| Water eutrophication is a serious worldwide environmental problem. It has proved that using macrophytes to treat, adjust and control eutrophication was an effective bioremediation way. And compound microorganism technology is a new wastewater treatment technique which developed recent years too. In most of the studies microbes and plants were put into the system at the same time, however, the microbial colonization in the roots of aquatic plants has not been reported. Based on of the studies of the effects of traditional sewage treatment plants: ( Eichhornia crassipes), (Myriophyllum aquaticum Vell.), (Hydrocharis dubia (Bl.)Backer)and compound microorganism- EM (Effective Microorganisms) in purifying wastewater,we attempt to construct a plants-microbial coupling degradation system which adapts to the recirculating aquaculture. The major results and conclusions obtained are summarized as follows:1. The composition of the EM (effective microorganisms) were analysed, the result showed that the proportion of Lactobacillus acidophilus and yeast was 70-75%, besides, there were a small quantity of photosynthetic bacterium, acetic acid bacteria and actinomycetes. To enrich EM, we cultured EM for 6 days in airtight conical flask with continual illumination at 25℃using brown sugar medium (according to the ratio of 97 ml sterile water: 3 ml EM: 3 g brown sugar). The reaults showed that the microbes of EM were activated.2. The results showed that the purification efficiency of EM was better in aquaculture wastewater than in the campus pond water, indicating that EM was more suitable to purify wastewater which contented high level of nitrogen and phosphorus. Disposed the fish culture wastewater using different EM addition, results showed that: without aeration, NO3- - N, NO2- - N removal rate all reached more than 97% with 3‰, 5‰addition after 1d, there were no significant difference between the two groups. NH4+- N removal rate reached 71.1%, with 5‰addition, better than other inoculation volume including 1‰and 3‰. During the course of purifying pond eutrophic water in the campus, under aeration condition, the average removal rate of NO3- - N was 68.4% after 4d treatment with 1‰inoculation volume. However the removal effect of NO2- - N was relatively bad. NH4+- N removal efficiency had no significant difference with control group. The inoculation of EM which concentrated using brown sugar medium, would cause rising of CODMn in the water, so the CODMn removal effective was not obvious.3. Experimental results showed that Eichhornia crassipes Solms. and Myriophyllum aquaticum Vell. had good purifying effect on nitrogen and phosphorus as long as the water temperature at 15-35℃. The water temperature of experimental area in autumns 2008 remained above 15℃, and the weather kept sunny most time during the trial period, so it was appropriate for plant to grow. The TN removal rate reached 97% after 15 d, TP removal efficiency reached more than 99% after 12 d in the group which the initial N level of simulated wastewater was 14 mg/L. The TN and TP removal rates all reached over 95% after 9 d in the group which the initial N level was 7 mg/L. The experiment in summer 2009 showed that the high temperature and rainy weather in this season affected the growth of plant, and the purifying effect in summer was worse than in the autumn.4. The study results of colonization of EM in Eichhornia crassipes Solms. roots indicated that the population of lactobacillus acidophilus, yeast and photosynthetic bacterium in rhizosphere rised 102-103, 102-103and 101 respectively. In the rhizosphere of Ipomoea aqutica the population of lactobacillus acidophilus and yeast all increased by 102, but small changes appeared in photosynthetic bacteria population. However, after replanted the plant to the nutrient solution, the population of colonization bacteria could maintain dominance for 10d, and then got back normal level.5. Before the population of bacteria which colonization in the plant rhizosphere dropped to normal levels, utilized Eichhornia crassipes Solms. and Ipomoea aqutica to depose wastewater. The results showed that Ipomoea aqutica cultured in water is one effective species of aquatic vegetation in phytoremeidiation for eutrophic water, besise, Ipomoea aqutica have economic value; the colonization of EM in Eichhornia crassipes Solms. and Ipomoea aqutica rhizosphere could not enhance the ability of removing TN, TP, NO3--N, NH4+-N from the eutrophic water.
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