A/O+MBBR组合工艺在炼油废水处理中的应用

采用厌氧-好氧-移动床生物膜反应器(A/O+MBBR)组合工艺进行了炼油废水处理试验研究,考察了试验装置对炼油废水中COD,氨氮的去除情况及该装置的耐冲击负荷能力.研究结果表明,与传统的生化处理工艺相比,A/O+MBBR组合工艺具有脱碳能力强、脱氮效果好、出水水质稳定、剩余污泥产量低、运行方式灵活、运行管理简捷、运行能耗低等优点.     

载体移动床生物膜反应器(MBBR)在炼油废水处理工程中的研究与应用

载体移动床生物膜反应器(Moving Bed Biofilm Reactor,简称为MBBR)是在流化床基础上形成的污水处理新技术.它具有处理效率高、脱氮和抗冲击负荷能力强、不需要反冲洗、不发生堵塞的工艺特点.本课题采用"活性污泥法(A/O)+MBBR"工艺对MBBR工艺在炼油废水处理中的应用进行了中试研究,考察中试装置对COD、氨氮、悬浮物的去除情况及系统的耐冲击负荷能力,并对MBBR在呼炼污水厂的改造应用可行性进行了分析.研究结果表明,MBBR应用于炼油废水处理效果显著:①在进水量为240L/h时,COD容积负荷为1.00～1.70kgCOD/m3.d、NH3-N容积负荷为0.06～0.11kgNH3-N/m3.d,中试装置出水水质均能满足以下指标:COD≤60mg/L、NH3-N≤3mg/L、SS≤70mg/L;②中试试验与同期呼炼污水厂生化系统效果做对比,结果表明,A/O/MBBR工艺出水水质明显优于与A/O工艺出水,说明MBBR工艺可以提高A/O工艺的容积负荷率和处理效率,具有高效、出水稳定和耐冲击负荷的特点.     

A/三级MBBR法处理炼油废水的中试研究

在容积为10.5 m3的装置中,采用A/三级MBBR工艺对炼油废水的处理进行了中试研究。考察了中试装置对炼油废水中CODCr、NH4+—N的去除率。结果表明,采用A/三级MBBR工艺生化反应停留时间(14.3 h)远低于现有炼油废水处理厂的生化反应停留时间(66 h),对COD和NH4+—N的平均去除率分别达到92.4%和99.8%,具有处理效率高、停留时间短的特点,出水水质达到了《国家综合排放标准》(GB8978—1996)中的一级排放标准。     

生物膜法A2/O2焦化废水处理系统中好氧反应器工艺特性

以焦化厂废水处理系统气浮设备出水为水源,在中试规模上研究了生物膜法A2/O2系统中好氧反应器的工艺特性和效果.研究结果表明,系统进水COD为1 000～2 200 mg/L,NH3-N质量浓度为200~400mg/L,水解酸化反应器HRT为20 h,缺氧反应器HRT为24 h,一级好氧反应器和二级好氧反应器HRT均为48 h,二级好氧反应器硝化液回流比为3,一级好氧反应器COD容积负荷为0.40 ks/(m3·d),二级好氧反应器COD容积负荷<0.07 kg/(m3.d).NH3-N容积负荷为0.022 kg/(m3·d)时,生物膜法A2/O2系统处理出水COD和NH3-N浓度可以同时达到<污水综合排放标准>(GB 8978-1996)中的一级排放标准.     

A/O~2-Fenton-BAF工艺处理焚烧垃圾渗滤液试验研究

以某垃圾焚烧厂渗滤液为对象,采用厌氧-2级好氧(A/O2)-Fenton-曝气生物滤池(BAF)组合工艺进行中试。结果表明,在COD负荷为220 g.m-.3d-1下,COD和氨氮去除率可达到85.3%和92.9%;Fenton反应适宜投加量为H2O2:COD=2,n(Fe2+):n(H2O2)=1,BAF参考设计处理COD负荷为188.6 g.m-3.d-1,处理后出水COD低于80 mg.L-1,氨氮的质量浓度低于2 mg.L-1。通过提升负荷考察其对生化处理的影响,确定高负荷下采用2级好氧对去除氨氮的必要性,为工艺改造应用于工程中提供参考。     

不同生化工艺处理炼油废水的GC/MS分析及评价

采用生物吸附-厌氧-移动生物膜反应器(BA-H-MBBR)组合工艺进行炼油废水处理实验研究,并平行模拟原有工艺厌氧-好氧-好氧(A-O-O)工艺进行对比实验,同时利用紫外-可见吸收光谱和顶空-固相微萃取(HS-SPME)-气质联用仪(GC/MS)对现有A-O-O工艺和新开发的BA-H-MBBR工艺的处理效果进行评价。紫外-可见吸收光谱监测结果显示,BAH-MBBR工艺出水水质优于A-O-O工艺,且具有更好的单环芳烃族化合物(苯酚、苯胺等)去除能力;GC/MC在进水中共检出60种有机污染物,在A-O-O工艺出水(O_2)、BA-H-MBBR工艺出水(M2)中只分别检出14种和6种有机物,表明进水经过生化工艺处理后,大多数有机污染物均得到降解和去除;M2中检出的有机物种类较O2中的低得多,并且M_2和O_2分别检出2种、7种含氮有机物,显示出BA-H-MBBR工艺更优异的有机物处理能力,并且在处理含氮有机物方面具明显优势。     

A~2/O工艺强化脱氮效果中试研究

针对郑州某一城市污水处理厂"混合型城市污水"的特征,以厂区曝气沉砂池出水作为处理对象,设计1套A2/O工艺强化脱氮中试装置。该A2/O工艺采用氧化沟作为好氧池,氧化沟对总氮和氨氮的去除具有强化作用,同时可降低硝化液回流的能耗;当进水COD、NH3-N、TN的平均质量浓度分别为513.6、22.4、34.2 mg/L时,经A2/O工艺处理后,对COD、NH3-N、TN的平均去除率分别达到了91.2%、84.4%、71.44%,出水水质达到城镇污水处理厂污染物排放标准(GB 18918-2002)一级A标准,取得了良好的污染物去除和脱氮的效果,总体出水水质相对稳定。     

利用A2/O2工艺处理中药类制药废水的研究

试验将活性污泥法和接触氧化法结合使用,组合成为复合式A2/O2工艺(厌氧/好氧/厌氧/好氧)对中药类制药废水进行了中试研究,以考察该系统的处理效果.结果表明,废水经过调节池的水解酸化作用后,进入两级A2/O2(厌氧/好氧)设备,最后得到了良好的处理效果.进水的COD为119～1440mg·L-1,出水的COD降到15.9～71.6mg·L-1,去除率在60.0%～92.7%之间,平均去除率为78.O%;进水的氨氮质量浓度为2.25～50.3 mg·L-1,出水中的氨氮质量浓度在1.38～27.6 mg·L-1,氨氮的去除率在41.5%～88.4%之间;总氮的出水质量浓度为1.46～27.75 mg·L-1,去除率最高达到了87.7%.各项指标均达到了国家污水综合排放标准(GB 8978-1996).     

A/O膜生物反应器生活污水回用处理中试研究

采用中试规模的缺氧-好氧一体式膜生物反应器(A/O MBR)对生活污水处理回用进行了试验研究。试验结果表明,该工艺处理效果优良,系统对COD、氨氮的平均去除率分别为94.7%和99.08%,膜分离截留对COD的去除起到了决定性作用,生物对NH4 -N的去除占主要作用,膜本身对NH4 -N的直接去除作用不大。出水COD、氨氮的浓度分别为16.02 mg/L和0.35 mg/L,出水水质优于城市杂用水水质标准(GB/T l8920-2002)和河道景观环境用水水质标准(GB/T l8921-2002)。该系统运行稳定,具有较强的抗冲击负荷能力,工艺基本无污泥排放。     

MBBR工艺的应用研究及发展前景

在介绍MBBR工艺原理的基础上,结合现有工程实例阐述了MBBR工艺,MBBR+A/O组合工艺、MBBR+A²/O组合工艺、MBBR+MBR组合工艺应用效果。同时对此三种组合工艺从经济、处理能力以及发展趋势做出比较分析。旨在为污水处理提量提标要求下节约污水处理时间,充分发挥成熟工艺潜能,推进组合工艺发展,为提标改造工艺方案设计提出合理方向和参考价值。     

Polymorphism of LiGa5O8 and of LiGa5O8-MgGa2O4Solid Solutions

High-temperature X-ray diffraction and differential thermal analyses showed that LiGa₅O₈ exists in two polymorphs related by the first-order transition at 1138°±3°C of the low-temperature simple-cubic form, space group (probably) O⁷, to the high-temperature spinel (fcc) form, space group O _h ⁷. The transition is rapid, and the high-temperature form in pure LiGa₅O₈ could not be quenched to room temperature under the conditions used. However, the high-temperature polymorph can be quenched under equilibrium conditions when 40 mol% or more MgGa₂O₄ is present. The subsolidus equilibrium relations in the system MgGa₂O₄-LiGa₅O₈ are discussed.     

Magnetoresistance of CuxCo1-xFe2O4 Ferrites

Magnetoresistance measurements (Δ/R) were carried out on Cu _x Co_{1- x} Fe₂O₄ samples with x =1, 0.75, 0.50, 0.25 and cobalt ferrite in the range of magnetic intensity (H) from 1.0 to 4.5 kG. Linear plots were obtained between log (Δ/R) and log H for all compositions except that of cobalt ferrite. The values of n at x =0.5 do not agree with the results of some authors. The discrepancy may be attributed to the value of magnetic field intensity at which such measurements were carried out. The similarity of features of n and μ_D with composition leads us to believe that the magnetoresistance may arise from the scattering of conduction electrons by localized electrons involving the s-d exchange interaction.     

Sintering of Si3N4-Y2O3-Al2O3

Sintering kinetics of the system Si₃N4-Y2O₃-Al₂O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si₃N₄ were studied with additions of 4 to 17 wt% Y₂O₃ and 4 wt% A1₂O₃. Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si₃N₄ and glass or β '-Si₃N₄, α '-Si₃N₄, and glass. The compositions and amounts of the residual glassy phases are estimated.     

Expansive properties of the mixture C4ASH12 − 2CS III. Effects of temperature and restraint

The effects of temperature and restraint upon the hydration and the expansion of $\text{C}{}_4\text{A}\text{S}\text{H}{}_{12}\text{? 2}\text{C}\text{S}$ mixture compacts in different contact solutions have been investigated. Temperatures above 20°C do apparently hinder the formation of an impervious felt-like layer of ettringite around the $\text{C}{}_4\text{A}\text{S}\text{H}{}_{12}$ particles, thus greatly reducing the retarding effect of the lime. An uniaxial restraint of 1 Kg/cm² is enough to reduce sensibly the expansions which remain however high (about 100%). The results can be satisfactorily interpreted by the reaction and expansion mechanism hypothesized in our previous papers.     

Raman Study of Glasses of Ba2TiSi2O8 and Ba2TiGe2O8

Raman spectra are reported for fresnoite (Ba₂Ti(Si,Ge)₂O₈ glasses, and comparison is made between the Raman spectra of the corresponding crystalline powders and glasses of Ba₂TiSi₂O₈ and Ba₂TiGe₂O₈. The Ba₂TiGe₂O₈ glass spectra show correspondence with the Ba₂TiGe₂O₈ crystalline Raman spectra; the v _s(Ge–O–Ge) mode occurs at 518 cm⁻¹ in the glass and at 521 cm⁻¹ in the crystalline material. Five-fold coordinated titanium is the majority species present in the Ba₂TiGe₂O₈ glass as revealed by a strong band at 824 cm⁻¹ in the I glass spectrum. The Ba₂TiSi₂O₈ glass spectra are similar to the Ba₂TiSi₂O₈ crystalline spectrum; the strongest band is found at 836 cm⁻¹ in the I glass spectrum. Through comparison with the previous Raman data of other titania silicate glasses, we conclude that the Ba₂TiSi₂O₈ glass has a structure similar to the crystalline phase.     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Effects of metal-support interactions on the hydrogenation of CO over PdSiO2 and PdLa2O3

A study of CO hydrogenation over $\text{Pd}\text{SiO}{}_2$ and $\text{Pd}\text{La}{}_2\text{O}{}_3$ has been carried out for the purpose of identifying the effects of Pd dispersion, Pd morphology, and support composition on the catalytic activity of supported Pd. The specific activity of each catalyst for methanol and methane synthesis was determined from microreactor studies carried out at a fixed set of reaction conditions. Palladium dispersion was measured by H₂O₂ titration, and the morphology of the Pd crystallites, as expressed by the distribution of Pd(100) and Pd(111) planes, was determined from in situ infrared spectra of adsorbed CO. The crystallite morphology of the $\text{Pd}\text{SiO}{}_2$ catalysts is the same, independent of Pd weight loading: 90% of the surface is comprised of Pd(100) planes and 10% of the surface is comprised of Pd(111) planes. By contrast, the crystallite morphology of the $\text{Pd}\text{La}{}_2\text{O}{}_3$ catalysts changes with Pd loading. Primarily Pd(100) planes are exposed at low-weight loadings while Pd(111) planes are exposed at high-weight loadings. The Pd dispersion has little effect on the methanol turnover frequency over both $\text{Pd}\text{SiO}{}_2$ and $\text{Pd}\text{La}{}_2\text{O}{}_3$, for dispersions between 10 and 20%. On the other hand, the methane turnover frequency is independent of Pd dispersion over $\text{Pd}\text{SiO}{}_2$, but increases with decreasing dispersion over $\text{Pd}\text{La}{}_2\text{O}{}_3$. It is further observed that the Pd morphology influences the specific activity of $\text{Pd}\text{La}{}_2\text{O}{}_3$ for methanol synthesis: Pd(100) is nearly threefold more active than Pd(111). For a fixed morphology, the specific methanol synthesis activity of $\text{Pd}\text{La}{}_2\text{O}{}_3$ is a factor of 7.5 greater than that of $\text{Pd}\text{SiO}{}_2$.     

Wet Milling of Fe/Al/Al2O3 and Fe2O3/Al/Al2O3 Powder Mixtures

Wet milling of Al₂O₃-aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al₂O₃ and Fe₂O₃/Al/Al₂O₃ powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe₂O₃/Al/Al₂O₃ powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al₂O₃ powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8.     

In situ laser raman spectroscopy of the sulfiding of Moγ-Al2O3 catalysts

Raman spectra of sulfided $\text{Mo}\text{γ-}\text{Al}{}_2\text{O}{}_3$ catalysts were obtained using in situ techniques for two sulfiding methods. For samples sulfided by 10% $\text{H}{}_2\text{S}\text{H}{}_2$ at 400 °C, MoS₂ structures were observed. A stepwise sulfiding using 10% $\text{H}{}_2\text{S}\text{H}{}_2$, with spectra recorded at 150, 250, and 350 °C, resulted in observation of molybdenum oxysulfide, reduced molybdate, and surface “MoS₂” phases. Reexposure of these samples to air led to radical modification of the oxysulfide structures as well as transformation of some sulfide phases. A model incorporating terminal and bridging MoS bonding and anion vacancies is proposed. This model is based on the conversion of isolated and aggregated molybdate and MoO₃ species to oxysulfide and reduced molybdenum phases. Conversion of reduced molybdenum phases to sulfides is observed to be slow.