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Study on the Biofilm Growth Characteristics in Aquatic Environment and the Adsorption and Biodegradation of Microcystins by Biofilms

Author: MeiQiong
Tutor: LiuJianTong
School: Institute of Hydrobiology
Course: Environmental Science
Keywords: East Lake Biofilm Microcystin Adsorption Biodegradable
CLC: X52
Type: Master's thesis
Year: 2007
Downloads: 371
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Abstract

The cyanobacteria bloom microcystins pollution and its release harmful to the environment has become a global environmental concerns, water bodies microcystin toxin removal has become the focus of the study. The condition of the natural environment, biofilms exist in almost all of the solid surface exposed to water bodies, thus biofilm trend has some influence on the transfer of pollutants in water and Naturalization. This study used a self-designed simple biofilm sampling device in the eutrophication of shallow lakes - Wuhan East Lake 20 and 100 cm water depths natural culture and collect biofilm study their formation, development and activity characteristics, aimed at deepening the water body in biofilm understanding of the biochemical properties; Second, studied different water depths of the biofilm on the adsorption of microcystins and different water depths, the same training time as well as the same water depth, different culture time biofilm microcystin biodegradation, the purpose is to reveal the mechanism of biofilm waters microcapsules microcystin environmental behavior and biological means of control and governance microcystin contamination of the water bodies provide a theoretical basis and technical guidance. The main findings are as follows: (1) Biofilms growth by factors such as light, water temperature, pH, DO and nutrient, and the climate and hydrological conditions will also affect the growth and development of the biofilm. With the growth time of the extension, the Donghu Lake in Wuhan biofilm growth experienced latent adaptation period, a period of growth, shedding period and restore the four stages of the growing season the the biofilm extracellular polysaccharide, COD and dehydrogenase activity and biological film of biomass exist significant positive relationship biofilm grew faster than the water depth of 20 cm culture biofilm cultured in water depths of 100 cm, and biomass and biological activity higher than 100 cm water depth training film. (2) East Lake in water culture 15d biofilm adsorption MC-RR, adsorption equilibrium time is about 6-8h, maximum adsorption accounts for the initial MC-RR 6.94% of the total balance. With the increase in the equilibrium concentration of MC-RR, MC-RR in the biofilm on the adsorbed amount gradually increased, and, MC-RR in the biofilm on the adsorption behavior of Langmuir isotherm to describe the most appropriate (R gt; 0.99) . pH and ionic strength will affect the adsorption of MC-RR on the biofilm pH value decrease or increase of the ionic strength will promote the adsorption of MC-RR on the biofilm. (3) the Donghu Water biofilm cultured under aerobic conditions experienced on the degradation of the MC of the lag phase of the 2-3d, in the degradation process, the pH value of the solution was continued to rise. Biofilm cultured in water depths of 100 cm 20 cm water depths of culture biofilm faster than the rate of degradation of MC, MC degradation rate is accelerated with the increased the biofilm slides quantity of attached biofilm degradation of MC is closely related with the incubation time of the biofilm. In addition, the process of biofilm degradation of MC obey the equation y = A / [1 Bexp (-Ct)] degradation rate with the reaction temperature and the biofilm microbial biomass increase and speed up.

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