Dissertation > Excellent graduate degree dissertation topics show

Study on Analytical Method and Fate of Volatile Organic Sulfur Compounds in the Subsurface Flow Constructed Wetlands

Author: GanLi
Tutor: HuangYuMing
School: Southwestern University
Course: Analytical Chemistry
Keywords: Wastewater treatment Constructed wetland Dimethyl sulfide Dimethyl disulfide Volatile alkyl sulfides
CLC: X132
Type: Master's thesis
Year: 2007
Downloads: 141
Quote: 0
Read: Download Dissertation

Abstract

Volatile organic sulfide, dimethyl sulfide (DMS), dimethyl disulfide (DMDS) and methyl mercaptan (MT) to global warming, acid rain deposition and global sulfur cycle process has an important impact. There is a balance between the production and degradation of these compounds at very low concentrations in freshwater ecosystems. Freshwater ecosystems volatile organic sulfides (VOSCs) is generated by the methylation of sulfide, followed by degradation of sulfur-chain amino acids. Artificial wetland for conventional organic pollutants (such as chemical oxygen demand (COD) and biochemical oxygen demand (BOD)) removal, and study the constructed wetland wastewater treatment organic degradation intermediates (such as volatile alkyl sulfides) is still a lack of in-depth study the behavior of these compounds in the constructed wetland wastewater treatment system is of great significance to elucidate the degradation of organic matter in the constructed wetland. To solve the above problem, the research to create a new pilot-scale constructed wetland water treatment test site (an area of ??approximately 150m ^{2 ), the main research the following: (1) organic sulfur compounds and other organic matter degradation characterization and analytical methods of the intermediate product; (2) through long-term monitoring of the hydraulic load and under different process parameters the constructed wetland import and export of organic sulfur compounds in the water concentration, the monitoring data for statistical processing and analysis; assess wetland system of organic sulfides the treatment effect analysis of the influencing factors affect the removal of organic sulfur compounds in constructed wetlands; (3) by measuring the electron acceptor of import and export water, dissolved oxygen and redox potential with the water level changes of constructed wetlands in the generation and degradation mechanism of organic sulfur . Through years of research, the following main results: 1, headspace solid phase micro-extraction (HS-SPME) and gas chromatography / mass spectrometry (GC / MS) coupled with determination of constructed wetland wastewater trace volatile alkyl yl sulphide. Wastewater is in two main volatile alkyl sulfide (DMS, DMDS), a detailed study of the types of extracted fiber head, the extraction time, extraction temperature, pH value, ionic strength, sample volume and analysis conditions for the HS-SPME affected. Under optimum conditions applied to the determination of the linear range of DMS and DMDS were of 10-10000 ng L ^{-1 the of 1-10000 ng L ^{-1 ; detection limit (3 sigma) were 1.87 and 1.76 ng L ^{-1 ; relative standard deviation of less than 10%; recoveries were 81.03% -94.64% 84.01% -100.09%. With diethyl sulfur as the internal standard substance, the method has been applied to the determination of DMS and DMDS constructed wetland wastewater with satisfactory results. 2, through the analysis of the hydraulic loading, the bed, the packing size, the water level and seasonal factors, the hydraulic loading and seasonal impact research pollutant removal are two major factors. Seasonal concentration of export water DMS and DMDS the significant impact (p <0.05); hydraulic loading export water DMS concentrations have significant impact (p <0.05); bed, filler size and the water level on the export of water DMS and DMDS the concentration does not have a significant effect (p> 0.05); Therefore, the hydraulic loading and season play to remove the wetland system are two important factors. Wastewater sulfate, acetic acid and dissolved organic carbon level have a major impact on the attribution of artificial wetlands DMS, DMDS; export water DMS concentration of sulfate, acetic acid and dissolved organic carbon removal in constructed wetlands increases . 4, through the electron acceptor and oxidation. Reduction potential analysis, we found the wetland system has a strong reducing environment (Eh <-300), combined with the trend of the sulfate concentration in the wetland system, suggesting that the removal of organic pollutants by sulfate-reducing and production methanation role. DMS the generation and degradation in constructed wetlands is a cyclic process. On the one hand, under anaerobic conditions, the degradation of sulfur-containing amino acid, and methyl sulfide DMS, on the other hand, the same are under anaerobic conditions, methane production, sulfate reduction process will lead to the DMS tired oxidative degradation. One year of operation and monitoring and analysis results show that the wetland system research volatile alkyl sulfides has good removal of the degradation rate of the wetland system for the study of volatile alkyl sulfides greater than its generate speed. The study was supported by the National Natural Science Foundation project \}}}}

Related Dissertations

CLC: > Environmental science, safety science > The basic theory for the Environment and Science > Environmental Chemistry > Environmental Analytical Chemistry
© 2012 www.DissertationTopic.Net Mobile