| The rapid development of intensive farming, flood irrigation and rain erosion forming a large number of agricultural return flow contained the rich nitrogen, phosphorus and other nutrients, which enter groundwater and rivers, lakes and other water bodies through the surface run off and underground penetration leaching, promote the water bodies eutrophication process and restrict the sustainable development of agriculture.Nitrogen is an essential nutrient for plant growth. Agricultural nonpoint source pollution due to nitrogen loss is caused by one of the current needed to solve environmental problems. Based on previous studies, this paper constructed the "plant-Matrix-microorganism" of simulated wetland system to purifying NO3--N of agricultural eutrophic wastewater, systematic study on the use of Canna generalis constructed wetland system for the effect of treating agricultural eutrophic wastewater, associated microbial community, the purification mechanism of NO3--N of agricultural eutrophic wastewater and to optimize nitrogen removal through Canna generalis by mathematical model, and based on the parameters of purifying agricultural eutrophic wastewater by simulation model and previous research, construction demonstration project of agricultural eutrophic wastewater testing the effects of constructed wetland model which is purification agricultural eutrophic wastewater to provide a theoretical basis and technical support for the management of the same type of contaminated water.(1) Analysis of the purified Canna generalis agricultural eutrophic wastewater capacity utilization and metabolism of nitrate absorption characteristics. The results shown that treatment Canna generalis agricultural eutrophic wastewater 7d, nitrate removal rate of 61.70%, fresh weight increase of 15.37%; roots, stems, leaves NO3--N were higher than the control treated with distilled water, indicating Canna generalis rapid absorption and utilization of nitrate in agricultural eutrophic wastewater.13C-NMR analysis show that the ability of roots and stems of Canna generalis to assimilate the NO3- to N-transported amino acids was strong, but the contents of N-transported amino acids in the tissues of blades are greatly reduced. A significant increase glyceraldehyde 3-phosphate acid, sucrose, glucose and fructose content of roots, stems and leaves of Canna generalis in agricultural eutrophic wastewater. Description Canna generalis capable of absorbing purification nitrate in agricultural eutrophic wastewater and exploited to promote physiological metabolism and growth.(2) Technical analysis of the use of PCR- DGGE planting Canna generalis vertical flow constructed wetland table series flow constructed wetland treatment differences and advantages of bacterial community structure matrix wetlands and water samples Microbial retreat after eutrophication farmland. The results suggested that there are not only microorganisms but also various bacterial taxonomies found in the IVCW-Surface Flow Artificial Wetland matrices. The quantity and proportion of different microorganisms differ among different lanes. In the analysis of PCR-DGGE on structural diversity and community of bacterial, the number of gravels and OTU of water sample is lager than it of haydites and zeolites, in the comparison of wetlands with Canna and the ones without. Choosing three clones from every OTU and sequencing them, the result turns out to be 69 series. Through sequence alignment,57 series out of 69 series are uncultured bacteria. Only 12 of them are Escherichia coli, Pseudomonas sp, Acidovorax sp, and Pantoea sp. In the analysis of PCR-DGGE on structural diversity and community of fungi, the OTU number of gravels and haydites is larger than that of zeolites and water samples. Choosing three colones from every OTU and sequencing them, the result turns out to be 39 series. Among them, there are 12 kinds of yeasts,27 kinds of moulds.(3) Using the roots of canna, analyze the molecular mechanism of canna purifying NO3--N of wastewater. The result proves that the nunber of original series of agricultural wastewater pretreated canna roots is 27152829, while the number of untreated ones is 34073843. There are 65535 Unigenes in total are annotated in to 7 databases separately. The most successfully annotated databases are GO database and NR database. Their propotions are 61.42%(40250) and 58.60%(38401) separately. There are 326 differential genes selected from MF and MZ samples and 220 of them are up-regulated expression while 106 of them are down-regulated expression. In order to get a more complete gene expression, differential expressed genes are separated into different functional clusters through the method of GOseq. Among MF and MZ samples whose q is below 0.5 and log2 (fold change)>1,251 differential expressed genes are separated into three main classes namely biological process, cellular component, and molecular function. Among MF and MZ, differential expressed genes are separated into 63 KEGG pathways. In these pathways, the most representative ones include 52 metabolic pathways of gene (ko01100) and 23 synthesis of secondary metabolites of genes(ko01100).The result of PCR shows that after four days of agricultural-wastewater pretreatment,the ATP2B4, TA14-3-3, PR-1, GS1.a and Ca2+-ATPase of canna roots are all up-regulated expression while NR and Gh 14-3-3 are down-regulated expression. Results quantitative PCR amplification verify the correct reliability transcriptome sequencing.(4) In order to study constructed wetland system to effectively purify farmland rapid withdrawal of water, the system is administered with the promotion of plant growth and the use of methanol as a carbon source of microorganisms, response surface method, by setting affects the concentration of methanol, nitrate concentration and treatment time experimental study of several key factors in the wetland nitrogen removal in order to explore Canna absorb NO3-N in the wetland system the optimal combination of conditions. The result shows that the optimizing design through response surface way is practicable. The optimizing conditions of canna absorbing Nitrate ions obtained from the response surface optimization and the analysis of Binomial regression equation are:pretreating the roots of canna with 2.75mM methanol for 6h,and pretreating the roots of canna with 38mg/L Nitrate ions for 4h. Under this condition, the amount of Nitrate ions that canna absorbs is 0.061 mg/(L-g)FW, which matches the predictive value 0.062 mg/(L-g)FW. These results indicate that the model’s simulation value is adoptable. We can also test the absorption without the pretreatment of methanol at the same time, and the absorbing value of Nitrate ions is 0.047 mg/(L-g)FW, which indicates that the methanol pretreatment obviously improved the canna’s absorption of Nitrate ions.(5) Analog purification mechanism of constructed wetland system parameters and greenhouse Canna based Qilu basins sixty-one combined area of high agricultural return water nitrate content, low organic matter, and other large water feature, pond dam in sixty-one horns at setting an artificial wetland treatment system withdrawal farmland water demonstration project. Tracking and monitoring through long-term field test, from water purification plant physiology changes characteristics systematically evaluated in terms of artificial wetland system aquatic Canna water purification farmland back nitrate effect. The results show that the demonstration project for TN, NO3--N, NH4+-N, COD, TP average removal rates were 55.94%,50%,40.07%,60.63% and 40%. In the process of strengthening precipitation pound, the decrease of COD is quite obvious, followed by TN and TP. While the multiple infiltration system has obvious removal effect on all kinds of pollution. Canna bottom diameter, tillers, plant height, crown rate of increase is 50.8%, 78.9%,85.7%,61.5%. The contents of nitrogen, total pnosphorus and organic matters increase with the canna’s growth, and the pollution load decreases by harvest. |
PDF Full Text Request