HOOKSETT, N.H. — About 3.7 million of the estimated 4.3 million of the bacteria-collecting sewage disks discharged from a New Hampshire sewage treatment plant in March have been recovered.

Geoff Brown, vice president of Enpro, the company hired to collect the thin plastic, 2-inch in diameter disks, says he is confident most will be recovered, but some may never be found.

Heavy rains caused the disks and 300,000 gallons of raw sewage to leave the Hooksett Wastewater Treatment Plant on March 6. The disks spilled into the Merrimack River and traveled to the Atlantic Ocean.

They have been discovered as far away as the Maine coast, Cape Cod and the islands of Nantucket and Martha’s Vineyard and Rhode Island.

Brown tells The Concord Monitor the disks are not considered hazardous.