A Comparative Study And New Methods On Control Algae In Eutrophic Lakes

Eutrophication of lakes became a main environmental problem in China, not only they restricted utilization of lake resource, but also they impacted directly human health and survival and sustainable development of social economy. The practice of controlling lake eutrophication has come along and difficult way from controlling nutrient, direct killing algae to biomanipulation and ecological restoration. Although many countries have put a huge amount of money into it, little effect has been produced yet. At present, no perfect theories or nature methods for treatment of the eutrophication of lakes have been summarized in the country and lots of respects in control of internal-sourced pollution and in the principle of bioremediation are yet to be further studied.The theme of this paper is control technology on algae in eutrophic lakes. Firstly,the paper summarizes control theory and technology of lake eutrophication. The traits and feasibilities are discussed and relevant direction is brought forward. Secondly, in view of ecology, this paper analyzed the function of every technique in the technical system. At the same time, two new technologies on removal algae are studied by chemistry and biology methods. Furthermore, the article points out that the control of eutrophication is a complex systemic engineering, in which, implement must be carried out stage by stage, based on controlling the source of pollution and emphasizing on carrying on the ecological restoration and perfecting the management counter measure.This study also includes two experiments on the improvement measures of algae removal. Following are the main results:(1) Polymeric Phosphorus Ferric Sulfate (PPFS) had high removal rates of turbidity and chlorophyll-a,which reached 86.6% and 89.2%, respectively. The optimum range of pH , temperature were 2~9 and 20~25℃, respectively. Furthermore, PPFS had a significant flocculation on Microcytis. (2) The results showed Hyriopsis cumingii Lea had high removal rates of chorophyll-a. At the same time, H. cumingii had great effect on the phytoplankton community. In eutrophic waters, in condition of enough mussel biomass, H. cumingii could effectively control the overgrowth of phytoplankton by suitable biomanipulation. At the same time, the dominant algae changed from Microcytis to Selenastrum. The algae species composition and phytoplankton diversity had been changed inside the enclosure with mussel, improving the structure and function of lake ecosystem.