人工湿地填料除砷效率及影响因素试验研究

人工湿地是净化含砷水体的重要途径之一,而填料是决定人工湿地除砷效果的关键因素。通过填料如砾石、锰砂、沸石和陶粒的理化性质的测定,以及各种填料的吸附动力学、吸附等温线和吸附影响因素试验,研究了填料的除砷性能及影响因素。结果表明:4种填料均能在24 h内达到吸附平衡,一级动力学方程和二级动力学方程能很好地拟合其吸附过程;锰砂、陶粒、沸石和砾石最大吸附容量依次为36.62,25.39,11.96,7.04 mg/kg,Freundlich方程能较好地拟合填料的等温吸附过程;在0.25~0.50 mm范围内,粒径对锰砂和陶粒吸附砷影响不显著;溶液中氨氮浓度在0.50~2.50 mg/L范围内几乎不影响填料对砷的吸附;当砷初始浓度低于0.4 mg/L时,磷酸盐在0.25~0.50 mg/L范围内对填料吸附砷的影响不显著;砷初始浓度高于0.4 mg/L时,随着磷酸盐浓度从0.25 mg/L增加至0.50 mg/L时,陶粒对砷的最大吸附量降低了2.57 mg/kg,对锰砂的吸附量降低了1.85 mg/kg。     

天然沸石对地下水中铁锰的吸附性能研究

地下水常含有铁锰,吸附法除铁除锰简单实用。采用天然沸石对地下水中铁锰进行吸附试验研究。试验结果表明:天然沸石对铁锰的吸附符合弗劳德利希吸附等温式,去除率随着沸石投加量的增大而逐渐提高;原溶液浓度越高,铁、锰的吸附量则越大;原溶液浓度不同时,铁的去除率随原溶液浓度增加而逐渐下降;锰的去除率在溶液浓度5 mg/L时呈现下降趋势;铁和锰的最佳吸附时间分别为30 min和20 min,铁锰吸附时间大于相应最佳吸附时间时,则两者吸附量都会下降。为期70 d的试验表明,天然沸石除锰效果不好,出水水质最低含锰量超过0.1 mg/L,出水水质基本都没达到国家标准(≤0.1 mg/L),而除铁的出水水质基本都在国家饮用水卫生标准值0.3 mg/L以内,最低值接近0.0 mg/L,其整体除铁效果要好于除锰。     

Fenton接触氧化法强化石英砂—锰砂滤料处理铁锰矿井废水

为了解决目前常用的接触氧化法除铁除锰工艺中铁离子存在时锰离子难去除的问题,本文重点研究了Fenton接触氧化法强化石英砂-锰砂滤料的除铁除锰效率和机理。结果表明:Fenton试剂+锰砂+石英砂工艺除铁锰的效果很好,影响因素的最佳值如下:加入H2O2形成Fenton试剂后可以强化石英砂-锰砂工艺除铁除锰的效果,当H2O2投加量为0.15 mg/L、滤速为8 m/h、pH为7时,铁离子的去除率可达到92%,当H2O2投加量为0.17mg/L、滤速为8 m/h、pH为7时,锰离子的去除率可以达到97%。     

Distribution and removal efficiency of heavy metals in two constructed wetlands treating landfill leachate

The results of heavy metals (Fe, Mn, Zn, Ni, Cu, Cr, Pb, Cd) removal and partitioning between aqueous and solid phases at two treatment wetlands (TWs) treating municipal landfill leachates are presented. One of the TWs is a surface flow facility consisting of 10 ponds. The other TW is a newly constructed pilot-scale facility consisting of three beds with alternately vertical and horizontal subsurface flow. The metals concentrations were analysed in leachate (both TWs) and bottom sediments (surface flow TW). Very high (90.9-99.9%) removal rates of metals were observed in a mature surface flow TW. The effectiveness of metals removal in a newly constructed pilot-scale sub-surface flow wetland were considerably lower (range 0-73%). This is attributed to young age of the TW, different hydraulic conditions (sub-surface flow system with much shorter retention time, unoxic conditions) and presence of metallic complexes with refractory organic matter.     

Enhancing phosphorus removal in constructed wetlands with ochre from mine drainage treatment.

No single end-use has yet been identified that is capable of consuming the projected production of ochre (mainly iron (III) oxides) from mine drainage treatment. However, the high sorption capacity of ochre for phosphorus (up to 26 mg kg(-1)) means that it could be used in constructed wetlands to enhance phosphorus removal. Laboratory batch experiments showed that coarse-grained ochre removes 90% of all phosphorus forms from sewage effluent after 15 minutes of shaking. From a larger-scale experiment, it is estimated that constructed wetlands with an ochre substrate should remove phosphorus from sewage effluent for up to 200-300 years. The suitability of ochre for phosphorus removal is being investigated at the field scale in a wastewater constructed wetland (175 m2 area) in Berwickshire, UK. The hydraulic and treatment performance of the wetland were monitored for 15 months prior to installation at the inlet in November 2003 of a tank containing approximately 1200 kg ochre. Results so far show that improved hydraulic design is required for ochre to increase the mean phosphorus removal efficiency of the system (27 +/- 28%), but potentially toxic metals (Al, Cd, Cr, Cu, Fe, Ni, Pb, Zn) have not been released from the ochre into the wetland outflow.     

温度和基质对人工湿地脱氮除磷效果的影响

构建由潜流人工湿地和表流人工湿地串联而成的复合人工湿地系统,研究了复合人工湿地脱氮除磷效果以及温度和基质对人工湿地脱氮除磷效果的影响。结果表明,复合人工湿地TP、氨氮平均去除率为33.64%、57.24%;水温降低会导致人工湿地氮磷去除率下降;基质为粗砂的潜流人工湿地脱氮除磷能力大于基质为砾石的潜流人工湿地。     

Chemical Loadings to Southwestern Lake Superior from Red Clay Erosion and Resuspension

Inputs of chemical parameters were calculated from estimated erosion and resuspension data and by using experimental measurements of chemical releases from both bluff samples and Lake Superior sediments in suspensions with Lake Superior water. The ability of suspended clay particles to remove manganese and copper ions from Lake Superior water was investigated. The loadings of easily leachable dissolved solids, phosphorus, nitrogen, chloride, silica, sodium, potassium, calcium, magnesium, aluminum and heavy metals from shoreline erosion and resuspended sediment were small compared to Lake Superior tributary inputs. Suspended sediment particles have a large capacity to remove copper and manganese ions from Lake Superior water. Each kilogram of suspended sediment particles of clay size can remove 175 mg of copper and 11 mg of manganese in Lake Superior water spiked to contain 10 μg/L of each metal.     

Mechanical resistance properties of gravel used in subsurface flow constructed wetlands: implications for clogging

Gravel constitutes the filter medium in subsurface flow constructed wetlands (SSF CWs) and its porosity and hydraulic conductivity decrease over time (clogging), limiting the lifespan of the systems. Using gravel of poor quality accelerates clogging in wetlands. In this study, gravel samples from six different wetland systems were compared with regards to their mineral composition and mechanical resistance properties. Results showed that both mineralogy and texture are related to mechanical resistance. Accordingly, gravel with high content of quartz (> 80%) showed a lower percentage of broken particles (0.18-1.03%) than those with lower content of quartz (2.42-4.56% media broken). Although granite is formed by high durability minerals, its non-uniform texture results in a lower resistance to abrasion (ca. 10% less resistance than calcareous gravel). Therefore, it is recommended to use gravels composed mainly of quartz or, when it is not available, limestone gravels (rounded and uniform) are recommended instead. The resistance to abrasion (LAA test) seems to be a good indicator to determine the mechanical properties of gravels used in CWs. It is recommended to use gravels with LAA below 30% in order to avoid a rapid clogging due to gravel crumbling and subsequent mineral solids accumulation.     

Trace Element Concentrations in Near-Surface Waters of the Great Lakes and Methods of Collection,Storage, and Analysis

From 1980 through 1985, waters of the Great Lakes were sequentially sampled for dissolved, paniculate, and total trace elements. Major sampling occurred in 1980 for Lake Huron, in 1981 for Lakes Erie and Michigan, in 1983 for Lake Superior, and in 1985 for Lake Ontario. Great care was taken during collection, storage, and analysis to prevent sample contamination and to document any contamination occurring. Trace elements measured by atomic absorption techniques were silver, aluminum, arsenic, boron, barium, beryllium, bismuth, cadmium, cobalt, chromium, copper, iron, mercury, lithium, manganese, molybdenum, nickel, lead, antimony, selenium, tin, strontium, vanadium, and zinc. All results were field and laboratory blank corrected. Excluding aluminum, barium, iron, and strontium, concentrations of trace elements in most of the Great Lakes were a few ppb or less, with many elements being below one ppb. Element concentrations were highest in Lakes Erie and Michigan and lowest in Lakes Huron and Superior. All five Great Lakes had more than 50% of their total iron, aluminum, and manganese associated with paniculate matter.     

太阳能曝气人工垂直潜流湿地去除生活污水氮磷的试验研究

利用芦苇和砾石构建太阳能曝气人工垂直潜流湿地处理生活污水。设定水力负荷400 mm/d,气水比10∶1,当进水氨氮(NH₄-N)、总氮(TN)、溶解性反应磷(SRP)和总磷(TP)平均浓度为5.14,7.56,0.40,0.53 mg/L时,引入太阳能曝气后,各自的平均去除率分别提高24.8%,9.4%,15.7%和11.5%。随着气温下降和进水浓度降低,湿地微生物脱氮除磷能力下降,曝气对改善生活污水氮磷去除作用不显著。对试验系统而言,太阳能曝气湿地基本建设费用是无曝气湿地的2.85倍;但以20 a运行为基础折算出的污水处理费比无曝气湿地仅高0.02元/m³。综上,从污染去除性能和污水长期处理费用来看,太阳能曝气湿地在生活污水处理方面具有较好的技术经济优势。     

Quantification of biofilms in a sub-surface flow wetland and their role in nutrient removal.

Subsurface flow wetlands contain gravel or sand substrates through which the wastewater flows vertically or horizontally. The aims of this study were, firstly, to quantify biofilm development associated with different size gravel in sections of a subsurface flow wetland with and without plants, and secondly, to conduct laboratory experiments to examine the role of biofilms in nutrient removal. Techniques to quantify biofilm included: bacterial cell counts, EPS and total protein extraction. Based on comparative gravel sample volume, only EPS was greater on the smaller 5 mm gravel particles. There was no significant difference between biofilm growth in sections with and without plants. Two vertical flow laboratory-scale reactors, one containing fresh wetland gravel, the other containing autoclaved gravel, were constructed to determine nutrient transformations. The autoclaved gravel in the "sterile" reactor rapidly became colonised with biofilm. Both reactors were dosed with two types of influent. Initially the influent contained 7.25 mg/L NO3-N and 0.3 mg/L NH4-N; the biofilm reactor removed most of the ammonium and nitrite but nitrate concentrations were only reduced by 20%. In the "sterile" reactor there was negligible removal of ammonium and nitrite indicating little nitrification, however nitrate was reduced by 72%, possibly due to assimilatory nitrate reduction associated with new biofilm development. When the influent contained 3 mg/L NO3-N and 16 mg/L NH4-N almost 100% removal and transformation of NH4-N occurred in both reactors providing an effluent high in NO3-N. Organic P was reduced but inorganic soluble P increased possibly due to mineralisation.     

垂直潜流锰砂人工湿地处理钢铁废水

研究了以锰砂为填料的垂直流人工湿地处理钢铁废水的效果,试验结果表明:湿地系统对CODCr、Fe、Mn、TP、NH3-N的平均去除率分别为52%、97%、94%、95%和83%.夏季湿地对各种污染物的去除效果最好.HRT在2～5 d时,其改变对污染物的去除影响很小,低温条件对NH3-N的去除效果有一定的影响.对以Fe、Mn、浊度的去除为目的的人工湿地而言,在南方的冬季仍可达到良好效果.     

沸石处理农村高铁锰地下水的改性研究

采用廉价易得的沸石矿物处理高铁锰地下水,用3种不同方法对天然沸石改性,强化其对铁锰的吸附效果。试验结果表明：采用NaCl改性,随着NaCl浓度的升高,改性后沸石对铁锰吸附量明显提高,在NaCl浓度饱和时达到最高,铁去除率提高了13.81%,锰去除率提高了26.4%;采用盐酸改性,随着盐酸浓度的增大,沸石吸附铁锰的量增加;随着微波对沸石作用时间的增加,沸石对铁锰的吸附量大幅度提升,在10min以后趋于平稳。3种改性方法中,NaCl改性最为经济有效。     

Influence of groundwater composition on subsurface iron and arsenic removal

Subsurface arsenic and iron removal (SAR/SIR) is a novel technology to remove arsenic, iron and other groundwater components by using the subsoil. This research project investigated the influence of the groundwater composition on subsurface treatment. In anoxic sand column experiments, with synthetic groundwater and virgin sand, it was found that several dissolved substances in groundwater compete for adsorption sites with arsenic and iron. The presence of 0.01 mmol L(-1) phosphate, 0.2 mmol L(-1) silicate, and 1 mmol L(-1) nitrate greatly reduced the efficiency of SAR, illustrating the vulnerability of this technology in diverse geochemical settings. SIR was not as sensitive to other inorganic groundwater compounds, though iron retardation was limited by 1.2 mmol L(-1) calcium and 0.06 mmol L(-1) manganese.     

不同pH值条件下重金属捕集剂有效性的研究

采用高分子有机捕集剂与废水中的多种重金属离子发生螯合反应,生成稳定且不溶于水的金属螯合物来去除废水中的重金属离子。对4种捕集剂在不同pH值的条件下对含有汞、铜、镉、铅等重金属污水的去除效果进行了试验研究。结果表明,利用重金属捕集剂方法处理重金属废水的效率较高,有很好的应用前景。     

Use of laboratory-grown bacterial alginate in copper removal

Industrial production leads to toxic heavy metal pollution in water bodies. Copper is one of the examples that requires removal from effluents before being discharged. It is difficult and sometimes very expensive to remove toxic heavy metals by conventional treatment techniques. This study aims to remove copper by the use of bacterial alginate as a non-conventional technique. Bacterial alginates (natural polymers composed of mannuronic and guluronic acid monomers) were synthesized by Azotobacter vinelandii ATCC(?) 9046 in a laboratory fermentor under controlled environmental conditions. The alginates produced, with a range of different characteristics in terms of monomer distribution and viscosity, were investigated for maximum copper uptake capacities. The average copper uptake capacities of alginates produced were found to be about 1.90 mmol/L Cu(2+)/g alginate. Although the GG-block amount of alginates was varied from 12 to 87% and culture broth viscosities were changed within the range of 1.47 and 14 cP, neither the block distribution nor viscosities of alginate samples considerably affected the copper uptake of alginates.     

北方某人工湿地净化能力分析

在对北方某人工湿地长期观测取得的大量详尽数据的基础上,分析了人工湿地系统总体净化能力和潜流人工湿地水质动态变化特征。结果表明:该人工湿地示范工程对水质净化效果较为明显,对各类污染物的去除率平均可达40%;潜流人工湿地可对污水进行深度处理,对BOD5、NH4-N的去除效果最好,去除率为80%～90%,对NO3-N、TN的去除效果较好,去除率为65%～75%,对CODMn和SS的去除效果一般,去除率为40%～60%,对TP的去除效果随着时间推移逐渐减弱,碎石吸附对TP去除起主要作用。     

Determination of toxic heavy metals in sea water by FAAS after preconcentration with a novel chelating resin

A solid phase extraction procedure was developed for preconcentration of toxic heavy metals such as cadmium, cobalt, copper, manganese, lead and zinc in sea water samples. A microcolumn packed with 6-[(4-hydroxyphenyl)diazenyl]naphthalene-2,3-diol-formaldehyde (HPDN-F) resin acts as a sorbent to retain the analyte ions by forming metal chelates. The retained trace level metal was subsequently eluted with 1 mol/L HCl and the acid eluent was analysed by Flame Atomic Absorption Spectrophotometer (FAAS). The HPDN-F chelating resin and its metal chelates were characterized by spectral and thermal analysis. The chelating property of the HPDN-F resin towards divalent metal ions was studied as a function of pH and preconcentration flow rate. The recoveries of cadmium, cobalt, copper, manganese, lead and zinc under the optimum working conditions were above 95%. The relative standard deviations were < 2%. The limits of detection were < 0.1 microg/L. The method presented was applied for the determination of cadmium, cobalt, copper, manganese, lead and zinc in sea water samples.     

Development of a horizontal subsurface flow modular constructed wetland for urban runoff treatment

Constructed wetlands (CWs) are well recognized as having low construction and maintenance cost and low energy requirement. However, CW design has been mainly based on rule-of-thumb approaches. In this study, the efficiency of a modular horizontal subsurface flow (HSSF) CW using four different design schemes was investigated. Based on the results, the four systems have attained more than 90% removal of total suspended solids and more than 50% removal efficiency for total phosphorus, PO(4)-P and Zn. The planted system achieved higher pollutant removal rates than the unplanted system. In terms of media, bottom ash was more effective than woodchip in reducing the pollutants. Considering the flow length, optimum removal efficiency was achieved after passing the sedimentation tank and vertical media layer; with respect to depth, more pollutants were removed in the upper sand layer than in the lower gravel layer. This study recommended a surface area of 0.25 to 0.8% of catchment area for planted CW and 0.26 to 0.9% for unplanted CW using the 7.5 to 10 mm design rainfall.     

Co-precipitation of Ni, Cr, Mn, Pb and Zn in industrial wastewater and sediment samples with copper(II) cyclo-hexylmethyldithiocarbamate for their flame atomic absorption spectrometric determination

A co-precipitation technique for nickel(II), chromium(II), manganese(II), lead(II) and zinc(II) with the aid of copper(II) cyclo-hexylmethyldithiocarbamate was established. The influences of some analytical parameters such as pH, sample volume, amounts of cyclo-hexylmethyldithiocarbamate and copper(II) on the recovery of metal ions were investigated. The heavy metals in the precipitate were determined by flame atomic absorption spectrophotometry. The range of detection limits for the heavy metals was 0.003-0.005 mg/L. The atomic spectrometric technique with co-precipitation procedure was successfully applied for the determination of Ni, Cr, Mn, Pb and Zn in industrial wastewater and sediment samples from Ladipo stream in Lagos, Nigeria. The mean concentrations for these metals using co-precipitation procedure were not significantly different from corresponding concentrations obtained using spectrometric techniques without co-precipitation procedure.