具氮、磷吸附特性的多孔混凝土材料优选

研究了粒径在25～30mm的天然沸石、浮石、钢渣、砾石在低浓度下对溶液中氮、磷的吸附特性,优选出具氮、磷高效吸附的多孔混凝土材料;通过静态试验和动态试验研究,对数据进行模型拟合及回归分析,得到了各材料对氮、磷的饱和吸附量.结果表明:4种材料对溶液中氨氮的吸附能力大小排列为沸石＞浮石＞钢渣＞砾石,对总磷的吸附能力大小依次为浮石＞钢渣＞沸石＞砾石.沸石对氨氮和浮石对总磷的吸附结果均能很好的拟合Lagergren准二级反应动力学模型.静态试验中当氨氮浓度为2 mg/L时,沸石对氨氮的吸附容量相应为116.28 mg/kg;浮石在总磷浓度为0.2 mg/L时,浮石对总磷的饱和吸附量为10.06 mg/kg.动态试验中各材料吸附效果明显优于静态吸附效果,在氨氮浓度为5 mg/L时,沸石对氨氮的吸附量达到了823 mg/kg,在总磷浓度为0.5 mg/L时浮石对总磷的吸附量为49 mg/kg.沸石和浮石可作为具氮、磷吸附特性的多孔混凝土优选材料.     

硫酸铝钾改性活性氧化铝除氟性能研究

为提高活性氧化铝对氟的吸附能力,采用硫酸铝钾对其进行改性处理,考察了硫酸铝钾浓度、改性时间、固液比、吸附时间、p H值、温度等因素对改性活性氧化铝吸附性能的影响,确定了除氟剂的最佳改性条件是:10 g/L的硫酸铝钾溶液按固液比为1 g∶7 m L浸泡活性氧化铝4h。通过连续吸附试验考察了改性活性氧化铝除氟性能,并验证了其可再生性、无二次污染。结果表明:活性氧化铝改性后的饱和吸附量为1.59 mg/g,是未改活性氧化铝的2.7倍。     

铁砷复合污染下铁砷比对除砷效果的影响研究

针对铁砷复合污染型地下水,以原水铁砷比作为控制参数,通过烧杯试验研究了曝气接触氧化除铁工艺的除砷效果。结果表明,当初始砷含量分别为100,200,300和400μg/L时,原水铁砷比分别为35∶1,50∶1,52∶1和55∶1,能达到除铁效果且同时满足出水砷含量小于10μg/L的限值要求;根据氢氧化铁对砷的吸附机理,利用Freundlich吸附等温式建立了铁砷比与残余砷含量的数学模型,试验数据拟合结果与模型相吻合。此外,采用曝气氧化工艺处理铁砷复合污染地下水时,可以通过投加二价铁盐控制原水铁砷比,以实现同时去除铁砷的目的。     

受硝基苯污染松花江原水的应急处理工艺研究

针对受硝基苯污染的松花江原水,通过小试和生产性试验研究了粉末活性炭吸附协同高锰酸盐复合药剂（PPC）强化复合铝铁（PAF）混凝工艺对硝基苯的去除效果.小试结果表明,粉末活性炭（PAC）对硝基苯的吸附遵循一级反应动力学模型,达到吸附平衡大约需40 min,在硝基苯的平衡浓度为5.0μg/L时,PAC对其吸附容量大约为2 mg/g.根据试验结果,将PAC的投加点选在松花江饮用水源地,投加量为40 mg/L;当PPC的投量为0.3～0.5 mg/L时有明显的强化混凝效果.生产性试验的结果表明,当原水硝基苯浓度为25.9～66.2μg/L时,经PAC在取水管道中吸附约2 h后,进厂水的硝基苯浓度稳定在2μg/L以下,滤后水的硝基苯浓度＜1μg/L,滤后水的浊度在1 NTU左右。PAC预吸附协同PPC强化PAF混凝是控制受污染松花江水中硝基苯的一种有效应急工艺。     

混凝-微滤工艺处理含氟地下水的试验研究

采用混凝-微滤工艺进行了地下水除氟的试验研究.静态试验表明了硫酸铝的混凝除氟效果比聚合硫酸铝的更佳.动态试验中发现,在改善饮用水水质及降低运行成本方面,采用CO2降低反应体系的pH比采用H2SO4更具有优越性.当原水F^-浓度为2.74 mg/L、硫酸铝投加量为154 mg/L、混凝反应器内CO2的溶入量为183.2 mg/L时,出水F^-浓度为0.98 mg/L、浊度＜0.10 NTU、UV254为0.012 cm^-1、Al^3＋＜0.02 mg/L、SO4^2-浓度为125.77 mg/L、pH值为7.51,出水水质满足《生活饮用水卫生标准》（GB 5749-2006）的要求.     

载锰活性氧化铝除氟降铁效能研究

针对我国北方地区地下水型饮用水水源地铁氟超标问题,采用硫酸铝和硫酸锰改性制备载锰活性氧化铝对地下水进行同步除氟降铁,并通过静态试验和动态试验分析载锰活性氧化铝除氟降铁的影响因素、去除机理和再生效果。结果表明,活性氧化铝改性后表面呈现不规则凸起刺状颗粒结构,并出现锰的氧化物和氢氧化物特征峰,碱式氧化锰成功附着在氧化铝表面,改性后的除氟效果比改性前提高了70%,铁离子和氟离子去除率分别可以达到80. 5%和81%。BoxBehnken响应曲面试验模型得出,载锰活性氧化铝去除氟离子和铁离子的最优参数如下:吸附时间为8 h、pH值为4、温度为25℃,其中p H值对除氟降铁的影响最大。载锰活性氧化铝吸附氟离子的动力学过程符合准二级动力学方程,吸附等温线符合Freundlich模型,表明该吸附过程主要以多层化学吸附为主。动态试验结果表明,载锰活性氧化铝的出水氟超标时间由原来的11 h延长至27h,铁离子达标时间由原来的60 h缩短至5 h。改性后的载锰活性氧化铝的除氟降铁效果大大提高。经过3次再生后,载锰活性氧化铝滤柱的氟离子吸附量从0. 7 mg/g降低至0. 6 mg/g,再生后的载锰活性氧化...     

铁改性活性氧化铝的制备及其除As(Ⅴ)性能

以活性氧化铝(AA)为原料,采用铁盐浸渍法制备负载铁氧化物的活性氧化铝(FAA)除砷吸附剂。采用BET、SEM和EDS等技术对其进行表征,并考察了投加量、pH值、共存离子对FAA除砷的影响。结果表明,铁盐浸渍法能有效地将铁氧化物负载于活性氧化铝上;初始pH值在2～10时除砷效率能达到95%;除砷性能受SiO_3~(2-)和H_2PO_4~-的影响较大,Ca~(2+)、CO_3~(2-)、SO_4~(2-)对除砷性能基本无影响;吸附等温线符合Langmuir等温吸附模型,吸附除砷过程符合准二级动力学方程;采用50 g铁改性活性氧化铝连续过滤砷含量为40～60μg/L的地下水,能获得约590 L砷达标出水,表明铁改性活性氧化铝具有一定实际应用潜力。     

黄河水体对北郊水源地砷污染的影响研究

通过分析北郊水源地砷污染现状、黄河对地下水补给和影响以及黄河水质泥沙中砷含量与地下水关系几个方面,研究了黄河水体对地下水砷超标的影响。检测数据表明,水源地区域黄河水体中砷、铁和锰的平均含量分别为2.75μg/L、0.44 mg/L、0.14 mg/L,铁、锰含量均高于集中式生活饮用水地表水源地补充项目标准限值(0.3 mg/L和0.1 mg/L),加之水体为氧化环境,Eh为30.9~78.2 m V,致使水中微量砷会被粘土颗粒及形成的铁/锰氧化物或氢氧化物吸附沉积,并在地层中富集。由于黄河水本身含有一定浓度砷,强蒸发作用加剧了潜水-微承压含水层砷的富集,但是黄河水及沙层沉积物中砷含量释放能力有限。     

C_3S和C_2S对萘系高效减水剂的吸附研究

采用紫外-可见吸收光谱法测定了萘系高效减水剂(FDN)在C_3S,C_2S颗粒表面的吸附量,并对该减水剂在这2种单矿物颗粒表面的吸附行为进行了研究.结果表明:C_3S,C_2S对FDN的极限吸附量随着时间的延长而变小;在相同的水化时间下,FDN在C_3S颗粒上的吸附量略大于在C_2S颗粒上的吸附量;当初始质量浓度ρ_0小于1020mg/L时,C_3 S,C_2S对FDN的吸附量随着时间的延长而增大,当ρ_0大于1300mg/L时,它们对FDN的吸附量随着时间的延长而减小.     

预氧化-化学沉淀法去除水中砷的试验研究

研究了预氧化-化学沉淀法对水中砷的去除效果及其影响因素。结果表明,原水砷质量浓度为5倍标准限值时,在NaClO预氧化条件下,投加8 mg/L的聚合氯化铝可使砷去除率达到84%,且出水砷含量可以满足《生活饮用水卫生标准》(GB 5749—2006)限值要求;在KMnO4预氧化条件下,投加8 mg/L的聚合氯化铝可使砷去除率达到90%,且出水砷含量满足标准限值要求,而投加8 mg/L的聚合硫酸铁可使出水砷含量降至18.72μg/L,无法满足标准限值要求;采用聚合氯化铝作为混凝剂时的除砷效果优于聚合硫酸铁,以KMnO4作为预氧化剂时的除砷效果优于NaClO。     

Arsenic removal from aqueous solutions by adsorption on magnetite nanoparticles

Magnetite nanoparticles were used to treat arsenic‐contaminated water. Because of their large surface area, these particles have an affinity for heavy metals by adsorbing them from a liquid phase. The results of the study showed that the maximum arsenic adsorption occurred at pH 2, with a value of approximately 3.70 mg/g for both As(III) and As(V) when the initial concentration of both arsenic species was maintained at 2 mg/L. The study showed that, apart from pH, the removal of arsenic from contaminated water also depends on the contact time, the initial concentration of arsenic, the phosphate concentration in the water and the adsorbent concentration. The results suggest that arsenic adsorption involved the formation of weak arsenic–iron oxide complexes at the magnetite surface. At a fixed adsorbent (magnetite nanoparticles) concentration of 0.4 g/L, percent arsenic removal decreased with increasing phosphate concentration. Magnetite nanoparticles removed <50% of arsenic from water containing >6 mg/L phosphate. In this case, an optimum design for achieving high arsenic removal by magnetite nanoparticles may be required.     

Conventional oxidation treatments for the removal of arsenic with chlorine dioxide, hypochlorite, potassium permanganate and monochloramine

Arsenic is widespread in soils, water and air. In natural water the main forms are arsenite (As(III)) and arsenate (As(V)). The consumption of water containing high concentration of arsenic produces serious effects on human health, like skin and lung cancer. In Italy, Legislative Decree 2001/31 reduced the limit of arsenic from 50 to 10 μg/L, in agreement with the European Directive 98/83/EC. As consequence, many drinking water treatment plant companies needed to upgrade the existing plants where arsenic was previously removed or to build up new plants for arsenic removal when this contaminant was not previously a critical parameter.Arsenic removal from water may occur through the precipitation with iron or aluminum salts, adsorption on iron hydroxide or granular activated alumina (AA), reverse osmosis and ion exchange (IE). Some of the above techniques, especially precipitation, adsorption with AA and IE, can reach good arsenic removal yields only if arsenic is oxidized.The aim of the present work is to investigate the efficiency of the oxidation of As(III) by means of four conventional oxidants (chlorine dioxide, sodium hypochlorite, potassium permanganate and monochloramine) with different test conditions: different type of water (demineralised and real water), different pH values (5.7-6-7 and 8) and different doses of chemicals.The arsenic oxidation yields were excellent with potassium permanganate, very good with hypochlorite and low with monochloramine. These results were observed both on demineralised and real water for all the tested reagents with the exception of chlorine dioxide that showed a better arsenic oxidation on real groundwater than demineralised water.     

Effects of water chemistry on arsenic removal from drinking water by electrocoagulation

Exposure to arsenic through drinking water poses a threat to human health. Electrocoagulation is a water treatment technology that involves electrolytic oxidation of anode materials and in-situ generation of coagulant. The electrochemical generation of coagulant is an alternative to using chemical coagulants, and the process can also oxidize As(III) to As(V). Batch electrocoagulation experiments were performed in the laboratory using iron electrodes. The experiments quantified the effects of pH, initial arsenic concentration and oxidation state, and concentrations of dissolved phosphate, silica and sulfate on the rate and extent of arsenic removal. The iron generated during electrocoagulation precipitated as lepidocrocite (γ-FeOOH), except when dissolved silica was present, and arsenic was removed by adsorption to the lepidocrocite. Arsenic removal was slower at higher pH. When solutions initially contained As(III), a portion of the As(III) was oxidized to As(V) during electrocoagulation. As(V) removal was faster than As(III) removal. The presence of 1 and 4 mg/L phosphate inhibited arsenic removal, while the presence of 5 and 20 mg/L silica or 10 and 50 mg/L sulfate had no significant effect on arsenic removal. For most conditions examined in this study, over 99.9% arsenic removal efficiency was achieved. Electrocoagulation was also highly effective at removing arsenic from drinking water in field trials conducted in a village in Eastern India. By using operation times long enough to produce sufficient iron oxide for removal of both phosphate and arsenate, the performance of the systems in field trials was not inhibited by high phosphate concentrations.     

粉末活性炭对水中呋喃丹的吸附性能研究

考察了粉末活性炭吸附去除水中呋喃丹的可行性,并采用Freundlich公式拟合去离子水和自来水条件下的吸附等温方程.结果表明,采用粉末活性炭可有效去除水中的呋喃丹,在去离子水条件下,呋喃丹初始质量浓度为0.035 mg/L,投炭量为20 mg/L,吸附时间为120 min时,呋喃丹的去除率大于98％.根据吸附等温方程计...     

Well-head arsenic removal units in remote villages of Indian subcontinent: field results and performance evaluation

Since 1997, over 135 well-head arsenic removal units have been installed in remote villages in the Indian state of West Bengal bordering Bangladesh. Every component of the arsenic removal treatment system including activated alumina sorbent is procured indigenously. Each unit serves approximately 200-300 households and contains about 100 L of activated alumina. No chemical addition, pH adjustment or electricity is required for operating these units. The arsenic concentration in the influent varies from around 100 μg/L to greater than 500 μg/L. In the treated water, arsenic concentration is consistently below 50 μg/L. The units are capable of removing both arsenites and arsenates from the contaminated groundwater for several months, often exceeding 10,000 bed volumes. In the top portion of the column, the dissolved iron present in ground water is oxidized by atmospheric oxygen into hydrated Fe(III) oxides or HFO particles which in turn selectively bind both As(III) and As(V). Upon exhaustion, these units are regenerated by caustic soda solution followed by acid wash. The arsenic-laden spent regenerant is converted into a small volume sludge (less than 500 g) and contained over a coarse sand filter in the same premise requiring no disposal. Many units have been operating for several years without any significant operational difficulty. The treated water is used for drinking and cooking. Most importantly, the villagers are responsible for the day to day operation and the upkeep of the units.     

粉末活性炭对甲基对硫磷和对硫磷的去除研究

通过对粉末活性炭吸附特性的研究,探讨了活性炭工艺去除饮用水中甲基对硫磷和对硫磷有机磷农药的可行性。用Freundlich公式拟合吸附等温线的数据,并用来估算活性炭的吸附容量和最大投加量。试验结果表明,向甲基对硫磷、对硫磷浓度分别为0.22,0.06mg/L的配水中投加10mg/L粉末活性炭,吸附时间20min时两者的去除率为93.66%～98.11%。针对南方某水厂原水,试验所确定的活性炭最佳投加量为1.5～2.0mg/L。试验证明投加粉末活性炭是去除饮用水中甲基对硫磷和对硫磷的有效方法。     

臭氧催化氧化去除水中MTBE的连续流试验

通过连续流试验,考察了流速、臭氧初始浓度、臭氧分解以及甲基叔丁基醚(MTBE)在催化剂上的吸附对高硅沸石、氧化镁、活性氧化铝催化臭氧氧化分解水中MTBE的影响。结果表明,高硅沸石对臭氧和MTBE有很强的吸附能力,经高硅沸石吸附后,出水臭氧浓度0.2 mg/L,而氧化镁、活性氧化铝对MTBE几乎没有吸附能力;高硅沸石与氧化镁都具有一定的催化臭氧氧化分解MTBE的能力,且高硅沸石和氧化镁催化臭氧氧化分解MTBE的效果均随臭氧初始浓度的增加而提高,随流速的增大而降低。     

粉末活性炭去除水中石油类污染物的试验研究

以0#柴油为研究对象,考察了粉末活性炭对水中石油类污染物的吸附性能.结果表明,采用粉末活性炭可有效去除水中的石油类污染物,当柴油初始质量浓度为3 mg/L,吸附时间为30 min,投炭量为20 mg/L时,纯水及原水条件下柴油的去除率均大于70％,且在最大投炭量(80 mg/L)条件下,粉末活性炭可以应对在纯水和原水条...     

粉末活性炭对内吸磷的吸附性能研究

研究了粉末活性炭对內吸磷的吸附去除效果以及吸附时间、活性炭投加量和水质条件对吸附效果的影响.结果表明,当內吸磷质量浓度为0.30 mg/L,活性炭投加量为20 mg/L时,在去离子水中吸附60 min后,出水內吸磷为0.02 mg/L;在去离子水中的吸附效果优于原水,在实际应用中需根据原水水质适当调整活性炭投加量或吸附...