| Currently, most rivers and lakes in China are in moderate or serious suffered fom eutrophication. Frequently-used water remediation technology like physical and chemical methods requires high capital cost and may causes many subsequent problems. Traditional activated sludge process is not suit for mechanism of ground water pollution control. Eutrophic phenomena of ground water involves a wide rang of watersheds and its mechanism is sophisticated. Till now, no effective strategies have been found to solve the problem. Nowadays, with conception of sustainable development, the idea of environment protection is changing. People begin to realize the importance of ecological technology for water remediation due to excellent performance, minimal capital cost and ecological benefit. However, the majority study concentrated on remediation in wamer condiations and the research in winter is scare. As a result, the present study was mainly concentrated on selecting perennial grasses species that could not only adapt low temperature environment but also with high nutrients removal efficiency, studying their biomass production and nitrogen, phosphorus reduction during the growth period, investigating the relationship between plant biomass production and nutrients removal efficiency, aiming at determine plant characters that associated with its purification capacity; screening high nitrogen and phosphorus removal microorganisms, studying the effect of perennial grasses and microorganisms intergraded system on nutrients removal as well as the relationship between some enzyme and N, P removal; researching the changes in microbes diversity of eutrophic water treated with perennial grasses,and the results showed:1. Field study on the response of 8 species of perennial grasses in eutrophic water revealed that these perennial grasses could all adapt the aquatic environment. Among all the perennial grasses, Lolium perenne Topone (LPT) could uptake 17.5g nitrogen and 7.5g phosphorus from eutrophic water per square meter during its growth period when proper management practices were conducted. When perennial grasses were harvested, the utilization of them as animal feeds was feasible and crude protein, crude fat, crude fiber and nitrites contents in plant tissues meet the national standard. The most flourishing perennial grasses were selected to investigate their purification efficiency on eutrophic water and the correlation between plant uptake and nutrients removal in laboratory scale. The results showed that they can remove total nitrogen, total phosphorus, ammonium nitrogen, nitrate nitrogen and chemical oxygen demand from water significantly. Among these perennial grasses, LPT also showed the most remarkable removal efficiency.of total nitrogen, total phosphorus, and chemical oxygen demand, which were 64.1%, 92.1%, 70.7% and 80.7%, respectively. The correlation between total nitrogen removal efficiency and aboveground biomass accumulation were extremely significant for LCC and LPR, whereas not significant for LPT.2. After determining the phosphorus removal capacity and identification of these two strains of microorganisms (Bacillus sp., Microbacterium sp.) by 16S rDNA, these microbes could remove phosphorus up to 92.8%, 92.9%, and belonged to bacillus and mycobacterium, respectively.3 Four species of perennial grasses, including Geophila herbacea 0 Kumtze(GHK), Lolium perenn CV.Caddieshack (LCC), Lolium perenne Topone(LPT), Lolium perenne respect(LPR) and two strains of denitrifying polyphosphate -accumulating organisms (DPAOs), including (Bacillus sp., Microbacterium sp.) were adopted to remediate eutrophic water. The results revealed that these perennial grasses had performed extremely well in removing the nutrients and pollutants and were capable of removing up to 62% of TN and 66% of TP during 30-day treatment period the removal efficiency enhanced. when combined with immobilized denitrifying polyphosphate-accumulating organisms (DPAOs), Among the 4 species of perennial grasses, LPT had a much more prominent efficiency in the removal of total nitrogen, as well as phosphorus and CODMn than others. The immobilized- DPAOs acted well in the removal of phosphorus. When combined with perennial grasses, the removal efficiency enhanced and the removals of TN, NH4+-N, and NO2--N were most remarkable with LPT combined with immobilized- DPAOs treatment. The activities of urease, invertase as well as alkaline phosphatases changed correspondingly. Besides, the correlation between these enzyme activities and wastewater purification efficiency was analyzed and significant relationship between TN removal efficiencies and urease activities was found, especially when combined with microorganisms. For TP removal efficiencies and alkaline phosphatases activities, the correlation coefficient increased when the immobilized-PAMs were combined with these perennial grasses.4. The removal efficiency of pollutants were enhanced when treated with perennial grasses, although they were not as significantly as Pistia stratiotes L and Eichhornia crassipe, when microorganism inhibitor were added, total nitrogen, ammonia nitrogen, nitrate nitrogen concentration increased, whereas total phosphorus, chemical oxygen demand and nitrite nitrogen concentration increased but not as obvious as the indicators mentioned above. It is obvious that microorganisms played different role in nutrients removal and nitrogen removal was accomplished mainly by microbes and phosphorus relies on microbes and other factors. The analysis of the quantity of fungi, bacteria, actinomycetes revealed that the microorganism inhibitor had a more significant effects on bacteria and actinomycetes, indicating the important role of them in pollutants removal. Besides, the excitation of microbes varied among plant species. The overall research demonstrated that quantity and diversity of microorganism changes with plant treatment was an important factor for pollutants removal. |
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