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。     

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.     

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—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％。     

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。     

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.     

Comparison of inclined plate sedimentation and dissolved air flotation for the minimisation of subsequent nitrogenous disinfection by-product formation

The formation of disinfection by-products (DBPs), including both nitrogenous disinfection by-products (N-DBPs) and carbonaceous disinfection by-products (C-DBPs), was investigated upon chlorination of water samples following two treatment processes: (i) coagulation-inclined plate sedimentation (IPS)-filtration and (ii) coagulation-dissolved air flotation (DAF)-filtration. The removal of algae, dissolved organic nitrogen (DON), dissolved organic carbon (DOC) and UV₂₅₄ by coagulation-DAF-filtration was superior to coagulation-IPS-filtration. On average, 53%, 53% and 31% of DOC, DON and UV₂₅₄ were removed by coagulation-DAF-filtration process, which were higher than 47%, 31% and 27% of that by coagulation-IPS-filtration process. Additionally, coagulation-IPS-filtration performed less well at removing the low molecular weight organics than coagulation-DAF-filtration process. The concentrations of chloroform, dichloroacetamide (DCAcAm) and dichloroacetonitrile (DCAN) formed during chlorination after coagulation-DAF-filtration reached their maximum values of 13, 1.5 and 4.7 μg L⁻¹, respectively, and were lower than those after coagulation-IPS-filtration with the maximum detected levels of 17, 2.9 and 6.3 μg L⁻¹. However, the trichloronitromethane (TCNM) concentration after the two processes was similar, suggesting that DON may have less of a contribution to TCNM formation than DCAcAm and DCAN.     

用于氨氮去除的13X分子筛／PES膜吸附剂的制备与性能表征

针对氨氮排放对环境造成的污染以及给人类带来的危害这一问题,将分子筛吸附与膜技术相结合,以13x分子筛为功能颗粒,以聚醚砜（PES）为膜的基质材料,以二甲基乙酰胺（DMAc）为溶剂,通过相转化法制备了不同13x分子筛填充量的13x／PEs膜吸附剂。研究发现,随着13x分子筛填充量的增加,膜的指状孔变得细密、短小,其吸附容量,断裂强度都在增加,但是水通量逐渐降低。料液温度与pH值对吸附性能的影响表明,该膜吸附剂在293K,pH=7时对氨氮有较好的吸附容量,可达21．69mg／g;吸附热力学研究表明,该类型膜吸附剂对氨氮的吸附等温线符合Langmuir方程。     

含松醇油实际选矿废水的COD生物降解

从广东省某铅锌矿尾矿库周边的土壤中分离并纯化出3株能有效降解松醇油的菌株,分别命名为KS-1、KS-2和KS-3,实验表明KS-1菌株对含松醇油的模拟选矿废水化学需氧量（COD）降解效果最好,鉴定结果表明该菌株为枯草芽孢杆菌。在此基础上,重点研究了KS-1菌株对尾矿库实际外排选矿废水的处理效果,探索了不同接种量、pH和温度对COD降解效果的影响。结果表明,在接种量为5％、pH为6．0、温度为25℃的条件下,菌株KS-1降解实际废水COD的效果最佳,且搅拌有利于菌株对废水COD的降解。该工艺参数下,48h内COD降低到12．87mg／L,达到了国家新的《铅锌工业污染物排放标准》（GB25466．2010）的要求。     

Attempt to adsorb N-nitrosamines in solution by use of zeolites

The strong adsorption of zeolite for N-nitrosamines in solution was first revealed by use of adsorption, and temperature programmed surface reaction (TPSR) techniques. N-nitrosodimethylamine (NDMA) and N-nitrosopyrrolidine (NPYR) as well as N-nitrosohexamethyleneimine (NHMI) can be adsorbed on zeolite Y, ZSM-5 and A in the solution of methylene chloride or water, which will be helpful for removal of the N-nitrosamines pollution in environmental protection. The equilibrium data were fitted to Freundlich-type isotherms, but the adsorption capacity of zeolites mainly depended on their pore size, surface area and acid-basic properties. Molecular size of adsorbate and solute-solvent interaction also strongly affected the adsorption of N-nitrosamines on zeolite in solution. The extraordinary adsorption properties of NaA zeolite for N-nitrosamines in aqueous solution is first reported and discussed.     

One-step analysis of bubble-particle capture interaction in dissolved-air flotation

The capture of particles by air microbubbles in dissolved air flotation has been analysed using a one-step (holistic) approach, which numerically solved the motion equation (with the inclusion of microhydrodynamic resistance functions and surface forces) for both the bubble-particle collision and attachment interactions. Model predictions with the inclusion of non-DLVO attractive surface force agreed with the experimental trajectories of latex particles. The non-DLVO attractive force reduced the force barrier between non-attaching particles and bubbles, and significantly increased the attractive net force between attaching particles and air bubbles.     

Two-phase simulations of an off-nominally operating dissolved-air flotation tank

The flow patterns of the contaminated water and the air bubbles inside a large-scale Dissolved Air Flotation (DAF) tank were examined using CFD modelling. The DAF tank was operating off-nominally in the sense that it was supplied with bubbles larger than originally designed for. Attention was drawn to the location for air injection and the effect of having more than one-size bubbles in the tank, regarding the good contact between phases and the subsequent bubble recovery at the tank free surface. The role of the inclination of the internal baffle of the tank and liquid flow rate was also examined.     

调理剂对CAF污泥浓缩工艺影响的试验研究

涡凹气浮（CAF）已广泛应用于工业废水和城市污水的预处理中.由于污泥本身的特性原因,CAF在污泥处理中尚没有应用.通过试验投加污泥调理剂改变污泥的特性,以达到将CAF工艺用于浓缩活性污泥的目的.试验表明,CAF工艺浓缩低浓度剩余活性污泥效果很好,但正确选择污泥调理剂的投加点和投加量对CAF污泥浓缩工艺至关重要.     

天然及CaCl_2改性沸石对四环素的吸附

通过静态吸附实验研究了水中四环素在天然和CaCl2改性沸石上的吸附行为及机制。实验表明,天然沸石对四环素具有吸附能力,CaCl2改性可以提高沸石对四环素的吸附能力。天然和改性沸石对四环素的吸附符合拟二级动力学模型,颗粒内扩散不是吸附过程的主要控制步骤。Freundlich和Dubinin-Radushkevich（D-R）等温吸附模型可以较好地描述实验所用2种沸石对四环素的吸附行为,D-R等温方程拟合结果显示吸附过程包含离子交换作用。通过对天然和改性沸石吸附四环素前后溶液中主要阳离子浓度变化分析证实了该吸附过程包含离子交换作用。实验研究了pH值变化对沸石吸附四环素的影响,当pH=3～5时,天然和改性沸石对四环素的吸附量均随pH值的增加而急剧下降,而pH=5～10时,天然和改性沸石对四环素的吸附量变化均不明显,推测可能是离子交换作用和化学沉淀吸附作用所致。另外,实验还初步探索了溶液离子强度对沸石吸附四环素的影响情况,随着溶液中Na＋和Ca2＋离子强度的增加,吸附量先急剧降低随后趋向平稳,进一步说明了沸石对四环素的吸附过程不是由单一机制控制的。     

混凝一气浮控制三卤甲烷生成势的研究

研究了混凝一气浮工艺对不同分子量区间三卤甲烷生成势（trihalomethanes formation potential,THMFP）的去除效果及絮体形态对THMFP去除效果的影响。结果表明,混凝一气浮工艺以去除大分子量区间THMFP为主,对小分子量区间THMFP的去除效果较差。UV254值与THMFP值的线性相关系数为0．9449,UV254值可以较好地反映THMFP的含量。絮体的分形维数为1．17～1．2时,孔隙率较大,可增加絮体对THMFP的活性吸附空间,且絮体相对密度较小,可增强同向絮凝作用,增加絮体和THMFP的接触概率,有利于气浮对THMFP的去除。     

用兼氧,好氧生物接触氧化一气浮工艺处理高浓度印染废水

介绍了常温条件下,采用兼氧、好氧化生物接触氧化一气浮高浓度印染废水的工程应用,结果表明,在常温下印染废水经该工艺纺织印染綮不的实际工程中。