Deteemination of Total Chlorine Residual in Treated Wastewaters by Electrode

Abstract

Total chlorine residuals of wastewater effluents as determined by an Orion 97–70 residual chlorine electrode and the phenylarsine oxide (PAO) back-titration were compared. At ≤1 ppm levels, the electrode and titrimetric methods compared favorably, but at>l ppm chlorine concentration the electrode was preferred. Use of the electrode for measuring chlorine residuals was limited to samples with a biochemical oxygen demand ≥50 mg/1 oxygen, while the PAO back-titration could be employed above this limit. The electrode was useful for field analysis; however, the electrode reading was strongly dependent upon temperature. An empirical graph was developed which allowed a post-analysis correction for the temperature differential between samples and standards.

Key Words:

• potentiometry
• chlorine electrode
• wastewater analysis