固体废渣制取复合净水剂的研究

研究了以硫铁矿烧渣和电厂粉煤灰为原料,通过酸溶等过程,制取新型复合净水剂－聚硅氯化铝铁的原理和方法,考察了制备工艺条件对产品絮效果的影响。结果表明,硅的引入不但延长了产品的贮存期,而且净水效果明显优于聚合碱式氯化铝。     

硫铁矿烧渣湿法制备铁系产品的原理和途径分析

本文叙述了硫铁矿烧渣的化学成分和物相 ,以及酸浸还原烧渣提取铁的基本原理。论述了硫铁矿烧渣湿法制备铁盐 ,铁氧化物颜料 ,铁基磁粉以及铁粉等铁系产品的原理 ,并对铁系产品的途径进行了分析。     

硫铁矿煤渣湿法制备铁系产品的原理和途径分析

本文叙述了硫铁矿烧渣的化学成分和物相,以及酸浸还原烧渣提取铁的基本原理。论述了硫铁硫烧渣湿法制备铁盐,铁氧化物颜料,铁基磁粉以及铁粉等铁系产品的原理,并对铁系产品的途径进行了分析。     

低品位硫铁矿烧渣制备导电掺合料

采用川南低品位硫铁矿烧渣为主要原料,利用其中的高铁含量及大量活性烧粘土组分,通过在还原气氛下将硫铁矿烧渣与少量还原剂混合粉磨均匀后成型焙烧这一最优工艺,制备电阻率较低的具有胶结性质的导电掺合料,研究了温度、保温时间、配合比、粉磨细度等关键参数对电阻率的影响。结果表明:还原剂为混合料质量分数的9.1%(还原剂与烧渣比值=0.1),5～30 MPa成型后在800℃高温中焙烧60 min,可制备出电阻率为2.02Ω.m的导电掺合料。该方法不仅能解决川南硫铁矿烧渣的综合利用问题,而且工艺流程简单,产品附加值高。     

聚硅酸氯化铝铁絮凝剂制备及絮凝效果的研究

以粉煤灰和硫铁矿烧渣两种工业固体废弃物为主要原料,制取聚硅酸氯化铝铁(PSAFC)无机高分子絮凝剂。粉煤灰、硫铁矿烧渣和纯碱按1：1：0．8混合．在800～900(焙烧15～30min,用定量1：1盐酸浸取,固体溶出率高达94％,陈化后即为PSAFC絮凝剂。通过模拟和真实印染废水絮凝试验．表明PSAFC絮凝效果与聚合氯化铝(PAC)相当,在沉降速度、污泥体积等方面要优于PAC,且成本比PAC低．具有较大的市场前景。     

环境污染与防治 网络版论文摘要

O3／H2O2／UV降解水中邻二氯苯的性能研究,粉煤灰协同H2O2处理酸性黑210^#染料废水的研究,废铁屑修复土壤镉污染初步研究,硫铁矿烧渣制备聚合磷硫酸铁及应用研究,投加煤粉对膜生物反应器处理效果及膜污染的影响     

针对含砷硫酸烧渣酸浸液的铁盐沉淀固砷

为考察含砷硫酸烧渣中酸浸脱砷效果和铁盐沉淀固砷行为,采用常温常压酸浸法脱除硫酸烧渣中的砷,并对进入浸出液中的砷以铁盐沉淀的形式脱除,进而对沉淀渣的浸出毒性进行研究。同时,研究了磨矿细度、酸浓度、固液比、浸出时间对硫酸烧渣中砷脱除效率的影响。结果表明,通过控制浸出参数可以将硫酸烧渣中砷的质量分数降低到0.2%以下,通过调节浸出液的pH和Fe/As摩尔比将其中的砷以沉淀的形式脱除。当Fe/As 2、pH=4～6时,溶液中砷浓度降到了0.5 mg·L~(-1)以下。沉淀砷渣主要是以非晶态的形式存在,提高铁砷比有利于提高砷渣稳定性,从而降低浸出毒性。在Fe/As=3、pH=6.04～6.22的条件下,得到的沉淀渣的浸出毒性为0.711 mg·L~(-1)。因此,通过酸浸脱除硫酸烧渣中的砷,进而采用铁盐沉淀的方法能够实现硫酸烧渣中砷的安全处置。     

硫铁矿烧渣催化类Fenton法深度处理维生素C废水

采用硫铁矿烧渣协同Fe2+催化H2O2的类Fenton法深度处理维生素C制药废水,通过正交实验考察FeSO4投加量、H2O2投加量、搅拌反应时间、曝气时间等因素对低浓度难降解有机物去除的影响程度,并结合单因素实验确定最佳反应条件。结果表明:(1)正交实验中,各因素对催化氧化反应效果的影响程度依次为H2O2投加量搅拌反应时间曝气时间FeSO4投加量;(2)单因素实验中,最佳反应条件为烧渣投加量10g/L、H2O2投加量4.9mmol/L、FeSO4投加量3.9mmol/L、搅拌反应时间20min、曝气时间20min、絮凝沉淀部分聚丙烯酰胺(PAM)投加量5mg/L。在此条件下,COD去除率最高达63.21%。     

基于粒径分布的不同异位修复工艺除Cr特性

以我国某铬盐厂的铬污染土壤为研究对象,采用改进的BCR顺序提取法研究了粒径对不同修复工艺(异位淋洗、异位稳定化、湿法解毒)去除土壤中各形态Cr的影响。实验结果表明:粒径是影响铬渣污染土壤总铬和Cr(VI)去除的关键影响因素之一,粒径越细,越有利于3种异位修复工艺对土壤中Cr(Ⅵ)的去除或还原,粒径越细越有利于异位淋洗工艺对总铬的消减。粒径对水溶态Cr、酸溶态Cr的去除影响显著,粒径越细,水溶态Cr、酸溶态Cr的去除率越高,水溶态Cr和酸溶态Cr的分离或去除是不同异位修复工艺实现铬渣污染土壤中Cr(Ⅵ)高效去除的有效手段;粒径对可还原态Cr的去除影响不显著,pH是影响可还原态Cr去除的主要影响因素;粒径对可氧化态Cr含量提升显著,尤其是对异位稳定化和湿法解毒工艺,粒径越细,可氧化态Cr增大倍数越高;粒径对残渣态Cr的去除影响不显著。     

硫铁矿烧渣和劣质铁尾矿制备聚硅酸铁铝混凝剂

研究了以硫铁矿烧渣和劣质铁尾矿为原料联合制备高效混凝剂聚硅酸铁铝(PSAF)的方法,确定了合理的生产工艺和操作条件。用该混凝剂处理工业废水,并与聚合硫酸铁(PFS)的处理效果比较,结果表明,出水COD和色度去除率分别提高约25%和28%,SS去除率提高约10%。     

Effects of pH and iron concentrations on sulfide precipitation in wastewater collection systems.

Sulfide precipitation by addition of iron salts is a widely used strategy for sulfide control in wastewater collection systems. Several parameters, such as pH, oxidation-reduction conditions, and reactant concentrations, are known to affect the feasibility of the method. However, their combined effects are difficult to predict for complex media, such as wastewater. This study investigates the effect of pH and reactant concentrations on the efficiency of iron sulfide precipitation in anaerobic municipal wastewater. Laboratory experiments showed that, when the pH was below 7, typically less than 40% of the added ferrous iron reacted by sulfide precipitation, although sulfide was in excess. However, when the pH was above 8, almost complete precipitation of all the added ferrous iron was observed. Varying the ferric-iron-to-ferrous-iron ratio demonstrated that improved efficiency could be achieved when using a 1:1 mixture of ferric chloride and ferrous sulfate.     

Evaluation of long-term sulfide oxidation processes within pyrrhotite-rich tailings, Lynn Lake, Manitoba

Oxidation reactions have depleted sulfide minerals in the shallow tailings and have generated sulfate- and metal-rich pore water throughout the East Tailings Management Area (ETMA) at Lynn Lake, Manitoba, Canada. Information concerning the tailings geochemistry and mineralogy suggest the sulfide oxidation processes have reached an advanced stage in the area proximal to the point of tailings discharge. In contrast, the distal tailings, or slimes area, have a higher moisture content close to the impoundment surface, thereby impeding the ingress of oxygen and limiting sulfide oxidation. Numerical modelling of sulfide oxidation indicates the maximum rate of release for sulfate, Fe, and Ni occurred shortly after tailings deposition ceased. Although the sulfide minerals have been depleted in the very shallow tailings, the modelling suggests that sulfide oxidation will continue for hundreds and possibly thousands of years. The combination of sulfide minerals, principally pyrrhotite, that is susceptible to weathering processes and the relatively dry, coarse-grained nature of the tailings have resulted in the formation of a massive-hardpan layer in the proximal area of the ETMA. Because extensive accumulations of secondary oxyhydroxides of ferric iron are already present, remediation strategies for the ETMA should focus on mitigating the release of sulfide oxidation products rather than on preventing further oxidation.     

Regeneration of iron for trichloroethylene reduction by Shewanella alga BrY

Zero valent iron (ZVI), the primary reactive material in several permeable reactive barriers, is often oxidized to ferrous or ferric iron, resulting in decreased reactivity with time. Iron reducing bacteria can reconvert the ferric iron to its ferrous form, prolonging the reduction of chlorinated organic contaminants. In this study, the reduction of Fe(II,III) oxide and Fe(III) oxide by a strain of iron reducing bacteria of the group Shewanella alga BrY(S. alga BrY) was observed in both aqueous and solid phases. S. alga BrY preferentially reduced dissolved ferric iron over the solid ferric iron. In the presence of iron oxide the Fe(II) ions reduced by S. alga BrY efficiently reduced trichloroethylene (TCE). On the other hand, Fe(II) produced by S. alga BrY covered the reactive surfaces of ZVI iron filings and inhibited the reduction of TCE by ZVI. The formation of precipitates on the iron oxide or Fe0 surface was confirmed by scanning electron microscopy. The results suggest that iron-reducing bacteria in the oxidized Fe0 barriers can enhance the removal rate of chlorinated organic compounds and influence on the long-term performance of Fe0 reactive barriers.     

Effects of ferric hydroxide on methanogenesis from lipids and long-chain fatty acids in anaerobic digestion.

The addition of ferric hydroxide to sludge from a municipal anaerobic digester stimulated the rate of methanogenesis from canola oil when the initial oil concentration was high (4600 mg/L; P < 0.002), but not when it was low (920 mg/L; P > 0.05). Similar trends were observed when oleic acid, a fatty acid that is a major component of canola oil triglycerides, was provided, but the effects were statistically significant only when the initial concentration of ferric hydroxide was also high (18 g/L; P = 0.015). Iron reduction occurred when ferric hydroxide was added to microcosms containing anaerobic digester sludge, but the extent of ferrous iron production was much less in acetate-amended microcosms than in those that were provided with canola oil or oleic acid. Methanogenesis and acetate consumption were completely inhibited when the initial acetate concentration was approximately 5000 mg/L, regardless of the initial ferric hydroxide concentration. The main effect of ferric hydroxide in this system appears to have been a result of stimulation of the rate of fatty acid oxidation.     

Zn/Fe体系湿法催化氧化高效脱除沼气中H2S的研究

提出了Zn/Fe体系湿法催化氧化脱除沼气中H₂S新工艺,阐述了反应机理、实验装置和工艺流程,考察了各单因素操作条件对H₂S脱除效率的影响,在此基础上进行的综合条件实验,脱硫效率都维持在99.6%以上,净化后沼气中H₂S含量低于国家标准。过程不消耗任何化工原料,不产生二次污染,体系无降解问题。     

铁盐改性砂制备及其吸附Zn~(2+)的性能研究

通过改变石英砂表面的物理化学性质,提高石英砂的吸附效率,考察其对废水中的Zn~(2+)去除效果.以石英砂为载体,分别用反复高温加热法和反复碱性沉积法制备了三氯化铁改性砂、硝酸铁改性砂,测定2种方法制备的铁盐改性砂的表面含铁量、铁盐的酸稳定性及比表面积,并比较2种铁盐改性砂对Zn~(2+)的吸附效果.结果表明,三氯化铁改性砂、硝酸铁改性砂的比表面积分别为2.468、4.247 m~2/g,比石英砂比表面积分别提高6.910、12.612倍;在pH为中性条件下,石英砂对Zn~(2+)去除率为43%左右,三氯化铁改性砂对Zn~(2+)去除率达到70%左右,硝酸铁改性砂对Zn~(2+)去除率达到85%左右,表明铁盐改性砂对Zn~(2+)去除能力比石英砂有很大提高;铁盐改性砂对Zn~(2+)的吸附有一定容量,表面的活性中心越多,吸附能力越大;铁盐改性砂对Zn~(2+)的去除率随着pH的升高而增加,当pH>8.5时,Zn~(2+)去除率可达90%左右.     

磷酸根和硫离子在纳米铁表面的竞争吸附

通过纳米铁对磷酸根和硫离子的单吸附和竞争吸附的研究,从吸附动力学和吸附等温线两个方面分析并验证了其吸附特性和模式。分析表明,相对于磷酸根,纳米铁对硫离子的吸附能力更强,在竞争条件下居优势地位。采用准一级和准二级吸附动力学方程对实验数据进行模拟分析,结果表明,纳米铁对磷酸根和硫离子的吸附符合二级动力学方程。吸附等温线分析采用Freundlich和Langmuir吸附等温线方程模拟分析,分析结果表明,纳米铁颗粒对磷酸根的吸附符合Freundlich吸附模式,而对硫离子的吸附符合Langmuir吸附模式。     

Adsorption of hydrogen sulfide on montmorillonites modified with iron

Sodium-rich montmorillonite was modified with iron in order to introduce active centers for hydrogen sulfide adsorption. In the first modification, interlayer sodium cations were exchanged with iron. In another modification, iron oxocations were introduced to the clay surface. The most elaborated modification was based on doping of iron within the interlayer space of aluminum-pillared clay. The modified clay samples were tested as hydrogen sulfide adsorbents. Iron-doped samples showed a significant improvement in the capacity for H2S removal, despite of a noticeable decrease in microporosity compared to the initial pillared clay. The smallest capacity was obtained for the clay modified with iron oxocations. Variations in adsorption capacity are likely due to differences in the chemistry of iron species, degree of their dispersion on the surface, and accessibility of small pores for H2S molecule. The results suggest that on the surface of iron-modified clay hydrogen sulfide reacts with Fe(+3) forming sulfides or it is catalytically oxidized to SO2 on iron (hydro)oxides. Subsequent oxidation may lead to sulfate formation.     

Hybrid process for heavy metal removal from wastewater sludge.

Bioleaching processes have been demonstrated to be effective technologies in removing heavy metals from wastewater sludge, but long hydraulic retention times are typically required to operate these bioprocesses. A hybrid process (coupling biological and chemical processes) has been explored in laboratory pilot-scale experiments for heavy metals (cadmium [Cd], copper [Cu], chromium [Cr], and zinc [Zn]) removal from three types of sludge (primary sludge, secondary activated sludge, and a mixture of primary and secondary sludge). The hybrid process consisted of producing a concentrate ferric ion solution followed by chemical treatment of sludges. Ferric iron solution was produced biologically via oxidation of ferrous iron by A. ferrooxidans in a continuous-flow stirred tank (5.2 L) reactor (CSTR). Wastewater sludge filtrate (WSF) containing nutrients (phosphorus and nitrogen) has been used as culture media to support the growth and activity of indigenous iron-oxidizing bacteria. Results showed that total organic carbon (TOC) concentrations of the culture media in excess of 235 mg/L were found to be inhibitory to bacterial growth. The oxidation rate increased as ferrous iron concentrations ranged from 10 to 40 g Fe2+/L. The percentage of ferrous iron (Fe2+) oxidized to ferric iron (Fe3+) increased as the hydraulic retention time (HRT) increased from 12 to 48 h. Successful and complete Fe2+ oxidation was recorded at a HRT of 48 h using 10 g Fe2+/L. Subsequently, ferric ion solution produced by A. ferrooxidans in sludge filtrate was used to solubilize heavy metals contained in wastewater sludge. The best solubilization was obtained with a mixture of primary and secondary sludge, demonstrating a removal efficiency of 63, 71, 49, and 80% for Cd, Cu, Cr, and Zn, respectively.