Prince George's County officials, bowing to complaints from local citizens, delayed action yesterday on a request by a Washington firm to dump chemically treated sludge in a privately owned landfill in the county.

The firm, which manufactures the treated material called "Chemfix," sought permission to haul Chemfix from the regional Blue Plains wastewater treatment plant to the Cross Trails Road Rubblefill, east of Rte. 301 and Cheltenham subdivision. The firm made its request after the District government halted dumping on two city sites, including the grounds of a federal hospital for the mentally ill.

Last week, County Executive Parris Glendening approved a permit for hauling about 150,000 tons of Chemfix to the Cross Trails landfill over a year's time. Yesterday, however, Glendening withdrew the letter from the County Council agenda. Glendening said the Chemfix firm had asked him to delay any action until it could hold "informational briefings" with concerned community members.

But council vice chairman Floyd Wilson said the firm had another reason for asking for the delay. "It doesn't have the votes," Wilson said.

Glendening spokesman Tim Ayers said the Chemfix company would determine when the matter would be brought up again. Company officials could not be reached for comment.

Wilson said although he initially wanted to vote for the permit, he and other council members had been besieged by phone calls from citizens in the area near the landfill. Residents were concerned that the treated sludge might pollute the air, contaminate their water supply or otherwise endanger their health, he said.

"I can't believe there wouldn't be harmful effects," said Marian Conway, one of about a dozen members of the Brandywine civic association who turned up at the meeting to oppose the permit. Conway said that company officials had met with her and several other community leaders last week, but she was not reassured by their claims that the material is harmless.

Bonnie Meloy, an Upper Marlboro resident, also spoke against the dumping request. "We've already taken our share of the sludge," she said, referring to a regional agreement signed in 1979 under which the county disposes of 300 tons of sludge per day from Blue Plains.

County officials are particularly concerned about taking in waste from outside the county when current county landfills are filling up rapidly with just county waste.

The Chemfix firm, National Environmental Controls Inc., is under pressure to find a place to dispose of its waste. In conjunction with the Jones & Artis Co. in the District, it signed an $8 million-a-year contract with the District in August to dispose of about 40 percent of the sludge that builds up at Blue Plains. The companies at that time did not have access to a permanent dumping site.

William Johnson, director of the D.C. Department of Environmental Services said the city could allow the Chemfix company to store sludge temporarily at Blue Plains for another 15 days before running out of space. Johnson said the city is confident that the Prince George's council will grant the permit during the next week or two.

Last Monday, D.C. Mayor Marion Barry called council vice chairman Wilson and council chairman Frank Casula to secure their support for the permit, according to Wilson. John Wesley White, chief administrative officer, said that Barry contacted him also.

Wilson said he originally wanted to support the permit partly because of the involvement of Jones and Artis, a politically well-connected minority firm. "I was willing to go with it to give a minority firm some business," he said.

Chemfix-treated sludge has been used as a cover material at the Prince George's County landfill on Brown Station Road in Largo, with little complaint and without any adverse environmental effects, White said yesterday.