Agricultural runoff — particularly that containing livestock manure — has long been fingered as a major contributor to excess phosphorus in waterways. Scientists from Pennsylvania State University and the U.S. Department of Agriculture's Agricultural Research Service have developed technology for extracting phosphorus from MAPHEX was designed to be a mobile system that fits on two large flatbed trailers to service a number of small- or medium-size dairies. Source: Hristov Research Group/Penn Statestored animal wastes in an effort to reduce nutrient pollution and eutrophication in receiving waters.

The MAPHEX (MAnure PHosphorus EXtraction) method includes liquid-solid separation with an auger press and centrifuge, chemical treatment with the addition of iron sulfate and final filtration with diatomaceous earth. The equipment is designed to process manure from storage tanks or pits on dairy farms.

When tested at 150- and 2,700-cow dairies, about 98 percent of the phosphorus was removed from manure slurries, along with 93 percent of the solids. The current version of the MAPHEX system would cost approximately $750 per dairy cow per year for a dairy operation — an unrealistic cost when EPA is not imposing restrictions on phosphorus runoff from farms and no government subsidies exist to pay for such technology. To contain costs, the researchers are exploring alternatives to the use of expensive diatomaceous earth.

MAPHEX was designed as a mobile system that fits on two large flatbed trailers to service a number of small- or medium-size dairies. Scaling it up for application on large dairies would require building a stationary system. And it’s not just for cow manure: the technology can also be used to treat swine manure. The dry nature of chicken manure would require dilution prior to treatment with MAPHEX.

The developers were granted a joint patent on the system in 2017 and are looking to license the technology, probably to a large agricultural or waste-processing company.