In a report released last week, New York City Comptrller Elizabeth Holtzman blasted the city's proposed $1 billion sludge program, saying it could cost an additional $400 million and questioning the program's technology.

"This mammoth $1 billion program could become a white elephant," Ms. Holtzman said in a statement. "Not only is the city spending much more than needed to haul sludge, [but] it is also investing huge sums of tax dollars in technologies that -- in at least one case -- have caused problems in another city."

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