PROVIDENCE — They are largely unnoticed as environmentalists, but the unheralded work of wastewater treatment plant operators keeps the unrelenting flow of human waste from compromising public health and degrading the natural world.

For the past decade, a free yearlong program in Rhode Island has been providing this group of local men and women with educational opportunities to learn new information and skills and helping them network with individuals in the wastewater, regulatory, and other related professions.