Electrochemical Degradation of Indigocarmine Dye at Ni/Graphite Modified Electrode in Aqueous Solution

Nickel Graphite modified electrode (Ni/GME) was prepared by electrochemical method and degradation of Indigocarmine (IC) dye was carried out. An investigation between the efficiency of degradation by graphite electrode and the Ni/graphite modified electrode has been carried out. The different effects of concentration, current density and temperature on the rate of degradation were studied. This study shows that the rate of the degradation is more for Ni doped modified graphite electrode. UV-Visible spectra before and after degradation of the dye solution were observed. The thin film formation of Ni or encapsulated in graphite rod is observed by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM & EDAX). The instantaneous current effectiveness values of different experimental conditions are evaluated. The anodic oxidation by Ni/ graphite modified electrode showed the complete degradation of aqueous solution indigocarmine, which is confirmed by UV-Visible and chemical oxygen demand (COD) measurements. The dye is converted into CO2, H2O and simpler inorganic salts. The results observed for reuse of modified electrodes indicate that the Ni/graphite modified electrode would be a promising anode for electrochemical degradation of indigocarmine. This method can be applied for the remediation of waste water containing organics, cost-effective and simple.

近红外光谱的水体污染指标COD定量预测模型

针对传统化学需氧量(chemical oxygen demand, COD)检测存在检测成本高、耗时、易造成二次污染,以及现有检测模型泛化性较差等不足,难以满足水环境实时监测需求的问题,提出基于近红外光谱技术的COD快速无损定量预测模型.实验结果表明,本模型在污水COD光谱数据集上的预测性能,相较于传统机器学习算法和现有其他深度学习算法更优.测试的决定系数(R^(2))和均方根误差(E_(RMS))分别达到0.992 1和27.47 mg·L^(-1),模型卷积层的输出特征可解释性强,能有效表征关键波长点.该预测模型为实际水体COD含量快速检测提供一种新的方法.

污水中化学需氧量(COD)与浊度的关系

【目的】研究某采油管理区生活污水处理站出水样品中化学需氧量与浊度之间的关系,提出便捷、快速判断污水水质的方式,为该处理站运营人员提供管理依据。【方法】使用快速测定仪,对2023年8月份不同日期,在该采油管理区生活污水处理站出口处采取的16个水样的化学需氧量与浊度进行检测,并使用最小二乘法对检测数据进行整理、分析。【结果】结果表明,该采油管理区生活污水处理站出水水样中化学需氧量与浊度存在线性正相关关系,线性方程为y=0.247 1x-4.848 8,线性回归判定系数R2=0.931 5(即化学需氧量与浊度具有较高的相关性)。【结论】可以通过简单易测的浊度来表征该采油管理区生活污水处理站出水中的化学需氧量。

一种高盐高COD废水处理技术在化工废水治理中的应用

在我国工业化发展进程中,产生了大量包括高盐高COD在内类型的工业废水。高盐高COD废水盐分高,有机物浓度高,可生化性差,较难治理。文章介绍了一种高盐高COD废水的治理技术,该处理工艺具有污染物去除率高、运行效果稳定、自动化程度高等优点。

高盐化工水COD检测方法的对比分析与选择

为了降低现代工业生产过程中高盐对于废水COD含量检测的影响,技术人员普遍会采取稀释、掩蔽等多种方法优化COD检测质量。本文通过对相关文献进行查阅,以高盐化工水为研究对象,对高盐干扰背景下的COD检测方法进行对比研究,并提出了针对性较强的处理建议。希望本文的研究内容能够为高盐化工水COD检测工作质量提升提供一定理论支持。

Chemical oxygen demand reduction in coffee wastewater through chemical flocculation and advanced oxidation processes

The removal of the natural organic matter present in coffee processing wastewater through chemical coagulation-flocculation and advanced oxidation processes （AOP） had been studied. The effectiveness of the removal of natural organic matter using commercial flocculants and UV/H202, UV/O3 and UV/H2O2/O3 processes was determined under acidic conditions. For each of these processes, different operational conditions were explored to optimize the treatment efficiency of the coffee wastewater. Coffee wastewater is characterized by a high chemical oxygen demand （COD） and low total suspended solids. The outcomes of coffee wastewater treatment using coagulation-flocculation and photodegradation processes were assessed in terms of reduction of COD, color, and turbidity. It was found that a reduction in COD of 67% could be realized when the coffee wastewater was treated by chemical coagulation-flocculation with lime and coagulant T-1. When coffee wastewater was treated by coagulation-flocculation in combination with UV/H2O2, a COD reduction of 86% was achieved, although only after prolonged UV irradiation. Of the three advanced oxidation processes considered, UV/H2O2, UV/O3 and UV/H2O2/O3, we found that the treatment with UV/H2O2/O3 was the most effective, with an efficiency of color, turbidity and further COD removal of 87%, when applied to the flocculated coffee wastewater.

Disruption of biofilms from sewage pipes under physical and chemical conditioning

Biofilms grown inside two sewage collecting pipes located in industrial and residential areas are studied. Bacterial biomass inside three layers of biofilms was evaluated. Biofilm cohesion under different mixing rate and ionic strength was also investigated. Effects of physical and chemical parameters in the biofilms were evaluated by monitoring turbidity, chemical and biochemical oxygen demands. Extracted organic matter from biofilms was partitioned to polar, aromatic and saturated fractions using activated silica column chromatography. Results revealed that bacterial biomass growth depending on biofilm thickness and stratification. The most loaded stratum in bacteria/biomass was the sewage-biofilm interface stratum that represented 51% of the total bacteria/biomass. Stirring rate and ionic strength of mono- and bivalent salts showed a major influence in biofilm disruption. The stirring time enhanced the exchange dynamic and matter capture between biofilm fragments at the critical stirring rate 90 r/min. Sodium chloride showed the dispersing effect on biofilms in suspension, and decreased the BOD5 （biochemical oxygen demand） beyond the physiological salt concentration.

Environmental capacity of chemical oxygen demand in the Bohai Sea: modeling and calculation

A three-dimensional advection-diffusion model coupled with the degradation process is established for describing the transport of chemical oxygen demand (COD). Comparison of the simulated distribution of COD at the surface in the Bohai Sea in August, 2001 with field observations, shows that the model simulates the dataset reasonably well. The Laizhou Bay, Bohai Bay, and Liaodong Bay were contaminated heavily near shore. Based on the optimal discharge flux method, the Environmental Capacity (EC) and allocated capacities of COD in the Bohai Sea are calculated. For seawater of Grades I to IV of the Chinese National Standard, the ECs of COD in the Bohai Sea were 77×104 t/a, 116×104 t/a, 154×104 t/a and 193×104 t/a, respectively. The Huanghe (Yellow) River pollutant discharge accounted for the largest percentage of COD at 14.3%, followed by that of from the Liugu River (11.5%), and other nine local rivers below 10%. The COD level in 2005 was worse than that of Grade II seawater and was beyond the environmental capacity. In average, 35% COD reduction is called to meet the standard of Grade I seawater.

Effects of Urechis unicinctus Juveniles on Chemical Characteristics of Organically Contaminated Coastal Sediment

Biological activities of marine benthos such as burrowing and feeding may change sediment characteristics.We conducted three experiments to examine the potential of using juveniles of a spoon worm Urechis unicinctus to improve the quality of organically contaminated coastal sediment.Sediment samples were collected from a site that was heavily contaminated with organic matter (Seonso) and two sites that were clean (Myo-do,Dolsan-do).Urechis juveniles,obtained by artificial fertilization and cultured in the laboratory,were introduced to the sediment (weight 3 kg,depth 10 cm) at a density of 500 individuals per aquarium (length 50 cm,width 35 cm,height 30 cm) (Experiment 1),or at densities ranging from 100 to 900 individuals per beaker (Experiment 2).To examine how sediment contamination can be modified by the effects of Urechis,500 individuals (per aquarium) were exposed to the Seonso contaminated sediment that had been mixed with 0-100% clean sand (Experiment 3).Each experiment lasted two months and sediment samples were collected every 15 d to determine the several indexes of sediment quality,which included acid volatile sulfide (AVS),chemical oxygen demand (COD) and total ignition loss (TIL).In Experiment 1,the existence of Urechis did not result in significant changes in quality indexes in the sediments collected from Myo-do,Dolsan-do.However,AVS,COD and TIL of the Seonso sediment all decreased significantly after co-incubation with Urechis juveniles for 30 to 45 d.Experiment 2 showed that a density of at least 300 juveniles per beaker was necessary to significantly reduce all three quality indexes,and the magnitude of reduction was positively correlated with juvenile density.Experiment 3 revealed that Urechis juveniles were effective in reducing the AVS,COD and TIL of the Seonso sediment that had been mixed with 60%,80%,and 80% of clean sand,respectively.The results of the present study therefore indicated that juveniles of this spoon worm have the potential to be used to improve the quality of organically contaminated sediment in coastal waters.

On-Line Measurement of the Chemical Oxygen Demand in Wastewater in a Pulp and Paper Mill Using Near Infrared Spectroscopy

Although near infrared (NIR) spectroscopy has been evaluated for numerous applications, the number of actual on-line or even on-site industrial applications seems to be very limited. In the present paper, the attempts to produce online predictions of the chemical oxygen demand (COD) in wastewater from a pulp and paper mill using NIR spectroscopy are described. The task was perceived as very challenging, but with a root mean square error of prediction of 149 mg/l, roughly corresponding to 1/10 of the studied concentration interval, this attempt was deemed as successful. This result was obtained by using partial least squares model regression, interpolated reference values for calibration purposes, and by evenly distributing the calibration data in the concentration space. This work may also represent the first industrial application of online COD measurements in wastewater using NIR spectroscopy.

重铬酸盐滴定法测定COD的影响因素研究

消解酸度、滴定酸度、还原性离子、消解时间等是影响重铬酸钾滴定法测定水中化学需氧量(COD)的重要因素。本文对这些影响因素开展研究,结果表明,消解酸度从50%(v/v)减少至30%,COD的测定值降低了35%~57%。氯离子的氧化产物为氯气,但采取0.025 mol/L的重铬酸盐时不能被完全氧化;铵离子单独存在时对测定COD值无贡献,但与氯离子共存时有贡献;碘离子则无此现象。

掺杂碳酸钙污泥生物炭去除废水中化学需氧量(COD)的实验研究

通过在污泥生物炭中添加不同含量的碳酸钙(CaCO_(3)),不同碳酸钙掺量污泥生物炭(Sludge biochar of calcium carbonate,SBC-Ca)在相同条件下得到制备,对其去除废水中化学需氧量(chemical oxygen demand,COD)的效果进行了评估。结果表明:CaCO_(3)比例为9%的污泥生物炭为最佳掺量;通过正交试验,最佳设计组合为A_(1)B_(2)C_(1)D_(3)E_(1),即吸附时间为60min,生物炭投加量为4.0g/L,pH6.0,温度为25℃,COD初始质量浓度为689.09mg/L;在最佳碳酸钙掺量下,SBC-Ca对废水中COD的去除量为166.08mg/g,去除率高达97.83%;比表面积和孔径分析显示SBC-Ca比表面积为39.86m^(2)/g,中孔量较多;红外光谱图表明含有-OH、C=O、C-O、Si-H等官能团;X射线衍射(X-Ray diffraction,XRD)谱图和扫描电子显微镜(scanning electron microscope,SEM)图显示SBC-Ca负载了CaCO_(3)。

废液再生型COD_(Cr)分析仪的研制及试验方法研究

针对重铬酸钾法检测水中化学需氧量(COD)产生的废液会造成环境污染的问题,设计并开发了一款可实现COD废液再生及循环利用的新型COD_(Cr)分析仪(CODet-5000型)。首先,通过向COD_(Cr)废液中加入氧化剂来氧化Cr^(3+),以提高Cr^(6+)的浓度、减小空白的吸光度。然后,采用蒸馏浓缩的方式提高废液的酸度,并过滤不溶性物质。最后,将得到的再生液作为COD_(Cr)分析仪测量所需的消解液循环使用,从而实现环境零污染。试验结果表明,该分析仪测量时具有较好的重复性和稳定性,所得数据示值误差在允许范围内。该分析仪的研制为常规COD_(Cr)分析仪实现废液循环利用、环境友好等目标提供了参考,并在环境监测仪表开发领域有着十分重要的意义,具有广阔的应用前景和市场潜力。

典型重金属离子对SBR脱氮工艺及COD去除的影响研究进展

氮是目前导致水体富营养化的主要污染物质,而化学需氧量(COD)是体现水体中有机物污染情况的主要指标。近年来,SBR工艺作为一种应用广泛的污水处理工艺,在生物脱氮技术中也备受关注。实际含氮废水中,通常含有一定量的重金属,包括Zn、Cu和Ni等。这些重金属的存在,会抑制微生物的代谢能力,严重影响氮和COD的去除。选取含氮废水中的3种典型重金属离子(Cu^(2+)、Zn^(2+)和Ni^(2+)),进行了其对SBR工艺中脱氮效能的相关影响研究。研究结果表明:在较低质量浓度情况下,Cu^(2+)、Zn^(2+)和Ni^(2+)3种典型重金属离子对脱氮及COD的去除有一定的促进作用;在高质量浓度情况下,对脱氮及COD去除会产生抑制作用,且随质量浓度的增加而抑制作用增强。

表面活性剂与纳米颗粒协同稳定Pickering有机硅乳液的制备及其应用性能

针对目前有机硅平滑剂乳液往往存在分散稳定性差或高剂量表面活性剂引起的应用性能降低等问题,以聚丙烯酸异辛酯的共聚物胶乳(PEHA)为Pickering颗粒,协同表面活性剂,用于制备“油/水”Pickering有机硅乳液,并将其用于织物后整理。考察了PEHA粒径、表面亲水改性及PEHA质量分数对有机硅乳液分散稳定性的影响,通过对整理残液化学需氧量(COD)和整理织物表面摩擦因数的研究,考察了表面活性剂与Pickering纳米颗粒协同稳定对有机硅乳液应用性能的影响。结果表明:PEHA颗粒吸附在有机硅液滴的表面,形成机械阻隔,提升有机硅乳液的分散稳定性,180 nm的PEHA颗粒的稳定效率最佳,90 nm时的稳定效率最差;表面亲水改性能显著提高PEHA稳定乳液的效率,在质量分数仅为10%时,即可实现乳液稳定;最佳稳定方案可使表面活性剂质量分数降低60%以上;浸轧整理织物时,相比表面活性剂独自稳定的体系,Pickering体系吸附织物效率更高,整理后残液的COD值降低63%,整理织物表面静、动摩擦因数分别降低至0.51与0.49,即“Pickering/表面活性剂”协同稳定有机硅乳液具有良好的应用性能。

油田污水处理工艺中COD的去除研究进展

概述了油田污水的组成特点,并从近年来聚合物驱油和三元复合驱油产生污水带来的新问题出发,阐述了油田污水处理的难点所在。同时对当前油田污水处理工艺流程特点、实际工艺中存在的不足等作了比较,得出当前油田污水处理过程中工艺流程的选择标准和目标。重点对工艺处理中的絮凝沉降、生化处理以及膜法处理等不同的工艺流程中COD的去除进行了研究,通过比较各种方法得出在油田污水处理中利用生化法和膜处理方法的有机结合将是油田污水处理的主要发展方向。同时对当前油田污水处理中亟待需要解决的问题作了进一步表述。

一种快速测定化学需氧量(COD)的方法

提出用混酸来代替单一酸测定废水中的化学需氧量(COD)含量的方法。采用混酸(硫酸∶磷酸=4∶1)、重铬酸钾反应体系,氧化反应时间由标准方法的2h缩短为15min,是原来的1/8。用两种方法分别测试了标准物质所配制的废水和实际废水,经t检验和相关性分析,两种测试方法间不存在显著性差异,相关系数为0.95,相关性良好,同时实验得出本方法的检测限为5.15mg/L。本方法由于具有反应时间短,节省药剂和电费等优点,具有一定的可行性。

高浓度氯离子化工废水中COD测定方法比较

高浓度氯离子的存在直接影响化工废水中COD值的测定准确性,通过对稀释法、硝酸银沉淀法、硝酸银和硫酸铬钾法、氯气校正法以及标准曲线法等测定方法的比较,得出采用相应的标准曲线校正系数,以最有效地消除氯离子的干扰,而且操作灵活,可获得较为准确的COD测定值,同时还可减少因使用有毒药品而造成的人体伤害和环境二次污染。

重铬酸钾法测定COD存在问题及改进研究进展

肯定了传统的COD测定方法——重铬酸钾法的优点,指出了存在的不足和问题：耗时长、试剂用量大、耗水、耗电、费人工、排污严重、存在氯的干扰、贵金属的浪费。较为全面地叙述了对上述各问题改进的国内外研究进展,简单介绍了COD测定的几种新方法,指出了未来需要的是准确、快速、稳定、灵敏、价格合理、携带方便、无二次污染的环境友好型COD在线自动监测仪。

近红外光谱透射法测量废水化学需氧量(COD)的光程选择

在用近红外光谱法测量废水化学需氧量（COD）时,水是一个强干扰因素,如何选择合适的光程长以提高测量灵敏度,减少测量误差很重要.本文通过在傅里叶变换近红外光谱仪上用透射光谱法测量废水COD实验来讨论废水测量的光程选择.采集了60个养猪废水水样,分别用1mm、2mm、5mm和10mm的样品池作对比研究,用PLS回归建模,比较不同光程长对废水COD预测的效果,结果显示在800-1350nm谱区选用10mm的光程,在1350-2500nm谱区选用1mm或2mm的光程测量,使用双光程组合方法建模可以提高模型在800-2500nm谱区的预测性能.该光程组合方法对其它复杂组分的水溶液的近红外定量测量也具有一定的参考意义.