【作者】 刘娇；

【导师】 王震宇； 孟范平；

【作者基本信息】 中国海洋大学 ， 环境科学， 2011， 博士

【摘要】 有机质在河口沉积物中的累积引起河口生态环境的退化,已成为沿海区域普遍存在的环境问题,因此,有机污染型沉积物的治理日益受到重视。目前常用的治理措施以物理、化学方法为主,虽然见效快,但成本高、对环境破坏大,而且不能从根本上解决污染问题。与物理、化学方法相比,微生物修复技术具有明显的优势,将高效微生物引入沉积物中,可降解其中的多种有机污染物,有效解决沉积物有机污染问题。本文以位于烟台市牟平区的三八河河口污染潮滩为例,研究了有机污染型河口潮滩的微生物修复技术,先后比较了生物促进技术、生物强化技术和Fenton-微生物联合修复技术对污染物的去除效果,探讨有机污染的修复机制,并提出适宜的修复方案,可为有机污染型河口潮滩的实地修复工作提供理论依据和技术支持。为了评价三八河河口潮滩中主要污染物的分布及土著微生物的修复潜力,研究了该潮滩的沉积物中w（TOC）,w（油类）,w（硫化物）和微生物的水平、垂直分布规律。利用单因子污染指数法对潮滩污染状况进行了分析。结果表明:各因子污染指数大小为:TOC>硫化物>油类,距离河口越近,表层（0²0 cm）沉积物的污染程度越高,说明潮滩沉积物的污染主要源于河流排污。在0⁵0 cm深度范围内,w（TOC）,w（油类）和w（硫化物）随深度的增加呈先增大后减小的趋势,污染物主要集中在5²0 cm深度范围。微生物在潮滩中的分布规律表明,外源有机物的输入可提高沉积物中异养菌数量（HBC）和呼吸强度,潮滩微生物可通过呼吸过程实现有机质的矿化和输出,具有一定的修复潜力。为了促进沉积物中土著降解菌的生长,加快污染物的去除,向沉积物中投加NH₄-N、NO₃-N和PO₄-P,通过测定处理过程中微生物的生长情况、污染物和营养盐含量的变化情况,研究了营养盐种类及其用量对修复效果的影响,并利用红外光谱分析了修复过程中沉积物有机质结构组成的变化。结果表明:同时加入NO₃-N和PO₄-P,可促进反硝化自养菌和反硝化异养菌的生长,加快硫化物、油类和TOC的去除,而投加NH₄-N对污染物的去除有抑制效应。在NO₃-N用量为0.5mg·g^-1、N:P比例为10:1条件下处理40d,可获得较好的修复效果,硫化物、油类、TOC的去除率分别达到89.7%、90.6%和13.8%。红外光谱分析表明,NO₃-N和PO₄-P加入后,脂肪族化合物比芳香族化合物更容易被降解,处理后沉积物的芳构化程度增加。为了提高沉积物中降解菌数量,向沉积物中投加有效微生物菌剂（EM）、土著好氧异养菌富集液（IHM）以及增氧剂CaO₂。通过测定沉积物中微生物生长和污染物含量变化,研究了外源微生物种类及增氧剂的使用对修复效果的影响。结果表明,同时加入EM和CaO₂可以显著促进TOC的去除。利用正交试验对EM和CaO₂的用量、以及二者投加的时间间隔进行优化,并利用红外光谱表征处理过程中有机质结构组成的变化。结果表明:同时投加EM和CaO₂,可明显促进沉积物中芳香族化合物的降解,这种强化处理的最佳条件为:按照1%质量比投加CaO₂,间隔1 d后再以2×10⁷ cells·g^-1的比例投加EM菌剂。处理40 d后,油类和TOC去除率分别达到44.4%和17.8%,而硫化物含量却升高34.8%。现场应用该技术时,硫化物的产生可能对周围生态环境造成不利影响。为了进一步提高修复效果,采用Fenton氧化作为微生物修复的预处理。首先研究了反应条件对基于CaO₂的Fenton反应的影响,在磷酸盐缓冲溶液中,通过单因素试验研究了催化剂种类、反应初始pH值、催化剂和CaO₂比例(n_Fe/n_CaO2)以及缓冲溶液浓度对Fenton反应体系中HO·产率的影响。结果表明:Fe2+对基于CaO₂的Fenton反应有较好的催化效果,稳定反应体系的pH值对HO·产率非常重要。当反应初始pH值为2⁴、n_Fe/n_CaO2为1/5¹/20、磷酸盐缓冲溶液浓度为40¹00 mmol·L^-1时,HO·的产率较高。在此基础上,利用正交试验对作为微生物修复预处理的Fenton试剂最佳配比进行优化。之后,为了获得Fenton预处理与投加EM菌剂联合作用的最佳效果,以处理40 d后的硫化物、油类和TOC去除率为评价指标,结合处理过程中微生物生长及污染物含量的变化情况,对Fenton预处理强度、Fenton预处理时间和EM投加量进行优化,并利用红外光谱表征处理过程中有机质组成的变化,探讨Fenton-微生物联合修复机理。结果表明,Fenton预处理的适宜条件为:磷酸盐缓冲溶液浓度100 mmol·L^-1,缓冲溶液初始pH=4,催化剂用量(n_Fe/n_CaO2)=1/20,CaO₂投加量（mCaO₂/mTOC）=1/1;预处理进行5 d后,按照1×10⁶ cells·g^-1的用量投加EM菌剂,可获得最佳处理效果,40 d后的沉积物中硫化物、油类和TOC去除率分别达到46.3%、43.8%和31.1%。为了确定有机污染潮滩的最佳修复方案,对三种修复技术的处理效果、处理成本及环境效应进行了综合比较。结果表明,生物促进技术处理成本最低、对环境产生的不利影响较小;Fenton氧化—微生物联合修复技术对环境产生的不利影响相对较大,但是其处理效果最好;而生物强化技术在各方面均不占优势。根据三八河河口潮滩不同区域的污染现状,为了经济有效地实现河口区域有机污染潮滩的修复,并将修复过程中产生的不利环境影响减少到最低程度,建议采用的修复模式为:以投加NO₃-N和PO₄-P的生物促进技术为主、辅以Fenton氧化—微生物联合修复技术。更多还原

【Abstract】 The accelerated accumulation of organic matter in estuary sediments is a ubiquitous and significant environmental issue in the world. The excessive organic input may induce seriously negative effects which may lead to the deterioration of estuary environment. The remediation of organic-rich estuary sediments becomes increasingly prominent. The physical and chemical techniques have been currently used in the treatment of contaminated sediments. These methods, although effective, are usually with high cost and great damage to the environment. Compared with physical and chemical methods, microbial remediation has great advantages and has been applied to remove various organic pollutants. The application of microbial remediation in the removal of organic matter from organic-rich sediments is expected to be a fundamental method to solve the organically pollution problems. This study made use of biostimulation, bioaugmentation and combined Fenton-microbial treatment to eliminate excessive organic matter in the sediment. Both the effectiveness and removal mechanisms of each bioremediation method were evaluated and discussed. Results from this study may provide a theoretical basis and technical support for the in situ remediation of organic-rich sediments.In order to investigate the distribution of contaminants and the environmental bioremediation potential of indigenous microorganisms in the tidal beach of Sanba River estuary at Muping, Yantai, Shandong, the horizontal and vertical distribution characteristics of total organic carbon （TOC）, oil, sulphide and microorganisms in the sediment samples collected from this area were determined. The environmental quality in this area was also evaluated using single factor pollution index method. The results showed that the pollution index was in an order of TOC > sulphide > oil. Moreover, the pollution degrees of TOC, oil and sulphide in contaminated estuary area were significantly higher than those in control site; and the further closer to the estuary the more serious pollution was found in this area. These results indicated that estuary pollution could be mainly attributed to the pollution discharge in the river. The investigation of the vertical profile of pollutants revealed that pollutant contents were highest in the subsurface layer（5-20 cm）, and with the depth increasing （0-50 cm）, they increase firstly but then decrease in the deep layer. For the distribution profile of microorganism, it suggested that the organic matter input could elevate the number of microorganisms and respiratory intensity of sediment. This indicated that indigenous microorganisms could improve the mineralization and output of organic material by respiration process, showing a bioremediation potential.Experiments was conducted to investigate the effects of ammonium, phosphorous and nitrate on bioremediation of organic-rich tidal beach sediment. Microbial growth and activity, dynamics of nutrients, electron acceptor, oil, sulfide, total organic carbon （TOC） and dissolved organic carbon were monitored. Infrared spectroscopy was used to study changes in structure and composition of sediment organic matter during the treatment process. After nitrate was added, oil and sulfide contents decreased due to the autotrophic and heterotrophic denitrification in the sediment. By contrast, the addition of ammonium showed negative effects on oil and sulfide removal, as well as on TOC reduction. The highest remediation efficiency was observed when 0.5 mg·g^-1 NO₃-N was amended with N:P ratio of 10:1. After 40 days of treatment, the highest removal rate for sulphide, oil and TOC were 89.7%, 90.6% and 13.8%, respectively. Infrared spectroscopy showed that fatty compounds were degraded faster than aromatic compounds after the addition of nitrate and phosphorous, the biostimulation treatment caused an increase in the degree of aromatization.The effectiveness of effective microorganisms（EM） and indigenous aerobic heterotrophicl bacteria was compared. The effect of oxygen supply was also evaluated by the addition of CaO₂. Microbial growth and activity, dynamics of nutrients, oil, sulfide, total organic carbon（TOC） and dissolved organic carbon（DOC） were monitored. The orthogonal experimental design was used to optimize the amount of microorganisms and CaO₂, as well as the interval between the two additions. Infrared spectroscopy was used to study changes in structure and composition of sediment organic matter during the treatment process. The results indicated that the addition of EM in the presence of CaO₂ could effectively accelerate the removal of organic matter, especially for the aromatic organic compounds. The optimal treatment conditions were: CaO₂ dose of 1%, addition interval of 1d and EM dose of 2×10⁷ cells·g^-1. After 40 days of treatment under optimal conditions the removal rate of oil and TOC were 44.4% and 17.8%, respectively. However, an increase of 34.8% in sulphide content was observed, indicating negative effect of bioaugmentation on environment.In order to eliminate the excessive organic matter in organic-rich tidal beach sediment, a combined treatment of Fenton oxidation based on CaO₂ followed by microbial inoculation was carried out. Experiments were conducted in phosphate buffer to investigate influences of catalyst type, initial pH, CaO₂ dose, catalyst to CaO₂ molar ratio (n_Fe/n_CaO2), and phosphate buffer concentration on the production of hydroxyl radicals （HO·）. The effects of Fenton reaction parameters as pretreatment for microbial remediation were investigated using the orthogonal experimental design. The optimal parameters were: initial buffer pH = 4; phosphate buffer concentration = 100 mmol·L^-1; n_Fe/n_CaO2 = 1/20; mCaO₂/mTOC = 1/1. Infrared spectroscopy study indicated that Fenton oxidation resulted in the decrease in aromatization and the increase in biodegradability of organic matter. Best efficiency was observed when 1×10⁶ cells·g^-1 EM was added after 5 days of Fenton pretreatment. The removal rates for sulphide, oil and TOC were 46.3%, 43.8% and 31.1%, respectively.Comprehensive assessment of the three remediation techniques was carried out by comparing the treatment efficiency, economic costs and environmental negative impacts. The results indicated that biostimulation treatment showed both the lowest economic cost and the smallest negative impact on environment. Using Fenton-microbial treatment, highest pollutant removal efficiency was observed, although the environmental negative impact was greater than the other two treatments. Considering both the remediation cost and the remediation effectivness, biostimulation by adding NO₃-N and PO₄-P was suitable for the recovery of the area far from the estuary. However, Fenton-microbial treatment was also essential for the recovery of heavily polluted areas.更多还原