The application of flotation for the downstream separation of metal-loaded microorganisms

The studied innovative wastewater treatment process involved the initial abstraction of heavy metal ions onto fungal or stalks biomass (biosorption), followed by the application of a typical flotation stage for the efficient downstream separation of metal-laden biosorbent particles. The ability of microorganisms to remove metal ions from dilute aqueous solutions is a well-known property. Flotation originated from the minerals' processing field; however, it has nowadays found application in the wastewater treatment field. The two processes of biosorption and flotation can be efficiently combined, forming the so-called 'biosorptive flotation' process.     

The process of flotation: an efficient solid/liquid separation technique for biological materials

The studied innovative wastewater treatment process involved the initial abstraction of heavy metal ions onto fungal or stalks biomass (biosorption), followed by the application of a typical flotation stage for the efficient downstream separation of metal-laden biosorbent particles. The ability of microorganisms to remove metal ions from dilute aqueous solutions is a well-known property. Flotation originated from the minerals' processing field; however, it has nowadays found application in the wastewater treatment field. The two processes of biosorption and flotation can be efficiently combined, forming the so-called 'biosorptive flotation' process.     

Flotation of metal-loaded clay anion exchangers. Part I: the case of chromates

Synthetic hydrotalcite-like layered materials are known for their ability to remove anions, like the chromates. These sorbents usually exist in powder form, thereby exhibiting high surface area and rapid kinetics for adsorption, but presenting appreciable problems in the subsequent solid/liquid separation process. Almost complete removals were obtained in this paper, from batchwork dispersed-air flotation in presence of a flocculant. Due to the experienced difficulty of flotation of thermally activated (at 500 degrees C) hydrotalcite metal-loaded particles, the application of various surfactants was studied. Continuous-flow laboratory runs certified also the effectiveness of this combined process of sorptive flotation, a promising innovative treatment technology.     

Flotation of metal-loaded clay anion exchangers. Part II: the case of arsenates

Hydrotalcite-like materials, or otherwise termed layered double hydroxides, are clays with an ability to remove anions. As they usually are in powder form, these sorbents often present appreciable problems in the solid/liquid separation process following the sorption stage. Sorptive flotation of metal-loaded particles was investigated in this paper, as an alternative two-stage process. In the sorption process, satisfactory removals of arsenic(V) were obtained onto synthetic hydrotalcite particles from water. The effect of some parameters, like the solution ionic strength, concentrations, temperature, etc. was examined. During the second stage of the process, hydrotalcite fine particles were removed from the liquid phase by dispersed-air flotation; various surfactants were tested in relation to the ionic strength of the solution. The combined process of sorptive flotation provides promising results for arsenic removal.     

高气泡表面积通量浮选柱气浮除藻的研究

湖泊、水库等水源的富营养化,使藻类去除成为饮用水生产的重要任务.本研究采用高气泡表面积通量浮选柱气浮除藻,考察了混凝剂、气泡表面积通量和浮选柱高度等因素的影响.试验表明,高气泡表面积通量浮选柱气浮可高效地去除绿藻、硅藻和蓝藻,叶绿素a和藻类去除率达95%以上,比传统浮选柱气浮和沉降作业有较大幅度提高.与普通气浮柱比较,高气泡表面积通量浮选柱增加了气泡与藻的碰撞几率,防止因大表观充气速率造成的紊流和扰动,使气泡/藻结合体有相对静态的浮升环境,避免了气泡/藻结合体在浮升过程中的脱落,实现对藻类的迅速捕集和转移.     

高气泡表面积通量浮选柱气浮除藻的研究

湖泊、水库等水源的富营养化，使藻类去除成为饮用水生产的重要任务。本研究采用高气泡表面积通量浮选柱气浮除藻，考察了混凝剂、气泡表面积通量和浮选柱高度等因素的影响。试验表明，高气泡表面积通量浮选柱气浮可高效地去除绿藻、硅藻和蓝藻，叶绿素a和藻类去除率达95％以上，比传统浮选柱气浮和沉降作业有较大幅度提高。与普通气浮柱比较，高气泡表面积通量浮选柱增加了气泡与藻的碰撞几率，防止因大表观充气速率造成的紊流和扰动，使气泡／藻结合体有相对静态的浮升环境，避免了气泡／藻结合体在浮升过程中的脱落，实现对藻类的迅速捕集和转移。     

沸石对降雨径流中氨氮的吸附特性

城市面源污染是重要水体污染源之一,降雨发生时,雨水径流会携带累积在路面、屋面的含有机物、氮磷、重金属等污染物质进入水体,其中氮磷是造成水体富营养化的重要因素。针对这一情况,采用不同种类沸石,对雨水径流中的氮磷进行了吸附研究,着重考察了沸石对氨氮的吸附动力学,吸附等温线特征,并考察了pH、共存阳离子以及COD对吸附能力的影响。结果表明,Na型改性沸石吸附性能优于其他2种,饱和吸附量达到9.09 mg/g,沸石的吸附过程符合准二级动力学模型。Mg2+、Ca2+对Na型改性沸石的影响较大,Na型改性沸石吸附氨氮的适宜pH为5~8。本研究为探索用物化方法来处理雨水提供了依据,Na型改性沸石可以作为吸附雨水中氨氮的优选吸附剂。     

Synthetic zeolites as amendments for sewage sludge-based compost

The effects of incorporating a synthetic zeolite (Zeolite P) in a range of concentrations (0.1-1.0 w:w) into an experimental horticultural compost, derived from sewage sludge, have been investigated. The impact of zeolite treatment on time-related changes of the labile zinc, copper, iron and manganese pools within the compost was compared to lime incorporation (5% w:w) and to a proprietary unamended peat-based compost. Addition of 0.5% and 1.0% zeolite significantly reduced labile zinc over a 90 day period. The highest zeolite treatment was more effective than liming; 0.5% zeolite was as effective as lime. Plant growth trials measuring transfer of metals to ryegrass (Lolium perenne L. cv Elka) in successive harvests demonstrated that both 1.0% zeolite and 5% lime treatment caused significant reduction in total metal transfer from soil-plant over a 116 day growth period. It is concluded that the use of synthetic zeolite as an amendment for compost of this type significantly reduces potential for soil metal mobility and soil-plant transfer.     

膜分离技术在染料工业中的应用进展

在染料工业中 ,膜分离技术主要用于传统生产工艺改造和工业废水处理两个方面 ,旨在实现节水、减污和降耗等目的。本文介绍了其主要应用进展 ,并结合染料工业特点 ,概述了影响膜污染的主要因素 ,如膜的荷电性、亲疏水性、截留分子量、料液性质等。     

粉煤灰合成分子筛及处理含氟废水的研究

实验利用工业废渣——循环流化床粉煤灰合成出较高结晶度的X型和P型分子筛,合成过程无须高温焙烧预处理.通过XRD分析表征,发现该法合成分子筛结晶度较高,X型和P型分子筛相对结晶度分别达68%～75%和55%.实验应用合成分子筛进行载铁改性,并对NaF模拟的工业含氟废水进行了除氟实验.结果表明,载铁X型分子筛处理工业含氟废水效果良好,除氟率可达74%～98%,除氟容量达25.0～30.0 mg/g.在处理含氟废水过程中,载铁合成分子筛与其他除氟剂相比较,具有除氟率高、除氟容量大、反应迅速的特点.     

用于含油污水处理的气浮旋流耦合技术研究

建立了气浮旋流耦合装置.测试了气浮旋流耦合装置的分离效果,实验表明,在加气量质量比为0.003～0.020,含油污水浓度为50～300 mg/L条件下,气浮旋流耦合装置可比单纯的旋流分离装置的分离效率提高10%～50%.     

用于含油污水处理的气浮旋流耦合技术研究

建立了气浮旋流耦合装置。测试了气浮旋流耦合装置的分离效果，实验表明，在加气量质量比为0．003-0.020，含油污水浓度为50—300mg／L条件下，气浮旋流耦合装置可比单纯的旋流分离装置的分离效率提高10％，50％。     

聚结分离技术在含油污水处理中的应用研究进展

工业含油污水量大且面广,因其成分复杂,处理较困难。聚结分离技术因其独特的物理破乳优势,以及成本低廉、分离高效、环境友好备受重视,并应用于工业含油污水的处理中。梳理了聚结除油技术的发展历程,剖析了该技术的基本原理,在归纳聚结材料研究进展的基础上,总结了聚结分离器在典型工业含油污水领域的应用,并对该技术的应用研究和发展方向进行了展望。     

Adsorption of nitrosamines in acidic solution by zeolites

Adsorption of N-nitrosopyrrolidine (NPYR) by zeolite NaZSM-5, Hbeta and NaZSM-11 in acidic solution with pH of 1 was investigated. The NPYR uptake process obeyed the first-rate Lagegren kinetic equation describing adsorption, and the equilibrium data were fitted to the Langmuir or Freundlich adsorption equation. Zeolite ZSM-5, Hbeta and NaZSM-11 possessed a higher adsorption capacity than amorphous silica or ordered mesoporous siliceous SBA-15, implying their potential application for adsorption of nitrosamines in gastric juice to anti-cancer.     

Effects of zeolites on cultures of marine micro-algae

GOAL, SCOPE AND BACKGROUND: The cation-exchange capacity of zeolites is well known and has been increasingly explored in different fields with both economic and environmental successes. In aquatic medium with low salinity, zeolites have found multiple applications. However, a review of the literature on the applications of zeolites in salt waters found relatively few articles, including some recently published papers. The purpose of this review is to present the state-of-the-art on applications of using zeolites for amending the trace elemental contents of salt water as well as the implications of this property for promoting marine micro-algal growth. MAIN FEATURES: This paper deals with the following features: Sorption capacity of zeolites including 1. application of zeolites in saltwater, 2. the role of silicon and zeolites on cultures of micro-algae, and 3. the role of organically chelated trace metals. RESULTS: The following competing factors have been identified as effects of zeolites on algal growth in salt water: (i) ammonia decrease: growth inhibition reduced; (ii) macro-nutrients increase, mainly silicon: stimulation of silicon-dependent algae; (iii) trace metals increase (desorption from zeolites) or decrease (adsorption): inhibition or stimulation, depending on the nature of the element and its concentration; and, (iv) changes in the chelating organics exudation: inhibition or stimulation of growth, depending on the (a) nature of the complexed element; (b) bioavailability of the complex; and (c) concentration of the elements simultaneously present in inorganic forms. DISCUSSION: Zeolites have been capable of stimulating the growth of the silicon-demanding marine micro-algae, like diatoms, mainly because they can act as a silicon buffer in seawater. Zeolites can also influence the yield of non-silicon-demanding algae, because the changes they can cause (liberation and adsorption of trace elements) in the composition of the medium. CONCLUSIONS: Zeolites have been capable of stimulating the growth of the marine micro-algae. However, the extent of ion exchange between zeolite and seawater, which conditions the effects, will depend on several factors: (1) initial metal concentration in seawater; (2) levels of trace metals in the zeolites (contaminants); (3) characteristics of the zeolites in terms of both ion-exchange capacity and specific affinities for the different cations; (4) quantity of zeolite per litre of solution; (5) pH and (6) response of the organism in terms of liberation of organic ligands. RECOMMENDATIONS AND PERSPECTIVES: RECOMMENDATIONS: Therefore, a previous investigation in each particular case is recommended, in order to select the zeolitic characteristics and concentrations that will maximize the algal yield. PERSPECTIVES: Stimulation of phytoplankton growth can be economically relevant since phytoplankton constitutes the basis of the marine food webs and is required in fish farming nurseries in the marine aquaculture industry. Zeolites are cheap, only small amounts (few milligrams per liter of culture) are required and the addition of some micro-nutrients may be omitted. Therefore, the inclusion of zeolites in algal cultures in aquaculture may have economic advantages.     

加压溶气生化气浮法处理生活污水的脱氮试验研究

将加压溶气气浮技术与加压曝气生物氧化技术相结合,开发了加压溶气生化气浮(PA-DAF)法,用于处理生活污水。结果表明,DO和C/N对反应器的脱氮效果有显著影响。DO质量浓度提高到3.5mg/L后,氨氮去除率提高到将近99%。当DO质量浓度为2.5mg/L时,TN去除率达到最大值77.50%。高C/N条件下系统会抑制硝化能力。该反应器能很好地创造缺氧微环境,出现了同步硝化反硝化现象,并对其形成机制进行了分析。     

铝土矿浮选尾矿对水泥砂浆性能的影响

以铝土矿浮选尾矿为研究对象,探讨了烘干尾矿、尾矿浆用作水泥基材料掺和料的可行性,测定了其对砂浆基本性能的影响。结果表明,尾矿作为混合材料能显著缩短水泥的凝结硬化时间;尾矿作为掺和料能够增加砂浆的保水性,提高砂浆的吸水率,降低砂浆的稠度;掺入10%的尾矿对砂浆的密度和力学性能具有较好的改善作用。因此,尾矿作为掺和料是可行的,有利于消耗废渣,改善生态环境。     

气浮与沉淀切换运行的新型气浮-沉淀工艺设计和工程应用

当水体中藻类含量高、浊度低时,所形成的絮体沉淀性不好,沉淀工艺处理效果差,但气浮工艺处理效果相对较好;而当原水浊度高时,气浮工艺处理效果差,而沉淀工艺处理效果却很好。为解决季节性水源水质变化对供水生产的影响,结合上述2种工艺特点,在给水工程中设置同时包含气浮和沉淀工艺的构筑物,开发出新型气浮-沉淀工艺。该工艺的构造可满足2种工艺运行要求,亦可根据水源水质在同一构筑物内切换气浮或沉淀运行模式,能节省用地和建设成本。珠海三灶水厂改造工程项目(处理量2×10⁴ m³·d⁻¹)即该工艺的技术应用案例,其生产运行结果表明：当运行气浮模式时,平均除藻率可达96.9%,平均除浊率可达94.1%;当运行沉淀模式时,除浊率为98.5%。     

Inactivation of cadmium in contaminated soils using synthetic zeolites

The addition of synthetic zeolite pellets to soils contaminated with cadmium significantly reduced the concentrations of cadmium in the roots and shoots of a range of crop plants. Use of synthetic foyazite group zeolites types 4A and 13X, at application rates of 1% by soil weight, caused reductions in cadmium concentrations of up to 86% in leaves of lettuce grown in pots, compared to controls with no added zeolites. The potential of these substances to reduce cadmium entry into the food chain, and as a clean up method, is noted.