|其他题名: ||Studies on the Characteristics and Purification Capacity of Substrate Biofilms in Constructed Wetland|
1. 自然水体生物膜厚度随着培养天数增加而增大。在一定的生长时间后，0.3 m水深处生物膜样品重量大于1.5 m水深处样品。复合垂直流人工湿地基质生物膜上仅仅观察到一些藻类，主要是硅藻，无浮游动物出现。
2. 上、下行流池中各层基质生物膜脱氢酶活性和多糖含量分别与挥发性膜重显著相关 ( P<0.001)。对同一个池子来说，不同深度处生物膜脱氢酶活性、多糖含量以及挥发性生物膜重显著不同。对上层基质生物膜来说，下行流池中生物膜脱氢酶活性、多糖含量以及挥发性生物膜重显著高于上行流池。夏季生物膜脱氢酶活性比秋季高，多糖含量也比秋季增加，而挥发性膜重在夏、秋季相当。
生物膜酶活性和多糖含量分别与不同形态N浓度之间呈一定的二次曲线关系。72 h内，N源对生物膜脱氢酶活性表现为抑制作用。以硝酸钾、亚硝酸钠和碳酸氢铵为N源时，多糖含量随N浓度的增加而增加。污水中的P浓度＞3.2 mg/L时，生物膜脱氢酶活性升高，多糖含量增加。
不同营养元素的正交实验表明，葡萄糖是影响脱氢酶活性的主要因素，硝酸钾是影响多糖含量的主要因素。获得最大生物膜酶活性的营养元素优化组合为：C6H12O6，0.2 g/L；KNO3，0.8 g/L；NaH2PO4，0.05 g/L。获得最大多糖含量的营养元素优化组合为：C6H12O6，0.2 g/L； KNO3，0.4 g/L；NaH2PO4，0.2 g/L，与之对应的脱氢酶活性和多糖含量分别为5.40 µgTF/g/12h和3454.6 µg/g。
培养时间≤72 h时，温度为37 °C时的生物膜酶活性最高；培养时间＞72 h后，在25 °C条件下培养的生物膜脱氢酶活性最高。
72 h内，添加2 mg/L的Zn2+有利于生物膜酶活性的提高和多糖的积累。Co2+和 Mn2+对脱氢酶活性表现为抑制作用，并且随着浓度的增加和时间的延长，抑制作用越来越明显。Co2+和 Mn2+对多糖含量没有明显影响。
无论是单一作用还是复合作用，6 h和24 h时生物膜脱氢酶活性均随着Cd2+和Pb2+浓度的增加显著下降。Cd2+和Pb2+对脱氢酶活性的抑制作用有协同效应。不同浓度和时间条件下的多糖含量没有显著统计学意义上的差别。
4. 生物膜对NO3--N一直表现为一定的净化能力。生物膜去除N的最佳时间为48 h。15 °C条件下生物膜对N仍然有15%左右的去除率，温度升高使生物膜净化N的能力变弱。pH为8.5的碱性条件有利于生物膜对N的去除。添加腐殖酸对于提高生物膜净化N的能力是有利的。较高浓度的C6H12O6能够提高N的去除率，然而较高浓度的KNO3使N去除率下降。生物膜对N的去除率与生物膜脱氢酶活性存在一定的负相关关系 (R2 =0.415)。
尽管生物膜对磷的去除率为负值，但时间、温度和腐殖酸对生物膜净化N、P能力的影响是相似的。pH为5.5的酸性条件有利于生物膜对P的去除。与C6H12O6对N的去除的影响相反，高浓度的C6H12O6不利于生物膜对P的去除，并且高浓度的C6H12O6和KNO3组合条件下，生物膜对P的去除率降为负值。生物膜对P的去除率与生物膜多糖含量之间呈三次曲线关系 (R2 =0.518)。
5. 实验所设6个不同处理中，处理1 (以尿素和乙酸钠分别为氮源和碳源)、处理4 (以碳酸氢铵为氮源和碳源) 以及处理5 (以硫酸铵和碳酸氢钠分别为氮源和碳源) 中pH值的变化趋势较为相似，即pH先下降然后再上升。但是，3个处理中pH值下降和上升的幅度不同。与此同时，处理2 (以亚硝酸钠和乙酸钠分别为氮源和碳源)、处理3 (以硝酸钾和乙酸钠分别为氮源和碳源) 以及处理6 (以磷酸二氢钾和碳酸氢钠分别为磷源和碳源) 中pH值的变化趋势也非常相似，即添加碳源前，pH值基本在7.3~7.4之间缓慢变化，而添加碳源后均上升至9.0左右。|
|英文摘要: ||Biofilms play an important role in wastewater treatment by constructed wetlands. The structure, time and spatial distributions, dehydrogenase activity and polysaccharide, N and P purification capacity of substrate biofilms in the integrated vertical-flow constructed wetland (IVCW) as well as pH changes of suspended solution of substrate biofilms in the case of different nutrients were studied. The main results were summarized as follows:
1. The thickness of biofilms increased with the culture time in the lakes investigated. The dry weight of biofilms in the depth of 0.3 m was higher than that in the depth of 1.5 m. Only some algae, especially diatom species, were observed in the substrate biofilms of the IVCW system, but no zooplankton were observed.
2. The dehydrogenase activity and polysaccharide content of substrate biofilms were significantly correlated with the volatile weight of substrate biofilms in the up-flow and down-flow chambers, respectively (P<0.001). For the same chamber, the dehydrogenase activity, polysaccharide content and volatile weight of biofilms were significantly different among different depths. For the surface layer, the values of all the parameters measured in the down-flow chamber were significantly higher than that in the up-flow chamber. The activity and polysaccharide content of biofilms in summer were respectively higher than the activity and polysaccharide content in autumn, and the volatile weight of biofilms in summer was almost the same as that in autumn.
3. The dehydrogenase activity of biofilms increased with the extended sampling time, and the activity data at different concentrations of carbon sources were fit with a quadratic curve.
The dehydrogenase activities of biofilms showed a quadratic curve relationship to the concentration of nitrogen source. The nitrogen sources inhibited the activity of biofilms within 72 hours. When KNO3, NaNO2 or NH4HCO3 was add in the artificial wastewater, the polysaccharide content of biofilms increased with the increasing concentration of nitrogen source. When the concentration of P was in excess of 3.2 mg/L, the dehydrogenase activity of biofilms was improved and the polysaccharide was accumulated advantageously.
Results of the orthogonal array showed that C6H12O6 and KNO3 were the main factors for the dehydrogenase activity and polysaccharide content of biofilms, respectively. The optimal combination for dehydrogenase activity was obtained by locating the concentrations of C6H12O6, KNO3 and NaH2PO4 at 0.2, 0.8 and 0.05 g/L, and the optimal combination for polysaccharide content was obtained by locating the concentrations of C6H12O6, KNO3 and NaH2PO4 at 0.2, 0.4 and 0.2 g/L. The corresponding maximum activity and polysaccharide content were 5.40 µg TF/g /12h and 3454.6 µg/g, respectively.
Of the dehydrogenase activities of biofilms at 15 °C, 25 °C and 37 °C, the activity at 37 °C was the highest before 72 h, and the activity at 25 °C was the highest after 72 h.
The dehydrogenase activity of biofilms was the highest when the solution was neutral (pH=7). At the same time, the more the acidity or basicity of the solution increased, the more the activity of biofilms declined.
The dehydrogenase activity of biofilms which were cultured in the dark was higher than the activity of biofilms which were cultured with light before 48 h, subsequently the light condition took advantage over the dark condition.
Within 72 hours, PCP was disadvantageous to the dehydrogenase activity and polysaccharide of biofims. Moreover, both vitamin C and humic acid could stimulate the dehydrogenase activity and polysaccharide of biofilms inhibited by PCP.
2 mg/L Zn2+ additons benefited the dehydrogenase activity and polysaccharide of biofilms within 72 hours. Co2+ and Mn2+ inhibited the dehydrogenase activity of biofilms, and the inhibitory effects became increasingly obvious with the increasing concentrations of these two metal ions and extended experimental time. Besides, Co2+ and Mn2+ presented no obvious effects on the polysaccharide content of biofilms.
Dehydrogenase activities decreased significantly with the increasing concentrations of Cd2+ and Pb2+ at 6 h and 24 h in the case of single and combined treatments. A synergistic effect of Cd2+ and Pb2+ was observed. For polysaccharide content of biofilms, there were no significant statistical differences within the range of concentration and time studied, whether singly or in combination.
4. NO3--N could be always removed by the substrate biofilms in the IVCW system in this study. The optimal time for N removal was 48 hours. N removal rate was about 15% at 15 °C, and the rate decreased with the increasing temperature. The alkaline condition (pH=8.5) benefited N removal. Exogenous humid acid additions benefited N removal. C6H12O6 at higher concentrations improved N removal rate, whereas KNO3 at higher concentrations deteriorated the rate. It indicated a weak linear relationship between NO3--N removal rate and the dehydrogenase activity of substrate biofilms (R2 =0.415).
Although the negative removal rate of P occurred in this study, the effects of time, temperature and humic acid on P removal rate were similar to that of time, temperature and humic acid on N removal rate. The acidic condition (pH=5.5) benefited P removal. In opposition to the effect of C6H12O6 on N removal rate, C6H12O6 at higher concentrations was disadvantageous to P removal, and the combinations of C6H12O6 and KNO3 at higher concentrations caused the negative removal rate. The polysaccharide contents of substrate biofilms were cubicly correlated with the P removal rates (R2 =0.518).
5. Of the six treatments studied, pH changes in treatment 1 (CO(NH2)2 and CH3COONa were nitrogen and carbon sources, respectively), treatment 4 (NH4HCO3 was nitrogen source as well as carbon source) and treatment 5 ((NH4)2SO4 and NaHCO3 were nitrogen and carbon sources, respectively) were similar, namely pH decreased first, then increased. However, the ranges of their respective changes in these three treatments were different. On the other hand, pH changes in treatment 2 (NaNO2 and CH3COONa were nitrogen and carbon sources, respectively), treatment 3 (KNO3 and CH3COONa were nitrogen and carbon sources, respectively) and treatment 6 (KH2PO4 and NaHCO3 were nitrogen and carbon sources, respectively) were also similar, namely pH values ranged from 7.3 to 7.4 before carbon source was added, and increased to about 9.0 after carbon source was added.|
|Appears in Collections:||中科院水生所知识产出（2009年前）_学位论文|
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