Waste Management Inc. is betting time, energy and millions of dollars that pollution control will be big business in Mexico over the next decade.

The Oak Brook, Ill., company joined forces with Mexico's Protecol S.A. de C.V. six years ago to plan this country's largest hazardous waste treatment facility.The joint venture, which is now waiting for the final permit needed to start construction, expects to handle about one-quarter of the 390,000 tons of chemical wastes produced in Mexico each year. That's the expectation of Ian Bird, secretary and general counsel of Waste Management International Inc., a subsidiary of the parent company.

"The Mexican market has tremendous potential," Mr. Bird said. "The problems of pollution are great. The government is moving to approve legislation that is quite sophisticated. But there's a long way to go to."

With $4.5 billion in revenue last year and operations in more than a dozen countries, Waste Management is one of the world's largest pollution-cont rol companies.

Although Mr. Bird declined to specify Waste Management's investment in Mexico, the company is also investigating other possibilities here, including solid waste landfills and collection and disposal operations. "When we look at a country, we look at long-term business opportunities," Mr. Bird said. ''We build off the business of the first project."

Another U.S. company eyeing the pollution-control business south of the border is Morrison-Knudsen Corp. "Mexico is an attractive market because of its openness," said Ben Sandoval, Morrison-Knudsen's director of marketing for Latin America. "We'd like to develop business."

The operations of the Boise, Idaho-based engineering and construction giant, which took in $2.1 billion in revenues last year, include the development of solid waste management and water purification systems.

Gerardo de la Pena, a manager at a Dallas environmental consulting firm, predicts that opportunities for consulting firms will mushroom as the Mexican government puts more teeth in its regulations.

"The big firms have their own environmental consultants, but the mid-size firms, both Mexican and U.S., are going to be hit with environmental awareness," said Mr. de la Pena, manager of international services for Conlan Engineering Co.

If Mexico and the United States move ahead with a free trade agreement, he said, Mexico will become home to even more companies needing environmental consultants.

Mr. de la Pena predicts especially strong growth in the cleanup of underground storage tanks and ground-water pollution, an area Mexico hasn't even considered yet.

For the first time, the U.S. Department of Commerce is organizing a trade mission for U.S. companies interested in investing in the control of air, water and solid-waste pollution in Mexico. Robert W. Miller, commercial counselor at the U.S. Embassy here, said it's not yet known which U.S. companies will participate in the October mission.

Early this month, Mexico hosted the United Nations' fourth annual World Environment Day. Highlights included the planting of a million trees throughout Mexico, as well as arts festivals, ecological expositions and a report by children on the state of the environment.

The Confederation of Industrial Chambers, a Mexico City-based association of 250,000 companies that run the gamut from textiles to petrochemicals, set up an ecological commission a year ago to keep members abreast of new regulations and to promote compliance.

"Changes have to be made, and I expect we will be very busy over the next two to three years," said Guillermo Barroso, commission president. "We have to find solutions to lower the contamination problems. We're not protecting anyone from the law."

Jose Antonio Ortega, an environmental consultant based here, agrees that the pollution-control business is likely to grow rapidly in Mexico over the next decade.