A few weeks ago, however, the city closed its giant Bordo Poniente landfill for good, transporting the garbage to distant new dumps. Officials have optimistically outlined fast-track strategies to recycle, burn and compost all but a small fraction of the garbage that the city now generates.

But that European-style vision of handling garbage stands in sharp contrast with the needs of the 1,500 trash pickers, or pepenadores, who rely on the refuse at Bordo Poniente for their livelihood.

''The garbage will never run out,'' predicted Mr. Téllez, 74, at the start of an hourlong monologue during which he cited Socrates (despite being illiterate himself) and compared himself to Galileo. ''We have made great advances, and now others are coming to take the business we have created.''

Don Pablo, as all the workers call Mr. Téllez, presides from an office decorated with photographs showing him with presidents. In the old days, politicians counted on the trash pickers as a base of support. The pepenadores would help swell campaign crowds, wave flags for visiting dignitaries or provide pro-government troops to counter opposition protests.

Presidents no longer come calling. But the pepenadores can still make politicians take notice.

Several times last year they blocked the arrival of giant trash trailers at the dump to protest the planned shutdown. In response, when Mayor Marcelo Ebrard of Mexico City turned up on Dec. 19 to close the 400-hectare, or 975-acre, landfill and to announce a project for a power plant fueled by methane from the dump, he also had to promise that the pepenadores could stay.

The city agreed not to close the separation plant where the pepenadores pick through garbage, even though it means the trash must first be delivered to Bordo Poniente and then reloaded onto trucks to be hauled to the new dumps hours after the pepenadores have finished extracting what they can sell.

''Marcelo pledged that we would be working here for 25 years,'' Mr. Téllez said. ''He has to fulfill his commitment.''

In the gloom of the separation plant, which is a vast shed, workers sift through garbage passing by them on three raised conveyor belts, striking an atonal note with every bottle or can they drop into bags below. Outside, teenagers scrape rust off metal or slice hair and faces off dolls, tossing them into a disconcerting heap of pink vinyl limbs and torsos.

Only one-tenth of the garbage they sort through can be set aside for recycling. And for all that effort, each pepenador makes 500 to 800 pesos, or $39 to $62 a week. The work will most likely become harder.

''Since they closed Bordo, you can tell there is less garbage,'' said César Laguna, 46. ''The street sweepers and pickers on the trucks go through it, and it doesn't get here anymore.''

The neighborhood garbage trucks carry their own pepenadores, three or four volunteers who dig through household waste. They make even less money than the workers at Bordo Poniente, but ''we get fewer illnesses working here,'' one of them, Adrián Castellanos, said.

Héctor Castillo Berthier, a sociologist at the National Autonomous University of Mexico, estimates that a quarter of a million people in Mexico City depend on trash for their livelihood: street sweepers, garbage collectors, pepenadores, junk dealers and their families.

''Anything you change is going to alter that tradition,'' he said. ''There are more and more layers of informality. These are complex processes.''

Mr. Castillo has no confidence in city officials' plans to reduce and compost garbage. ''They have no Plan A,'' let alone a Plan B, he said. ''They are going to bet on a reshuffling of the informal systems.''

Indeed, while keeping the separation plant open at Bordo Poniente placates the pepenadores, it makes little economic sense. The 20-ton trailers that collect the garbage from neighborhood trucks must now make a detour to the plant before driving to far-off landfills that the city is paying to take its garbage.

Specialists say the new landfills are an imperfect solution because it is expensive to haul the trash that far and because they will fill up relatively soon. In January, protests in the towns near the landfills temporarily blocked Mexico City from trucking the garbage there.

Gabriel Quadri de la Torre, a former federal environmental official who is running for president under the banner of a minor party, said that with proper management, the city could have used Bordo Poniente for many more years, piling new layers on older parts of the dump.

But city officials say that they are bringing the problem of Mexico City's trash under control, finding uses for much of the garbage before sending the remainder to the dump. ''The whole issue of the Bordo Poniente is a great opportunity that will allow us to change people's habits in managing garbage,'' Fernando Aboitiz, the city's secretary of works and services, said recently.

Mr. Aboitiz said that over the past 14 months, the city had greatly reduced the amount of trash that needed to go to the new dumps, to about 4,000 tons a day from 12,600 tons. First, officials cracked down on illegal dumping by other states at Bordo Poniente. Then the city started enforcing a law to separate organic waste, which now goes to a composting plant at Bordo Poniente that will remain open. The director of Mexico's National Water Commission has questioned whether the city can process it all.

Another 500 tons of inorganic waste are used each day as an alternative fuel for cement kilns operated by Cemex, the giant cement company, which said it could take up to 3,000 tons a day.

The city has also started a plan to install large plastic containers at street corners so that households can separate and deposit their waste without waiting for the unpredictable neighborhood truck. That would allow the city to recycle and compost even more garbage, Mr. Aboitiz said.

But Mr. Quadri disputes the city's trash-reduction figures, calling them ''a dance of numbers.''

''It's just a stupid idea,'' David Cosme, a truck driver, said of the new containers, shrugging. ''They won't last a month. The drunks will steal from them.''

Pointing to volunteers standing knee-deep in garbage in his 22-year-old truck, Mr. Cosme proposed a simpler solution: ''Why don't they give them real contracts? Or buy some modern trucks?''