Heavy Metals Removal with the Du Pont/oberlin Microfiltration

Du Pont has commercialized a new filter media based on flash spinning technology for Tyvek spunbonded olefin. It has'an 'asymmetric pore structure, a greater number of submicron pores, and a smaller average pore size (1). As a consequence, it has superior filtration properties and longer life, and in many instances it can compete with microporous membranes, PTFE laminates, and various melt-blown media (1). Its key property is its tight pore structure at a very low cost compared to competitive products. Table I outlines the media cost per gallon of waste filtered and shows that the T-980 grade, hich is the lowest basis weight manufactured (0.9 oz/yd*) and the only grade e ated here, is very cost effective. In most applications the T-980 grade was sufficient so the added cost for a higher basis weight grade was not warranted. For example, T-980 produced slightly poorer effluent quality than the 'standard' 0 .45~ microporous membrane at a fraction of the cost; equivalent effluent quality to the PTFE laminate at a fraction of the cost; and much better effluent quality than typical 1and 5micron melt-blowns at equal or significantly lower cost (depending on ). Tests with actual wastes showed the greatest cost benefit (Table lar cost benefit was obtained in operation with a low-level radioactiv ste at the Savannah River Plant (2, 3). This installation realized almost annual savings when T-980 media was used with a more efficient filte added benefit is its superior strength compared to microporous membranes and the PTFE laminate media. This strength permits its use in robust automatic pressure filters (4). The high strength (5) coupled with the tight , -1micron pore structure (1) led to its use in the EPA Superfund SITE program (6-9).