水中总磷测定方法的改进

针对目前总磷测定方法GB11894—89消解过程中存在的不安全因素,以及温度难以控制﹑稳定性比较差﹑消解不彻底﹑速度慢等缺点,本论文以水热反应釜代替比色管﹑烘箱代替压力蒸汽消毒器进行消解,用钼酸铵分光光度法测定水中总磷的含量。采用改进后的方法测定水中的总磷,其相关系数为0.9999,加标回收率为94%—103%,RSD<5%。实验证明,改进后的方法优化了消解环境,提高了总磷测定方法的稳定性,缩短了消解时间,且灵敏度﹑准确度﹑精密度等均能符合相关标准要求。     

对测定总氮新标准(HJ 636-2012)的探讨

碱性过硫酸钾消解紫外光度法是测定总氮的常用方法.对《水质总氮的测定碱性过硫酸钾消解紫外分光光度法》(HJ 636-2012)进行了探讨和改进,结论如下:采用标准曲线代替工作曲线不影响测定;减少消解液的用量,准确控制消解液的加入量,可以使空白值降低并且保持稳定,满足大部分实际样品的测定.通过碱性过硫酸钾溶液的配制、贮存方式、比色管的清洗方式等试验,对新标准部分内容进行了探讨.     

微波消解联合测定水中总磷总氮

探讨了微波消解联合测定总磷、总氮的新方法，确定了碱性过硫酸钾的碱度、加入量和微波消解的最佳条件，氮的回收率为96．5％～102．8％，磷的回收率为94．1％～104．3％。与标准法相比，该方法具有快速、能耗少、操作方便等优点，测定精密度和准确度均令人满意。     

废水中总氮含量低于氨氮含量原因探讨

针对废水水质分析过程中出现的氨氮含量高于总氮含量的情况,对氨氮测定过程和总氮测定过程中的金属离子干扰、标准曲线绘制、消解时间等进行了分析,提出氨氮含量高于总氮含量是由于总氮消解时间不够,导致过硫酸钾的转化不完全造成的。实验结果表明,将总氮消解时间设定为40min可以解决此问题。为提高测定的准确性,在实验中还应注意实验环境、计量器具及高压灭菌锅的密封性等问题。     

地表水检测中氨氮高于总氮的原因探讨

针对采用国标方法测定同一水样的氨氮和总氮时所出现的氨氮浓度高于总氮浓度的情况，分析了测定方法的准确性，并分析了各影响因素对测定结果的影响。结果表明，消解时间不足造成了总氮测定结果偏低，提出对于成分复杂、色度较高的地表水水样，将消解时间延长至60min可提高测定结果的准确度。     

TOC/TN分析仪测定水质中总氮的方法研究及应用

目前测定水中总氮（TN）含量采用的是HJ 636—2012《水质 总氮的测定 碱性过硫酸钾消解紫外分光光度法》,其实验条件要求较为苛刻。用TOC/TN分析仪测定水质中总氮含量,测定样品的相对标准偏差为0.72％～4.64％,加标回收率为97.5％～103.0％,测定标准样品的相对误差为－4.33％～7.00％,精密度、准确度均能达到标准要求。该方法简化了实验步骤,提高了工作效率,可代替标准方法。     

微波消解/流动注射光度法在线测定水中的总氮

利用微波在线消解水样，将流动注射分析技术与分光光度法相结合，建立了一种在线测定水中总氮的快速分析方法。在优化试验条件下，该方法对TN的检出限为0．04mg／L，对总氮含量为0．491mg／L的标准样品测定11次的相对标准偏差为1．2％。采用该方法测定河水、生活污水、工业废水水样中的TN含量，其相对标准偏差≤1％，加标回收率为97％～101％，结果令人满意。     

紫外分光光度法测定水样中总氮的新方法

针对采用传统方法测定水样中总氮时存在的不足,研究了紫外分光光度法测定水样中总氮的新方法,并与碱性过硫酸钾消解/紫外分光光度法( GB 11894-89)进行对比.结果表明:对标准样品进行测定的结果与推荐值基本一致,相对误差为-0.83％ ～3.66％,相对标准偏差为1.10％～3.87％;对实际水样进行了测定,加标回收率为94.0％～103.0％,与标准方法测定结果吻合较好,适用于水样中总氮的测定.     

污水中总氮和总磷连续测定方法探讨

采用同一消解液消解污水水样,并连续测定水中的总氮和总磷.试验结果表明,只要选择适当的消解液浓度,即可经同一消解液消解后连续测定水中的总氮和总磷.采用该方法分析了标样和各种水样,结果表明,该方法准确、简便且可连续测定水中的总氮和总磷.     

硝酸盐氮、总氮的测定 气相分子吸收光谱法

HJ／T 198—2005规定了地表水和污水中硝酸盐氮的气相分子吸收测定方法，适用于地表水、地下水、海水、饮用水、生活污水及工业污水中硝酸盐氮的测定，检出限为0．006mg／L，测定上限为10mg／L。HJ／T 199—2005规定了总氮的气相分子吸收测定方法，适用于地表水、水库、湖泊、江河水中总氮的测定，检出限为0．050mg／L，测定下限为0．200mg／L，测定上限为100mg／L。本标准为首次制订，于2006年1月1日实施。     

绿化用有机基质中总汞和总砷测定方法的研究

建立了一种联用王水水浴消解和原子荧光分光光度计(AFS)测定绿化用有机基质中总汞和总砷的测定方法.对比了传统消解和王水水浴消解两种样品前处理方法对有机基质重金属元素的消解效果.结果 表明:(1)王水水浴消解法对总砷和总汞的检出限为0.624 mg/kg和0.024 mg/kg;方法对3种有机基质中总汞和总砷测定的相对标...     

王水消解/冷原子吸收测定污泥总汞方法的改进

建立了一种灵敏度高、操作简便的分析方法,采用(1+1)王水作为消解试剂水浴消解样品,以冷原子吸收法测定城市污水处理厂污泥中的总汞。在优化的试验条件下,该方法检出限为0.003 9 mg/kg,线性范围为0～10.0μg/L,加标回收率在91.9%～104.2%之间,测定结果的相对标准偏差<4%。在测定标准参考样品及污泥实际样品时均取得满意结果。该方法具有操作简单、快速、重现性好等特点,可满足环境监测行业对污泥样品总汞浓度的日常测定要求。     

高压消解/流动注射光度法同时测定水中总氮与总磷

采用流动注射分析仪测定水中的总氮与总磷,结果显示,总氮在0.00～10.0 mg/L、总磷在0.00～1.00 mg/L的范围内,均可以获得良好的线性方程,相对误差<5%,相对标准差为1%～3%,方法的最低检出限分别为2.27μg/L和2.11μg/L,低于国标方法检出限,总氮的回收率为97.2%～108%,总磷的回收率为100%～106%,该方法适用于同时自动检测水中总氮与总磷的含量.     

等离子光谱法测定城市污泥中总镉、总铬的方法改进

目前检测城市污泥中总镉、总铬的标准方法为<城市污水处理厂污泥检验方法>(CJ/T 221-2005),该方法样品消解时间长、酸用量大,为此改进了样品消解方法,分别采用HNO3-H2O2常压消解、HNO3-H2O2微波消解法处理污泥样品,然后采用等离子光谱法检测污泥中的总镉、总铬.与标准方法的对比试验结果表明,两种方法的相对偏差为0.8%～7.2%.改进的常压消解法的加标回收率:总镉为98.5%～105%,总铬为94.2%～95.6%;微波消解的加标回收率:总镉为104%～106%,总铬为98.5%～102%;改进方法的检出限:总镉为0.000 75 mg/L,总铬为0.002 3 mg/L.     

Evaluation of a second derivative UV/visible spectroscopy technique for nitrate and total nitrogen analysis of wastewater samples

A method for nitrate analysis based on second derivative UV/Visible spectroscopy was developed by Simal et al. (1985: Simal J., Lage M. A., and Iglesias I. (1985) Second derivative ultraviolet spectroscopy and sulfamic acid method for determination of nitrates in water. J. Assoc. Analyt. Chem. 68, 962-964) and Suzuki and Kuroda (1987: Suzuki, N. and Kuroda R. (1987) Direct simultaneous determination of nitrate and nitrite by ultraviolet second-derivative spectrophotometry. Analyst 112, 1077-1079), and later modified for the analysis of total nitrogen in aqueous samples of varying nitrate:organic nitrogen ratios (Crumpton et al., 1992: Crumption W. G., Isenhart T. M. and Mitchell P. D. (1992) Nitrate and organic N analyses with second-derivative spectroscopy. Limnol. Oceanogr. 37, 907-913). The procedure uses the second derivative of the absorption spectrum for nitrate (NO3-), which has a peak at approximately 224 nm that is proportional to the NO3- concentration. Samples for total N analysis are first oxidized to NO3- by persulfate digestion. The objectives of this study were to: (1) test the accuracy and precision of the second derivative method through the use of NIST-traceable wastewater check samples; (2) determine whether the second derivative method for nitrate analysis can be used for wastewater samples and whether the method compares favorably with other currently used nitrate analysis methods; and (3) use the method to analyze wastewater samples containing a range of nitrate and total nitrogen concentrations. Our results indicated that the method needed to be modified to include a longer digestion time (60 min) and dilution of samples prior to digestion (if needed). With the modified method, nitrogen recoveries were not significantly different (P > or = 0.05) from samples with known N concentrations. In addition, nitrate concentrations in constructed wetland and wastewater samples analyzed by both second derivative spectroscopy and ion chromatography were not significantly different. Total nitrogen concentrations in wastewater samples also compared favorably to the same samples analyzed by Kjeldahl digestion. The method is faster, simpler, requires smaller sample volumes, and generates less waste than many EPA-approved methods of N analysis, and may offer a suitable alternative to current methods for analysis of nitrate and total N in wastewater samples.     

组合高级氧化水样预处理在水质总磷检测中的应用

在水样总磷含量的测定中,采用组合高级氧化技术对水样进行预处理,与传统国标法添加过硫酸钾高压消解相比,具有操作简单、消解速度快、无需添加化学试剂、无二次污染、便于实现水质总磷的在线检测等优点。通过试验分析对比,用本方法对水样总磷氧化消解则完全、稳定,测量结果与国标法(GB 11893—89)消解后测量结果基本一致,是一种"环境友好型"的绿色水处理技术,应用于在线监测系统中具有良好的实用价值。     

On the peroxodisulphate oxidation of total nitrogen in waters to nitrate

The method proposed by Koroleff of oxidizing total nitrogen in natural waters to nitrate by means of peroxodisulphate in alkaline medium at 120°C is studied in some detail applying earlier experiences concerning the reduction of nitrate by cadmium and the determination of nitrite formed as an azo dye. The choice of the proper concentrations of peroxodisulphate and sodium hydroxide for the digestion is critically discussed as well as the choice of the proper pH and buffer system for the reduction. As a result a new reagent is proposed whose concentrations of peroxodisulphate and sodium hydroxide are founded on the stoichiometric relations at the autodecomposition of the peroxodisulphate; the proper pH of 8.0 for the reduction is achieved by addition of the calculated amount of Tris(hydroximethyl)aminomethane hydrochloride. A method for the preparation of potassium peroxodisulphate of a very low nitrogen blank is given. The digestion is performed at 100° or at 120°C. The requisite digestion time, a function of the autodecomposition of the peroxodisulphate, is found to be 90 min at 100°C and 15 min at 120°C. The yields obtained by oxidation of various nitrogen compounds are studied. The same yields are obtained at both temperatures but are dependent on the form of the nitrogen linkage. Thus, for example, nitrate, nitrite, ammonia and urea give a yield of >99%, the yield for some aliphatic amino acids varies from 92 to >99% and the yield for some proteins from 92 to 95% while a double bond between nitrogen atoms seems entirely to prevent their oxidation to nitrate. The requisite excess of peroxodisulphate is dependent not only on the amount of nitrogen in the sample but rather on the total amount of oxidizable substances, primarily organic matter; the COD of the sample portion should not appreciably exceed 10% of the oxygen available from the peroxodisulphate. A study of the concentration dependence at constant ratio reagent to nitrogen compound shows that the yield as a rule decreases with increasing dilution (exceptions are glycine and ammonia) thus often preventing the use of large sample volumes at low nitrogen content in order to increase the accuracy. Aspects on the practical use of the method are presented together with some illustrations, also including its application on sea water which can be analyzed by the method if only care is taken to keep up the hydroxide ion concentration which is lowered by precipitation of magnesium hydroxide. The expected precision and accuracy are discussed. While the precision by analysis of clear waters of not too low nitrogen content need not be poorer than 1%, the accuracy will be dependent on the nature of the nitrogen compounds and their relative concentrations and a negative error varying from 0 to 8%, all according to these circumstances, seems probable.     

南方某污水处理厂提标改造工艺运行优化

南方某污水处理厂提标改造后,排放标准从一级B提高至一级A标准和广东省地标两者之严者。总氮、氨氮、总磷的排放值分别比原标准降低了25%、37. 5%、50%,而该厂提标后的主体工艺仍然为改良AAO氧化沟,这对污水处理厂的运行管理提出很大挑战。通过污泥硝化速率分析,总氮、总磷成分检测,精确加药,跌水复氧分析及改造等措施优化工艺运行后,运行效率明显提升,在确保水质稳定达标的同时,节约了生产成本,对同类污水处理厂的工艺优化改造具有一定的参考意义。