Research On The Detection Method Of Chemical Oxygen Demand In Domestic Sewage From Offshore Oil Exploration Industry

Domestic sewage of offshore oil Eexploration industry contains a lot of chloride ions.It brings relatively large positive interference to COD monitoring result.In this study,we carried out the optimization experiment of silver precipitation method,established a clean,accurate,low consumption and low pollution determination method.In addition,through the optimization experiment of fast digestion spectrophotometric method,we established a COD qualitative detection method,in order to achieve real-time monitoring of domestic sewage discharge on offshore platforms.Silver salt precipitation method optimization experiments show that,the indoor relative standard deviations(RSDs)of the new method to the standard samples are 0.46%?4.27%.The indoor relative errors of the standard sample test resultsare-4.87%?5.54%.The upper limit of determination is 700mg/L and the lower limit of determination is 15.0mg/L.The results of the seven laboratory tests are in line with the test requirements for precision and room accuracy.Spike recoveriesare 90%?106%;Verify monitoring resultsare close to the true value and the reference method.Obviously,the method of this study is fully applicable to the monitoring of COD in the domestic sewage from offshore oil exploration and development.Fast digestion spectrophotometric method ptimization experiments show that,the test results are closest to the true value,when water samples dilute 5 times or 10 times,using low-range tube,without adding shielding agent.The new method has the advantages of small floor area,simple operation steps,outstanding chloride ion shielding effect,safe experimental environment.It can realize the real-time monitoring of domestic platform sewage discharge.