Special Report No. 75-01: A Preliminary Review of Analytical Methods for the Determination of Suspended Solids in Paper Industry Effluents for Compliance with EPA-NPDES Permit Term

Our interest in the methods employed to measure residual suspended solids in mill effluents has recently taken on greater importance as a result of two related developments. First, it was established in the last three years that much of the suspended solids determination data for secondary effluents available in the literature or in mill system performance records has been obtained using non-standard methods. It was found further that conversion factors for translating "non-standard" filter paper results to "standard" glass fibre-type filtration media results were reported to range from 2 to 10 by different mill laboratories. Most recently it was found that substantial variation in results could be obtained even when using standard methods procedures, simply by employing officially sanctioned "ease for the analyst" procedural variations within the standard methods. Since all EPA-NPDES mill effluent discharge permits contain restrictions on suspended solids discharge, differences in analytical results have more than academic importance. They may determine whether a particular mill is or is not in legal compliance with its permit terms, opening the way to various penalties for non-compliance. At an NCASI conference on "The Significance and Control of Discharge of Bio-treatment System Organic Suspended Solids to Surface Waters" the problems encountered in obtaining uniform analytical results received due recognition. NCASI staff was asked to examine the problem, document its existence and procedural sources, and propose steps for systematizing this measurement, recognizing the importance attached to it as a result of the organization of the EPA-NPDES permit and compliance program.