Phosphorus and other nutrients found in wastewater can present a host of problems for treatment plant operators. They can clog internal piping and pumps, which raises maintenance costs. And treatment plants are typically restricted by how much phosphorus can end up back in rivers and other water ways.

Ostara Nutrient Recovery Technologies, which announced today it raised $14.5 million in venture capital, has developed a way to remove up to 90 percent of phosphorus and 40 percent of the ammonia load from sewage sludge and turn it into commercial-grade slow release fertilizer pellets that can be sold to nurseries, turf farms, and specialty agriculture businesses. Ostara plans to use the venture funding, which was raised in a round led by VantagePoint Capital Partners, to expand its operations.

Farms have reused waste as fertilizer for centuries. Ostara’s tech puts a new spin on the concept by turning wastewater into a marketable product on an industrial scale and without using harmful chemicals.

Ostara has four commercial nutrient recovery facilities in operation in the United States, including a system at Clean Water Services, a water utility west of Portland that serves more than 500,000 customers. The $4.5 facility will be paid for in six years through reduced maintenance costs, savings from chemical and electrical use and revenue from the sale of the fertilizer.

Three other facilities are under construction, including one in Canada and its first European operation for Thames Water in London.