Monitoring and sampling liquid effluents

This paper is concerned with chemical plants' effluent monitoring, which is more an art than a science - despite the sophisticated sample-collection equipment currently in use. In fact, by careful selection of the sampling method and frequency, and analytical methodology, one can obtain almost any answer desired. It is pointed out that the biggest sources of monitoring-data uncertainties generally are found in flow-measurement and sampling procedures; these uncertainties are much larger than the limits of analytical accuracy in the laboratory. Careful equipment selection, careful installation of equipment, and comprehensive planning of a sampling program can increase the reliability and accuracy of the data collected. Finally, the sampling of suspended solids and of toxic pollutants are two types that may pose unusual difficulty for the person collecting the sample: suspended solids sampling poses difficulty because of the physical characteristics of the materials and the lack of approved analytical techniques; toxic-pollutant sampling poses difficulty because of the special materials and contamination-control procedures required.