H_2O_2分次投加对Fenton氧化修复石油污染土壤及后续生物降解的影响

Fenton化学氧化和生物联合修复可以有效提高土壤有机污染物的去除效率.本文考察了H_2O_2分次投加对Fenton氧化过程中,土壤有机物(SOM)氧化量、石油烃(TPH)去除量、营养物质释放情况以及后续生物修复过程中的营养利用情况和修复效果的影响.结果表明,H_2O_2分次投加可以有效减少SOM的氧化、提高TPH去除率并能促进后续生物修复.实验发现,当900 mmol·L~(-1) H_2O_2分4次投加时,Fenton氧化阶段SOM氧化率最低(1.86%)、TPH去除率最高(32.14%),且土著细菌的残余量也最高(5.0×10~6 CFU·g~(-1)),这使得该体系营养物质在生物修复阶段得以充分利用,生物去除率高达38%,总TPH去除率达到70%,在4种投加方式下是最高的.H_2O_2分次投加的Fenton氧化方式是提高TPH去除率并促进后续生物降解的有效方法.     

地下水水化学特征对纳米乳化油稳定性的影响

原位强化土著微生物修复地下水污染的应用中,纳米乳化油的迁移性和分散性制约其修复效果,其中地下水水化学特征引起的纳米乳化油聚集和失稳可能是阻碍修复效率的重要影响因素.据此,本文选取常见的HCO3-Na、HCO3-Ca、SO4-Na的3种典型地下水化学类型,配制不同含盐量的水化学溶液,探讨水化学类型及含盐量对纳米乳化油稳定...     

某铀尾矿库周边地下水的水化学特征分析

选取某铀尾矿周边地下水作为研究对象,对比分析地下水与排放水在主要水化学成分、水化学参数、水化学类型及放射性元素铀和微量元素氟含量上的差异,探明铀尾矿库对其周边地下水的影响程度.分析结果表明:地下水主要水化学成分为HCO-3和Na+,水化学类型以HCO3·Cl-Ca·Na为主,排放水主要水化学成分为SO2-4和Ca2+,水化学类型以SO4-Ca为主.说明在主要水化学成分、水化学参数、水化学类型上,可能尾矿库对地下水的影响不大;地下水中铀和氟含量分别超过美国EPA标准和我国《地下水质量标准》,超标率分别为100%和85.7%.可能是受矿山开釆产生的废石和铀尾矿库堆积的矿砂及p H的影响,说明尾矿库对地下水铀、氟含量的增加有一定影响.     

整流电絮凝技术对缺氧地下水中As(Ⅲ)的原位修复

地下水中砷污染的原位修复治理对人类社会的可持续发展具有重要意义.本文研发了一种新型整流电絮凝反应体系,可实现对缺氧地下水As(Ⅲ)的原位修复.实验结果表明,最优操作条件为:电流密度为4.4 m A·cm~(-2),铁棒和MMO的阳极工作时间比值(TFe-anode/TMMO-anode)为1∶2,反应周期为24 s.在最优条件下,含有500μg·L~(-1)As(Ⅲ)的模拟地下水经过30 min电絮凝处理后砷的固定脱除效率达92%,总能耗为0.11 kW·hm~(-3).此外,水体中的HCO_3~-和PO_4~(3-)等无机阴离子对砷的固定具有抑制作用.在该反应体系内,电解生成的Fe(Ⅱ)与O2之间的氧化反应生成具有强氧化性的Fe(Ⅳ)可有效将As(Ⅲ)氧化成毒性较小且更易于固定脱除的As(Ⅴ),进而显著促进了砷在Fe(Ⅲ)絮凝沉淀作用下的固定脱除.     

Fenton试剂氧化法修复2,4-二氯酚污染土壤的研究

在泥浆体系中采用Fenton试剂氧化法修复2,4-二氯酚(2,4-DCP)污染的土壤.在恒温、避光条件下,研究2,4-DCP在泥浆体系中的解吸作用,并考察过氧化氢、硫酸亚铁、pH值、水土比、磷酸二氢钾、腐殖酸(HA)等因素对2,4-二氯酚去除效率的影响.试验结果显示,2,4-DCP在泥浆体系中有较高的解吸速率;2,4-DCP的解吸效率与水土比有关,水土比越大,解吸效率越高.研究表明:Fenton试剂氧化法能够有效地去除土壤中的2,4-DCP,过氧化氢和铁的最佳质量比为5:1,最佳pH值范围为2-3;水土比越大,2,4-DCP的去除效果越好;在pH=3时,磷酸二氢钾浓度、腐殖酸投加量和催化剂种类对2,4-DCP的去除效率影响很小.     

高铁酸钾氧化降解硝基苯水溶液

采用高铁酸钾氧化降解硝基苯水溶液,研究表明,反应时间、pH值、高铁酸钾投加量、硝基苯水溶液浓度4个因素都会对硝基苯的降解效果产生影响.硝基苯水溶液浓度为55mg·l~(-1)时,初始pH=7-9,高铁酸钾投加量n_(k_2FeO_4):n_(C_6H_5NO_2)10:1,反应时间30min为最优反应条件,硝基苯去除率达到85%左右,COD_(Cr)去除率达到55%左右.通过对反应产物的分析,推测硝基苯首先被高铁酸钾氧化为对硝基苯酚,再进一步被氧化开环生成终产物.     

紫外-Fenton试剂的作用机理及在废水处理中的应用

本文研究了紫外光、铁离子对过氧化氢的催化分解作用.证实了紫外光和铁离子对过氧化氢的催化分解存在协同效应,并通过研究三价铁离子与紫外光的相互作用,探讨了协同效应产生的机理.UV-Fenton试剂对硝基苯、十二烷基苯磺酸钠(DBS)模拟废水的处理结果表明:将紫外光引入Fenton试剂可大大提高Fen-ton试剂的氧化性能,对生物难降解或难化学氧化的有机污染物具有良好的处理效果.     

生物修复PAHs污染土壤对酶活性的影响

在PAHs污染土壤生物修复过程中,以黑麦草、苜蓿为修复植物,固定化微生物菌剂为外源微生物,通过盆栽实验研究了不同处理对土壤酶活性的影响,以及酶活性与PAHs的去除效果之间的相关性。结果表明,植物修复、微生物修复及两者联合修复均显著提高了土壤PAHs的去除效果,其中黑麦草和苜蓿与微生物菌剂联合修复效果分别达到37.57%和38.41%,比单独的植物修复和菌剂修复高出一倍左右。各种生物修复同时促进了土壤多酚氧化酶、脱氢酶及脲酶的活性,减少了过氧化氢酶活性。过氧化氢酶活性与多酚氧化酶活性呈显著负相关（P〈0.05）、而脲酶与多酚氧化酶显著正相关（P〈0.05）。进一步分析表明PAHs的去除率与脱氢酶活性极显著正相关（P〈0.01）,与多酚氧化酶活性呈显著正相关（P〈0.05）,与过氧化氢酶活性呈负相关（P=0.564）;因此,在PAHs污染土壤生物修复过程中,可以选择土壤脱氢酶活性和多酚氧化酶活性作为PAHs修复效率的微生态指示指标。     

垃圾渗滤液的Fenton氧化预处理研究

采用Fenton氧化法对垃圾渗滤液进行预处理,考察了渗滤液初始pH值、H2O2和FeSO4.7H2O投加量、H2O2/Fe2＋投加的物质的量比及氧化反应时间等对Fenton氧化处理效果的影响,获得Fenton氧化处理垃圾渗滤液的最佳工艺条件：初始pH=3.0,H2O2投加量为5.0 mL.L-1,FeSO4.7H2O投加量为3.48 g.L-1,H2O2/Fe2＋物质的量比为4-1,反应时间为1.5 h。最佳条件下处理后垃圾渗滤液COD为5 220 mg.L-1,COD去除率达57.8%。凝胶渗透色谱和三维荧光光谱分析结果表明,垃圾渗滤液中主要含有腐殖酸类大分子物质,经Fenton氧化后降解变成小分子化合物。     

珠江三角洲小流域地下水化学特征及演化规律

珠江三角洲地下水环境日益恶化,已成为制约经济社会发展的重要因素。以珠海市具有典型特征的闭合小流域作为研究对象,分旱、雨两季采集地下水分析主要离子及D、18O同位素,全面系统地研究了地下水水化学的时空变异特征与演变规律。结果表明:研究区内地下水主要受大气降水及附近地表水体渗透补给,以蒸发及地下水径流排泄,季节变化对区域内水化学空间变异性影响较小。沿地下水流方向(补给区-径流区-排泄区),地下水化学类型主要从Ca-Na(Mg)-HCO3型向Na-Cl和Na-K-HCO3-CO3型演化,风化-溶滤、离子交换、海陆交互作用是控制当地地下水质演变的主要水文化学过程。     

Groundwater resources at risk in the glaciofluvial formation of Jokkavaara in Rovaniemi area, Northern Finland

The best groundwater resources in Finland are generally situated in glaciofluvial formations with thick sand and gravel deposits. The glaciofluvial formation of Jokkavaara, in northern Finland near the town of Rovaniemi, is important for both its groundwater reserves and its sand and gravel resources. The groundwater and mineral resources of Jokkavaara was studied to define their quantity and quality, and to develop a land-use plan which would help civil servants of the municipality to make the decisions necessary for exploiting sand and gravel. The land-use plan shows the areas where exploiting mineral resources is not allowed or recommended because of the risks of contamination of groundwater, or because of injurious effects on the environment caused by noise and dust from gravel pits, or by spoilt landscape. The size of Jokkavaara is 5 km2, and its mineral resources are about 53 million cubic metres. The sand and gravel deposits are at the most, 50 m thick. Risks of contamination by fallout are small, due to the thick sand and gravel deposits above groundwater level. Exploiting mineral resources have no effect on groundwater quality either. By the land-use plan and legislation, good groundwater can also be protected in the future. Legislation limits the exploitation of mineral resources especially in groundwater areas.     

Carbon nanotubes-incorporated MIL-88B-Fe as highly efficient Fenton-like catalyst for degradation of organic pollutants

CNTs were incorporated into MIL-88B-Fe to get a new Fenton-like catalyst (C@M). Fe(II) was introduced in C@M to get a fast initiation of Fenton-like reaction. Fe(II) content in C@M was related with oxygen-containing functional groups on CNTs. C@M shows efficient catalytic degradation of pollutants over a wide pH range. Iron-based metal organic frameworks have been verified to be efficient heterogeneous Fenton catalysts due to their open pore channels and highly uniform distribution of metallic centers. In these catalysts, however, the iron element is mainly in the form of Fe(III), which results in a process required to reduce Fe(III) to Fe(II) to initiate Fenton reaction. To address this problem, carbon nanotubes (CNTs) with electron-rich oxygen-functional groups on the surface were incorporated into the metal organic frameworks (MIL-88B-Fe) to improve Fe(II) content for an enhanced Fenton-like performance. The prepared CNT@MIL-88B-Fe (C@M) showed much stronger catalytic ability toward H₂O₂ than MIL-88B-Fe. The pseudo-first-order kinetic constant for phenol degradation by C@M (0.32 min^–1) was about 7 times that of MIL-88B-Fe, and even higher than or comparable to the values of reported heterogeneous Fenton-like catalysts. Moreover, the Fenton-like system could effectively degrade various kinds of refractory organic pollutants and exhibited excellent catalytic activity over a wide pH range (4–9). XPS analysis confirmed that Fe(II) content of the catalyst gradually increased with CNT loadings. Electron spin resonance analysis showed that the signal intensity (•OH) of C@M was much higher than MIL-88B-Fe, which was consistent with the degradation efficiency of pollutants. Furthermore, the Fe(II) content of the catalyst gradually increased along with the oxygen-functional group content of CNTs. The result demonstrated that oxygen-containing functional groups of CNTs have a significant impact on the enhanced catalytic performance of C@M. This study provides a new insight to enhance Fenton reaction by using nanocarbon materials.     

Window of opportunity of <Emphasis Type="Italic">Liparis loeselii</Emphasis> populations during vegetation succession on the Wadden Sea islands

The present study aims at assessing the life span of populations of the orchid L. loeselii during successional in dune slacks on the Wadden Sea islands. An inventory of Liparis loeselii populations was carried out on 6 islands, while the population structure was assessed in more detail on the island of Texel. The occurrence of the orchid was related to soil factors and hydrological conditions. Groundwater levels were measured in a dune area with natural dune slack formation. The groundwater composition was analyses and the freshwater lenses were modelled. Various scenarios were investigated, including sea level rise and sand nourishment. The window of opportunity for L. loeselii to colonize a new slack is relatively narrow. Under favorable management, the population can survive c. 20 years. Soil pH was positively correlated with the occurrence of L. loeselii populations, while a high organic matter content was negatively correlated. Sites with large populations of L. loeselii, were situated in young dune slacks, that functioned as flow-through lakes and has top soilsinfluenced by anoxic calcareous groundwater. Modelling showed that the freshwater lens would decrease due to sea level rise, while artificial sand nourishment could counteract this effect. The populations of the Hors area on Texel, the Netherlands, can survive for several decades due to continuous formation of new slacks. Discharge of calcareous groundwater is essential to keep the pH on a high level. The hydrological systems that supply dune slack with groundwater are relatively small and are vulnerable for changes in sea level rise.     

Characteristics and mechanisms of 4A zeolite supported nanoparticulate zero-valent iron as Fenton-like catalyst to degrade methylene blue

4A zeolite supported nanoparticulate zero-valent iron (nZVI/4A zeolite), synthesized through borohydride reduction method, was used as a catalyst with H₂O₂ to build Fenton-like reaction system to degrade methylene blue (MB) in model wastewater. The characteristics and primary mechanisms of the catalyst were investigated. The results show that nZVI/4A zeolite has the potential as a Fenton-like catalyst, and (about 30 mg/L) MB was degraded completely in 3 h with 10 mM H₂O₂, 0.2 g/L catalyst, and initial pH of 3.0. The MB degradation rates were obtained at least 70% in the tests with initial pH ranged from 2.0 to 9.0 and the catalyst dose rose from 0.2 to 5.0 g/L. Importantly, the catalyst also has a distinctive ability to increase the solution pH value from its initial acidic pH and then maintain the value at close to neutrality. This ability was controlled by both the initial pH and the catalyst dose. MB degradation clarified that hydroxyl radical was the dominated active oxidative specie in the tests with initial acidic pH and low catalyst dose (less 2.5 g/L); otherwise, Fe(VI) oxidation was the main mechanism for MB degradation; and the two processes shared synergistic effect in MB degradation in the present test. The catalyst has high operational stability in both of the composites with low iron leaching (less 2%) and catalyzing ability. Therefore, nZVI/4A zeolite has great potential as a Fenton-like catalyst and is used with H₂O₂ to build Fenton-like system which could be used to degrade MB efficiently.     

A conceptual snapsot of a big coastal dune aquifer: Magilligan,Northern Ireland

The Magilligan sand spit dune field is situated on the eastern mouth of Lough Foyle in County Londonderry, Northern Ireland. It is a large triangular-shaped site some 7 km by 4 km by 1.5 km wide (about 800 ha) and maintains areas, particularly in the eastern part, with slacks that regularly flood in winter. The size of the system acts as a buffer to external drivers due to the large volume of groundwater stored, the longer travel distances and lower hydraulic gradients. However, unlike many other coastal dune sites with humid dune slacks in the British Isles the sand is not wholly underlain by silt and clay, as raised beach sand and gravel deposits are in contact with the sand aquifer in some places. A preliminary water balance suggests that the majority of the discharge from the sand aquifer occurs via the underlying raised beach deposits and only a small amount discharges directly from the sand aquifer beneath the foredunes. Available water level monitoring is skewed towards the wetter end of the dune system; no significant short-term water level trends are apparent. The data also indicate that recharge regularly takes place within the sand aquifer interspersed by periods of groundwater level recession.     

山东省地下水硝酸盐溯源研究

针对山东全省农村地区进行地下水取样,采用离子交换色层法对地下水NO3--N质量浓度大于10 mg·L-1的地下水样品进行预处理,做溯源研究,同时采集当地植物、化学肥料、人畜粪便、土壤等样品,测定δ15N值,以针对山东地区,对现存的δ15N值数据库进行完善与补充,使本研究更具代表性与准确性。研究结果表明,如以研究区域整体为单位,有35.45%地下水样品的NO3--N来自于粪肥污染,有27.1%的地下水样品是受化肥污染,还有37.45%的地下水样品的NO3--N污染来自于化肥、粪肥以及生活污水的混合污染。作者还进一步分析了地下水中NO3--N平均质量浓度高于20 mg·L-1的烟台和潍坊,结果表明,烟台地区的地下水NO3--N污染有55.56%来自于粪肥污染,有5.56%来自于化肥污染,有38.88%来自于化肥、粪肥以及生活污水的混合污染;潍坊地区的地下水NO3--N污染有16.13%来自于粪肥污染,有48.39%来自于化肥污染,还有35.48%来自于化肥、粪肥以及生活污水的混合污染。     

Assessment of contamination by percolation of septic tank effluent through natural and amended soils

Fly ash has been found to be a potential material for the treatment of municipal and industrial wastewater, and may be useful in the treatment of septic tank effluent. Laboratory columns (30 cm) were used to determine the sorption capacity and hydraulic properties of lagoon fly ash, loamy sand, sand, and sand amended by lagoon fly ash (30 and 60%) and red mud gypsum (20%). The removal of chemical oxygen demand (COD) was high in all column effluents (71-93%). Extent of nitrification was high in Spearwood sand, Merribrook loamy sand and 20% red mud gypsum amended Spearwood sand. However, actual removal of nitrogen (N) was high in columns containing lagoon fly ash. Unamended Spearwood sand possessed only minimal capacity for P sorption. Merribrook loamy sand and red mud gypsum amended sand affected complete P removal throughout the study period of 12 weeks. Significant P leakage occurred from lagoon fly ash amended sand columns following 6-10 weeks of operation. Neither lagoon fly ash nor red mud gypsum caused any studied heavy metal contamination including manganese (Mn), lead (Pb), zinc (Zn), cadmium (Cd) and chromium (Cr) of effluent. It can be concluded that Merribrook loamy sand is better natural soil than Spearwood sand as a filter medium. The addition of lagoon fly ash enhanced the removal of P in Spearwood sand but the efficiency was lower than with red mud gypsum amendment.     

Factors affecting arsenic concentration in groundwater in West Bengal

Groundwater is the major source of drinking water for the population in Malda district, West Bengal. Holocene sediments from Himalayas have contaminated those places through the river Ganges and arsenic was found a potential groundwater contaminant. Field and laboratory experiments were attempted to identify the relationship between arsenic versus Eh of groundwater and content specific elements (As, Co, Mn, Fe, C and S) in different types of Holocene sediments on a freshly constructed wells. Arsenic versus Eh of groundwater and Holocene clay over Holocene sand were found performing a major role in the aquifers of arsenic affected areas.     

Assessment of Contamination By Percolation Of Septic Tank Effluent Through Natural and Amended Soils

Fly ash has been found to be a potential material for the treatment of municipal and industrial wastewater, and may be useful in the treatment of septic tank effluent. Laboratory columns (30 cm) were used to determine the sorption capacity and hydraulic properties of lagoon fly ash, loamy sand, sand, and sand amended by lagoon fly ash (30 and 60%) and red mud gypsum (20%). The removal of chemical oxygen demand (COD) was high in all column effluents (71–93%). Extent of nitrification was high in Spearwood sand, Merribrook loamy sand and 20% red mud gypsum amended Spearwood sand. However, actual removal of nitrogen (N) was high in columns containing lagoon fly ash. Unamended Spearwood sand possessed only minimal capacity for P sorption. Merribrook loamy sand and red mud gypsum amended sand affected complete P removal throughout the study period of 12 weeks. Significant P leakage occurred from lagoon fly ash amended sand columns following 6–10 weeks of operation. Neither lagoon fly ash nor red mud gypsum caused any studied heavy metal contamination including manganese (Mn), lead (Pb), zinc (Zn), cadmium (Cd) and chromium (Cr) of effluent. It can be concluded that Merribrook loamy sand is better natural soil than Spearwood sand as a filter medium. The addition of lagoon fly ash enhanced the removal of P in Spearwood sand but the efficiency was lower than with red mud gypsum amendment.     

粒状铁与甲醇支持的生物-化学联用法去除富氧地下水中硝酸盐

针对富氧地下水中硝酸盐,采用粒状铁和甲醇支持的生物-化学联用法开展了批实验研究,优化了脱氮反应参数,初步探讨了脱氧脱氮的能力及途径。结果表明,该法的优化参数是粒状铁种类为GI-北京,m（粒状铁）∶m（水）为3∶800,粒状铁粒径为0.425~1.0 mm,反应时间为5 d,甲醇用量为210.59 mg.L-1。生物-化学法、粒状铁和好氧异养菌完全脱氧所需的时间分别是174、206和2 746 min。生物-化学法脱氧依赖于粒状铁化学还原和好氧异养菌有氧呼吸,并且前者起着关键作用。随着反应时间的增加,异养脱氮、自养脱氮和化学还原各自引起的NO3-去除率亦增加。当反应时间≤5 d时,自养脱氮和化学还原的去除率均〈10%,而当反应时间为5 d时,生物-化学法的NO3-去除率达到近100%。生物-化学法内存在异养脱氮、自养脱氮和化学还原3种脱氮途径,其中异养脱氮是最主要的途径,且三者存在共生、协同和促进作用。生物-化学法脱氮期间硝酸盐还原速率≥亚硝酸盐还原速率。生物-化学法去除地下水中硝酸盐是有效可行的。