Opinion ID: 338698
Heading Depth: 3
Heading Rank: 2

Heading: Effluent Level Reduction in Other Industries.

Text: 74 Recognizing the lack of support for its proposed TSS standards from results within the corn wet milling industry, the EPA points to the use of deep bed filtration in other industries. It argues that these results support the proposed TSS standards for the corn wet milling industry. In our judgment, the results from other industries indicate that deep bed filtration will remove suspended solids but not with the efficiency or the consistency necessary to satisfy the proposed TSS standard for this industry. 75 The studies relating to municipal treatment plants indicate that deep bed filtration will remove an average of 70% of the suspended solids in the wastewater. However, the record also establishes that the removal rates range from a low of 20% to a high of 95% with no indication of consistency. Moreover, the level of suspended solid influent in most municipal treatment plants is considerably less than that found in the corn wet milling industry. 76 The record indicates that the strength or concentration of the influent wastewater substantially affects the success of deep bed filtration. If the wastewater has been effectively pretreated in a biological treatment system, deep bed filtration will remove a substantial percentage of the remaining suspended solids. However, one cannot say that a properly functioning system will reduce the TSS level below that of the BOD 5 level. In the winery industry, for example, treatment of heavily concentrated wastewaters similar to those found in the corn wet milling industry produce TSS levels that exceed the BOD 5 level by as much as 48 mg/1. Moreover, the deep bed filtration system there appears to remove less than 40% of the suspended solids. 12 77 Data from the brewery and edible oil industries is largely unusable because it is set forth in milligrams per liter and because it is not clear whether deep bed filtration is used or not in these industries. This data gives some support to the finding that corn wet milling plants can meet the 1977 existing plant guidelines but little or no support that 1983 or new source standards can be met. Again, TSS levels are often higher than BOD 5 levels. 78 The data from Morton Frozen Foods indicates only that TSS levels are often higher than BOD 5 levels and that there are wide variations in TSS levels between the minimum and maximum days. 79