Wastewater Residuals

Residuals are the organic, nutrient-rich solid, semi-solid, or liquid residues removed from wastewater during the treatment process.

There are various disposal methods for wastewater residuals including incineration or sending the solids to a landfill. However, if they are of sufficient quality, they may be applied to farmland as a fertilizer. Such residuals are often called biosolids. These biosolids may not be the prettiest material, but to crops hungry for nutrients, they can be a beautiful sight.

Since its creation in 1993, NEIWPCC’s Residuals Workgroup has been working to enhance interstate communication on issues associated with residuals from wastewater treatment, drinking water treatment, and on-site sewage disposal. The workgroup meets 3-4 times a year, and is comprised of staff from NEIWPCC, EPA, along with the residuals coordinators  from each of our member states’ environmental agencies.

The Residuals Workgroup works to promote compatibility among state and federal sludge and septage management programs. NEIWPCC provides a forum for interstate discussion as well as technical assistance and coordination.

A recent addition to NEIWPCC’s residuals management area of expertise has been focused on fats, oil, and grease (FOG). As the environmental community moves to more stringently manage FOG, it is essential that there be adequate treatment capacity to manage the material removed from private and municipal wastewater systems.

NEIWPCC’s FOG workshops and associated resources have highlighted various treatment alternatives for this material. Treatment options discussed include private grease pretreatment facilities, composting, land application, and incineration (with municipal solid waste and sewage sludge). The workshops have focused on treating the material once it is removed from the wastewater system and emphasized that there are properties within this material making it suitable for various types of beneficial reuse.