The ASTM method D1252-88, Standard Test Methods for Chemical Oxygen Demand (Dichromate Oxygen Demand) of Water is used as the basis of determining the COD for other materials, not just [waste] water. This procedure specifies the use of 1 gm of mecuric sulfate per sample to minimize the effect of chloride ions which may be present. The waste from such determinations contains considerable mercury. There are likely to be other procedures in which mercury is used. How do academic and commercial labs economically handle such waste that consists mostly of water containing Hg and a few other less regulated contaminants? I believe the current allowable level for discharge is 1.0 ppb Hg.

Regards,

Ernest Lippert