化工污水处理厂高氯低COD_(Cr)排水在线COD_(Cr)检测方法比对

Comparison of COD_(Cr) Detection Method Online in High Chlorine and Low COD_(Cr) Drainage of a Chemical Industry Wastewater Treatment Plant

针对某化工污水处理厂排放水Cl-含量高、COD_(Cr)低造成现有检测方法存在误差的情况,采用不同方法对纯水样品、标准样品和实际废水样品进行分析,并与在线TOC检测数据进行比对。结果表明,测定COD_(Cr),分别用250、25 mmol/L的重铬酸钾时,测定结果分别偏高和偏低;Cl-的质量浓度大于3 g/L时,加入硫酸汞难以消除不利影响;采用HJ/T399-2007用低浓度重铬酸钾(120 mmol/L)Cl-的影响较小。采用TOC在线测定仪测得TOC含量,可避免Cl-对测定的影响;再经与HJ/T 399-2007以低浓度重铬酸钾(120mmol/L)检测所得数据进行线性回归得到COD_(Cr),可真实地反映化工污水处理厂高氯低COD_(Cr)排放水中有机物的污染程度。

Aiming the scene that existing detection method had some errors because of content of Cl-was high and content of COD_(Cr)was low in drainage of a chemical industry wastewater treatment plant, adopted different methods to analyze pure water samples, standard samples and the actual wastewater samples, and then compared to the TOC inspection data online. The results showed that in determination of CODCr, the determination results higher and lower respectively when used 250 and 25 mmol/L potassium dichromate;adverse effect was difficulty to eliminate by adding mercury sulfate when mass fraction of Cl-higher than 3 g/L; less effect of Cl-when adopting HJ/T 399-399 with low concentration potassium dichromate(120 mmol/L);TOC content measured by TOC online meter could avoid the effect of Cl-on the determination; Then got COD_(Cr)by linear regression with test data using HJ/T 399- 2007 with low concentration potassium dichromate(120 mmol/ L), which could truly reflect the pollution degree of organic in high chlorine and low COD_(Cr)drainage of a chemical industry wastewater treatment plant.