In the U. S., more than 15,000 water resource recovery facilities (WRRFs) clean the water we use, returning it to rivers and the sea. These vital processes also produce biosolids (sewage sludges), which can be put in landfills, incinerated, or treated and tested and recycled to soils. Now, new data provide details about biosolids management in the U. S. The “National Biosolids Data Project” (NBDP), led by the North East Biosolids and Residuals Association (NEBRA), estimates that, in a typical recent year, the U. S. used or disposed of 5,823,000 dry metric tons of biosolids. More than half (53%) were treated and recycled to soils as biosolids fertilizers and soil amendments. The other 47% were placed in landfills or incinerated. The new data and supporting information are available online at a new website created for the project.
These data, compiled from one representative year, 2018, are comparable to data from 2004 that were published by NEBRA et al. in 2007. The new data reveal that the rate of biosolids recycling has increased about 4% from the 2004 rate of 49%. In addition, more of the highly-treated “Class A” biosolids are being used; they account for 27% of biosolids used or disposed in 2018, a 5% higher rate than in 2004. In contrast, the rate of Class B biosolids use has declined by 5%. Class B biosolids have had less treatment and require more specialized management at permitted sites such as farm fields.
Notably, the new data show not many other big changes from 2004 to 2018. “That’s somewhat of a surprise to us,” notes Janine Burke-Wells, Executive Director of NEBRA. “Over the past 15 years, there have been large advances and investments in how biosolids are treated and managed. Yet the overall numbers don’t show that. You have to look into the details to see all the improvements.”
NBDP chose 2018 as the data year for this nationwide compilation because it is representative of biosolids management in the late 2010s and early 2020s, after new U. S. Environmental Protection Agency (U. S. EPA) sewage sludge incinerator regulations took full effect in 2016 and before changes to biosolids management caused by concerns about traces of chemicals in biosolids, such as perfluorinated compounds commonly called “PFAS.”
NEBRA, which is celebrating its 25th year in 2022, is a regional nonprofit professional membership organization focused on biosolids management in New England and eastern Canada. The data project team include sister organizations California Association of Sanitation Agencies, Northwest Biosolids, the Mid-Atlantic Biosolids Association, and BioCycle. Lead funders were the National Association of Clean Water Agencies (NACWA), the Water Environment Federation (WEF), consulting firms, and biosolids management companies around the nation.
The new biosolids data come from more than two years of surveys, interviews, and data compilation and analysis. For each state and larger U. S. territories, the NBDP provides a summary of how much biosolids the state used or disposed of, how it was managed, and where it went. Each state’s story is told in data tables and a narrative summary. The project also presents nationwide totals. Examples include:
- About half of WRRFs report that biosolids are managed by WRRF staff, while the other half have contracted haulers and land appliers.
- When biosolids are applied to soils, they are used mostly for corn for animal feed and energy, followed by hay/grass/forage. Other popular crops for biosolids fertilization are wheat and other grains, followed by Class A EQ products widely used on turfgrass (lawns, erosion control, golf courses, landscaping).
- When identifying the greatest pressures on biosolids management in 2018, WRRFs showed most concern about rising costs and future outlets for biosolids. State biosolids regulators and WRRFs said that public involvement, contaminants, and the hassles of recycling — including declining nearby farmland — were significant pressures.
The new NBDP data include the largest ever data set looking at economic aspects of biosolids management. For example, surveys of WRRF biosolids programs show that the average costs to have a contractor take and manage solids is ~$49/wet ton for composting, ~$58.25/wet ton for landfill disposal, ~$62/wet ton for land application, and more than $95/wet ton for incineration.