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INSTRUCTIONS FOR USING THE CHART OF % OF PERC LEFT IN STILL RESIDUE
1. Obtain a calibrated container which can comfortably hold 1 gallon of still waste (you can use a ˝ gallon container, just multiply the weight of the container times 2 when consulting the chart). Either put a plastic liner in the container or use a container that you can throw into the hazardous waste drum when you’re done with it, this is going to get messy.
2. Remove the waste from the still and stir it in order to evenly distribute the liquid and solid debris.
3. Fill the container to the measured level and weigh it. Write down the weight.
4. Find the weight on the lower horizontal line of the chart labeled “POUNDS PER GALLON OF STILL RESIDUE”. Follow that position vertically until it intersects with the graph line with the dots on it, then look on the left side of the graph at the vertical height of the intersecting lines on the scale that says “% OF PERC REMAINING” and this will tell you what percentage of Perc you’re throwing away with your still waste. Write down the % OF PERC REMAINING.
To calculate how much money you could be saving by reclaiming solvent from your still waste, follow these steps:
SAVINGS IN SOLVENT:
1. Take the number of drums of still waste for which you were last invoiced and multiply that times the volume each drum; the product will be the total volume of waste you generated.
2. Now take that total volume of waste multiply that number times % OF PERC REMAINING then divide that number by 166; this will yield a conservative estimate of volume of recoverable perc (appx 60%).
3. Multiply the volume of recoverable perc times the cost of solvent per gallon; this will yield the dollar value of recovered perc by still azeotroping. Write this figure down.
SAVINGS IN HAZARDOUS WASTE HAULING:
1. Take volume of recoverable perc and divide it by the volume of your hazardous waste container; this will yield the number of hazardous waste containers that have been filled by recoverable solvent. Multiply this number times the disposal cost per waste container and product will be the potential savings in hazardous waste hauling costs. (Unless you are a large operator it will be more accurate to use quarterly or semi-annual hazardous waste hauling data to calculate the number of drums of still waste then pro-rate this figure to match the time period used in the calculation of SAVINGS IN SOLVENT figure. The volume of recoverable perc calculations should remain fairly constant over the course of time). Write this figure down.
1. Add the savings in hazardous waste hauling and value of recovered perc; the sum yields the actual dollar savings made possible by azeotroping the still waste.