重金属污染底泥堆肥改良及资源化利用

发布时间：2017-12-31 07:11

本文关键词：重金属污染底泥堆肥改良及资源化利用　出处：《安徽建筑大学》2015年硕士论文　论文类型：学位论文

【摘要】：河流污染问题逐渐得到人们的重视,在治理河流污染过程中清淤是一项常用而高效的治理手段,安全处置和利用清淤底泥是近些年环境保护领域研究的热点问题。本研究以南淝河不同流段底泥为研究对象,首先分析了底泥的物理、化学性质和重金属总量及重金属各形态含量进行细致分析,了解底泥的性质和污染状况,再利用堆肥对底泥进行改良。然后选取改良效果最优的底泥进行盆栽实验,验证改良效果并进一步研究种植条件下植物对改良底泥中重金属形态的影响。通过研究,本文主要得出如下结论:两河段底泥重金属Cr、Cd含量相近,马家渡段底泥总Pb含量高于凤凰桥段底泥,总Cu含量低于凤凰桥段底泥;马家渡段底泥含沙量大,密度、容重高于凤凰桥段底泥。通过堆肥可以达到改良底泥物理、化学性质,丰富底泥营养元素并使其能够适宜植物生长的目的;堆肥掺合物是采用稻草秸秆和枯树叶按质量比1:1配制并经发酵预处理后制成,以2%的质量比将掺合物与底泥进行堆肥可使得凤凰桥和马家渡底泥的综合改良效果最佳。盆栽实验结果表明凤凰桥组蕹菜产量高于对照组蕹菜产量,而马家渡组蕹菜产量低于对照组产量,凤凰桥底泥的资源化利用价值更高。通过堆肥凤凰桥底泥中酸可提取态Pb下降了53.1%,Cu下降了33.5%,Cr下降了53.1%,Cd下降了57.8%;可还原态Pb下降了22%,可还原态Cu下降了51.9%,可还原态Cd下降了50%,而可还原态Cr增加了47.2%。马家渡组底泥中各重金属的酸可提取态、可还原态含量也均有不同程度下降。这有利于降低底泥中重金属的迁移能力和生物有效性。通过研究蕹菜生长对改良底泥中重金属形态分布的影响发现,蕹菜在生长初期会使得根际土壤的pH降低。p H降低会使得酸可提取态含量升高,但是在蕹菜根系富集作用下,根际和非根际底泥中酸可提取态重金属含量呈下降趋势。根际底泥中可还原态Pb、Cu含量增加幅度较为明显,酸可提取态及可还原态Cr含量增加幅度不显著,但是可氧化态Cr的含量降低的幅度比较明显;在凤凰桥组底泥中酸可提取态、可氧化态Cd降低,而可还原态和残渣态含量升高;而在马家渡组底泥中只有残渣态Cd的含量表现为增加,其余三态Cd含量均下降。同时发现蕹菜根系会大量富集各种重金属,植物根系会吸附一定量重金属,而其中一部分向茎叶转移,少部分会转化成可还原态。蕹菜茎叶中重金属含量与根系重金属含量无正相关关系。种植30天蕹菜茎叶重金属含量只有Cr超标,种植90天后Pb、Cr、Cd含量均超标。凤凰桥组蕹菜重金属富集速度高于马家渡组蕹菜的重金属富集速度。在利用底泥栽培植物的过程中,植物根系有利于将重金属吸附在上层底泥中。改良底泥中存在未分解的秸秆、纤维素等物质,这些物质在后期腐烂分解的过程中可以进一步吸附重金属,从而降低底泥中金属迁移能力。
[Abstract]:The river pollution problem is getting more and more attention, in the process of dredging river pollution control is an effective means of governance and a common, safe disposal and utilization of dredging sediment is a hot issue in the field of environmental protection in recent years. In this study, Nanfeihe river sediments of different flow as the research object, firstly analyzed the sediment of physics. A detailed analysis of the chemical properties and the total amount of heavy metals and heavy metals content, understand the nature and sediment pollution, using compost to improve sediment. Sediment and then select the optimal improvement effect were improved, and further verify the effect effect of planting conditions on the form of heavy metals in sediment improved. Through the research, this paper mainly conclusion: the heavy metals in the sediments of Cr and Cd were similar, the total content of Pb of sediments is higher than that of the Phoenix horse bridge bottom mud, the total content of Cu Less than Phoenix plot sediment; Ma Du sediments of large sediment, density, bulk density is higher than that of the Phoenix Bridge. Sediment by composting can improve the physical and chemical properties of sediment, sediment, rich nutrients and make it suitable to the growth of plants; compost blend is made of straw and dry leaves according to the mass ratio of 1:1 prepared and after the fermentation pretreatment is made, with 2% mass ratio will blend with sediment composting can make comprehensive improvement effect of Phoenix Bridge and Ma Du sediment. The results show that the best pot experiment of Fenghuang Bridge Group yield of water spinach was higher than the control group and the yield of water spinach, Ma Jia Du group than in the control group yield of water spinach yield, sediment Phoenix Bridge the resource utilization of higher value. Through composting of Fenghuang bridge in the sediment of acid extractable Pb decreased 53.1%, Cu decreased 33.5%, Cr decreased 53.1%, Cd decreased by 57.8%; reducible Pb down 22%, can Reduced Cu fell 51.9%, reducible Cd decreased by 50%, and reduced Cr increase of various heavy metals in the sediment of 47.2%. Ma group of acid extractable, reducible content also decreased in different degrees. It is beneficial to reduce heavy metal mobility and bioavailability. Through the study of water spinach the growth of the influence of distribution of heavy metals in sediment improved, water spinach will make the rhizosphere soil pH decreased.P H reduction will make the acid extractable content increased in the early stage of growth, but in the water spinach root concentration under the action of rhizosphere and non rhizosphere sediments in the acid extractable heavy metal content decreased. Reduction state Pb in rhizosphere sediments, Cu content increased obviously, acid extractable and reduced Cr content increased significantly, but can reduce the content of oxidized Cr evidently; in the Phoenix Bridge Group in sediment acid Extractable, oxidizable Cd decreased, while the reducible and residual state content increased; while in group performance in the sediment content of the horse only residual Cd was increased, Cd decreased in the remaining three states. At the same time that water spinach root system will accumulate heavy metals, plant roots can absorb a certain amount of heavy metals, and one part of the transfer to stems and leaves, few will be converted into the reduced state. There is no positive correlation between the content of heavy metals and heavy metal content in the stems and leaves of spinach roots. Water spinach stems and leaves grown for 30 days only Cr heavy metal content exceed the standard, 90 days after planting Pb, Cr, Cd content exceed the standard. Heavy metal Phoenix Bridge Group of heavy metals in water spinach the enrichment rate is higher than the group of water spinach Ma Jia Du enriching speed. In the process the sediment of cultivated plants, plant roots is conducive to the adsorption of heavy metals in the upper sediments. There no decomposition of straw modified sediment, cellulose and other substances, this Some substances can further adsorb heavy metals during the decomposition of late decay, thus reducing the metal migration ability in the sediment.

【学位授予单位】：安徽建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S141.4;X522

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