Recycling. Getting the most out of our garbage. The nation's landfills are bulging at the seams, and cities are scrambling to find places for their garbage. Here is a look at the two leading options - one that's particularly promising and one that's increasingly popular.

LAST fall, the City of Philadelphia put 11 tons of odoriferous garbage on a plane to Leibstadt, Switzerland. Two weeks later the shipment came home. It was shredded, dry, chemically stable, odor-free, and separated into reusable products such as ceramics, plastics, paper fiber, metals, glass for road construction, and organic material for compost or fuel. The transatlantic trash flight was undertaken to test out a Swiss-designed recycling system known as ORFA, which turns conventional mixed garbage into a range of raw materials in just 17 minutes.

An ORFA plant is due to come on line in Philadelphia in October, and another one in Somerville, Mass., next year. A similar Swiss system developed by the B"uhler-Miag company is already in the testing stage at Eden Prairie, Minn.

Growing European concern over incinerating garbage has spurred a move toward recycling, and the Leibstadt plant is one of several systems designed to bring as much automation as possible into waste recycling.

Increasingly, waste is being seen as a resource that the world can no longer afford to squander. Cynthia Pollock, author of ``Worldwatch Paper 76 - Mining Urban Wastes: The Potential for Recycling,'' says society has no choice but to recycle if it is to preserve natural resources that are being depleted at geometrically increasing rates.

But is recycling a practical solution? Opinions range widely over how much solid waste can be easily recycled. A citizen recycling program in Wilton and several other New Hampshire towns recycles 45 percent of its solid-waste. New European mechanical systems can prepare all of the waste stream for recycling.

Neil Seldman, who has investigated waste-handling systems in much of the world for the Institute for Local Self-Reliance, says that up to 80 percent of the United States waste stream could readily be recycled, ``and at half the cost of current plans for long-term hauling and incineration, if it's done properly.''

By ``properly'' Mr. Seldman means recycling programs must be funded and managed by officials who do more than pay lip service to the concept. Too often, Seldman says, a city will call for recycling a quarter of its waste, but with only 1 or 2 percent of its solid-waste management budget. And cities seeking to recycle are faced with a chicken-or-the-egg problem: For recycling to pay off, there must be a market for the raw materials generated; but it's difficult to get buyers for the raw material until they can be assured of a steady supply.

The National Recycling Coalition recently called on Congress to pass tax incentives that would encourage development of new applications of waste materials. It also seeks controls on freight costs of recycled raw materials, which are now more expensive to transport than virgin raw materials.

Burying waste has long been a freely available and inexpensive option, so recycling has had to prove cost-effective to win public acceptance. Aluminum and tin from the plating on steel cans were among the very few materials profitable enough to recycle. But now, with landfill costs skyrocketing, recycling is becoming a competitive waste-disposal system.

A recent study done for St. Paul, Minn., bears this out. It puts the cost of disposing of waste through recycling at $30 a ton, after subtracting revenues from secondary material sales. By comparison, land-filling costs $90 a ton now, and will continue to rise; incineration runs $90 to $110 a ton.

Ideally, recycling begins at home, with individuals separating waste into various categories - glass, aluminum, paper - along with curbside pickup programs. Many such programs are now operating in the United States, and this is one aspect, says Seldman, ``where the US is ahead of Europe.''

To boost citizen participation in its recently introduced curbside recycling program, the city of Rockford, Ill., gave away $1,000 each week to a resident whose garbage was found, in a random check, to be separated into the appropriate categories.

Following home or office separation, hand picking of garbage from conveyor belts at recycling centers removes easily identifiable and valuable recyclables such as glass containers, plastic beverage bottles, aluminum, and steel cans.

Murray Fox, of Recycling Enterprises Inc. of North Oxford, Mass., designs systems involving initial hand separation. In one such plant, operated by a nonprofit organization in Flint, Mich., 800 tons a week of garbage is being processed. One of the shifts involves mentally handicapped workers, who have proved outstanding at the job. He describes the improved self-image of these people as one of the ``unexpected rewards'' to come his way since entering the recycling business more than a decade ago.

At the forefront of American solid-waste technology is the unique Agripost system, which has been tested in the US and abroad and will soon go into the construction phase in Dade County, Fla. (Miami). While not a recycling process in the full meaning of the word, the Agripost system converts all of solid waste - including steel, glass, rubber, and plastic - into a single, useful product: a finely ground, chemically stable compost, with no leftover needing to be landfilled. The end product has been fully approved by the US Department of Agriculture.

The two Swiss recycling systems, B"uhler-Miag and ORFA, also leave little or nothing for the landfill. The processes are designed to handle the waste stream as it comes: everything from yellowing cabbage leaves to the kitchen sink. Simply stated, the waste is shredded in hammermills and cutters before passing through a series of sieves, screens, and classifiers, which separate the waste into its component parts, leaving it in a stable, clean, odor-free condition.

At present the principal salable product from B"uhler-Miag's Minnesota plant will be fuel pellets made from recycled organic waste (paper and wood fiber), although the waste could also be diverted to paper manufacture, once there's a market for it, company spokesmen say. For its part, ORFA has contracts to sell recovered paper to manufacturers in the region. Aluminum and plastic separation will begin soon afterward.

These automated recycling plants, along with the Agripost operation, are designed to process 400 tons of city waste a day, with the capacity for more in the future. A rough calculation shows it would take 1,000 or so of these plants to handle the country's daily garbage production of 400,000 tons a day.

Will America make that commitment someday? At this point, it seems far off.