污水厂DO在线监测与便携式测试数据的对比

Comparison of Dissolved Oxygen Data from On-line Monitor and Portable Meter in WWTP

为了验证在线溶解氧监测仪表的准确性,常采用便携式溶解氧测试仪在现场测试水样并与在线测试数据做比对,但在低浓度溶解氧的水样测试比对中,常常出现两种数据相差巨大的现象。通过分析不同溶解氧测试仪的测试原理,并在此基础上进行了一系列试验,最终找到一种可行的数据比对方法,即先将便携式仪表在饱和湿空气中进行校准,校准后保持开机通电,并用亚硫酸钠无氧水消耗探头膜内的O2分子,然后再测试低溶解氧浓度水样中的溶解氧值,所测数据较准确且能与在线仪表的数据相符。

To verify the accuracy of the on-line dissolved oxygen monitor, a portable dissolved ox- ygen meter is often used to test water samples in field for comparison purpose. However, data gaps often appear when comparing on-line monitor and portable meter on low concentration dissolved oxygen sam- ples. Through analyzing the principles of dissolved oxygen test and a series of experiments, a better data comparison approach was proposed： calibrate the portable meter in saturated moist air, connect it to pow- er, use sodium sulfite to consume 02 molecules within the probe, and test the value of dissolved oxygen in the water samples with low dissolved oxygen concentration. The measured data were more accurate and matched the data from the on-line instrument.