近红外光谱法测定废水化学需氧量

为快速确定废水的污染程度，研究了运用近红外光谱法测量废水化学需氧量（COD）的可行性.实验用水样共180个，其中COD标准溶液（邻苯二甲酸氢钾标准溶液）水样22个,污水处理厂的废水水样158个.每一水样分成两组：一组测其800~2600 nm谱区近红外光谱，另一组测其COD，并把该化学值作为标定该水样光谱的“真值”.对水样近红光谱用偏最小二乘法（PLS）回归建模，分别建立标准液水样和废水样的COD预测模型.标准液水样的理论COD值与预测值之间的相关系数为0.9999,交叉验证均方差（RMSECV）为15.14 mg/L；污水处理厂废水水样的COD实测值与预测值之间的相关系数为0.9453,预测标准差（RMSEP）为35.4 mg/L.实验结果表明，用近红外光谱法测量废COD是可行的.

Determination of chemical oxygen demand in wastewater by near-infrared spectroscopy

To rapidly determine the pollution extent of wastewater,the potential of near infrared(NIR) spectroscopy for measurement of chemical oxygen demand(COD) in wastewater was investigated.A total of 180 samples including 158 wastewater samples collected from Hangzhou Wastewater Treatment Plant and 22 COD standard solutions(potassium hydrogen phthalate(KHP)) prepared in laboratory.Transmission spectral measurements and dichromate method tests of 180 samples were carried out.Spectral data from 800 to 2 600 nm were collected using InGaAs detectors at 0.717 nm resolution using a 10 mm transmission pathlength.Calibration models were developed from dichromate method as a reference method and NIR data using partial least squares(PLS) regression.The calibration model of standard solutions gave correlation coefficients of 0.999 9 and root mean square error of cross validation(RMSECV) of 15.14 mg/L,and the calibration model of wastewater samples gave correlation coefficients of 0.945 3 and root mean standard error of prediction(RMSEP) of 35.4 mg/L.The results shows that NIR spectroscopy is promising for detecting COD in wastewater.