【作者】 魏明蓉；

【导师】 姜应和；

【作者基本信息】 武汉理工大学 ， 市政工程， 2012， 博士

【摘要】 我国水体污染情况总体来说比较严重,底泥与其上覆水体之间存在物质交换的动态平衡,研究底泥特征对水体治理具有重要的意义；水体治理中常采用底泥疏浚的办法,疏浚出的底泥如何处置是个难题。本研究在南湖设置了12个表层底泥采样点、5个柱状底泥采样点,通过样点中有机物、营养盐、重金属等指标的含量及分布来研究南湖底泥的污染特征；利用湖底底泥进行批式和半连续厌氧消化试验,研究底泥产能的可行性；同时利用底泥及厌氧消化以后的残泥进行土地投放试验,研究其对植物生长和土壤性质的影响,分析其土地利用的可行性。研究结论如下：(1)表层底泥的有机质(OM)和总氮(TN)、总磷(TP)之间,各种氮的形态之间,TN和TP之间都显著相关。从TOC/TN的值来看外源与内源污染对南湖有机物污染贡献相差不大。OM和大部分重金属元素显著相关,表层泥样各项污染指标在空间的分布上都有强变异性。(2)柱状底泥基本呈现污染物含量随泥深而降低的规律,各样点的OM和TN、OM和TP之间大都显著相关,但TN和TP之间大都没有显著相关关系。底泥的各指标在垂直方向的变异性一般为中等或强变异。(3)通过对间隙水和上覆水氮磷含量分析,发现南湖底泥会向上覆水体释放氮元素,而释磷的可能性不大。上覆水、间隙水和底泥的氮、磷之间存在一定相关关系。(4)采用有机氮评价法和有机指数评价法判定南湖的有机污染情况,结果表明南湖有机污染比较严重。用地积累指数法和潜在生态危害指数法评价重金属污染,结果表明：除Cd属中度污染以外,其余元素(Hg、As、Cu、Pb、Cr、Zn)均为轻度污染；所有元素潜在生态危害均属轻微。(5)进行了批式厌氧发酵的正交试验,结果表明：温度、碳氮比、固体浓度都对产气量影响非常显著,接种比率对产气影响不显著。按影响程度大小对四个因素进行排序为：温度>碳氮比>固体浓度>接种比率。最佳的工艺参数组合是：温度55℃,C/N为20：1,TS为10%,接种比率按VS(基)为1：1。(6)在中温条件下进行半连续厌氧消化试验,反应器运行正常。容积负荷对产气率、排泥VS/TS含量以及甲烷含量都有一定影响,在1.96gVS/(L·d)时消化效果最好。根据厌氧消化产气的动力学模型,得到有机物的理论产气率和动力学参数分别为278.6ml/gVS和0.166d-1。(7)将南湖的原始底泥和厌氧消化后的残泥投放于红壤,结果表明：加入底泥后,容重、孔隙度都保持在土壤正常范围以内,但引起pH值升高；底泥投放促进了作物生长,作物重金属Cd含量也未超过农产品和食品的相关标准限值；土壤养分含量显著提高,Cd含量也有升高,但未超出土壤环境质量标准；加入粉煤灰或猪粪可对Cd起到一定的钝化作用,还可提高土壤孔隙度,说明其在底泥土地投放时可以起到辅助作用。(8)从容重、孔隙度、养分、重金属、阳离子含量、钾含量等各指标来分析,南湖原始底泥或消化残泥均适于农用或绿化使用,但若用于种植食用农产品应注意控制施用量(尤其是在酸性或中性土壤条件下)。更多还原

【Abstract】 Water pollution in china is serious, and there is dynamic balance of material exchange between the sediment and its overlying water; the study of sediment characteristics is of great significance for improving quality of water body; sediment dredging is often used in governance of water, but how to dispose dredged sediment is a problem. In this study,12surface sediment and5cylindrical sediment sampling points were set up in South Lake of Wuhan city, contents of organic matter, nutrients, heavy metals and other indicators in sediment of every sampling point were measured to analysis the pollution characteristics of sediment in South Lake; batch and semi-continuous anaerobic digestion test were conducted with sediment to study the feasibility of energy production; influence of land application of original sediment and anaerobic digestion residue on plant growth and soil properties and feasibility of land application were analyzed. The conclusions are as follows:(1) For the surface sediment, these characteristics were found:organic matter (OM) and total nitrogen (TN), OM and total phosphorus (TP) were significantly related; the TN and TP, the various forms of nitrogen were significantly related too. From point of view of TOC/TN, there was similar influence from external source and internal source pollution on sediment. OM and most of the heavy metals were significantly related. There was strong variability of spatial distribution of various pollutants.(2) For the stanchion form sediment:the contents of pollutants decrease along depth. OM and TN, OM and TP were significantly related; TN and TP weren’t significant related. There were strong or moderate variability of vertical distribution of various pollutants.(3) By comparing the contents of pollutants of pore water and overlying water, nitrogen may be released from sediments to overlying water but phosphorus may be not. There were certain correlation of nitrogen or phosphorus among overlying water, pore water and sediment.(4) The organic pollution status of sediment in Nanhu Lake were evaluated by organic nitrogen evaluation and organic index evaluation, results showed that the organic pollution of sediment in Nanhu Lake is serious. Two assessment methods were used to assess the pollution degree of heavy metals of sediment in Nanhu Lake, which were Index of Geoaccumulation and Potential Ecological Risk Index. The results showed that for cadmium the pollution degree was moderate; for mercury, arsenic, copper, lead, chromium, zinc, the pollution degree were slight; and potential ecology risk of all element were slight.(5) The orthogonal experiment of batch anaerobic digestion was conducted, the results showed that:gas yield was significantly impacted by temperature, carbon and nitrogen ratio (C/N), the solid concentration; and were affected indistinctively by Inoculum-Substrate ratio (ISR). The influence order of the four factors on biogas yield are temperature> C/N> solid concentration>ISR. The best optimum anaerobic digestion conditions are the temperature is55℃, the C/N value is12.5:1, solid concentration is10%and ISR is1:1.(6) Semi-continuous anaerobic digestion experiment was conducted on mesophilic condition, the reactor was operating normally. Volume load had influence on biogas yield, VS/TS of discharged sludge and percentage of methane in biogas, the best digestion efficiency is in the condition of1.96gVS/(L·d). The anaerobic digestion kinetics model has been deduced that theoretical gas yield was278.6ml/gVS and the reaction rate constant was0.166d-1(7) when applying sediments and anaerobic digestion residue from Nanhu Lake on red soil, the results showed that:bulk density and porosity were within the normal range of soil, pH was increased; crop growth was promoted, heavy metals contents in crop did not exceed the relevant standards of agricultural products and food; nutrient contents of soil were significantly increased; content of Cd in soil were also increased but did not overturn the soil environmental quality standards; after fly ash or pig manure was added, activation of Cd was decreased, available content of Cd in soil and absorption of Cd for crop were reduced; soil porosity increased; therefore fly ash and pig manure can play a supporting role in land application of sediment.(8) From view of bulk density, porosity, nutrients, heavy metals, cation exchange capacity and potassium, sediments of Nanhu Lake are suitable for agriculture or greening application. However, if the sediments are used to plant edible agricultural products, application amount should be controlled, especially under acidic or neutral soil conditions.更多还原