PORTAGE | Sheep's fleece might keep people -- and sheep -- warm in the winter, but it also is one of the newest products used in treating sanitary sewage.

Officials hope new filters made of fleece, due to be installed at the city's wastewater treatment plant next year, will help increase plant capacity.

The new filters will be installed in the first of two phases of improvements at the plant in the next year or so, Craig Hendrix, public works director, said.

In 2004 the city received a grant through the U.S.Army Corps of Engineers and the Calumet Region Environmental Infrastructure Plan for $3 million to install the new filters, which should increase process capacity from 3.5 million gallons per day to 14 million gallons per day. The city is contributing a local match of $1 million, funding already set aside for the project.

The city and corps are developing the project which should be ready for bids late this summer. Construction could begin early next spring.

The plant presently uses sand filters in the process, which allows for filtering 2 gallons of waste water per minute per square foot. The new filters, said Hendrix, could nearly double that capacity.

The second project, for which the city is seeking $3.75 million in federal funding and will contribute a $1.25 million local match, would change the process in which sludge is produced.

Presently, said Hendrix, the city produces class B sludge, which has to be land applied and creates a significant cost to the city because the sludge, which is usually applied to farm fields, must be trucked from the plant.

The new process would create class A sludge, which, said Hendrix, "can be given away" and can be used as a fertilizer in gardens, parks or yards.

"It is more environmentally friendly and a change in class of sludge would make it (the plant) more efficient and increase capacity," said Hendrix.

If federal funding is not received for the second phase of improvements, Hendrix said the city, through its Water Reclamation Board, likely will have to seek a bond issue for the project. The revenue bond issue would be repaid through increased water reclamation fees.

Hendrix said both projects were identified some years ago as priority measures the city could take to improve capacity and efficiency at the plant.