Recommendations of the Chesapeake Bay Program Expert Panel on Manure Treatment Technologies

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The US EPA Chesapeake Bay Program assesses nutrient loading to the Chesapeake Bay. There is a need to determine the impact of manure treatment technologies on reducing the nitrogen and phosphorus loading from agriculture. Furthermore, many states within the Chesapeake Bay Watershed control nutrient discharges through watershed nutrient trading programs. Tables of standard nutrient removal efficiencies of various technologies will allow states to implement these programs.

What did we do?

The panel standing on the dock of the Chesapeake Bay

An expert panel was convened by the EPA Chesapeake Bay Program to determine nutrient removal potential of manure treatment technologies. The following seven technology categories were reviewed: thermochemical processing, anaerobic digestion, composting, settling, mechanical solid-liquid separation, and wet chemical treatment. Within these categories, the panel defined 24 named technologies for detailed review. The scientific literature was reviewed to determine the ability of each technology to transfer volatile nitrogen to the atmosphere and transfer nutrients to a waste stream more likely to be used off-farm (or transported out of the Chesapeake Bay Watershed).

What have we learned?

Manure treatment technologies are used reduce to odors, solids, and organic matter from the manure stream, with only minor reductions in nutrient loading. The panel determined that Thermo-Chemical Processing and Composting have the potential to volatilize nitrogen, and all of the technologies have the ability to transfer nutrients into a more useful waste stream. The greatest effect of treatment technologies is the transformation of nutrients to more stable forms – such as precipitation of insoluble phosphorus from dissolved phosphorus.

Future Plans

The panel’s report is undergoing final authorization from the Chesapeake Bay Program for release to the public. Future panels may choose to revisit the issue of nutrient reduction from manure treatment technologies. The current panel recommends future panels expand the categories of technologies to include liquid aerobic treatment, and examine more named technologies as they become available within the Chesapeake Bay Watershed.

Corresponding author, title, and affiliation

Douglas W. Hamilton, Associate Professor Oklahoma State University

Corresponding author email

Other authors

Keri Cantrell, KBC Consulting;John Chastain, Clemson University; Andrea Ludwig, University of Tennessee; Robert Meinen, Penn State University; Jactone Ogejo, Virginia Tech; Jeff Porter, USDA Natural Resource Conservation Service, Eastern Technology Suppor

Additional information

Two related presentations given at the same session at Waste to Worth 2017


Funding for this panel was provided by the US EPA Chesapeake Bay Program and Virginia Tech University through EPA Grant No. CB96326201

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