高铁、高锰、高氨氮地下水的生物同层净化研究

采用生物滤柱净化高铁、高锰、高氨氮地下水,考察了生物净化效果及影响因素.结果表明,在设计滤速为5 m/h,试验用地下水的Fe2+、Mn2+和NH4+-N分别为15、1.5和1.2 mg/L的条件下,生物滤柱对其净化效果良好,但所需滤层较厚(为1.5 m),出水的Fe2+、Mn2+和氨氮分别可降至0.13、0.05和0.26 mg/L;在生物滤柱中,Fe2+的高效去除空间为最上部,NH4+-N的为中、上部,Mn2+的为中、下部;溶解氧为影响生物滤层除锰的关键因素.     

净化低温含铁高锰地下水锰极限浓度的探求

采用生物除铁除锰滤池处理低温含铁高锰地下水,考察了不同滤速下锰的极限浓度。以滤柱模拟水厂滤池,在水温为5~6℃、溶解氧为8.3~8.5 mg/L、进水总铁为0.5~3.0 mg/L的条件下,当滤速分别为6、7、8 m/h时,锰的极限浓度分别为(8.0~8.5)、(7.0~7.5)、(6.0~6.5)mg/L;进水总铁为12~20 mg/L时锰的极限浓度为(5.0~5.5)、(4.3~4.7)、(3.5~3.8)mg/L。沿程分析发现:随着进水锰浓度的升高,锰的去除带逐渐向下延伸;沿滤层向下一定深度,相同厚度滤料的除锰量逐渐减少;锰浓度升高过程中对除铁无影响。在滤层厚度和温度一定的条件下,锰的极限浓度受进水总铁浓度和滤速的影响,进水总铁浓度和滤速较低时其极限浓度较高。     

净化高铁锰伴生氨氮地下水的生物滤池快速启动

采用生物滤池处理高铁、高锰、高氨氮地下水时,存在启动时间长的问题,鉴于此,采用双层滤料、单层滤料回流、单层滤料不回流三种启动方式同时启动三根滤柱,考察双层滤料和回流对启动时间的影响。结果表明,采用双层滤料或回流均能有效缩短启动时间,三根滤柱出水中的总铁、锰、氨氮分别在第82、81、103天降到了0.3、0.05、0.2 mg/L以下。进一步的分析发现,铁主要在0～0.4 m滤层被去除,锰的去除最初是锰砂吸附,当氨氮浓度降到一定程度后,生物除锰效果迅速提高,锰和氨氮均主要在0～0.4 m滤层被去除。     

高铁高锰微污染地下水的生物同层净化研究

向经过曝气的高铁高锰深井地下水中加入生活污水以模拟微污染地下水,并考察了生物除铁除锰滤池对其的净化效果.滤柱高为2.7m,内径为60 mm,内装填除铁除锰能力已经成熟的锰砂,设计滤速为6 m/h.研究了去除有机物滤层的培养过程及在不同滤速下对各污染物的去除规律,结果表明:生物滤柱对微污染地下水具有良好的净化效果,其中,Fe的高效去除区间在滤层上部,Mn和有机物可以实现同层去除,高效去除区间在滤层中下部;当进水有机物浓度较高时,沿程的溶解氧浓度会逐渐降低,导致对CODMn和Mn的去除效果变差,此时应考虑在滤层中部或底部增加曝气来提高溶解氧.     

滤料粒径对地下水中铁、锰、氨氮、浊度去除效果的影响

滤料粒径是生物滤池设计的一个重要参数。采用滤料粒径分别为0. 8~1. 0、3~4、8~10 mm的3根成熟生物滤柱处理地下水,考察滤料粒径对铁、锰、氨氮、浊度去除效果的影响。结果表明,1^#、2^#、3^#滤柱出水的总铁平均浓度分别为0. 020、0. 037、0. 078 mg/L,锰平均浓度分别为0. 003 0、0. 005 1、0. 006 7 mg/L,氨氮平均浓度分别为0. 022、0. 030、0. 050 mg/L,浊度均值分别为0. 28、0. 69、1. 32 NTU,除3^#滤柱出水浊度不达标外,其余指标均满足国家标准。随着滤料粒径的增大,铁、锰、氨氮的沿程浓度明显升高,去除区域向下延伸,浊度主要在0~0. 4 m滤层被去除。     

溶解氧对含氨氮地下水生物除铁除锰效果的影响

采用生物滤柱进行了地下水除铁除锰效果的研究,通过检测滤柱不同滤层深度Mn^2＋、Fe^2＋、NH4^＋-N与DO浓度的变化,研究了各离子的去除效果与DO的关系,并对比了不同DO水平和不同滤速时离子的去除情况。结果表明,铁比锰和氨氮更优先被去除,滤速越低,溶解氧消耗越多。     

生物法去除地下水中铁、锰的影响因素探讨

从量化角度剖析了生物法去除地下水中铁、锰的影响因素.曝气后使地下水中DO为7.0～7.5 mg/L、pH为6.8～7.0时,生物滤层中的锰氧化菌能够保持较好活性及除锰能力,且能够达到铁、锰同除的要求;研究中所提出的"成熟滤料移植"的生物过滤方法,仅适用于对Mn2+吸附能力较强的优质锰砂滤层的接种,而对吸附能力较弱的石英砂滤层只能采用菌量较大的在实验室选择性培养基上培养、驯化锰氧化菌的接种方式;锰砂和石英砂生物滤层的反冲洗强度分别控制在6～9、7～11 L/(s·m2)时,滤层的微生物受扰动较小,反冲后对铁、锰的去除能力也能在5 h内恢复,同时滤层采用粒径为1.0～1.2 mm的均质滤料,在反冲洗强度较低的情况下过滤周期依然可延长至35～38 h.     

BAF工艺处理微污染含铁锰地下水试验研究

采用BAF工艺处理微污染含铁锰地下水,研究了其净化效能和适宜的运行条件.结果表明,在水力负荷为4-5 m3/(m2·h),气水比为3:1-4:1的试验条件下,BAF工艺能有效去除氨氮、锰、铁、CODMn.和浊度.当原水铁含量小于2 mg/L,滤层中部DO在4 mg/L左右时,对氨氮的去除效果最佳.微量Fe2+即可维系滤...     

地下水中氨氮、铁、锰的同步去除及其相互作用

在中试规模条件下,考察了接触催化氧化过滤工艺同步去除地下水中氨氮、铁、锰的效果,研究了三者在去除过程中的交互作用。结果表明:该工艺对原水中的氨氮、铁、锰具有良好的去除效果;铁优先于锰和氨氮被去除,提高进水亚铁离子浓度会导致除氨氮滤层向下迁移,出水氨氮浓度不达标,而铁离子对去除锰离子不产生影响的界限浓度为2 mg/L;提高进水锰离子浓度可以显著促进对高浓度氨氮的去除,表明锰质滤膜对氨氮的去除可能起到了催化氧化的作用。     

高铁高锰高氨氮地下水的两级净化研究

为解决高铁高锰高氨氮地下水同层净化中溶解氧不足的问题,同时提高产水量,进行了两级滤柱串联高速过滤的试验研究,分别启动接触氧化除铁一级滤柱和生物氧化除锰二级滤柱,将两者串联后在10~12 m/h的高滤速下运行。试验结果表明,在高滤速工况下,两级净化工艺能够保证出水水质达标,与单级过滤工艺相比,在单位面积产水量相同的条件下,两级净化系统的运行效果更稳定,具有更强的抗冲击负荷能力。     

Oxidation of arsenite in groundwater using ozone and oxygen

Oxidation of arsenite [As(III)] with ozone and oxygen was investigated in groundwater samples containing 46-62 micrograms/l total dissolved arsenic, 100-1130 micrograms/l Fe and 9-16 micrograms/l Mn. Conversion of As(III), which constituted over 70% of dissolved arsenic in the samples, to As(V) was fast with ozone, but sluggish with pure oxygen and air. Iron and manganese in the samples were also oxidized and, by sequestering the resultant As(V), played a significant role in the rate of reaction. Sorption capacity of freshly precipitated Fe(OH)3 was estimated to be 15.3 mg As/g. The kinetics of As(III) oxidation were interpreted using modified pseudo-first-order reaction. Half-lives of As(III) in experimental solutions involving saturation with each gas were approximately 4 min for the ozone reaction and, depending on the Fe concentrations, 2-5 days for pure oxygen and 4-9 days for air.     

两种改进型垂直潜流人工湿地脱氮途径分析研究

通过对两种改进型垂直潜流人工湿地中垂向沿程DO浓度、氨氮浓度以及硝态氮浓度的考察,从pH角度分析了两种改进型湿地中的脱氮途径.试验发现,两种改进型垂直潜流人工湿地均能满足硝化要求,出水氨氮浓度均能达到<城镇污水处理厂污染物排放标准>(GB 18918-2002)的一级A标准,且改进型序批式垂直潜流人工湿地(MCBW)的脱氮能力大于序批式垂直潜流人工湿地(CBW).此外,通过理论分析和物料衡算得出,序批式垂直潜流人工湿地的脱氮途径主要以传统硝化反硝化为主,而改进型序批式垂直潜流人工湿地中存在着同步硝化反硝化.     

新型生物反应器处理微污染原水的硝化效果

为探寻适宜的微污染原水处理工艺,将蜂窝陶瓷载体置于内循环管中而构成气升式内循环蜂窝陶瓷反应器(IAL-CHS)。采用该工艺处理上海漕河泾水,考察了HRT、水温、pH值、溶解氧对去除氨氮的影响。在反应器挂膜启动后,连续运行的去除效果比间歇运行的好。HRT是影响硝化效果的重要因素,通过连续运行试验确定了最佳的HRT为1.03 h,此时对氨氮的去除率稳定在84.8%～99.2%。对氨氮的去除率与水温近似呈直线关系,温度越高则去除效果越好;河水的pH值对硝化反应影响不大;DO达到3.16 mg/L就能获得较好的处理效果,此时的曝气量为0.15 m3/h。此外,该反应器还具有抗冲击负荷能力强、不易堵塞等优点。     

Biostimulation of iron reduction and subsequent oxidation of sediment containing Fe-silicates and Fe-oxides: effect of redox cycling on Fe(III) bioreduction

Sediment containing a mixture of iron (Fe)-phases, including Fe-oxides (mostly Al-goethite) and Fe-silicates (illites and vermiculite) was bioreduced in a long-term flow through column experiment followed by re-oxidation with dissolved oxygen. The objective of this study was (a) to determine the nature of the re-oxidized Fe(III), and (b) to determine how redox cycling of Fe would affect subsequent Fe(III)-bioavailability. In addition, the effect of Mn on Fe(III) reduction was explored.(57)Fe-M?ssbauer spectroscopy measurements showed that biostimulation resulted in partial reduction (20%) of silicate Fe(III) to silicate Fe(II) while the reduction of goethite was negligible. Furthermore, the reduction of Fe in the sediment was uniform throughout the column. When, after biostimulation, 3900 pore volumes of a solution containing dissolved oxygen was pumped through the column over a period of 81 days, approximately 46% of the reduced silicate Fe(II) was re-oxidized to silicate Fe(III). The M?ssbauer spectra of the re-oxidized sample were similar to that of pristine sediment implying that Fe-mineralogy of the re-oxidized sediment was mineralogically similar to that of the pristine sediment. In accordance to this, batch experiments showed that Fe(III) reduction occurred at a similar rate although time until Fe(II) buildup started was longer in the pristine sediment than re-oxidized sediment under identical seeding conditions. This was attributed to oxidized Mn that acted as a temporary redox buffer in the pristine sediment. The oxidized Mn was transformed to Mn(II) during bioreduction but, unlike silicate Fe(II), was not re-oxidized when exposed to oxygen.     

Oxidation and removal of arsenic (III) from aerated groundwater by filtration through sand and zero-valent iron

Removing arsenic from contaminated groundwater in Bangladesh is challenging due to high concentrations of As(III), phosphate and silicate. Application of zero-valent iron as a promising removal method was investigated in detail with synthetic groundwater containing 500 microg/L As(III), 2-3mg/L P, 20mg/L Si, 8.2mM HCO3-, 2.5mM Ca2+, 1.6mM Mg2+ and pH 7.0. In a series of experiments, 1L was repeatedly passed through a mixture of 1.5 g iron filings and 3-4 g quartz sand in a vertical glass column (10mm diameter), allowing the water to re-aerate between each filtration. At a flow rate of 1L/h, up to 8 mg/L dissolved Fe(II) was released. During the subsequent oxidation of Fe(II) by dissolved oxygen, As(III) was partially oxidized and As(V) sorbed on the forming hydrous ferric oxides (HFO). HFO was retained in the next filtration step and was removed by shaking of the sand-iron mixture with water. Rapid phosphate removal provided optimal conditions for the sorption of As(V). Four filtrations lead to almost complete As(III) oxidation and removal of As(tot) to below 50 microg/L. In a prototype treatment with a succession of four filters, each containing 1.5 g iron and 60 g sand, 36 L could be treated to below 50 microg/L in one continuous filtration, without an added oxidant.     

Manganese concentrations in Scottish groundwater

Groundwater is increasingly being used for public and private water supplies in Scotland, but there is growing evidence that manganese (Mn) concentrations in many groundwater supplies exceed the national drinking water limit of 0.05 mg l^− 1. This study examines the extent and magnitude of high Mn concentrations in groundwater in Scotland and investigates the factors controlling Mn concentrations. A dataset containing 475 high quality groundwater samples was compiled using new data from Baseline Scotland supplemented with additional high quality data where available. Concentrations ranged up to 1.9 mg l^− 1; median Mn concentration was 0.013 mg l^− 1 with 25th and 75th percentiles 0.0014 and 0.072 mg l^− 1 respectively. The Scottish drinking water limit (0.05 mg l^− 1) was exceeded for 30% of samples and the WHO health guideline (0.4 mg l^− 1) by 9%; concentrations were highest in the Carboniferous sedimentary aquifer in central Scotland, the Devonian sedimentary aquifer of Morayshire, and superficial aquifers. Further analysis using 137 samples from the Devonian aquifers indicated strong redox and pH controls (pH, Eh and dissolved oxygen accounted for 58% of variance in Mn concentrations). In addition, an independent relationship between Fe and Mn was observed, suggesting that Fe behaviour in groundwater may affect Mn solubility. Given the redox status and pH of Scottish groundwaters the most likely explanation is sorption of Mn to Fe oxides, which are released into solution when Fe is reduced.Since the occurrence of elevated Mn concentrations is widespread in groundwaters from all aquifer types, consideration should be given to monitoring Mn more widely in both public and private groundwater supplies in Scotland and by implication elsewhere.     

微好氧与厌氧水解酸化对明胶废水的预处理效果

以明胶废水为研究对象,采用微好氧与厌氧水解酸化工艺进行对比处理实验,探讨了不同水力停留时间下微好氧与厌氧水解酸化对明胶废水水质改善的效果。实验结果表明,在水力停留时间达到72h的时候,溶解氧为1.3~1.6mg/L的微好氧反应器的COD去除率最大可达25%,溶解氧为0.3~0.5mg/L的厌氧反应器的COD去除率最大可达22%;微好氧反应器的VFA的含量达到12mg/L左右,厌氧反应器只有8mg/L左右;微好氧反应器的pH值可由最初的12.5降至7.5左右,而厌氧反应器只能降至8.0左右;两个反应器对蛋白质去除效果的差别并不明显,都可以达到90%以上,但是微好氧反应器的氨氮浓度只有22mg/L,小于厌氧反应器中的氨氮浓度,说明微氧条件有利于氨氮的扩散挥发,低浓度的氨氮对微生物的危害较小。对比得出微好氧反应器的出水水质较好,更适合明胶废水水解酸化的预处理。     

组合生态系统氨氮去除最佳单元及其去除机制研究

通过考察稳定塘-湿地组合生态处理系统各单元对氨氮去除速率的差异，提出了去除氨氮的最佳单元类型，分析了该单元对氨氮的主导去除机制。结果表明，在该组合生态处理系统中，水深为1．0m左右、大量生长浮萍等水生植物及溶解氧浓度较高的水生植物塘是去除氨氮的最佳单元。在水生植物塘中，生物吸收（有机氮固定）作用是低温期去除氨氮的主导机制，同步硝化反硝化作用则是高温期去除氨氮的主导机制。