Prince George's County's problem-plagued sludge treatment plant reopened yesterday after four idle months but will operate at less than a third of its capacity indefinitely, according to county officials.

Meanwhile, County Executive Lawrence Hogan, who closed the plant after a deluge of citizen complaints last fall, warned the facility's owners that the new, $4 million plant would be closed permanently if last summer's serious odor problems recur.

In a letter to Robert McGarry, general manager of the Washington Suburban Sanitary Commission (WSSC), which owns the facility, Hogan said, "While I understand that all of the corrections required by the State Health Department at the Western Branch site have been made, the odor nuisance of last summer mandates an extremely cautious approach to resumption of composting at this site."

As a result, the plant will process only about 100 tons of sludge each day, instead of the 350 tons for which Prince George's is held responsible under a court order that apportions sludge from Washington's Blue Plains treatment facility. The rest will be tilled into vacant land sites in Prince George's county.

WSSC officials have not yet determined how much the shutdown and land acquisition will cost taxpayers. The new facility was designed to make money through the conversion of sludge, the solid waste from raw sewage, into useable, saleable compost. Instead, the shutdown has required the county to pay for additional construction, the services of maintenance workers to cure the existing piles of sludge, and costs for hauling and spreading the sludge. According to John Brusnighan, WSSC's assistant general manager, the county only has room available to spread 150 more days worth of sludge, and might have to pay for more sites.

The Western Branch facility, located outside the county seat of Upper Marlboro, angered citizens' groups and county officials alike even before its official opening in November. Built to process up to a maximum of 600 tons of sludge each day, Western Branch began to take in sludge beyond its capacity before the building was completely finished. One result was "unbearable, sickening odors" that swept the Upper Marlboro area, Hogan said.

WSSC officials blamed the District of Columbia, which processes the area's raw sewage at its Blue Plains treatment plant, for sending the county an excessive amount of improperly processed sludge. D.C. officials disagreed. In any case, Hogan ordered the facility shut in September, and the compost stockpile removed. The alternative method of land-tilling has sparked further citizen complaints throughout Prince George's county.