Mayor Peter Carlisle has signed into law a bill that eliminates a 2-decade-old subsidy aimed at encouraging private companies and nonprofit organizations to recycle.

Bill 47, signed by Carlisle on Wednesday, ends an 80 percent fee discount to companies that recycle materials and dispose of the nonrecyclable residue at the Waimanalo Gulch Landfill. The discount applied to landfill "tipping fees" charged per ton to the company or nonprofit delivering the waste.

First enacted in 1991 and revised in 2001, the discount was aimed at encouraging recycling but might no longer be needed today because the recycling industry is profitable, the city administration said. The subsidy has cost the city more than $26 million since 1998, including $2.3 million last year.

It has been criticized as overly generous to a single company, Schnitzer Steel Hawaii, which has received about $19 million in tipping fee discounts, including $1.9 million last year. Schnitzer argues that the discount is available equally to all recyclers and that Schnitzer recoups more because of the scale of its operation. Schnitzer recycles more than 100,000 tons of metal a year from automobiles, appliances and other bulky metal items.

The City Council has kept alive a proposal to reinstate the discount at a reduced level of 60 percent in the next fiscal year, 40 percent the year after that and 20 percent in subsequent years. Bill 36-11 is scheduled for a final vote at the next full Council meeting Friday.