PRB修复垃圾渗滤液污染地下水过程中pH值变化分析

随着城市化的不断发展,生活垃圾产生量越来越多,因管理不善,导致垃圾渗滤液污染地下水的问题越来越突出,污染地下水的修复研究迫在眉睫。实验模拟地下环境,以被垃圾渗滤液污染地下水为研究对象,分别用沸石、无烟煤、陶粒、活性炭、炉渣、粉煤灰、零价铁作为反应介质,设计了6种地下可渗透反应墙（PRB）,分别为反应器1、2、3、4、5和6。分3个阶段对PRB技术治理污染地下水中pH值影响和变化进行模拟研究,分析反应器pH值降低的原因并探讨pH值变化机理。实验结果表明,所有反应器pH值较进口降低,第三阶段出口pH值平均值较进口平均降低0.40;因水解酸化反应存在,产生一定量NH4＋和有机酸,造成反应器出水pH值降低和复合填充材料NH4＋相对去除率降低,说明PRB技术治理渗滤液污染地下水具有一定可行性,但技术方法有待继续深入研究。     

可渗透反应墙修复垃圾填埋场砷污染地下水模拟评估研究

以浙江省某垃圾填埋场为研究对象,采用Visual Modflow模拟软件预测了地下水污染羽分布规律及评估PRB修复的技术可行性。结果表明:垃圾填埋区重金属砷进入含水层,在地下水水流的作用下形成羽状体分布;填埋8 a后,地下水中砷的超标范围已经大面积扩散,增大危及人体健康的风险;在水流方向下游设置介质材料为Fe0填充的PRB,在清除污染源运行9 a时,污染程度显著降低。本研究可为地下水污染修复工程提供技术支撑。     

天然磁铁矿和商用Fe3O4修复Hg(II)污染地下水的模拟研究

目前汞污染地下水修复面临很大的技术和成本挑战,亟需发展修复效果好、经济效益性高的汞污染地下水修复技术和修复材料。通过批量实验和光谱分析探究了天然磁铁矿和商用Fe_3O_4对Hg(Ⅱ)的去除效率和去除机制,并分析了两种材料对模拟地下水中Hg(Ⅱ)的吸附和脱附行为。结果表明,天然磁铁矿和商用Fe_3O_4对Hg(Ⅱ)的去除受pH、Hg(Ⅱ)初始浓度、Cl-等因素的影响;二者对Hg(Ⅱ)的去除均符合准二级动力学模型和Freundlich模型;天然磁铁矿对Hg(Ⅱ)的去除机制主要是羟基络合与物理吸附,而商用Fe_3O_4对Hg(Ⅱ)的去除主要是化学还原与物理吸附。二者对模拟地下水中Hg(Ⅱ)的去除率分别达90%和95%,具有修复Hg(Ⅱ)污染地下水的应用潜力。     

人工模拟污水净化系统去除生活污水氮、磷效果的比较研究

在温室内,分别以炉渣、沸石和土壤为湿地基质,水芹(Oenanthe javanica)、黑麦草(Lolium mut-liflorum)和香根草(Vetiveria zizanioides)为植被构建了模拟人工湿地和无基质的浮床植物系统处理生活污水,比较研究了不同污水净化系统去除氮、磷的效果。结果表明,在较低氮、磷负荷和水力停留时间为6 d的条件下,炉渣、沸石和土壤基质人工湿地系统对生活污水中的全氮(TN)、NH4+-N和全磷(TP)均表现出很好的净化效果,平均去除率均在91.0%以上;对NO3--N的去除率较低,为58.0%~85.5%。浮床系统因承受较高的负荷,对TN、NH4+-N、NO3--N和TP的去除率均明显低于各基质湿地。而从污染负荷的去除率来看,土壤基质湿地对TN、NH4+-N、NO3--N和TP的负荷去除率低于炉渣和沸石基质湿地;浮床各系统NO3--N负荷去除率的负增加使TN的负荷去除率降低,但其NH4+-N的负荷去除率均高于各湿地系统;浮床水芹和黑麦草系统的TP负荷去除率也高于各湿地系统。植物种类不同,其吸收N、P的能力存在很大差异。以黑麦草为植被的人工湿地和浮床系统,植物的吸收作用是各系统去氮除磷的主要机制;水芹和香根草吸收的氮、磷总量在人工湿地中远小于黑麦草,其吸收作用仅是各湿地系统去除氮、磷的一个途径;而水芹和香根草对磷的吸收则是浮床系统除磷的主要机制。     

河岸带对地表径流截污的小试模拟以及不同基质处理表渗流能力的比较

采用潮白河河岸带土壤,设置不同基质填充类型的小试模拟装置,依照北京市降雨径流水质进行模拟径流配水,研究不同基质材料处理径流污染的能力,同时比较表渗流去除污染物的差异,以期强化河岸带截污能力,减少进入水体中的外源污染物。结果表明,将对照以及火山岩、砾石、石灰石、白云石和沸石作为改造基质的系统截污能力进行比较,总体而言,对于污染物的去除效果较佳的是沸石组,其在TN、TP以及COD的去除方面均表现出了一定的优势。对NH_4~+-N而言,处理效果最好的是沸石组,去除率达到了60.65%。同时,土壤组的表渗流量比为1.73,而沸石组的表渗流量比为1.02,COD和氮磷污染物的总去除率均与表渗流量比呈显著负相关。对河岸带选择合适基质进行一定的改造,不仅有利于提高截污性能,还可以降低表渗流量比值,提高下渗水量,从而利于地下水的补充。     

天然沸石负载氧化镁对氮磷吸附解吸特性的影响

采用平衡震荡法研究天然沸石负载氧化镁对溶液NH4+、H2PO4-的等温吸附-解吸行为,并运用Langmuir方程对其进行拟合分析,通过自由能的变化分析了吸附过程和吸附结合能.结果表明,天然沸石负载氧化镁与单一天然沸石相比,NH4+的最大吸附量降低了4.49 mg·g-1,H2PO4-提高了36倍;两种吸附材料对NH4+吸附机制主要以表面吸附为主,天然沸石负载氧化镁对H2PO4-的吸附机制主要以化学吸附(沉淀)为主,天然沸石主要以表面吸附和专性吸附为主;两种吸附材料对NH4+、H2PO4-的吸附均能自发进行,负载氧化镁后降低了天然沸石对NH4+的吸附能力,而显著提高了对H2PO4-的吸附能力.     

都市农业村域地下水非点源氮污染及其风险评估

以上海市南汇区新场镇果园村为研究区域,连续监测了该村域地下水中的总氮和"三氮"含量变化。结果表明:该村域地下水中的"三氮"主要以NO3--N形态存在,平均浓度范围为1.43～13.71 mg/L;地下水氮污染与土地利用类型有关,居民区地下水中NH4+-N污染最为严重,平均浓度范围为0.074～0.457 mg/L;河道旁地下水中NH4+-N污染较轻;果园旁和河道旁地下水总氮污染程度相当,平均浓度范围分别为33.67～62.57 mg/L,33.05～65.04 mg/L。均比居民区地下水污染严重。同时研究发现,该村域地下水中的总氮和"三氮"含量也受降雨强度和降雨时间的影响。同时,采用模糊综合评价法评价了该区域地下水氮污染的环境风险。     

控制排水条件下淹水稻田田面及地下水氮浓度变化

为了在减少农田面源污染,提高氮肥的利用效率。该文通过蒸渗测坑进行淹水稻田不同渗漏强度控制试验,研究了稻田施肥后NH4+-N、NO3--N浓度变化及各生育阶段不同渗漏强度稻田水NH4+-N、NO3--N浓度变化。结果表明：施分蘖肥后,地表水及地下水NH4+-N浓度急剧升高而后回落,均在施肥后第5天出现峰值,分别为17.75和10.34?mg/L;地表水NO3--N浓度短暂升高后便回落,在施肥后第2天出现峰值,但地下水NO3--N浓度急剧上升而后回落,在施肥后第5天出现峰值（3.25?mg/L）,6?d上升了249.4%。稻田补水会扰动土壤,促进土壤表层吸附的NH4+-N的释放及硝化进程,使地表水中NH4+-N和NO3--N浓度升高,随着淹水时间的延长,NH4+-N和NO3--N浓度会随之降低。不同渗漏强度（2和4?mm/d）对稻田水氮素变化有一定影响,但各处理之间差异不显著。因此,施肥后应该避免排水,应避免雨后和灌水后立即进行地表排水。     

不同灌期对农田氮素迁移及面源污染产生的影响

通过分析从秋灌到秋浇后河套灌区乌拉特灌域典型区不同类型土壤剖面（0～160 cm）、浅层地下水中和沟道中氮素质量分数的变化过程,以便为灌区氮素污染控制提供相应的理论指导。研究结果表明：秋灌期深层土壤剖面（120～160 cm）中NO-3-N累积不明显,秋浇后3种类型土壤剖面（80～160 cm）中NO-3-N平均质量分数分别增加了1.25、2.72和2.89 mg/kg。土壤剖面中的NH+4-N质量分数分布相对较均匀。3种耕地土壤剖面中NO-3-N和NH+4-N质量分数的变化具有季节性的增高或降低。盐荒地土壤剖面中NO-3-N和NH+4-N都处于积累状态,对整个灌区农业面源污染物的排泄有减缓作用。浅层地下水中NO-3-N和NH+4-N质量分数在秋浇期的增幅大于秋灌期。农田土壤、浅层地下水和沟道中的氮素质量分数有着较好的时间相关性,秋浇期河套灌区土壤中NO-3-N最易发生淋洗,且是灌区产生农业面源污染最严重的时期。     

改性沸石对Cu~(2+)的吸附、解吸特性研究

通过室内分析的方法研究了天然沸石及3种改性沸石对Cu2+的吸附及解吸特性。研究结果表明:沸石、改性沸石对Cu2+的等温吸附曲线符合Langmuir方程、Freundlich方程、Temkin方程,其中Freundlich方程的拟合性最好,相关系数在0.991～0.999之间。沸石及改性沸石对Cu2+吸附量大小顺序为NH4-Z>K-Z>Mg-Z>Z。该规律与改性阳离子水合半径、离子价数密切相关。沸石及改性沸石对Cu2+离子的解吸量和解吸率大小顺序为Z>Mg-Z>K-Z>NH4-Z。该规律与沸石的孔道居留效应有关。改性沸石一方面增加了Cu2+的吸附,同时又降低了Cu2+的解吸率,因此改性沸石在农业生产实践中,特别是土壤重金属污染的治理方面具有广阔的应用前景。     

Evaluation of Natural Zeolite as a Material for Permeable Reactive Barrier for Remediation of Zinc-Contaminated Groundwater Based on Column Study

The permeable reactive barrier (PRB) filled with natural zeolite plays the role of a reactive treatment zone for remediation of contaminated groundwater. Based on column lab experiments, the volume of remediated solution, the distribution (K_d) and retardation (R_d) coefficients were evaluated, confirming successful removal and retention of zinc from contaminated groundwater. The effect of hydrodynamic dispersion on zinc capturing by zeolite in PRB was evaluated by the hydrodynamic dispersion coefficient (D_L) and retarded hydrodynamic dispersion coefficient (D_LR) using the Brigham method. For different assumed distances of the barrier, the simulation of one-dimensional zinc concentration profile from the point source through the barrier has been modeled by a simple analytical pulse model. The results show that the flow rate has the most significant effect on the concentration profile, peaks, and broadening of curves. The residence contact time (τ) corresponding to higher K_d and R_d as well as lower D_L and D_LR values outcomes the optimal range of 6.2–9.4 min. This interval corresponds to the experimental performance at the bed length of 8 and 12 cm and flow rate in the range of 6.38–9.57 PV/h. The calculated minimum thickness and longevity confirm the successful application of zeolite as a material in PRB for remediation of zinc contaminated groundwater.     

NH4-N Removal Through Nitrification and Hydrogenotrophic Denitrification in Simple Attached Growth Reactors

To provide good quality of drinking water, a biological system to remove ammonium-nitrogen (NH₄-N) from groundwater was studied in this research. The NH₄-N removal system consists of two attached growth reactors: one for nitrification and the other for hydrogenotrophic denitrification (H. denitrification). The nitrification reactor, fed by the NH₄-N contained water, could remove NH₄-N without any need of aeration. The nitrification efficiency was increased by reactor length; the highest efficiency of 92?% was achieved at the longest reactor of 100?cm. A high Fe in groundwater affected the reactor performance by decreasing the efficiency, while a low inorganic carbon (IC) had no effects. Despite of good efficiency in terms of NH₄-N removal, the nitrification reactor increased the concentration of NO₃-N in its effluent. To treat the NO₃-N, a H. denitrification reactor was set up after the nitrification reactor. Efficiency of the H. denitrification reactor was enhanced by increasing H₂ flow rates. The efficiencies were 3, 27, and 90?% for 30, 50, and 70?mL/min of H₂ flow rates, respectively. It was also found that the NO₃-N contained water (water from the nitrification reactor) had to supply IC (i.e., NaHCO₃ or CO₂) for efficient H. denitrification; however, an on-site reactor showed that it can be achieved even without IC addition. The treated water contained low NH₄-N and NO₃-N of <1.5 and <11.3?mg/L, respectively, which comply with drinking water standards. The good performance of the reactors in terms of high efficiency, no aeration need, and low H₂ supply indicated appropriateness of the system for groundwater treatment.     

菌剂挂膜3D-RBC联合BCO工艺处理养猪沼液废水

针对养猪沼液废水寡营养、高氨氮的水质特征,该研究采用耐高氨氮、适应贫营养生长的异养硝化-好氧反硝化（Heterotrophic Nitrification-Aerobic Denitrification,以下简称HN-AD）菌挂膜启动三维结构生物转盘+生物接触氧化反应器（3D-RBC+BCO）组合工艺对沼液进行处理。该文研究了3D-RBC+BCO组合工艺在真实沼液条件下的启动过程及污染物去除效果,重点考察了溶解氧（Dissolved Oxygen,DO）浓度和C/N比2个关键因素对组合工艺污染物去除效果的影响。同时,借助高通量测序技术对DO和C/N比优化过程中微生物群落结构的变化规律进行解析。结果表明：在真实沼液条件下,采用HN-AD菌剂挂膜启动方法,仅用12和18 d就分别完成3D-RBC和BCO反应器的挂膜启动,同时组合工艺对COD、NH4+-N和TN的去除率分别稳定在94.8%、95.7%和80.1%,出水优于城镇污水厂排放一级B标准。在对3D-RBC反应器DO和C/N比的优化过程中,增设底曝后COD、NH4+-N和TN等指标的去除率分别降低了25.4%、15.4%和15.5%。高通量测序结果显示,增加底曝后3D-RBC盘片生物膜中微生物菌属的数量小幅下降,但HN-AD优势菌属的种类与丰度显著降低,导致脱氮效率下降;贫营养型Acinetobacter、Pseudomonas菌属是3D-RBC可以对真实沼液高效脱氮的关键,提高C/N比会显著降低其丰度,进而影响脱氮效果。     

剩余污泥厌氧发酵混合物提高低C/N污水处理效果

为了避免剩余污泥厌氧发酵液利用时泥液难分离的问题,探讨了直接将发酵混合物用作外加碳源处理低碳氮比(C/N)污水的可行性。为此,首先对比了酸性(pH值=4.0±0.2)、中性(不控pH值)、碱性(pH值=10.0±0.2)条件下长期运行的剩余污泥厌氧发酵混合物的特性;其次,分别考察了碱性厌氧发酵混合物的不同投加量(0、10、20、30、50、100、200 mL),在反硝化及释磷过程中的利用。结果表明:碱性条件下溶解性化学需氧量(soluble chemical oxygen demand,SCOD)和短链脂肪酸(short-chain fatty acids,SCFAs)产量要远高于酸性和中性条件的,其中C/N比和C/P比分别高达18.9和57.0,更适合作为外加碳源利用。反硝化过程中,当初始NO_3~--N=(15.0±0.5)mg/L时,最佳投加量为30 mL,此时NO_3~--N去除率为100%;释磷过程中,最佳投加量为20 mL,此时最大净释磷量为22.8 mg/L。剩余污泥碱性厌氧发酵混合物用作外加碳源是可行的,既解决了碳源不足及剩余污泥处理的双重问题,又简化了传统发酵液利用时泥液分离的操作步骤,适用于处理低C/N比乡镇生活污水。     

人工湿地基质对铵氮的动力学吸附研究

Constructed wetlands (CWs) are engineered systems that utilize natural systems including wetland vegetations,soils,and their associated microbial assemblages to assist in treating wastewater.The kinetic adsorption of ammonium nitrogen (NH4+-N) by CW substrate materials such as blast furnace slag (BFS),zeolite,ceramsite,vermiculite,gravel,paddy soil,red soil,and turf,was investigated using batch experiments and kinetic adsorption isotherms.Both Freundlich and Langmuir isotherms could adequately predict the NH4+-N adsorption process.The maximum adsorption capacities of NH4+-N,estimated from the Langmuir isotherm,ranked as:zeolite (33 333.33 mg kg-1) > turf (29 274.01 mg kg-1) > BFS (5 000 mg kg-1) > vermiculite (3 333.33 mg kg-1) > gravel (769.23 mg kg-1) > paddy soil (588.24 mg kg-1) > red soil (555.56 mg kg-1) > ceramsite (107.53 mg kg-1).Some properties of the substrate materials,including bulk density,specific gravity,hydraulic conductivity,uniformity coefficient (K60),curvature coefficient (Cc),organic matter,pH,exchangeable (or active) Cu,Fe,Zn and Mn,total Cu,and Fe,Mn,Zn,Cd,Pb and Ca,had negative correlations with NH4+-N adsorption.Other properties of the substrate materials like particle diameter values of D10,D30 and D60 (the diameters of particle sizes of a substrate material at which 10%,30% and 60%,respectively,of the particles pass through the sieve based on the accumulative frequency),cation exchange capacity (CEC),exchangeable (or active) Ca and Mg,and total K and Mg had positive correlations with NH4+-N adsorption.In addition,active K and Na as well as the total Na had significant positive correlations with NH4+-N adsorption.This information would be useful for selection of suitable substrate materials for CWs.     

潜流人工湿地中3种基质对氮磷净化的影响

通过潜流人工湿地装置,采用间歇运行方式考察不同停留时间下土壤、砾石、炉渣基质在以NO3--N、NH4+-N和PO4--P为主要氮组分的模拟污水对污水中氮的净化效能,并研究湿地系统基质与pH变化、NO3--N和NH4+-N净化效率的关系。结果表明,当水力停留时间为10d时,土壤-炉渣湿地的N,P净化效能高于以其他基质构建的湿地。在试验周期内,各基质的人工湿地系统NH4+-N的净化效率均高于NO3--N的净化效率,氮素的净化效能上层大于下层,湿地系统中pH值先降低后升高的拐点可作为NH4+-N氧化反应结束的指示参数。     

Electrokinetic-enhanced remediation of actual arsenic-contaminated soils with approaching cathode and Fe0 permeable reactive barrier

Purpose

The aim of this study was to investigate the remediation efficiency of actual arsenic-contaminated soils by electrokinetic (EK)-enhanced remediation with approaching cathode and Fe⁰ permeable reactive barrier (PRB).

Materials and methods

Experiments were conducted in a lab-made apparatus consisting of the anode reservoir, the soil specimen chamber, and the cathode reservoir.

Results and discussion

In this study, the enhanced combination methods (approaching cathode and Fe⁰-PRB) were assisted for EK remediation of actual arsenic-contaminated soils under a voltage gradient of 1 V/cm and a treatment period of 96 h. Experimental results showed that arsenic accumulated in the anode sections (I, II) of the soil by employing EK alone with an arsenic removal rate of less than 5%. In contrast, EK-enhanced remediation with either approaching cathode (EK/AC) or Fe⁰-PRB (EK/PRB) reduced the arsenic concentrations in both central and anode sections of the soil and afforded the removal rates of 20% in both cases. However, EK-enhanced remediation with the combination of approaching cathode and Fe⁰-PRB (EK/PRB/AC) reached the removal efficiency of 45% without arsenic accumulation in any soil sections. This phenomenon is mainly caused by the approaching cathode that creates an alkaline environment to promote the migration of arsenic, as well as PRB filled with Fe⁰ that achieves the adsorption and immobilization of arsenic.

Conclusions

The highest remediation efficiency was achieved in the EK/PRB/AC test, which was attributed to the fact that the combination of this two methods solved the problem of arsenic accumulation in treated soil and ensured a more thorough arsenic removal. Furthermore, enhanced remediation efficiency does not elevate the costs.

     

一株具有多途径氮代谢功能的荧光假单胞菌

为研究全自养脱氮过程，采用斯凯尔曼亚硝化单胞杆菌培养基，从南京某城市污水处理厂序批式处理系统（SBR）中分离得到一株具有多途径氮代谢功能的荧光假单胞菌Pseudomonas fluorescens dN13。该菌株在有氧条件下，无有机碳源存在，能进行氧化NH3-N产能代谢生长；有有机碳源存在且NO2^- -N和NO3^- -N的浓度较高时，它能将NO2^- -N和NO3^- -N还原为NH3-N。在厌氧条件下，只有乙酸钠作碳源时，该菌株仍能进行硝酸亚硝酸还原（反硝化）作用。在这个具有多途径氮代谢功能的菌株细胞内，硝化反硝化过程耦合成为可能。     

地下水硝酸盐去除中反硝化微生物的研究进展

地下水硝酸盐污染已经成为一个全球问题,由于饮用高硝酸盐含量的地下水会增加高铁血红蛋白症和癌症风险,地下水硝酸盐污染受到越来越多的关注。反硝化脱氮是地下水硝酸盐脱氮的主要途径之一。本文就参与地下水硝酸盐去除的反硝化微生物种类、反硝化机理、碳源类型以及地下水污染中微生物作用的国内外研究现状进行了较全面系统的评述。在此基础上,提出了该类研究中存在的不足,包括实验室研究较多但野外研究较少,野外原位应用中对特定微生物特性方面研究缺乏,碳源利用率低和硝酸盐去除速度慢,去除过程中有效微生物的代谢途径仍不清楚等问题。针对这些问题,本文认为以后的研究应该进一步开发野外原位应用中反硝化微生物资源,并借助先进的分子方法和功能基因鉴定此类特殊微生物的种类、功能及其生态学行为,选择最佳碳源,完整深入地了解地下水硝酸盐去除中微生物的代谢过程,识别反硝化过程中氮的来源与去向,为寻找提高处理效率的方法提供理论依据,真正将理论和实践结合起来。