Studies On Algal Control Mechanism Of Air Circulation Technology

In recent years, eutrophication phenomenon in China's lakes, reservoirs and other water sources has been growing, leading to overproduction of algae and frequent "algae bloom" disasters, which has been a serious threat to drinking water safety. To control algae growth and ensure the social function of lakes and reservoirs as important water resources, algal controlling situ- technique with high efficiency and low consumption has been in increasing wide range of applications. Air circulation is an emerging situ algal control technology, which has become the mainstream of European and American countries in algal control. But studies in algal control mechanism of this technology still remain at the qualitative stage, the specific algal control mechanism is not yet clear, which has brought a serious constraint in the large-scale application in China's lakes and reservoirs.In this study, air circulation conditions was simulated in laboratory, light and mixing intensity was set as variable factors to study algal spatial and temporary distribution in the water column, and study quantitative relationship between algal spatial and mixing intensity, between algal temporary distribution and light intensity. The preliminary model of algal spatial and temporary distribution was established in air circulation conditions. Outdoor field experiment in enclosures was explored to check algal control efficiency in air circulation conditions and provide a theoretical and data reference to practical application.The laboratory experimental results show that the increasing of illumination and mixing intensity are conducive to inhibit algae floating, and the two factors can enhance the efficiency. When the light intensity of illumination reached 40000lx or mixing intensity up to 1.35 cm / min, algal spatial distribution in the water column showed uniform state. Fitting the experimental results showed that changing rates of algal cell concentration at a point in the water column had negative linear correlation of mixing intensity and light illumination.Laboratory experimental results show that the reducing of incident light illumination and increasing Emix: Eu are conducive to inhibit algal growth. When the Emix: Eu reached 9:1, continuely increasing Emix: Eu on the promotion of algae control is very limited. Fitting the experimental results showed that algal growing rates has linear correlation with the incident light illumination, but exponentially related with Emix: Eu.Results of outdoor field experiment in enclosures further verify the laboratory findings that the increasing of Emix: Eu is conducive to inhibit algae growth. Under natural conditions, Emix: Eu at least 3:1 can really control algae growth.One-dimensional linear/ no-linear regression and Grey Reational Analysis were used to establish primary model of algae concentration changing rate in air circulation conditions.