The corridor near the vacant fish market still smells like fish, and the area by the vanished food court still smells like grease.

Soon even the odors of the Gallery will be gone, as the developer prepares to undertake a massive internal demolition and knock the inside of the mall to pieces. The work probably will start in late September.

The mountains of broken material won't all be headed to landfills. More likely, experts said, tons of metal and concrete will be sold and recycled.

Even with the Gallery in its death throes, there's money inside - offering savings to the builder, the Pennsylvania Real Estate Investment Trust, and benefits to the environment.

"There's a lot of value in this mall," said Diran Apelian, director of the Metal Processing Institute, a consortium that's part of Worcester Polytechnic Institute in Massachusetts.

The recycling of demolition and construction materials has surged as the recession has ended. But even with the best intentions, recycling remains challenging, with a third of waste still piling up in dumps.

Nor does the destruction of a mall tend to create a long, Craigslist trove of treasures for erstwhile Dumpster divers. Tables, chairs, and signs are hard to resell. When the J.C. Penney store at the Granite Run Mall liquidated its interior, only 15 percent of the fixtures were sold, the developer said.

A representative for PREIT said the executive in charge of recycling matters was away and could not be reached for comment last week.

But at a giant mall renovation across the river in South Jersey, PREIT went to lengths to extract value from the remains.

"Just about everything that can be recycled gets recycled, because it's a cost advantage," said Pete Gardner, sustainability manager at Torcon Inc., a construction-management firm with offices in the Navy Yard.

Gardner worked on the two-year, $220 million renovation of PREIT's Cherry Hill Mall. As much as 90 percent of what was demolished there, including steel and asphalt, was recycled - saving millions of dollars, he said.

Almost all the steel gets sold, with the current price at 3 or 4 cents a pound, and 30 cents for stainless. Other metals are more valuable. Aluminum sells for about 40 cents a pound, brass for $1.20, copper for close to $2.

Some of the biggest structures in the Gallery are the half-dozen steel escalators, which in their old age routinely break down.

"All the steel, there's no question it's going to get recycled," said Ted Reiff, president of the Reuse People of America, a California nonprofit that takes apart houses and buildings and resells salvaged materials.

Developers usually pay to get rid of concrete - the three-block Gallery holds a sea - but having it recycled is much cheaper than dumping it. A landfill may charge $600 a ton to take concrete, so if a firm dumps 20 tons, that's $12,000. A recycler may charge only $200 a ton, or $4,000, one-third the cost.

It's uncertain whether the Gallery will hold a public closing sale, selling off pieces for new uses or souvenirs - or whether people would want them.

Before razing Veterans Stadium in 2004, the Phillies auctioned, sold, or gave away almost everything that was useful or desired. They donated the sound system to a college, the lights to youth groups, the pitching machines to Little League teams. Office furniture went to the city school district, police department and recreation department.

Lockers used by legends such as Steve Carlton and Mike Schmidt went up for bid, and the stadium's blue seats were offered at $280 a pair. The team even sold the dirt from around home plate.

The Gallery's most distinctive feature may be its brown tile floor, a relic from an earlier age.

The mall opened in 1977 to wide acclaim, perceived as a savior for Market East. But over time, pricier stores moved out, anchor stores died or departed, and vagrants made themselves at home.

In coming weeks, the nearly empty mall will close for a $325 million, two-year renovation, emerging as the Fashion Outlets of Philadelphia. To make the plan work, the city will provide a $127.5 million tax break over 20 years.

The project, in which PREIT has partnered with California-based Macerich Co., is seen as a key to reviving the eight-block stretch of Market East between City Hall and Independence Mall. Millions of dollars in new apartments, stores and restaurants are being built or planned in what has been a notorious dead zone.

As the Gallery sheds its last stores, it still contains loads of manufactured goods, including trash cans, lights and signs. The food court, now behind a barrier, was filled with seating and kitchen equipment. Reiff said that, theoretically, those goods could help a community group build a park or recreation center. But finding that group, timing the transfer, and incurring storage fees in the meantime, can make giving away goods more expensive than buying new ones.

The other challenge, he said, is that construction codes have strengthened over time. It's often unfeasible to move old products to new buildings, which is why they end up in the dump.

Nationally, about 480 million tons of demolition and construction waste was generated in 2012, according to the Construction & Demolition Recycling Association, a trade group in Milwaukee. About 70 percent of that was recycled, achieving greenhouse-gas reduction equal to taking 4.7 million cars off the road for a year, and saving energy equal to 85 million barrels of oil.

"The only thing that turns out to be really valuable is the metal," said Michael Markman, president of BET Investments, the Horsham-based developer that's preparing to demolish the Granite Run Mall in Delaware County. "It's a shame, because there's a lot of unused equipment that's either scrapped or thrown away."

215-854-4906@JeffGammage