湿地生态系统对污水中重金属的修复作用

湿地污水处理技术的研究是国内外众多学者关注的热点之一。综合国内外在污水湿地处理技术方面的研究成果,对湿地生态系统及其各组成要素对重金属污染的修复作用及其作用机理进行了讨论,针对目前利用湿地生态系统进行重金属污染废水修复过程中应注意的几个问题进行了探讨,并对今后研究发展方向进行了评述。     

植物滞留系统草本植物对人工雨水中铅的富集及去除效果

采用盆栽试验研究4种草本植物(黑麦草,地毯草,早熟禾,高羊茅)对人工雨水中重金属铅的吸收富集和去除效率,并分析测定不同植物滞留系统介质、不同入口浓度情况下,植物地上部与根部铅含量及铅的去除率。结果表明,4种草本植物对人工降雨径流中的铅均有较好的去除效果,铅的平均去除率在94.73%～98.11%之间。不同草本植物去除人工降雨径流中铅的能力,从强到弱依次为高羊茅>黑麦草>地毯草>早熟禾。其中,4种草本植物对铅的去除率随着入口浓度的增加而增加;对于同一种草本植物同样的入口浓度情况下,沙土Ⅱ为最佳土壤介质,具有最佳的去除铅能力。4种草本植物地上部和地下部磷累积量分别在52.51～111.24μg和34.79～73.54μg之间;其中黑麦草铅累积总量最高,其次是地毯草,最低的是早熟禾。综合考虑污染物去除率和铅在植物体内的累积量,交替种植高羊茅和黑麦草能够提高植物滞留系统去除铅的能力且有利于延长植物滞留系统寿命。     

Assisted Washing for Heavy Metal and Metalloid Removal from Contaminated Dredged Materials

In the present study a chemical washing process was applied to dredged sea and river sediments. Five chelating agents (ethylenediaminetetraacetic, nitrilotriacetic, citric, [S,S]-ethylenediaminedisuccinic and oxalic acids), three surfactants (sodium dodecyl sulphate, cetylpyridinium chloride and saponin Q), as well as monobasic potassium phosphate were used as the extracting agents. The effect of sonication was also tested as a conditioning step to couple with chelant-based extraction. The extraction experiments were performed in both single and multiple washing stages. The results indicated that, for given experimental conditions, the remediation efficiency was strongly dependent on the specific contaminant under concern, with contaminant speciation and distribution in the solid matrix as well as affinity for the extracting agent playing a major role in the decontamination process. In this respect, the study also showed that in the presence of multiple contaminants the use of a single extraction agent is not sufficient to attain adequate quality levels for the treated sediment.     

Natural Removal of Crude and Heavy Fuel Oil on Rocky Shorelines in Arctic Climate Regimes

Water, Air, &; Soil Pollution - The ecotoxicity of nickel depends on water quality characteristics such as pH and dissolved organic carbon. Bioavailability models to predict nickel toxicity have...     

Field Performance of Bioretention Systems for Runoff Quantity Regulation and Pollutant Removal

Bioretention systems are of immense importance as they serve as small “sponges” for cities, cutting stormwater runoff, removing pollution, and using precipitation resources. However, performance data for these facilities are generally lacking, particularly at the field scale. This study investigated the runoff quantity regulation and pollutant removal performance of bioswale and rain garden systems from 2014 to 2017. A performance assessment of these facilities demonstrated that anti-seepage rain garden, bioswale-A, and bioswale-B effectively retained inflow volumes by the filter media, reducing runoff volumes by 54.08, 98.25, and 77.65%, respectively, on average, with only two events of overflowing. According to the water quality data in 24 rainfall events, the main pollutant indexes for the new city include total nitrogen and chemical oxygen demand, and the median values for their respective effluent event median concentrations were 1.29 and 40.13 mg/L for anti-seepage rain garden and 1.68 and 74.00 mg/L for bioswale-B systems. The mean values of pollutant removal of the three bioretention systems, except for infiltration rain garden, were 39.8–59.73% (median?=?54.32%), 61.06–72.66% (median?=?73.47%), and 76.67%–88.16% (median?=?80.64%). Meanwhile, outflow volume of water was found to be most influenced by inflow volumes for the bioswales and anti-seepage rain garden. Mass removals were higher than concentrations owing to water volume attenuation. Based on the data of monitored pollution loads, this study estimated the annual pollutant load removal as 75.45 and 90.7% for anti-seepage rain garden and bioswale-B according to the percent of monitoring rainfall depth in total annual precipitation. This study also established the target pollutant service life model on the basis of accumulated annual load and media adsorption capacity. The results of this study will contribute to a greater understanding of the treatment performance of bioretention systems, assisting in the design, operation, and maintenance of them.     

生物滞留设施对地表径流中磷去除效果的研究述评

城市地表径流污染是仅次于农业污染的第二大面污染源。地表雨水径流中含有较高浓度的营养物,若直接排放到城市水体中,会给城市水体造成污染。生物滞留设施作为一种LID原位雨水径流控制措施,水质净化效果非常突出,但也有研究表明该技术对营养物的去除效果较差且很不稳定。在参阅国内外大量文献的基础上,综述了生物滞留设施的研究及运行现状,并针对其目前存在的问题,提出了改善除磷效果的措施,以期为生物滞留设施的进一步研究、设计和运行提供借鉴。     

Seasonal Variability in Stormwater Quality Treatment of Permeable Pavements Situated Over Heavy Clay and in a Cold Climate

Permeable pavements mitigate the impacts of urbanization on surface waters through pollutant load reduction, both by sequestration of pollutants and stormwater volume reduction through exfiltration. This study examined the non-winter water quality performance of two side-by-side permeable pavements in the Ohio snowbelt. The permeable interlocking concrete pavements were designed to drain impervious catchments 2.2 (large) and 7.2 (small) times larger than their surface area, were located over clay soils, and incorporated the internal water storage design feature. Nutrient reduction was similar to past studies—organic nitrogen and particulate phosphorus were removed through filtration and settling, while dissolved constituents received little treatment. Because of 16 and 32 % volume reductions in the small and large installations, respectively, nutrient loads were often significantly reduced but generally by less than 50 %. Aluminum, calcium, iron, magnesium, lead, chloride, and total suspended solids (TSS) concentrations and loads often increased after passing through the permeable pavements; effluent TSS loads were three- to five-fold higher than influent TSS loads. This was apparently due to seasonal release of clay- and silt-sized particles from the soils underlying the permeable pavement and inversely related to elapsed time since winter. The application of de-icing salt is thought to have caused deflocculation of the underlying soils, allowing particulates to exit with stormwater as it discharged from the underdrain of the permeable pavements. By autumn, both permeable pavements discharged metals and TSS concentrations similar to others in the literature, suggesting the de-icing effects lasted 3–6 months post-winter. Sodium may substantially affect the performance of permeable pavements following winter de-icing salt application, particularly when 2:1 clay minerals, such as vermiculites and smectites, predominate.     

Colloidal Carbon-Based Nanoparticles as Heavy Metal Adsorbent in Aqueous Solution: Cadmium Removal as a Case Study

Hydrophilic carbonaceous nanoparticles (HNPs) of uniform sizes with a good degree of dispersion in water were produced from a commercial carbon black by nitric acid treatment. The surface treatment, performed at different reaction times, generates a variable number of oxygen functional groups, mainly carboxylic, which enhance the nanoparticles hydrophilicity and heavy metal adsorption capability. The HNPs were characterized by a number of analytical techniques, including FTIR spectroscopy, thermal and elemental analysis, N₂ adsorption, dynamic light scattering, and zeta-potential measurements. The acid–base properties of the functional groups on the HNPs surface were also investigated by coulometric–potentiometric titrations. Cadmium adsorption tests were carried out in stirred reactors containing colloidal aqueous suspensions of HNPs and HNPs supported over silica. The effects of several parameters, such as the cadmium concentration, the temperature, and the solution pH, were studied. Sorbents showed an appreciable cadmium adsorption capability at different temperatures and in a wide range of pH values comparable or superior to several carbon-based sorbents, indicating a feasible use in commercial units.     

牡蛎壳作生物滞留填料对城市地表径流污染物去除效果研究

选择磷吸附性能最强的牡蛎壳作为填料,在实验室构建3个生物滞留模拟装置(A柱:养殖牡蛎壳;B柱:海滩牡蛎壳;C柱:养殖牡蛎壳存在淹没区),采用道路径流模拟配水作为进水,研究牡蛎壳作为填料对青岛市城市径流常见污染物氮磷及COD的处理效果,并对各污染物去除机理进行探讨。结果表明:3种牡蛎壳填料的生物滞留设施对总磷的去除效果最好,在进水磷浓度为0.57～1.83 mg/L条件下,无淹没区装置平均去除率为96.12%,存在淹没区的装置平均去除率为91.02%。养殖牡蛎壳与海滩牡蛎壳对磷的去除效果并无明显差异,淹没区不利于磷的去除。在前期进水过程中(前5次进水)3个模拟装置氨氮(NH_4~+)的出水浓度高于进水浓度,延长落干期后,装置的NH_4~+去除率均上升,B柱NH_4~+平均去除率(58.83%)相对于A柱(48.77%)及C柱(53.06%)更高,有无淹没区对NH_4~+去除并无明显影响。由于填料中有机物的渗沥,首次进水出现严重COD淋出,在随后的进水过程中,COD去除效果迅速上升并稳定,3个模拟柱去除率分别为50.34%,23.47%和47.75%。由于反硝化作用受阻,对硝氮(NO_3~-)的去除效果不佳。整体看来,养殖牡蛎壳可以应用于青岛市生物滞留设施的填料,为加强滞留设施NO_3~-的去除效果,还需要采用强化脱氮措施。     

Arsenic and Heavy Metal Pollution of Soil,Water and Sediments in a Semi-Arid Climate Mining Area in Mexico

The environmental impact of arsenic and heavy metals on a 105 km² area of the historical and recent mining site of Villa de la Paz-Matehuala, San Luis Potosí (Mexico) was evaluated. Results of soil samples reported concentrations between 19–17 384 mg kg^-1 As, 15–7200 mg kg^-1 Cu, 31–3450 mg kg^-1 Pb and 26–6270 mg kg^-1 Zn, meanwhile, the concentrations in dry stream sediment samples were found to vary between 29–28 600 mg kg^-1 As, 50–2160 mg kg^-1 Pb, 71–2190 mg kg^-1 Cu, and 98–5940 mg kg^-1 Zn. The maximum arsenic concentration in pluvial water storage ponds (265 μg L^-1), near the main potential sources of pollution, exceed by 5 times the Mexican drinking water quality guideline (50 μg L^-1). The arsenic concentrations in water storage ponds and stream sediments decrease as distance from the potential sources increase. A special case is the `Cerrito Blanco' area located 5 km east of Matehuala, where the highest arsenic concentration in water was found (>5900 μg L^-1), exceeding by 100 times the established guideline, thus representing a severe health risk. The results suggest that arsenic and heavy metal dispersion from their pollution sources (historical and active tailings impoundments, waste rock dumps and historical slag piles), is mainly associated in this site with: (1) fluvial transportation of mine waste through streams that cross the area in W–E direction; and (2) aeolian transportation of mineral particles in SW–NE direction. Finally, control measures for pollution routes and remediation measures of the site are proposed.     

Chemically Modified Crop Residues as a Low-Cost Technique for the Removal of Heavy Metal Ions from Wastewater

Batch adsorption experiments were carried out to evaluate the effect of type of crop residues and chemical pretreatment solutions on the removal efficiency of heavy metal ions at different concentrations of synthetic wastewater solutions. Rice straw, cotton stalks, and maize stalks were pretreated with different solutions (i.e., sulfuric acid, oxalic acid, sodium hydroxide, and distilled water as the control treatment) in order to increase their metal-binding capacity. Results indicated that cotton stalks were the best biosorbent material according to their efficiency in removal of heavy metal ions. Sodium hydroxide was the best chemical pretreatment method for stimulating the biosorption capacity of crop residues. Ions of Pb²⁺ had the highest biosorption ratio among all competitive ions, whereas Mn²⁺ ions had the lowest. The removal efficiency decreased as the concentration of heavy metal ions increased in aqueous solutions. Sorption equilibrium isotherms could be described by the Langmuir model in most cases, whereas an isotherm of S shape was observed in other cases, which did not follow the Langmuir isotherm model. In conclusion, cotton stalks pretreated with sodium hydroxide could be used as an efficient technique for wastewater remediation prior to irrigation due to its low-cost, little processing, and high biosorption capacity.     

A Model for Evaluating the Feasibility of an Extraction Procedure for Heavy Metal Removal from Contaminated Soils

A model was developed that allowed for the evaluation of a soil metal cleaning technique in a rapid and cost effective manner. Metal flow (Pb, Cu, Zn, and Cd) during a counter-current soil-acid extraction procedure, consisting of a decarbonation, solubilisation, and washing step, was determined. Required input data are total soil metal content and metal equilibrium distribution coefficients, derived from batch equilibration experiments. The model was calibrated and validated against experimentally obtained results. Model predictions adequately described metal behaviour and removal in each of the extraction steps. Based on the results, optimum operating conditions for the steps involved in the extraction procedure were determined and the feasibility of the counter-current extraction procedure for heavy metal removal from a contaminated soil evaluated.     

Heavy Metal Uptake by Rape

Abstract

In pot experiments, the effect of single and combined pollution of soil by lead (Pb), cadmium (Cd), and zinc (Zn) and uptake of heavy metals in Brassica napus L. were investigated. There were two main factors that affected the assimilation of Pb, Cd, and Zn by rape: (i) level of soil pollution by the particular element and (ii) the combined influence of Pb, Cd, and Zn. In general, with the increase of the concentrations of Pb, Cd, and Zn in the soil, there were increases in the concentrations of those elements in the roots, stems, and seeds. The main part of the Pb and Zn amounts taken up by the roots from the soil are fixed and accumulated in the roots, and small amounts of them move through the conductive system to the seeds. Cadmium moves relatively easily from root to stem and is accumulated in higher concentrations in the top of the plant.

There is a well‐expressed synergistic interaction between Pb²⁺ and Cd²⁺, as well as of Cd²⁺ and Zn²⁺. Zinc has a highly depressing effect on the assimilation of Cd²⁺, as does Pb²⁺ on the assimilation of Zn²⁺. The combined pollution by Pb, Cd, and Zn stimulated the assimilation of these elements by the roots and foliage and eliminated the effect of Zn²⁺ on Cd²⁺ and of Pb²⁺ on Zn²⁺.     

皂角苷增强洗脱复合污染土壤中多环芳烃和重金属的作用及机理

通过增溶实验和土壤洗脱实验,研究了一种生物表面活性剂——皂角苷（saponin）对多环芳烃-重金属复合污染土壤的洗脱作用及机理。结果表明,皂角苷对菲、芘等多环芳烃有极强的增溶作用,当皂角苷浓度为0.04%时,菲、芘在液相中的表观溶解度分别增大了约22倍和128倍,因而皂角苷能显著增强多环芳烃污染土壤中菲、芘的洗脱,洗脱效率最大分别可达84.1%和81.4%,增大了约2倍和17倍。皂角苷可与重金属离子形成水溶性的络合物,从而增强洗脱重金属污染土壤中的Zn^2＋和Cd^2＋,在皂角苷浓度为0.4%时,Zn^2＋、Cd^2＋的洗脱效率分别可达93.0%和79.4%,增大了约75倍和8倍。皂角苷可同时洗脱多环芳烃-重金属复合污染土壤中的菲、芘和Zn^2＋、Cd^2＋,洗脱效率分别达87.6%、83.5%和92.3%、78.6%,重金属的存在略增大了皂角苷对菲、芘等多环芳烃的洗脱效率,但多环芳烃对Zn^2＋、Cd^2＋的洗脱效率没有明显影响。皂角苷可同时增强洗脱复合污染土壤中的多环芳烃和重金属,从而为多环芳烃-重金属复合污染土壤的修复奠定基础。     

三种无机萃取剂去除土壤中PbCd的条件研究

通过对重金属污染土壤的萃取实验,比较了HCl、Na2S2O3、CaCl2 3种常用无机萃取剂对重金属Ph和cd的萃取效果,并通过改变萃取条件（萃取剂浓度、时间、固液比、萃取次数和温度）,以期找到各种萃取剂达到最大萃取效率时所需的萃取条件。结果表明,萃取剂浓度对于萃取效率的影响最大,随着浓度的提高,3种萃取剂对Ph、Cd的去除作用增强;固液比和萃取次数对Ph、Cd的去除率也有较大的影响;时间对两金属的去除率也有一定的影响,但在本实验条件下,达到萃取平衡所需时间很短;温度对萃取效率的影响很小。本实验中,HCl去除Pb、Cd的能力远远大于其他两种萃取剂。对Cd进行萃取时,需增加萃取次数才能达到较好的萃取效果。     

我国烟用肥料中重金属含量调查分析

采集了我国12个主要植烟省份2010—2011年期间使用的95个烟用肥料样品(其中有机肥样品28个、无机复混肥样品39个、磷肥样品13个、钾肥样品15个),测定了其重金属As、Cd、Cr、Hg和Pb的含量。结果表明:我国烟用肥料中重金属含量均低于相应的国家限量标准,无超标现象,其中Pb、Cr含量相对较高,Cd、As、Hg含量相对较低;磷肥中5类重金属含量都较高,无机复混肥中As、Cd、Pb含量较高,有机肥中Hg、Cr含量较高,钾肥中Cr和Cd含量较高;黄淮烟区的肥料重金属含量较高,尤其是Cd和Cr。     

Heavy Metals Removal in a Horizontal Rotating Tubular Bioreactor

Mixed microbial culture was isolated from heavy metal-contaminated ground soils located inside iron, vinyl and cement factory area. Isolated mixed microbial culture was used for the heavy metal ions (Fe²⁺, Cu²⁺, Ni²⁺ and Zn²⁺) removal process in horizontal rotating tubular bioreactor (HRTB). In this research, the effect of bioreactor process parameters on the bioprocess dynamics in the HRTB was studied. Results of this research have shown that profiles of heavy metals concentration were gradually reduced along HRTB at all combinations of bioreactor process parameters [inflow rates (0.5?C2.0 L?h^-1) and rotation speed (5?C30 min^-1)]. Hydrodynamic conditions and biomass sorption capacity have main impact on the metal ions removal efficiency that was varied in the range of 38.1% to 95.5%. Notable pH gradient (cca 0.7 pH unit) along the HRTB was only observed at the inflow rate of 2.0 L?h^-1. On the basis of obtained results, it is clear that medium inflow rate (F) has higher impact on the heavy metal removal process than bioreactor rotation speed (n) due to the fact that increase of inflow rate was related to the reduction of equilibrium time for all examined metal ions. Furthermore, equilibrium times for all metal ions are significantly shorter than medium residence times at all examined combinations of bioreactor process parameters. The main impact on the biofilm sorption capacity has covalent index of metal ions and biofilm volumetric density. The sorption capacity of suspended microbial biomass is closely related to its concentration. Results of this research have also shown that the removal of heavy metals ion can be successfully conducted in an HRTB as a one-step process.     

重金属镉、铜在苹果幼树体内的分布特性及生物有机肥对减少重金属效应的研究

通过土壤追施镉、铜,研究了重金属在红富士苹果幼树体内的分布特性以及生物有机肥影响红富士苹果幼树根系吸收重金属的效应.结果表明,重金属镉、铜在苹果植株不同器官含量分布顺序为根系>二年生枝>一年生枝>叶片;根系富集铜的能力大于镉; 生物有机肥可以减少根系对铜的吸收.在低剂量处理下,施用生物肥处理的根系铜含量比不施用的降低15%,在中、高剂量处理下,根系铜含量降低幅度分别为30%和50%; 生物有机肥可以降低苹果根系对镉元素的吸收.在低、中、高剂量处理下,施用生物有机肥处理的苹果根系中镉含量比不施用生物肥处理分别降低了12%,15%,24%.随着土壤中镉浓度加大,生物肥处理的根系镉含量降低的效果越明显,在高剂量处理下,镉含量降低幅度最大.生物有机肥减少根系吸收铜的效果比镉更明显.