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Groundwater in the area of eastern Croatia contains high concentrations of iron, manganese, ammonia, organic substances and arsenic. The appearance of inorganic arsenic in groundwater is mainly caused by arsenic from natural geological sources. Since the groundwater is the main source of drinking water for the population in this area, almost 200,000 people are daily drinking water with arsenic concentration ranging from 10 to 610 μg/L. The Croatian legislation recently revised the maximum concentration limit (MCL) for arsenic in drinking water to 10 μg/L. The population in the two towns (Osijek and Vinkovci) of this region is supplied with groundwater processed by coagulation-filtration method, but in the other towns and villages water treatment implies only rapid sand filtration. Both methods for water treatment have resulted with higher arsenic concentration than MCL, so the main goal of this study was determination of population exposure to arsenic via drinking water and possible improvement of drinking water quality. Population exposure to arsenic via drinking water is determined with hair analysis, since the hair arsenic concentration is one of three most commonly employed biomarkers used to identify or quantify overall arsenic exposure. During this study the preliminary analyses of hair arsenic concentrations in several towns and villages in eastern Croatia were provided. The positive correlation between heightened arsenic concentration in drinking water and hair arsenic concentration was determined. In order to improve drinking water quality e.g. arsenic removal from contaminated drinking water, different modified adsorbents were used and compared (zeolite–clinoptilolite, manganese greensand and cationic exchange resin). Adsorbents were chemically modified and saturated with Fe(III) ions, while the arsenic solutions were prepared by processed groundwater. 相似文献
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Juan M. Triszcz Andrs Porta Fernando S. García Einschlag 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2009,150(2-3):431-439
Owing to newly established water quality standards, the use of the zero-valent iron (ZVI) method for arsenic removal is gaining attention. The spontaneous chemical oxidation of ZVI by dissolved oxygen, a complex process involving a variety of metastable ferrous–ferric intermediate species, was studied in short-term batch experiments using two different commercially available ZVI materials. Differences in corrosion rates may be attributed to the different specific reactivity of these materials. The effects of pH, ZVI loading, initial conductivity and dissolved oxygen concentration on both Fe(II) and Fe(III) kinetic profiles were investigated. ZVI corrosion rates in the presence of As(III) and As(V) were also studied. Depending on the pH, the concentrations of Fe(II) and Fe(III) are significantly influenced by the presence of As(III) and As(V). Our results may be important from a technological point of view, since it is well known that iron corrosion rates govern the generation of sites for arsenic removal. 相似文献
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Effect of operating conditions in removal of arsenic from water by nanofiltration membrane 总被引:2,自引:0,他引:2
The removal of arsenic from synthetic waters and surface water by nanofiltration (NF) membrane was investigated. In synthetic solutions, arsenic rejection experiments included variation of arsenic retentate concentration, transmembrane pressure, crossflow velocity and temperature. Arsenic rejection increased with arsenic retentate concentration. Arsenic was removed 93-99% from synthetic feed waters containing between 100 and 382 μg/L as V, resulting in permeate arsenic concentrations of about 5 μg/L. Under studied conditions, arsenic rejection was independent of transmembrane pressure, crossflow velocity and temperature. In surface water, the mean rejection of As V was 95% while the rejection of sulfate was 97%. The co-occurrence of dissolved inorganics does not significantly influence arsenic rejection. The mean concentration of As in collected permeated was 8 μg/L. The mean rejection of TDS, total hardness and conductivity were 75, 88 and 75% respectively. 相似文献
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烃类裂解原料脱砷方法及催化剂失活分析 总被引:4,自引:1,他引:3
本文概述了液态烃脱砷方法及特点,运用物理化学等实验方法对茂名乙烯脱砷催化剂工艺失败原因进行了测试分析,总结出可能是催化剂本身物理强度不足及生产前期等原因所致。 相似文献
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对沉淀法深度净化窑法磷酸中的铁、铅和砷进行了研究。理论计算表明,采用亚铁氰化铁沉淀法除铁,可以将w(Fe)降低至≤1 mg/kg;采用硫化物沉淀法除铅、除砷,当净化液中c(S)≥9.46×10-5mol/L时,可以将w(Pb)和w(As)分别降至10 mg/kg、1 mg/kg。实验结果表明,当亚铁氰化钠加入量为理论量、反应温度为50℃时,w(Fe)降至0.001 9%(折合w(H3PO4)85%磷酸中);当五硫化二磷加入量为理论量4.6倍、反应温度为20~30℃以及反应时间为0.5 h时,w(Pb)和w(As)分别降至7.5 mg/kg、0.15 mg/kg(折合w(H3PO4)85%磷酸中)。上述净化指标均达到了工业级磷酸国家标准(GB/T 2091—2008)的要求。 相似文献
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Arsenic removal by coagulation and filtration: comparison of groundwaters from the United States and Bangladesh 总被引:4,自引:0,他引:4
Arsenic contamination of drinking water is a concern in many parts of the world. In the United States, the Environmental Protection Agency recently reduced the maximum contaminant level of arsenic in drinking water from 50 to 10 μ/L (ppb). In Bangladesh the arsenic concentration in drinking water can be as high as hundreds of parts per billion while the maximum contaminant level is 50 ppb. Consequently, there is a great need for new cost-effective methods to remove arsenic from drinking water. Here arsenic removal by coagulation and filtration was investigated using groundwater from a city in southern Colorado in the United States and from Sonargaon in Bangladesh. The results of the bench-scale experiments conducted indicate that coagulation with ferric ions followed by filtration is effective in reducing arsenic concentration in the water tested. However, the actual efficiency of removal is highly dependent on the raw water quality. Further, addition of a polyelectrolyte coagulant aid may lead to improved permeate fluxes during tangential flow microfiltration but has little effect on the residual arsenic concentration. 相似文献
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地下水除铁除锰水厂反冲洗废水混凝试验研究 总被引:1,自引:0,他引:1
通过试验,研究了地下水除铁除锰水厂反冲洗废水混凝处理的效果、影响因素以及混凝机理。结果表明,CPF和PAM的混凝效果最好,氯化铁次之,PAC较差,硫酸铝最差;含铁量为100mgL左右的冲洗废水自然沉淀效果较差,而投加少量混凝剂后,这种冲洗废水可在较短的时间内获得很好的沉淀效果;在混凝后的最初的10.30min内,废水上清液的含铁量急剧下降,此后随着沉淀时间的增加,上清液含铁量缓慢降低;当pH值为7.5左右时,硫酸铝、氯化铁和PAC的混凝机理可能以电性中和作用与吸附架桥作用为主,PAM可能主要是吸附架桥作用,而CPF的混凝机理除了吸附架桥作用以外,还可能存在一定的电性中和作用。 相似文献
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Cemile 《中国化学工程学报》2021,37(9):121-127
In this study,a sequential process (heterotrophic up-flow column and completely mixed membrane bioreactors) was proposed combining advantages of the both processes.The system was operated for 249 days with simulated and real groundwater for nitrate removal at concentrations varying from 25 to 145 mg·L-1 NO3-N.The contribution of heterotrophic process to total nitrate removal in the system was controlled by dozing the ethanol considering the nitrate concentration.By this way,sulfur based autotrophic denitrification rate was decreased and the effluent sulfate concentrations were controlled.The alkalinity requirement in the autotrophic process was produced in the heterotrophic reactor,and the system was operated without alkalinity supplementation.Throughout the study,the chemical oxygen demand in the heterotrophic reactor effluent was (23.7 ± 22) mg·L-1 and it was further decreased to(7.5 ± 7.2) mg·L-1 in the system effluent,corresponding to a 70% reduction.In the last period of the study,the real groundwater containing 145 mg·L-1 NO3-N was completely removed.Membrane was operated without chemical washing in the first 114 days.Between days 115-249 weekly chemical washing was required. 相似文献
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Nitrate removal from groundwater by a novel three-dimensional electrode biofilm reactor 总被引:3,自引:0,他引:3
The contamination of nitrate in groundwater has become an ever-increasing environmental problem. To improve denitrification rate effectively, a novel three-dimensional (3D) bio-electrochemical reactor was developed, which introduced activated carbon (AC) into the cathode chamber as the third bipolar electrode. The influence parameters such as temperature, pH, current and initial nitrate loading were investigated systematically. The role of the third electrode was explored and a possible denitrification mechanism was suggested. The presence of AC not only provided much more sites for biofilm formation and hydrogen gas yield, but also produced carbon dioxide to afford a favorable anoxic environment. Thus, the 3D reactor showed good denitrification performance in wider conditions. The denitrification rate could reach 0.222 mg NO3 N/cm2/d while the current efficiency could reach as high as 227%, indicating promising for nitrate removal from groundwater. 相似文献
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水相氧化法脱除黄磷中砷的研究 总被引:1,自引:0,他引:1
采用水相氧化法,使用硝酸溶液和氧化增强剂进行工业黄磷脱砷试验。对硝酸质量分数、氧化增强剂中铁与黄磷中砷的质量比、硝酸溶液与黄磷的体积比、反应时间与反应温度等因素对黄磷中砷的脱除率的影响进行了单因素实验,并通过正交实验,得到了水相氧化法脱除黄磷中砷的最优工艺条件,即硝酸质量分数25%,反应温度65℃,铁与砷的质量比60,硝酸与黄磷体积比5:1,反应时间4h。实验结果表明,在最优条件下,可使黄磷中砷的质量分数由310mg/kg降至15mg/kg。水相氧化法工艺流程和设备简单,操作安全,易于实现工业放大。 相似文献
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《Journal of Industrial and Engineering Chemistry》2014,20(3):887-896
Arsenic removal from water was investigated using activated carbon. The chemical activated carbon (CAC) prepared using H3PO4 from jute stick largely featured micropore structure with surface functional groups, while meso- and macropore structures were mainly developed in physical activated carbon (PAC). The CAC and PAC reduced arsenic concentration to 45 and 55 μg L−1, respectively, from 100 μg L−1 while iron-loaded CAC reduced to 3 μg L−1, which is lower than the upper permissible limit (10 μg L−1). The micropore structure of CAC along with complexation affinity of iron species towards arsenic species attributed to enhanced separation of arsenic. 相似文献
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In this work, the removal of arsenic (III) using zeolite/chitosan nanocomposite membranes was studied and characterized using scanning electron microscopy (SEM), atomic force microscope (AFM), etc. The water contact angle of the membrane decreased from 74.2 to 59.2° and the porosity of the prepared membranes increased from 20.38 to 45.81% with an increase in the concentration of zeolite. The rejection of arsenic (III) increases with increase in the zeolite loading for 500 and 1000 µg/L; but at 100 and 150 µg/L, the trend was opposite. The membrane with 1.0 [Chi-Z (1.0)] and 1.25 [Chi-Z (1.25)] wt% zeolite showed the highest rejection (>94%) for 1000 µg/L concentration of arsenic trioxide aqueous solution. 相似文献