AAO+高效沉淀池+滤布滤池工艺在污水处理厂提标中的应用

江西某南部城市生活污水处理厂一期工程处理规模为1.0万m³/d,污水采用曝气生物流化池(ABFT)生物膜处理工艺，出水水质执行《城镇污水处理厂污染物排放标准》(GB 18918—2002)中的一级B标准。提标改造后，处理规模不变，污水处理工艺采用改良型厌氧-缺氧-好氧(AAO)+高效沉淀池+纤维转盘滤池处理工艺，出水水质执行上述标准一级A排放标准。提标改造中分析了一期工程运行现状及存在问题，强化了生物脱氮，并增加了高效沉淀池及纤维滤布滤池深度处理工艺，出水稳定达标。该工程建设用地指标低，投资少，周期短，取得了较好的社会和经济效益，为类似污水处理厂提标改造提供参考和借鉴。     

多级多段AO工艺在市政污水处理中的应用

山西某市政污水处理厂提标改造规模 4×10⁴ m³/d。污水处理厂原采用厌氧+氧化沟生化处理工艺,出水执行一级 A 标准（GB 18918-2002）,提标改造要求出水指标 COD、氨氮、总磷执行地表水环境质量标准（GB 3838-2002）Ⅴ类标准。针对生化系统中脱氮、除磷效果不稳定等特点,改造工程生化系统采用厌氧+多级 AO 工艺,将原有氧化沟改造成多级 AO 池,配置底部曝气系统及推流系统,且出水增设混凝加药等措施,工艺升级改造后稳定运行。结果表明,通过一系列提标改造,出水水质明显优于设计标准。     

磁混凝沉淀池在CAST工艺提标改造中的应用

荔浦市某污水处理厂处理规模为3×10⁴m³/d,原污水处理采用CAST工艺,出水水质执行《城镇污水处理厂污染物排放标准》(GB 18918-2002)一级B标准,现需进行提标改造,将出水水质提升至一级A标准。提标改造工艺采用磁混凝沉淀池,与传统深度处理工艺相比,磁混凝沉淀池可大幅度减小占地面积并降低工程投资。实际运行数据表明,通过提标改造后,污水处理厂出水水质显著优于GB 18918-2002的一级A标准。     

新疆某污水处理厂提标改扩工程案例

新疆某污水处理厂，一期采用氧化沟工艺，二期采用水解+五段Bardenpho工艺+二沉池+高密度沉淀池+微絮凝滤池+消毒工艺，出水执行一级A标准。稳定运行阶段平均出水COD为19.67 mg/L,NH₄⁺-N、TN、TP、SS平均出水质量浓度分别为1.39、5.00、0.22、5.25 mg/L，均优于一级A标准，无超标现象出现。可为该地区其他城镇污水处理厂提标改扩工程提供借鉴和参考。     

木渎新城污水处理厂提标改造工程设计

木渎新城污水处理厂工程规模为10.0万m³/d,提标前采用倒置AAO生物池为主的工艺技术,出水水质执行《城镇污水处理厂污染物排放标准》(GB18918-2002)一级A标准。提标后出水水质要满足“苏州特别排放限值”要求。提标改造工程将现状AAO生物池改造为Bardenpho生物池,新建反硝化滤池,新增精确曝气系统。实际出水数据表明,该工艺运行稳定,各项出水指标(COD_Cr、NH₃-N、TP、TN)达到“苏州特别排放限值”。     

汕头市某生活污水处理厂提标改造工程设计探讨

汕头市某生活污水处理厂处理规模为12万m³/d,采用完全混合A²/O+二沉池+消毒工艺,出水执行《城镇污水处理厂污染物排放标准》GB 18918—2008中二级标准。通过提标改造方案比选确定,提标改造工程设计在原处理基础上增加磁混凝沉淀池工艺,在A²/O生化池增加填料(MBBR),并辅以化学除磷,该工程具有节省投资、运行稳定可靠的特点,提标改造后各项出水指标提升到《城镇污水处理厂污染物排放标准》一级A标准及广东省地方标准《水污染物排放限值》(DB 44/26—2001)的较严值排放。     

西北某高浓度城市污水处理厂SBR工艺提标改造设计

随着污染物排放标准的进一步提高，原有采用序批式间歇活性污泥(SBR)工艺的污水处理厂面临提标改造。文中以西北某高浓度城市污水处理厂提标改造工程为例，对该厂原SBR工艺提标改造方案及实际运行效果进行了介绍，出水水质由《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级B标准提标至一级A标准。原SBR工艺改造为功能分区独立、运行成本低、出水水质稳定、设备利用率高的AAO工艺；增加预处理设施；强化生物处理并设置二沉池；后置均质滤料滤池。改造完成后，该厂出水水质各项指标均优于GB 18918—2002中的一级A标准，可为西北该类型污水处理厂的提标改造提供实际工程借鉴。     

深圳某低浓度进水污水处理厂的提标改造及其运行分析

深圳市某低浓度进水污水处理厂处理规模3 000 m³/d,原设计出水执行GB8918-2002一级B标准。为满足更加严格的水质考核要求,需对污水处理厂进行提标改造,出水执行GB 8918-2002一级A标准。提标改造工程充分利用原有设施及场地,优化处理工艺,将原蚝壳接触氧化池改造成MBBR池,水解沉淀池(初沉池)改造成斜管沉淀池(二沉池),将原蚝壳接触氧化池的反冲洗水池改造为曝气沉砂池,加装砂水分离器、加药及回流装置等,改造后出水稳定达标。改造成本按日均污水量计算为521元/m³,直接运行成本仅提高0.047元/m³。     

MBR工艺在污水处理厂提标扩建工程中的设计研究

四川资阳某污水处理厂原设计规模5×10~4 m~3/d,采用氧化沟工艺,出水执行《城镇污水处理厂污染物排放标准》(GB18918—2002)一级B标准,需提标至地方标准《四川岷江、沱江流域水污染物排放标准》并扩容至7.5×10~4 m~3/d。提标扩建工程在原厂址内改造,尽量利用原有构筑物设备及工艺管线,采用AAO+MBR工艺,将原氧化沟改造为AAO生化池,原二沉池改造为MBR膜池,膜池出水经紫外消毒渠排入沱江。实际运行数据表明,提标扩建后出水水质稳定达到设计出水标准。     

武汉市某CASS工艺污水厂提标改造工程实践

随着污水排放标准的提高，原有城市污水处理厂普遍面临提标改造的要求。本研究以武汉市某污水厂CASS工艺为例，通过实施改造将出水标准由《城镇污水处理厂污染物排放标准》(GB18918-2002)一级B标准提高至一级A标准。该厂处理规模为4.5×10⁴ m³/d,基于原CASS工艺缺少缺氧池，无深度处理系统，缺少碳源投加系统等问题，提标改造工程采用CASS+中途提升泵房+生物磁高效沉淀池+精密过滤器工艺，改造工程实施两年多，在进水水质满足设计要求的情况下，通过调整CASS池各阶段运行时间等，出水水质可稳定达标。     

Compact Swelling in Bi1.4Pb0.6Sr2Ca2Cu3.6Oy During the Formation of High-Tc Superconducting Phase

Compact swelling in Pb-doped Bi-Sr-Ca-Cu-O superconductor has been studied by observing the effects of the size of calcined powders, volatilization of materials, and sintering of high- T _c (2223) powders. The bulk density increases at the early stage of sintering, for about 20 h, and then decreases. Densification occurs when the low- T _c (2212) phase and a liquid phase exist, whereas dedensification occurs with the formation of the 2223 phase regardless of the presence of the liquid. Gas evolution from specimens does not appear to be responsible for compact swelling. Compact swelling is explained by anisotropic growth of thin, platelike 2223 grains in random orientation. When 2223 grains grow in a preferred direction, compact swelling is suppressed.     

Synthetic routes to nanoscale BxCyNz architectures

B_xC_yN_z nanoscale materials, hybrids of h-BN and graphite, have been recently synthesised using various techniques. Here, we present the latest advances in the synthesis and characterisation of B-C-N nanotubes and nanofibres. In particular, we focus on layered BC₂N, BN, BC and CN_x systems, reviewing their production methods as well as their structural and electronic properties. These materials may find important applications in the fabrication of nanotransistors, robust nanocomposites, conducting polymers, storage components and field emission sources.     

Structure Evolution from Pb(Mg1/3Nb2/3)O3 to La(Mg2/3Nb1/3)O3

The crystal structure of lanthanum-modified lead magnesium niobates having composition (Pb_{1− x} La _x ) (Mg_{(1+ x )/3}-Nb_{(2− x )/3})O₃ with X = 0 to 1 was investigated by X-ray powder diffraction. It was found that the fundamental reflections from perovskite structure remain in the whole range of composition. The superlattice reflections from the A(B'_1/2-B"_1/2)O₃ ordered structure are also well preserved for La content greater than 50 at.%; however, a series of extra peaks of mixing indices appears, with intensities gradually enhanced with the increase of La content. For the complete substitution of Pb by La, a splitting of some reflections can be observed in the diffraction pattern. The results indicate that the crystal structure evolves continuously with the La content, from disordered cubic perovskite of space group Pm 3 m for X = 0, to ordered cubic perovskite of space group Fm 3 m for X = 0.5, distorted cubic perovskite of space group Pa 3 for 0.5 < X < 0.9, and finally to a rhombohedral perovskite, possibly belonging to the space group R 3 , for X ≥ 0.9. In the evolution of structure, a linear reduction of the lattice constant of the perovskite cell from 4.048 to 3.964 Å was observed.     

Microwave Dielectric Properties of CaTiO3-CaAl1/2Nb1/2O3 Ceramics Doped with Li3NbO4

The microwave dielectric properties of CaTi_{1− x} (Al_1/2Nb_1/2) _x O₃ solid solutions (0.3 ≤ x ≤ 0.7) have been investigated. The sintered samples had perovskite structures similar to CaTiO₃. The substitution of Ti⁴⁺ by Al³⁺/Nb⁵⁺ improved the quality factor Q of the sintered specimens. A small addition of Li₃NbO₄ (about 1 wt%) was found to be very effective for lowering sintering temperature of ceramics from 1450–1500° to 1300°C. The composition with x = 0.5 sintered at 1300°C for 5 h revealed excellent dielectric properties, namely, a dielectric constant (ɛ_r) of 48, a Q × f value of 32 100 GHz, and a temperature coefficient of the resonant frequency (τ_f) of −2 ppm/K. Li₃NbO₄ as a sintering additive had no harmful influence on τ_f of ceramics.     

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.     

Dielectric-State Analysis in Solid-Solution Pb(Yb1/2Ta1/2)O3–Pb(Lu1/2Nb1/2)O3

The structure and temperature dependence of complex lead perovskite dielectrics were investigated for the system (1 − x )Pb(Yb_1/2Ta_1/2)O₃– x Pb(Lu_1/2Nb_1/2)O₃. Superlattice reflections for the compositions 0.8 < x < 1.0 were observed by X-ray diffractometry, and the temperature-composition dielectric-state diagram was determined. In the present study, the disordered middle composition, with 0.2 < x < 0.8, showed a diffuse paraelectric–ferroelectric phase transition, whereas the ordered end compositions, with 0 ≤ x < 0.2 and 0.8 < x ≤ 1.0, revealed successive sharp paraelectric–antiferroelectric and weak antiferroelectric–ferroelectric phase transitions. The dielectric state was confirmed by examining the variation of polarization ( P ) with electric field ( E ).