Characteristics Of Biofilm By The Micro-Aeration Enhanced Ecological Floating Bed

With the rapid development of economy, the problem of environmental pollution is increasingly serious. Especially with the shortage of China’s freshwater resources, the problem of water pollution is particularly prominent. Because of some companies discharging sewage furtively, organic pollutants (CODcr), ammonia and other contaminants in rivers,lakes and other natural water bodies can not meet the standards. In recent years, Ecological Floating Bed Technology, one method of treating the polluted natural water bodies, has attracted more and more attention from experts and scholars. Although this method was introduced to China quite late, it developed rapidly. After several years’research, it has been widely used in the treatment of contaminative natural water bodies.Ecological floating bed technology is a method that using the powerful plant roots in the water to absorb, hold back nitrogen, phosphorus and other nutrients in water, and remove them from water by harvesting plants in order to purify the sewage. However, the traditional ecological floating beds treat sewage only with the absorption of plants and degradation of microorganisms on roots,and the processing system is too simple, resulting in low efficient and effective treatment. The microaeration strengthen ecological floating bed is put forward originally in this paper, and it is added aeration and suspensed packing on the basis of traditional ecological floating bed,which increases dissolved oxygen and surface area attached by microorganism in the water bodies. It not only can increase plants’removal efficiency of pollutants but also form biofilm on the surface of the filler which increases the purification effect of wastewater.This study builded a strengthen ecological floating bed which used purple iris as floating plants and suspensed fillers under them, increasing artificial microaeration; carried out research about characteristics of biofilm on the surface of fillers; compared the growth of biofilm and and microbial activity using different fillers in different aeration strength; analyzed the growth and changes of biofilm and the number of microorganism at different temperatures, and summarized the distribution of microorganism in different water depths, providing a theoretical basis and design support for the application of strengthened ecological floating bed technology. Via a series of experiments we reached the following conclusions:1、The growth rate and the number of microorganisms increase with the amount of aeration increasing,and they level off after the aeration intensity increasing to 7.5L/min, which is used during the operation of strengthen ecological floating bed. Microbial activity are also different under different aeration amount. Overall, microbial activity increases with the increasing amount of aeration.2、In the experiments,water samples were taken underwater 5cm,25cm,50cm respectively. The data shows that the distribution of microorganism numbers on the surface of fillers is:the number of microorganism at 5cm> the number of microorganism at 25cm> the number of microorganism at 50cm. While the microbial activities are similar, this illustrates that the impact of water depth on microbial activity is minimal.3、Under the same experimental conditions, comparison of microorganism numbers on different types of filler:the number of microorganism on combined filler> the number of microorganism on waterweed-shaped filler> the number of microorganism on elastic filler; activities of microorganisms on the surface of three different fillers are similar.4、The percentage of organic pollutants removed by biofilm is 47.17% in the microaeration strengthened ecological floating bed.