Studies On Purification Of Eutrophic Water By A Composite Bioremediation System

Water pollution is one of the major environment problems all over the word, and eutrophication has been a serious phenomenon. With prosperous economy and high density of population, eutrophication is becoming a more and more serious and important problem in the body of the Tai-Lake, which afferts the sunstainable development of society and economy. With the increasing attention to the ecological environment, people become to pay more attention to use ecological remediation methods to treat eutrophic water, which can remove endogenous nutrients from water significantly with low cost and high efficiency. We can gradually restore the ecological system by using ecological remediation methods. In this paper, we choose water spinach (Ipomoea aquatic), water cress (Oenanthe javanica), loach (Misgurus anguillicaudatus) and a kind of pseudomonad (Rhodopseudomonas palustris) as the engineering species. This composite bioremediation system combined aquatic economical plant-aquatic animal-microorganism has been constructed to improve water quality in artificial simulation eutrophic water in laboratory, an upstream river of Tai-Lake and a pond near Tai-Lake basin. The results have enriched the related knowledge of plant nutritional ecology, wetland restoration ecology, and have provided a necessary foundation of knowledge and theoretical guidance for the development and utilization of plant, animal and microbial resources in the restoration of eutrophic water bodies. Research and the main results are as follows:1、We use the method of artificial simulation in laboratory to study the purification of this composite bioremediation system. The water quality indexes were tested and the biomasses of loaches and water spinaches were weighed. The results showed that nutrient concentration decreased significantly in this combined restoration system. The removal rates of NH4+-N, N03+-N, TP and CODMn were96.5%,82.2%,53.2%and24.5%, respectively, during the23d experimental period. Meanwhile, rates of the water spinach and loaches growth were31.2%and6.1%, respectively. Good economic benefits and environmental benefits could be advanced by this composite bioremediation system model.2、We select Bafang estuary in Yixing for the trial sites, and design the placement of the artificial floating island ecosystem of four groups with12cages, in order to configure the complex biological species in the the natural river water and study this water pollution control technology. The test results show that, the ecological floating islands provide a relatively stable living environment for the species because of the lower coefficient variation of water indexes in the cages. The plant biomass basically turned over10times, and the biodiversity in the ecological floating islands is not only the several model organisms we firet put, but also a considerable number of quantities of the local eel, fish, shrimp, frogs, aquatic insects and so on.3、We select this trial site at a pond near Tai-Lake basin to have eco-culture in net-enclosures, and we design four aquatoriums of200square meters to configure the complex biological species in the the natural river water and study this water pollution control technology. The test results show that, this composite bioremediation system has a certain effect on reducing water nutrients. The average biomass of water spinach has doubled from October to November. We can achieve good additional economic benefits by harvesting of aquatic economic plant timely. The loach biomass growth is not significant, with egrets feeding, salvage missing, escaping and other reasons.