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

Enpro, the company hired to collect the thin plastic, 2-inch in diameter disks, said in a statement that they have been recovered in coastal areas from Maine, to Massachusetts and Rhode Island. The disks are not considered hazardous.

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.

The Concord Monitor reports that Enpro, an environmental services company with offices in Pembroke, was paid $125,000 by the town of Hooksett to recover as many as possible.