Madison Sewerage District's new technology to turn phosphorus into fertilizer pellets

The Madison Metropolitan Sewerage District is usingcutting-edge technologyto try and tackle the problem of phosphorus in area lakes.

The district spent roughly $40 million to upgrade the Nine Springs wastewater treatment plant off South Towne Drive. It processes wastewater from a number of cities, villages and towns in the greater Madison area.

Plans for the project have been in the works since 2008.

The district partnered with British Columbia-based Ostara, on a portion of the upgrade that relates to a completely new nutrient recovery, or phosphorus harvesting system.

The system will help reduce nutrient management costs, resolve costly nutrient build-up, and help the district meet new, more stringent phosphorus levels in the entire Yahara Watershed by capturing phosphorus in the dirty sewerage water and creating fertilizer pellets.

The recovery facility, which began operating in November, is one of the priciest for the district. Officials from the sewerage district, Dane County Executive Joe Parisi and Ostara officials, including board member Robert F. Kennedy Jr., will host an event Wednesday to highlight the latest plant addition.

Plans for the project have been in the works since 2008. The nutrient recovery, or phosphorus harvesting system, will help reduce nutrient management costs, resolve costly nutrient build-up and help the district meet new, more stringent phosphorus reduction levels in the entire Yahara Watershed imposed by state government.

The Capital Times and the Wisconsin Center for Investigative Journalism explored these new rules and the urban and rural challenges of reducing phosphorus in the "Murky Waters" series.

The Madison Metropolitan Sewerage District is leading the charge in Wisconsin and nationally with its adaptive management practice, which collectively pulls in all polluters, including non-point sources like farms, to help meet reduced phosphorus levels. Ostara's technology adds another component to that effort.

It will reduce the amount of phosphorus in biosolids leaving the plant by one-third, said Michael Mucha, the sewerage district's chief engineer and director.

It also will reduce the amount of struvite, a cement-like substance produced by phosphorus and nitrogen which builds up inside the pipes, pumps and other equipment of a waste water treatment plant.

"It is almost like calcium deposits," Mucha said. "Over time, a pipe that is 6 inches in diameter can become 1 inch in diameter. There is a high cost to replace the pipes."

Ostara's patented phosphorus recovery system, known as thePearl Process, works by funneling the sewerage water into a cone-shaped vessel roughly 20 feet high and 30 feet in diameter.

The sewer fluid enters at the narrow bottom, where it reacts with other chemicals and is pumped upward. The vessel converts dirty, phosphorus-rich water and waste into a fertilizer with less phosphorus that can be used on land.

The fertilizer created by the technology, known as Crystal Green pellets, reacts to organic acids generated by the roots of plants when they are ready to feed, Ostara president Philip Abrary said. The acid dissolves nearby minerals in the soil, including the pellets, becoming available to the plant.

"It is a very efficient and environmentally friendly way to fertilize," Abrary said. "Not only are we recovering the phosphorus but we are redeploying it in a better way than it started out."

Abrary said a difference between the Crystal Green pellets and most traditional fertilizer is it doesn't dissolve in water.

"It is an extremely different way for a fertilizer to behave," he said. "You tend to avoid runoff problems. This type of fertilizer is very interesting because it releases the nutrients when the plants need it."

Abrary said the Madison plant is the largest of seven plants using its technology and is producing more Crystal Green fertilizer pellets than any of its other six plants.

Mucha said details are still in the works but the sewerage district would like to be able to sell the fertilizer pellets to the commercial market by the end of the year.

Source

Media

Taxonomy

• Filtration
• Wastewater Treatment