DETROIT-In November, the city of Detroit received state approval to move forward with a $300 million contract that would pay Minergy Corp. of Milwaukee to burn wastewater sludge.

The 15-year contract to replace the Detroit Water and Sewer Department's wastewater solids incinerators comes in response to a federal court order mandating that the city upgrade its outdated equipment, which was built in the 1940s and 50s.

With state approval, plans now are to begin construction in the Delray area this coming spring of a 15-acre plant costing $150 million. The plant will burn 500-600 tons of waste daily, which it will turn into a glass-like material that company officials say will be recycled to make ceramic floor tiles and sand blasting grit.

Minergy believes its incinerator will reduce air pollution emissions from wastewater sludge incineration by 72 percent, and Detroit officials believe it will save the city about $50 million over the course of its 15-year contract.