共查询到20条相似文献,搜索用时 142 毫秒
1.
A pilot-scale plant consisting of an oxidation basin (OB), a neutralization basin (NB), a reaction basin (RB), and a settling basin (SB) was designed and built to conduct pilot-scale experiments. With this system, the effects of aeration and pH on ferrous oxidation and on precipitation of the oxidized products were studied systemically. The results of pilot-scale tests showed that aeration at 300 L/min was optimum for oxidation of Fe(II) in the OB, and the efficiency of oxidation of Fe(II) increased linearly with increasing retention time. However, Fe(II) was still present in the subsequent basins—NB, RB, and SB. Results from pilot-scale tests in which neutralization was excluded were used to obtain rate constants for heterogeneous and homogeneous oxidation. Oxidation of Fe(II) reached almost 100% when the pH of the mine drainage was increased to more than 7.5, and there was a linear relationship between total rate constant, log (K total), and pH. Absorbance changes for samples from the NB under different pH conditions were measured to determine the precipitation properties of suspended solids in the SB. Because ferrous remained in the inflow to the SB, oxidation of Fe(II) was dominant initially, resulting in increased absorbance, and the rate of precipitation was slow. However, the absorbance of the suspension in the SB rapidly dropped when pH was higher than 7.5. 相似文献
2.
研究了由FeSO4制备聚合硫酸铁过程中,钛对聚铁聚合态分布和稳定性的影响,并进一步考察了含钛聚合硫酸铁的絮凝性能.应用络合比色法对聚铁中不同水解形态聚铁的含量进行了分析测定,并通过沉淀实验考察了不同钛含量对聚铁稳定性的影响;随后,通过出水浊度、TOC、金属离子残余量和出水pH等指标测试,研究了钛对聚合硫酸铁混凝性能的影响.结果表明,较低的钛含量(<0.025)在一定程度上有利于中聚态聚铁的形成,提高了聚铁絮凝剂的混凝效率;反之,钛含量超过0.025时不仅聚铁的稳定性显著下降,而且处理后出水的钛残留增加,pH降低. 相似文献
3.
Xiaowei ZHANG Qinyan YUE Dongting YUE Baoyu GAO Xiaojuan WANG 《Frontiers of Environmental Science & Engineering》2015,9(3):402
Dyes are common pollutants in textile wastewaters, and the treatment of the wastewater has now attracted much attention due to its wide application and low biodegradability. In this study, Fe0/C/Clay ceramics, a kind of novel micro-electrolysis filler, were sintered and employed in a dynamic micro-electrolysis reactor for synthetic Acid Red 73 (AR73) and Reactive Blue 4 (RB4) wastewater treatment. The effects of influent pH, hydraulic retention time (HRT), and aeration on the decoloration efficiencies of AR73 and RB4 were studied. The optimum conditions for wastewater treatment were: AR73, influent pH of 4, HRT of 2 h and aeration; RB4, influent pH of 5, HRT of 6 h and aeration. Under the optimum conditions, decoloration efficiency of AR73 and RB4 wastewater was 96% and 83%, respectively. Results of UV-vis spectrum scanning demonstrated that the chromophores were broken. Continuous running tests showed that improvement of micro-electrolysis system with Fe0/C/Clay ceramics for AR73 and RB4 synthetic wastewater treatment could avoid failure of micro-electrolysis reactor, which indicated great potential for the practical application of the ceramics in the field of actual industrial wastewater treatment. 相似文献
4.
Subsurface geochemical behavior of As(V) with Fe(II) was studied under strict anoxic conditions. Abiotic reduction of As(V) (0.1 mM) to As(III) by aqueous Fe(II) and sorbed Fe(II) in pH range 5.0-7.0 and Fe(II)(aq) concentration (0.6-1.2 mM) was investigated along with the effect of As(V) on the oxidation of Fe(II) by dissolved oxygen (DO). Although the reduction was thermodynamically feasible for homogeneous chemical conditions, practically no As(V) reduction by aqueous Fe(II) was observed. Similarly, no sorbed As(V) reduction was observed under the heterogeneous experimental conditions by sorbed Fe(II) onto synthetic iron oxide (hematite, α-Fe?O?). Experimental results on Fe(II) oxidation by DO in the presence of 0.1 mM As(V) showed a significantly slower Fe(II) oxidation, which might be due to the formation of Fe(II)-As(V) complex in the aqueous phase. The results of this study demonstrate that As(V) is relatively stable in the presence of Fe(II) under subsurface environment and interfere the oxidation of Fe(II). 相似文献
5.
Shikazono N. Tatewaki K. Mohiuddin K. M. Nakano T. Zakir H. M. 《Environmental geochemistry and health》2011,33(1):13-22
Subsurface geochemical behavior of As(V) with Fe(II) was studied under strict anoxic conditions. Abiotic reduction of As(V) (0.1 mM) to As(III) by aqueous Fe(II) and sorbed Fe(II) in pH range 5.0–7.0 and Fe(II)aq concentration (0.6–1.2 mM) was investigated along with the effect of As(V) on the oxidation of Fe(II) by dissolved oxygen (DO). Although the reduction was thermodynamically feasible for homogeneous chemical conditions, practically no As(V) reduction by aqueous Fe(II) was observed. Similarly, no sorbed As(V) reduction was observed under the heterogeneous experimental conditions by sorbed Fe(II) onto synthetic iron oxide (hematite, α-Fe2O3). Experimental results on Fe(II) oxidation by DO in the presence of 0.1 mM As(V) showed a significantly slower Fe(II) oxidation, which might be due to the formation of Fe(II)–As(V) complex in the aqueous phase. The results of this study demonstrate that As(V) is relatively stable in the presence of Fe(II) under subsurface environment and interfere the oxidation of Fe(II). 相似文献
6.
Microwave and Fenton's reagent oxidation of wastewater 总被引:16,自引:0,他引:16
We compared two H2O2 oxidation methods for the treatment of industrial wastewater: oxidation using Fenton's reagent [H2O2/Fe(II)] and microwave irradiation. Both methods were applied to the treatment of synthetic phenol solutions (100 mg L−1) and of an industrial effluent containing a mixture of ionic and non-ionic surfactants at high load (20 g L−1 of COD). The effects of initial pH, initial H2O2 concentration, Fenton catalyst amount and irradiation time were assessed. According to the oxidation of phenol, it has been
found that the oxidation by Fenton's reagent is dependent on the pH, contrary to the microwave system, which is not influenced
by this parameter. For both systems, a limiting amount of oxidant has been found; above this point the oxidation of phenol
is not improved by a further addition of peroxide. The oxidation of the industrial surfactant effluent has only been successful
with the Fenton's reagent. In this case, large amounts of ferrous ions are necessary for the precipitation of the ionic surfactants
of the effluent, followed by the oxidation of the non-ionic constituents of the solution.
Electronic Publication 相似文献
7.
在一套小型搅拌反应器中,研究了碱沉淀(KOH,处理a)、碱沉淀及硫酸盐废水厌氧处理产生的硫化物出水混合(KOH+出水混合,处理b)、碱沉淀及N2吹脱硫酸盐废水厌氧处理产生的硫化物(KOH+N2吹脱,处理c),以及碱沉淀、硫酸盐废水厌氧处理产生的硫化物出水混合和N2吹脱硫化物联合(KOH+出水混合+N2吹脱,处理d)等4组处理方式对含Zn2+、Pb2+的钢丝绳酸洗废水处理效果的影响.废水pH值为0.7,Zn2+和Pb2+含量分别为450和3274 mg.L-1.结果表明,KOH+出水混合+N2吹脱的处理方式对废水有较好的处理效果,Zn2+和Pb2+的去除为氢氧化物、硫化物沉淀的共同作用结果,处理后,废水中Zn2+和Pb2+的去除率均达99.6%以上,满足污水综合排放标准(GB 8978—1996). 相似文献
8.
六方水钠锰矿作为环境中一种具有较强氧化与吸附能力的氧化锰矿物,对环境中的有机染料有着一定的去除作用。采用常压回流法一步合成纳米六方水钠锰矿,运用X射线衍射(XRD)、电感耦合等离子体光谱仪(ICP-AES)、BET氮气吸附法、场发射扫描电镜(FESEM)和透射电镜(TEM)对其矿物晶体结构、化学组成、比表面积、孔径分布和微观形貌进行表征,选用罗丹明(RB)作为目标有机染料,研究反应条件对纳米六方水钠锰矿对RB的去除效果的影响(包括pH值、六方水钠锰矿浓度、染料浓度和温度)。进而研究六方水钠锰矿对RB的去除机制,通过在反应后的溶液中加入盐酸羟胺,使矿物溶解,吸附在矿物上的染料重新释放到溶液中,以区分吸附去除率和氧化去除率。结果表明,降低反应pH、增加六方水钠锰矿浓度、减小染料浓度以及提高温度均有利于六方水钠锰矿对罗丹明B(RB)的去除。其中影响最大的pH,反应体系pH为2.87时,RB的去除率达到99.9%,而pH为10.29时,RB的去除率仅为8.33%。通过去除机制实验结果表明,在pH为4.5时,RB的氧化去除率是36.3%,吸附去除率为4.6%,六方水钠锰矿去除RB以氧化去除为主。纳米六方水钠锰矿材料的重复利用效果很好,重复使用3次去除率,RB的去除率仅从90.6%降至85.9%。合成的纳米六方水钠锰矿有着很好的去除有机染料的效果,并且有一定的重复利用性,机制的研究也有利于提升对有机染料的去除效果。 相似文献
9.
Yingbin Hu Ning Li Jin Jiang Yanbin Xu Xiaonan Luo Jie Cao 《Frontiers of Environmental Science & Engineering》2022,16(7):90
10.
Butler TW 《Environmental geochemistry and health》2006,28(3):231-241
Water samples collected in an acid mine impacted watershed indicated that the concentrations of dissolved trace metals were diurnally influenced by mineral saturation, which is controlled primarily by pH and water temperature. Measurements taken suggested that these variations only occur at sample locations immediately downstream from the confluence of acidic and alkaline waters. It is at these locations where initial mineral precipitation occurred and where subtle changes in solubility were most affected, increasing trace metal removal when both the rate of photosynthesis (influencing pH in headwaters) and water temperature were at a maximum. The role of iron photoreduction (increased midday production of ferrous iron) on overall Cu, Mn, and Zn transport was also evaluated, but found to be inconclusive. Iron photoreduction may however influence adsorption and/or coprecipitation of trace metals through associated changes in oxidation state, solubility, and mineralogy of various iron colloids, which are produced upon the neutralization of acidic, metal enriched water. Furthermore, measured values of copper and zinc were compared to relative USEPA chronic criterion for exposure to continuous concentration (CCC) of metals by the calculation of a “toxicity unit” (TU). It was found that average values of both copper and zinc only exceeded the CCC (TU>1) in the acid mine-impacted Leona Creek. In general, zinc toxicity decreased while copper toxicity increased downstream of the confluence of the mine impacted Leona Creek and background Lion Creek (sampled at Lake Aliso), indicating a significant source of zinc in upstream, non mine-impacted samples. 相似文献
11.
Wenchao Jiang Ping Tang Shuguang Lu Xiang Zhang Zhaofu Qiu Qian Sui 《Frontiers of Environmental Science & Engineering》2018,12(2):6
12.
Gaoling Wei Jinhua Zhang Jinqiu Luo Huajian Xue Deyin Huang Zhiyang Cheng Xinbai Jiang 《Frontiers of Environmental Science & Engineering》2019,13(4):61
13.
In the present study arsenic contaminated simulated water and groundwater was treated by the combination of biological oxidation of tri-valent arsenite [As (III)] to penta-valent arsenate [As (V)] in presence of Acidothiobacillus ferrooxidans bacteria and its removal by adsorptive filtration in a bioreactor system. This method includes the immobilisation of A.ferrooxidans on Granulated Activated Carbon (GAC) capable of oxidising ferrous [Fe (II)] to ferric [Fe (III)]. The Fe (III) significantly converts the As (III) to As (V) and ultimately removed greater than 95% by the bed of GAC, limestone, and sand. The significant influence of Fe (II) concentration (0.1–1.5?gL?1), flowrate (0.06–0.18?Lh?1), and initial As (III) concentration (100–1000?µgL?1) on the arsenic removal efficiency was investigated. The simulated water sample containing the different concentration of As (III) and other ions was used in the study. The removal of other co-existing ions present in contaminated water was also investigated in column study. The concentration of arsenic was found to be <10?µgL?1 which is below Maximum Contaminant Level (MCL) as per WHO in treated water. The results confirmed that the present system including adsorptive-filtration was successfully used for the treatment of contaminated water containing As (III) ions. 相似文献
14.
15.
Hana Měšťánková Gilles Mailhot Jaromír Jirkovský Josef Krýsa Michèle Bolte 《Environmental Chemistry Letters》2009,7(2):127-132
Photodegradation kinetics of Monuron (3-(4-chlorophenyl)-1,1-dimethylurea) in photoreactor with immobilized and suspended
TiO2 photocatalyst were studied. The effect of addition of ferric or ferrous perchlorate was investigated. Whatever the concentration
of Fe(III/II) added there is no significant negative effect on the photodegradation rate of pollutants. On the contrary, depending
on speciation and concentration of iron salts, slight or marked acceleration of the photodegradation kinetics was observed.
This positive influence was more pronounced in the case of TiO2 suspensions than for TiO2 layers. Fe(III) was generally more effective than Fe(II). 相似文献
16.
针对硝基苯污染底泥修复的活性覆盖技术,筛选了适合阻断底泥中硝基苯释放的还原剂和吸附剂.采用的零价铁可迅速将难生物降解的硝基苯还原为苯胺,提高其生物可降解性,有利于将污染物彻底去除.零价铁对硝基苯的还原反应速率随着零价铁剂量的提高而提高,反应速率常数≥>10.001 min~(-1).吸附试验结果表明,在煤渣、活性炭、焦炭以及硅藻土几种常见的吸附剂中,活性炭具有最佳的吸附能力,但是其价格昂贵,不适于大规模应用.而廉价易得的煤渣对硝基苯及其降解产物苯胺具有良好的吸附性能,对硝基苯和苯胺的最大理论吸附量达到924.9 mg·kg~(-1)和1692.2 mg·kg~(-1).因此提出以煤渣为吸附基质,并添加一定比例零价铁的复合活性覆盖材料,为硝基苯污染底泥修复提供一种新的方向和基本参数. 相似文献
17.
以模拟生活污水为研究对象,控制SBR反应器内pH值在7.5~8.5的条件下,实现了短程硝化生物脱氮工艺,NO2--N/NOx--N的比率始终维持在90%以上,同时发现pH值和DO浓度变化特征曲线在短程硝化过程中具有良好的重现性。另外,保持DO浓度在0.5~1.0mg/L,硝化时间为5.5h,可较好的维持短程硝化生物脱氮过程,且经过1个月的运行硝化类型没有发生改变,亚硝酸盐积累率仍保持在90%以上。在此基础上,研究了系统对COD和NH4+-N浓度的抗冲击负荷能力。结果表明,该系统具有较强的抗冲击能力。 相似文献
18.
Surface water enters the Haile Gold Mine, Lancaster County, South Carolina by means of a small stream and is ponded behind
a dam and in an abandoned pit. This water is affected by acidic drainage. In spite of the large exposures of potentially acid
producing pyritic rock, the flux of acid to the water is relatively low. Nevertheless, the resulting pH values of the mine
water are low (around 3.5) due to negligible buffering capacity. In view of the observed low release of acidity, the potential
for acid drainage abatement by limestone ameliorants appears feasible.
This study investigated the effects of limestone treatment on acid generation rates of the Haile mine pyritic rocks through
a series of leaching experiments. Below a critical alkalinity threshold value, solutions of dissolved limestone were found
consistently to accelerate the rate of pyrite oxidation by varying degrees. The oxidation rates were further accelerated by
admixing solid limestone with the pyritic rock. However, after a period of about a month, the pyrite oxidation rate of the
admixed samples declined to a level lower than that of untreated pyrite. Leachates produced by the pyrite and limestone mixtures
contained little if any iron. Further, in the mixtures, an alteration of the pyrite surface was apparent.
The observed behaviour of the treated pyrite appears to be related to the immersion of the pyrite grains within a high alkalinity/high
pH environment. The high pH increases the rate of oxidation of ferrous iron which results in a higher concentration of ferric
iron at the pyrite surface. This, in turn, increases the rate of pyrite oxidation. Above a threshold alkalinity value, the
precipitation of hydrous iron oxides at the pyrite surface eventually outpaces acid generation and coats the pyrite surface,
retarding the rate of pyrite oxidation. 相似文献
19.
水稻土中铁的厌氧生物氧化还原循环对砷的影响(The Effect of Anaerobic Redox Cycling of Iron on Arsenic Mobility in Paddy) 总被引:3,自引:0,他引:3
应用砷污染水稻土的厌氧富集培养,探讨水稻土中潜在存在铁厌氧生物循环及其对氮和砷的耦合作用.富集培养直接证明了水稻土中铁的厌氧生物循环:三价铁(人工合成针铁矿)在厌氧条件下被逐渐还原成二价铁;铁还原过程结束并外源添加硝酸根时,培养基中新生的二价铁在依赖于硝酸根的铁氧化菌的作用下被氧化;当提供新的电子供体乙酸时,生物合成的铁矿重新被还原.在铁氧化还原循环过程中,随着铁的还原,培养基中砷的浓度不断增加,反之,当铁逐渐氧化的同时不断地吸附固定培养基中的砷.在铁的厌氧氧化阶段,铁氧化的同时硝酸根被还原,培养基中积累了NH4+和NO2-.因此,厌氧水稻土中可以进行完整的铁氧化还原循环,同时这个循环过程耦合了氮和砷的迁移转化. 相似文献
20.
Tong Li Ke Xiao Bo Yang Guilong Peng Fenglei Liu Liyan Tao Siyuan Chen Haoran Wei Gang Yu Shubo Deng 《Frontiers of Environmental Science & Engineering》2019,13(6):91