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Research on the Microbial Deodorizer for the Odor Control in the Landfill and Its Deodorizing Mechanism

Author: CuiYuXue
Tutor: XieBing
School: East China Normal University
Course: Environmental Engineering
Keywords: landfill site odor microbial deodorizer microbial community structure deodorization mechanism
CLC: X703
Type: Master's thesis
Year: 2011
Downloads: 391
Quote: 3
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Abstract

According to statistics, the annual output of the solid waste is as much as 200 million tons in China, and will reach up to 660 million tons if the untreated solid waste over the years is calculated, which is close to those of the developed countries. About 95 percent of the solid waste is treated by landfill. A considerable amount of odor is produced in the process of transport, tile, compression, treatment and landfill, which will have direct or indirect influence on both the environment and the health of human being. Therefore, it is of utmost importance to control and treat the odor effectively, and that has been a crucial research project in the environmental protection field.At present, biological technology has been widely and successfully applied due to its high treatment efficiency, no secondary pollution and low operation cost. In recent years, the biological technology has gained more and more popularity in the deodorization of the solid waste. However, there are only a few kinds of microbial deodorizer in allusion to the solid waste, because it is difficult to screen and cultivate the effective strains that can adapt to the harsh environment in the landfill. Consequently, it has great significance to develop a new type of microbial deodorizer and to study on its deodorizing mechanism.In this paper, highly efficient deodorizing strains were isolated from the sludge and leachate collected from the Shanghai Laogang Disposal Plant, and they were made into microbial deodorizer. The odor removal efficiency of the deodorizer was studied in the lab experiment with different dosing method, adding dosage and cultural medium concentration, and was compared with that of the similar domestic deodorizer as well. The removal efficiency was further verified in the pilot test. Fianally, the application security was inspected in the toxicity test. Microbial community structure of various deodorizers was studied, and deodorizing mechanism was primarily explored. The main conclusions of this paper are as follows: (1) Seven highly-efficient deodorizing strains were isolated in our repetitious optimized cultivations process. The results showed that the odor removal efficiency of the strains was about 10% at the first day,20%～30% at both the second and the third day. The strains were proved to be Alcaligenes sp., Achromobacter sp., Bacillus sp., Lysinibacillus sp. and Caryophanon sp.. All of them have good environmental adaptability and stress resistance.(2) Two types of complex microbial deodorizer were developed. Deodorizer I was developed when the mixture of the wheat bran and EM bacteria solution were fermented for about one week. The selected strains were inoculated into certain liquid medium and cultivated for several days to develop Deodorizer II.(3) The ammonia removal efficiency of Deodorizer I was affected by the dosing method. When Deodorizer I was covered on the surface of the sludge, the ammonia removal efficiency was higher in the earlier period than that at the later stage. The maximum removal rate could reach up to 57.8% at the first day, and 44.4% at the second day,40.8% at the third day. When mixed around with the sludge, the removal rate increased gradually with the time going, which was 22.7% in 24 hours, 54.4% in 48 hours and 54.7% in 72 hours. In addition, the ammonia removal rate decreased with the adding dosage reduced. When the dosing proportion was 10%, the highest removal rate was achieved, which was up to 40%-60% in 72 hours.(4) When the concentration of the culture medium was 100%o, and the dosing proportion was 5%o, Deodorizer II had the maximum removal rate, which was 30%-40% in 48 hours. As the time went by, the ammonia removal rate of Deodorizer II decreased at the beginning and then increased gradually.(5) Deodorizer II was more favorable to remove the ammonia than the EM (Efficient Microorganism). Its removal rate was 10 percent points higher than that of the EM in 24hours. The quantity of ammonia released from the sludge decreased by 30%-45%, and 25%-35% from the waste solid in 48 hours, with 20 percent points higher than that of the EM. The ammonia released decreased by 37.5% in the pilot test, while the odor decreased by 19.1%.(6) The microbial deodorizer removed the ammonia by chemical absorption and microbial degradation. The dominant bacteria of Deodorize II were Alcaligenes sp., Bacillus sp. and Caryophanon sp., all of which were the selected strains. Lactobacillus sp. was the dominant bacteria of both Deodorizer I and EM. These strains produced acid during the fermentation. The acid medium was helpful for the ammonia absorption, and inhibited the metabolic activity of the bacteria producing odor. Therefore, the odor was effectively reduced. Heterotrophic bacteria of the Deodorizer I was more than that of the EM, and had better odor removal effect.(7) The results of the toxicity test demonstrated that Deodorizer I and Deodorize II showed no obvious toxic effect or potential of skin sensitization to the animals tested. Therefore, they were safe for the application in the practice.

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CLC: > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Wastewater treatment and utilization
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