeleton of the cell grows rapidly,the relative abundance of the fungus is more than 97%in 1d-3d.At the same time,the addition of compound deodorant can reduce the abundance of pathogenic bacteria.By predicting functional enzyme genes through PICRUSt2,the compound deodorant BY can significantly reduce the abundance of human disease-related pathways（Cancer:Specific,Infectious diseases:Viral/Parasitic）,and at the same time reduce odor-producing enzymes such as Urase,Tryptophanase,Allophanate hydrolase Relative abundance.The degree of yeast reduction is higher than that of Bacillus and lactic acid bacteria.Yeast has a large cell body,high protein content,rich enzyme system,and good inhibition effect.It may be a potential deodorizing microorganism.