Dewatering coarse wet rejects from paper mill recycling systems: the high costs and possible EPA penalties associated with landfilling wet waste can justify the expense of dewatering improvements.

Paper mills that use recycled furnishes to make new products create large volumes of wet waste material that must be handled separately from the mainstream process. The coarse waste material, rejected from the various pulping, screening, and cleaning operations within the recycling system, is often landfilled at direct cost to the mill.

Subtitle D of the Resource Conservation and Recovery Act (RCRA), a U.S. federal law, specifically prohibits landfilling of waste material containing "free liquids." Test Method 9095 (EPA Pub. No. SW-846) outlines the paint filter test, which is used to distinguish the suitability of wet waste materials for landfilling. Paper mills that fail to meet the Subtitle D requirements could receive substantial fines from the U.S. Environmental Protection Agency (EPA).

The RCRA and Subtitle D guidelines should not be seen as a legislative burden, but rather as an opportunity to reduce bottom line costs associated with the transportation and disposal of this waste material. With the costs of waste transportation and landfill tipping fees continuing to rise and the actual available landfill space being threatened, reducing the weight and volume (associated with the free water present in the rejects) of the mill's waste material becomes an obvious economic opportunity.

PROBLEM AND SOLUTION

Table 1 shows the average landfill tipping fees (US$/ton) for various U.S. regions. An average mill in the Midwest recycling 250 tons/day of furnish and generating at least 2.5% rejects at approximately 18% consistency would pay an estimated US$ 378,000 per year in tipping fees alone. Local waste haulers impose additional transportation fees that can significantly increase a mill's annual waste handling expenses.

Fortunately, advanced waste handling equipment is widely available. In particular, ram presses offer many process cost cutting benefits and, when properly applied, are efficient rejects dewatering machines. The mill in Table 1 could save an estimated US$ 242,000 per year in tipping fees at the landfill by implementing an efficient ram press to handle rejected wet waste material and reduce water weight from 82% to 50% going to the landfill. This mill would also achieve substantial transportation savings by reducing the total wastestream volume.

EQUIPMENT FUNDING

Capital investment dollars are hard to come by these days. Many mills come up short when trying to fund projects to improve the quality of their product(s). Dewatering wet waste material is not likely to directly improve product quality; but, if analyzed correctly, it will improve quality indirectly by reducing costs and freeing up capital dollars for other projects.

With several financial options available, including leasing and rental packages, most mills do not have to use capital investment funds for these projects. Part of each month's generated waste handling savings would pay for the equipment, while the rest is realized net savings that can be used to help fund other projects.

Take a look at your mill's current waste handling practices. Are your wet rejects being hauled to the landfill at 50% solids or higher? Does your current waste handling process require only minimal manual labor and attention? Are your process rejects in environmental compliance before they are hauled away? If you have answered "no" to any of these questions, your company most likely has an opportunity to significantly reduce its waste handling costs-or is risking a fine from the EPA.

Average Landfill Tipping Fees--by
U.S. Region

West              US$    36.08
West Central      US$    22.51
Midwest           US$    30.64
Northeast         US$    66.78
Mid-Atlantic      US$    44.11
South             US$    30.89
South Central     US$    21.02

Source. Waste Age Magazine-April 2000

Dave Kaminski is corporate project manager for Sebright Products Inc., Hopkins, Michigan. Reach him by phone at [phone], or by e-mail at [e-mail]