电化学技术用于污水脱氮除磷的研究进展

在污水的脱氮除磷处理技术中,电化学技术由于具有高效方便等优点逐渐成为人们关注的热点.综述了电化学氧化去除氨氮、电化学还原去除硝态氮和电絮凝除磷在污水处理中的原理和研究进展,并提出了今后的研究方向.     

化学除磷工艺研究进展

化学除磷是抑制水体富营养化以及从废水中回收磷资源的有效手段。本文阐述了铁盐、铝盐和石灰3种常见化学除磷药剂的除磷机理及其影响因素,如pH值、投加量、投药点以及经济性分析;概述了前置化学辅助除磷、协同化学辅助除磷、后置化学辅助除磷以及旁路化学辅助除磷4种化学辅助生物除磷工艺的特点,最后介绍了吸附法和结晶法除磷新兴工艺,阐明了磷资源回收是未来化学除磷工艺的方向发展。     

传统生物除磷脱氮工艺和反硝化除磷工艺对比

介绍了传统生物除磷脱氮和反硝化除磷的机理,比较了几个有代表性的传统除磷脱氮工艺和反硝化除磷工艺。通过分析认为反硝化除磷菌(DPB)能够以硝态氮为电子受体,从而大大节省耗氧量,缓解常规工艺对外加碳源的需求。如何在不增加工艺流程复杂性的同时,在工艺中充分富集DPB是反硝化除磷的关键。     

新型除磷填料的制备及除磷吸附床运行参数的优化

为解决现有除磷吸附剂粒径小造成的材料易流失和系统压降过大等问题,以实现吸附除磷工艺在实际工程中的应用,以聚氨酯填料为载体,水溶性聚氨酯为介质,将水化硅酸钙负载到聚氨酯填料上制成负载型除磷填料。研究了制备条件对除磷填料除磷效果的影响,采用扫描电子显微镜（SEM）和傅里叶变换红外光谱仪（FTIR）观察分析了负载前后水化硅酸钙微观结构及化学基团的变化;利用除磷填料作为除磷吸附床的滤料,研究了运行条件对吸附床除磷效果的影响。在此基础上,利用响应曲面法研究了除磷吸附床磷酸盐去除率和各变量之间的关系,并对工艺参数进行了优化。结果表明,水性聚氨酯溶液的浓度和用量分别为100 g/L和50 ml,水化硅酸钙的质量为12 g的条件下所制备的除磷填料除磷效果最好;SEM和FTIR分析结果显示,水化硅酸钙负载前后其孔隙结构和化学基团没有明显的变化;预测模型的方差分析结果表明,HRT(X ₁)、进水ρ(PO₄ ^3--P)(X ₂)、温度(X ₃)、初始pH(X ₄)以及X ₁ X ₂,X ₁ X ₄,X ₂ X ₃,X ₂ X ₄的交互作用均对磷酸盐的去除具有显著影响 (P＜0.05),但X ₁ X ₃的交互作用对磷酸盐的去除影响不显著。通过预测模型获得的最佳运行条件为：HRT为79.77 min,进水ρ(PO₄ ^3--P)为1.70 mg/L, 温度为34.04℃,pH为9.68。在该条件下,反应器对磷酸盐的去除率可以达到93.46%。     

污水中除磷工艺的优化研究

本文提出了一种新的污水中高效除磷工艺技术,对电化学除磷的技术要点进行了分析。结果表明,电压对电化学除磷的效果影响最大,电压越大除磷效果越显著。当电解磷的质量浓度在0.5 mg/m L～13 mg/m L,以铁作正极,铝作负极,在电压为30 V,电流为1A下电解60 min,对污水中磷的去除效率达到了96.2%以上,极大地提升了污水中除磷的效率和安全性。     

UNITANK工艺强化生物除磷运行矩阵的确定

分析了UNITANK工艺生物除磷的认识误区,在此基础上总结了UNITANK工艺强化生物脱氮除磷运行矩阵设置的基本原则,试验得出了UNITANK工艺强化生物脱氮除磷的核心控制矩阵和工艺运行控制参数,污水厂年度运行结果表明其出水水质稳定达到城镇污水处理厂污染物排放标准(GB 18918-2002)的一级B标准.     

高效脱氮除磷系统除磷效果优化分析

针对南方城市污水C\N较低的特点以及现有脱氮除磷工艺脱氮除磷效率不高的缺点,设计了一套高效脱氮除磷工艺来强化脱氮除磷的中试装置。本工艺以广州市石井污水处理厂细格栅出水作为处理对象,针对不同工艺参数的除磷效果进行研究,并对各种因素进行组合实验。实验研究结果表明,当好氧池末端的溶解氧质量浓度为1.5mg/L,水力停留时间(HRT)为8h,硝化液回流比为200%,缺氧混合液回流比为150%,体积比为1:2.6:6.4时,高效脱氮除磷工艺对有机物和总磷的处理效果最佳,出水平均COD为32.04 mg/L,TP的平均质量浓度为0.35mg/L,去除率分别为81.32%和85.60%,达到城镇污水处理厂污染物排放标准1级A标准,取得了较好的除磷效果,并且系统抗冲击负荷能力强,装置运行稳定。     

低温条件下A2/O生物强化除磷系统的反硝化除磷特性

以处理城市污水的中试规模A2/O工艺为研究对象,通过改变进水流量以及混合液回流比来调节缺氧区硝酸盐浓度,研究了低温((12±4)℃)条件下生物强化除磷(EBPR)系统的反硝化除磷特性.试验结果方差分析(ANOVA)表明,生物除磷与脱氮过程之间存在紧密相关性(p＜0.05),并观测到反硝化除磷现象;当进水流量为2.5m3...     

铜仁市污水处理厂除磷工艺运行研究

随着社会的发展和现代化工业的迅速发展及人们生活水平的不断提高,生活污水和工业废水的大量排放,氮、磷的污染也日趋严重,水体的富营养化问题引起了整个社会的关注及专家的重视。人们环保意识逐渐加强,生物除磷脱氮技术得到了较大的发展和应用,通过国家及地方投资建立了多种形式的除磷脱氮城市污水处理厂。本文结合铜仁市污水处理厂A2/O工艺系统的运行情况,对生物除磷脱氮机理、影响除磷效果的因素进行研究,为全面提高A2/O工艺系统的运行效果提供一定经验。     

分段进水一体化工艺除磷影响因素研究

采用分段式进水一体化工艺处理校园生活污水,考察了不同影响因素对除磷效率的影响。试验结果表明:在厌氧区和缺氧区进水流量比为3∶1时,总磷去除率最高,平均去除率达到了93%以上;在好氧区DO的质量浓度约为2.0 mg/L时,总磷去除率最高,平均去除率达到了91%以上;在HRT为8 h时,总磷去除率最高,平均去除率达到了93%左右;正交试验结果表明影响TP去除率的因素优先顺序为DO、进水流量比、 HRT,最佳组合工艺参数为厌氧区和缺氧区进水流量比为3∶1, DO的质量浓度为2.0 mg/L, HRT为8 h。     

循环冷却水DSA电极电化学除垢中试试验

以华北地区某机场中央空调循环冷却水为处理对象,进行了DSA电极电化学除垢中试试验.试验结果表明:工艺最佳运行工况是电流密度为25.56 A/m2、停留时间为4.0 min,硬度含量由进水的225.62 mg/L降至174.02 mg/L,比能耗为119.09 kW·h/kg;与实验室小试相比,阻垢剂的存在对除垢效果无显...     

电化学氧化煤浆特性研究

采用伏安法对六种煤浆的电解氧化特性进行研究,考察了煤种、铁离子溶液催化剂、温度和搅拌速度对氧化电流密度的影响。结果表明,温度、电压和转速的增加可以提高其氧化电流密度,在室温下加入5 mmol Fe3+,可以使神木煤浆的氧化电流密度提高至18.4 m A/cm2。通过XRD分析可知,电解破坏煤的大分子结构。     

电化学技术在印染废水处理中应用

对电化学技术处理印染废水进行了实验研究,分析了工艺参数(pH值、电流密度和进水流量)对电化学处理技术的影响。实验结果证明:在进水pH值4、电流密度0.8 A/dm2、进水流量0.8 L/h条件下进行处理效果最佳。此时,出水COD小于90 mg/L,SS小于35 mg/L,色度小于56,很好满足出水水质要求。     

Disinfection of Biologically Treated Municipal Wastewater using Electrochemical Process

The present study demonstrates the application of Al-Al electrode combination for electrochemical disinfection of biologically treated municipal wastewater (BTMW) of Sewage Treatment Plant. A glass chamber of 2 liter volume was used for the Electrochemical (EC) process using two electrode plates of aluminum (Al-Al) with DC power supply at different operating conditions of current density (CD), operating time (OT), inter electrode distance (IED), electrode area (EA), initial pH, and settling time (ST). The maximum removal of total coliforms (TC) (99.99%) and total bacteria (TB) (99.87%) from BTMW was achieved with the optimum operating conditions of CD (2.65 A/m²), OT (40 mins.), IED (0.5 cm), EA (160 cm²), initial pH (7.5), and ST (60 min.). The efficiency of the EC process for disinfection of BTMW was strongly affected by the CD, OT, IED, EA, pH, and ST. These effects can be explained by the formation of the reactive species such as OH^?, and ClO₂^?·during the electrochemical process. Under optimal operating conditions, the operating cost was found to be 1.01 $/m³ in terms of the electrode consumption (23.71 x 10^?5 kg Al/m³) and energy consumption (101.76 kwh/m³).     

电化学抛光对HR-1不锈钢表面的影响

以硫酸-磷酸混合液为电解液,考察了电化学抛光技术对HR-1不锈钢表面的影响。通过激光扫描共聚焦显微镜观察样品的表面形貌,并利用电子天平测量样品的质量变化。结果表明:当电流密度为80A/dm2,温度为90℃,抛光时间为60s时,样品表面的平整度最高,机械加工痕迹基本消失,无明显的尖峰与坑点,粗糙度小于0.18μm。为保证样品的尺寸精度,需要控制抛光时间。     

Studies Relating to Removal of Arsenate by Electrochemical Coagulation: Optimization,Kinetics, Coagulant Characterization

The present investigation aims to remove arsenate [As(V)] by electrochemical coagulation using mild steel as anode and cathode. The results showed that the optimum removal efficiency of 98.6% was achieved at a current density of 0.2 A dm^?2, at a pH of 7.0. The effect of current density, solution pH, temperature, co-existing ions, adsorption isotherm, and kinetics has been studied. Kinetics reveals that the removal of arsenate by electrochemical coagulation is very rapid in the first 15 min and remains almost constant with the progress of reaction. The adsorption kinetics obeys the second-order rate expression. An equilibrium isotherm was measured experimentally and the results were analyzed by Langmuir, Freundlich, Dubinin- Redushkevich, and Frumkin using the linearized correlation co-efficient. The characteristics parameters for each isotherm were determined. The Langmuir adsorption isotherm was found to fit the equilibrium data for arsenate adsorption. Temperature studies showed that the adsorption was endothermic and spontaneous in nature.     

AZ91D镁合金磷酸盐转化膜的制备与表征

为了提高AZ91D镁合金基体的耐蚀性,采用电化学转化方法在其表面制备一层非金属、不导电、难溶的多孔磷酸盐转化膜。通过金相显微镜和电化学工作站,研究了磷化时间和电流密度对磷化膜表面形貌和耐蚀性的影响。结果表明:当磷化时间为5min、电流密度为3.25A/dm2时,制备的磷化膜均匀、致密,完全覆盖基体,并且耐蚀性优异。     

Ga掺杂FeNb11O29材料的制备及其电化学性能

FeNb11O29由于其高的理论充电容量(400 mAh·g-1),作为锂离子电池(LIBs)负极材料具有很大的应用前景.然而,目前报道的FeNb11O29实际容量仅有168～273 mAh·g-1.因此,有必要进一步提高其电化学性能.本文介绍了一种制备Ga掺杂FeNb11O29材料的方法,成功合成了GaxFe1-xN...     

Electrochemical oxidation of several chlorophenols on diamond electrodes: Part II. Influence of waste characteristics and operating conditions

The electrochemical treatment of wastes containing several chlorophenols (4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol) using boron-doped diamond electrodes is described. Both direct and indirect processes are involved in the oxidation of the organics, indirect processes being mediated by oxidising agents (such as hypochlorite or peroxodisulphate) generated on the surface of the anode. The influence of the waste characteristics (initial concentration, pH and supporting media) is reported. The presence of reversible redox reagents, like the sulphate/peroxodisulphate redox couple, plays an important role in determining the global oxidation rate. Hypochlorite formation depends only on the organochlorinated compound and not on the presence of other reversible redox reagents in the waste. Alkaline pH favours the accumulation of carboxylic acid intermediates since, under these conditions, the oxidation rate of such compounds is low. The influence of the operating conditions (temperature and current density) is also discussed. The results show that high temperatures improve the rate of the mediated reactions and that high current density values decrease the efficiency of the direct electrochemical processes.     

Electrochemical conversion of phenolic wastewater on carbon electrodes in the presence of NaCl

The electrochemical conversion of highly concentrated synthetic phenolic wastewater was studied on carbon electrodes in a batch electrochemical reactor. The effects of reaction temperature, electrolyte concentration, current density and initial phenol concentration on phenol conversion were elucidated. The wastewater was synthetically prepared and used in reactions carried out generally at 25 °C with an initial phenol concentration of 3500 mg dm^?3. Although current density increased, phenol conversion% and initial phenol conversion rate did not increase correspondingly above 35 °C and an electrolyte concentration of 90 g dm^?3. As the voltage values applied were increased, the increasing current density resulted in fast phenol conversion. Kinetic investigations denoted that overall phenol destruction kinetics was of zero order with an activation energy of 10.9 kJ mol^?1. Under appropriate conditions, phenol was completely converted within 15 min for an initial phenol concentration of 98 mg dm^?3 while 8 h was required to gain 95% conversion using 4698 mg dm^?3. Solid polymeric materials were produced at initial phenol concentrations above 500 mg dm^?3 using the appropriate current density. In the reaction medium, only mono‐, di‐ and tri‐substituted chlorophenols were formed and 100% of all species were either oxidised or contributed to the formation of a polymeric structure. Almost all of the phenol loaded to the reactor was converted into non‐passivating polymeric products, denoting a safe and easy method for the separation of phenol. © 2001 Society of Chemical Industry