1998-03-23_REVISION - M1977348 - Laserfiche WebLink

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1.2.5 Weigh out a subsample of the sample (100 gram minimum) and r ,) record the weight. If the waste contains <0.5 percent dry solids (Step 7.1.2), the liquid portion of the waste, after filtration, is defined as the 1312 extract. Therefore, enough of the sample should be filtered so ' that the amount of filtered liquid will support all of th~a analyses required of the 1312 extract. For wastes containing >0.5 percent dry ' solids (Steps 7.1.1 or 1.1.2), use the percent solids information obtained in Step 7.1.1 to determine the optimum sample size (100 gram minimum) for filtration. Enough solids should be generated by filtration to support the analyses to be performed an the 1312 extract. ' 7.2.6 A71ow slurries to stand to permit the solid phase to settle. Samples that settle slowly may be centrifuged prior to filtration. Use ' centrifugation only as an aid to filtration. If the sample is centrifuged, the liquid should be decanted and filtered followed by filtration of the solid portion of the waste through the same filtration ' system. 7.2.7 Quantitatively transfer the sample (liquid and solid phases) to the filter holder (see Step 4.3.2). Spread the waste sample evenly ' over the surface of the filter. If filtration of the waste at 4•C reduces the amount of expressed liquid over what would be expressed at roam temperature, then allow the sample to warm up to room temperature in the I device before filtering. NOTE: If waste material (>1 percent of the original sample weight) has obviously -~~ adhered to the container used to transfer the sample to the filtration ~• apparatus, determine the weight of this residue and subtract it from the sample weight determined in Step 7.2.5, to determine the wei~lht of the waste sample that will be filtered. ' Gradually apply vacuum or gentle pressure of 1-10 psi, until air or pressurizing gas moves through the filter. If this point if not ' reached under 10 psi, and if no additional liquid has passed through the filter in any 2-minute interval, slowly increase the pressure in 10-psi increments to maximum of 50 psi. After each incremental increase of 10 ' psi, if the pressurizing gas has not moved through the filter, and if no additional liquid has passed through the filter in any 2-minute interval, proceed to the next 10-psi increment. When the pressurizing gas. begins to ' move through the filter, or when the liquid flow has ceased at 50 psi (i_e., filtration does not result in any additional filtratf~ within a 2-minute period), stop the filtration. ' NOTE: Instantaneous application of high pressure can degrade the glass fiber filter and may cause premature plugging. 7.2.8 The material in the filter holder is defined as the solid phase of the sample, and the filtrate is defined as the liquid phase. Weigh the filtrate. The liquid phase may now be either analyzed (see ' Steps 1.2.12) or stored at 4°C until time of analysis. 1312 - 11 Revision 0 ' November 1990