MINNEAPOLIS — The thought is a natural one for those going through the chore of sorting their recyclables: Do I have to do this?

It’s a question that even recycling haulers can’t agree on. And as recycled materials fetch higher prices, the stakes are rising as they compete for contracts.

The big national haulers, number one Waste Management and number two Allied Waste Industries are promoting a “single stream” system where customers put all recyclables — paper, glass, plastic and metals — into one cart. People prefer the convenience, so they recycle more, these companies argue.

Some recycling haulers, including Eureka Recycling in St. Paul, Minn., and Randy’s Environmental Services out of Delano, Minn., advocate sticking with the traditional “double-stream” system, where households sort their recyclables into two groups: separating the paper from containers of glass, plastic and metal. Maybe the big carts increase collections, but all those materials get smashed together inside, making them unusable, they argue.

The disagreement resurfaces periodically, as local governments bidding out the pickup contracts get hit with both sales pitches. And last month, Allied Waste said it’s sweetening the pot by offering store coupons as customer rewards, which it’s testing in three markets across the country, including the Twin Cities. The more a household recycles, the more coupons it wins, redeemable at scores of retailers as varied as grocery stores, Ikea and Target.com.

Looking for advice, cities went to the Minnesota Pollution Control Agency as long as two years ago. The agency commissioned a report, by Tim Goodman & Associates in St. Louis Park, Minn., but by citing pros and cons for each it resolves little.

“Right now, personally, I would have to give the edge to two-sort, in terms of the quality of the actual recycled materials,” Goodman said. “But people still have disagreements, and they feel very strongly one way or the other.”

Americans produce an average of 4.6 pounds of trash per person per day, according to the U.S. Environmental Protection Agency. Minnesota is near the top of the states in recycling its trash — at 43.2 percent of its solid waste, it is second only to Oregon. Market forces may start bumping up rates everywhere, however.

Commodities prices for the materials bailed or binned out of recycling centers — to be remade into new water bottles, cans, and more — are climbing steeply, with analysts citing once again voracious demand out of China. A ton of recycled newsprint in the New York market rose from $120 in January to $200 this month, said Mark Arzoumanian, editor of industry publication Official Board Markets. Comparable increases on the recyclables spot markets have aluminum priced at $2,000 a ton and plastics at $440 a ton.

That has haulers working to increase their emphasis on recycling, and the payoff is already showing up. At Allied Waste, for example, revenue from sales of recyclables rose 21 percent last year from 2006 to $257 million, according to its annual report.

One sign of Phoenix-based Allied Waste’s growing interest in the recycling business is the new RecycleBank partnership that it’s now marketing in some areas. RecycleBank weighs the recyclables collections and awards store coupons to customers based on how much they recycle. Popular coupons among customers include local grocery stores, saving families as much as $20 a month on their food bills, said Ron Gonen, CEO of the Pennsylvania-based company.

Randy’s Environmental Services just bet $8 million on double-stream recycling with a trash hauling and recycling facility it opened last summer. “The value of the commodities is better protected with the two streams,” said Jim Wollschlager, operations director. “We just feel it’s the better way of recycling.”