绿狐尾藻人工湿地对养殖废水除磷效应的研究

发布时间：2018-09-18 11:15

【摘要】：畜禽养殖废水的排放造成了江河、湖泊等地表水体的严重富营养化。人工湿地作为一项成本低、易操作、处理效果良好的生物处理技术,被广泛用于废水处理中。本研究通过绿狐尾藻(Myriophyllum aquaticum)表面流人工湿地对养殖废水的处理效果,对比分析不同污染负荷下的绿狐尾藻人工湿地对磷的去除效率,研究湿地除磷效率随时间的变化规律,分析湿地植物收割对除磷的影响,探明绿狐尾藻在人工湿地除磷过程中所起的重要作用;通过分析湿地底泥中磷的形态分布特征,讨论底泥特征与无机形态磷的影响关系,以期揭示底泥中磷的迁移转化机理,为有效提高表面流人工湿地的除磷能力、发展高效处理养殖废水的生态治污技术提供科学支撑。主要结果如下:(1)低、中、高负荷处理总磷(TP)去除率分别为89.4±14.6%,80.9±19.9%,70.1±23.3%,平均磷去除率为70.1%~89.4%;一级去除率常数分别为22.3±10.4,17.7±11.8,12.1±10.2 m/yr;湿地运行初期TP去除率接近100%,随后逐渐降低;春、秋季TP去除速率高于夏、冬季;除高负荷一级湿地外,年收割绿狐尾藻植物磷为15.1~40.9 g/m2·yr,收割绿狐尾藻所除磷质量占湿地总除磷质量的22.5%~59.6%,所有处理三级湿地中植物除磷占磷总去除量60.7%~100%,表明绿狐尾藻人工湿地能够高效去除养殖废水中的磷,绿狐尾藻在除磷过程中起重要作用,其除磷效率随季节而变化。(2)相关性分析结果显示低负荷处理进水和出水TP浓度显著正相关(p=0.005),而中负荷(p=0.081)和高负荷(p=0.101)处理进、出水TP浓度不相关,表明不同负荷处理除磷机理不同。底泥中TP浓度随着时间逐渐增加而与进水负荷无关,显示出底泥对磷的吸附以及磷沉降是绿狐尾藻人工湿地的主要除磷机制。一级湿地废水中TP主要通过底泥吸附和在底泥中沉降而被去除,三级湿地TP主要通过植物吸收利用被去除。(3)绿狐尾藻人工湿地表层底泥TP含量变化范围为167~865 mg/kg,其中有机磷占TP的66.0%~79.3%。各无机形态磷的含量高低顺序为:O-PFe-PCa-PAl-P可溶性磷。各形态无机磷随着底泥深度的增加变化不同,从表层到底层底泥,Al-P、Fe-P和Ca-P含量总体呈现降低趋势,O-P含量在低负荷的湿地中逐渐降低;而在中、高负荷的湿地中逐渐增加。相关分析结果显示Al-P、Fe-P、O-P的含量与底泥pH和溶解性有机碳呈显著正相关(p0.01),表明这三种形态磷在绿狐尾藻人工湿地易受底泥pH和溶解性有机碳含量的影响。
[Abstract]:The discharge of livestock and poultry breeding wastewater has caused serious eutrophication of rivers, lakes and other surface waters. As a low-cost, easy-to-operate and effective biological treatment technology, constructed wetlands have been widely used in wastewater treatment. The removal efficiency of phosphorus in constructed wetlands with different pollution loads was compared and analyzed. The variation of phosphorus removal efficiency with time was studied. The effect of plant harvesting on phosphorus removal in constructed wetlands was analyzed. The main results are as follows: (1) Total phosphorus (TP) removal rates of low, medium and high load treatment are 89, respectively. The average phosphorus removal rate was 70.1%~89.4%; the first-order removal rate constants were 22.3 [10.4], 17.7 [11.8], 12.1 [10.2 m/yr] respectively; the removal rate of TP was close to 100% at the beginning of wetland operation, and then gradually decreased; the removal rate of TP in spring and autumn was higher than that in summer and winter; besides the high-load first-order wetland, the annual phosphorus removal rate of green foxtail algae was 15.1%. 1~40.9 g/m2.yr, 22.5%~59.6% of the total phosphorus removal in wetland was achieved by harvesting green foxtail algae, and 60.7%~100% of the total phosphorus removal was achieved by plants in all three-stage wetland treatments. The results showed that green foxtail algae could efficiently remove phosphorus from aquaculture wastewater, and green foxtail algae played an important role in the phosphorus removal process. (2) Correlation analysis showed that there was a significant positive correlation (p = 0.005) between TP concentration in low-load treatment and effluent, but no correlation between TP concentration in middle-load (p = 0.081) and high-load (p = 0.101) treatment, indicating that the mechanism of phosphorus removal was different under different load treatment. Phosphorus adsorption by mud and phosphorus deposition are the main phosphorus removal mechanisms in the constructed wetland. TP in the primary wetland wastewater is mainly removed by sediment adsorption and sedimentation in the sediment. TP in the tertiary wetland is mainly removed by plant absorption and utilization. (3) TP content in the surface sediment of the constructed wetland varies from 167 mg/kg to 865 mg/kg. Organic phosphorus accounted for 66.0% ~ 79.3% of TP. The contents of inorganic forms of phosphorus were in the following order: O-PFe-PCa-PAl-P soluble phosphorus. The results of correlation analysis showed that the contents of Al-P, Fe-P and O-P were positively correlated with the pH and dissolved organic carbon (p0.01), indicating that the three forms of phosphorus were susceptible to the effects of pH and dissolved organic carbon (DOC) in the sediment of green foxtail algae constructed wetland.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X713

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