Waste Not, Want Not

Turning sewage into fertilizer

Donald Mavinic and his fellow researchers at The University of British Columbia's Department of Civil Engineering have created technology that produces valuable commercial fertilizer from wastewater, simultaneously solving a costly maintenance problem for sewage treatment plants.

Marketed through spinoff company Ostara Nutrient Recovery Technologies Inc., the system is now being sold around the world. In recognition of this success, Dr. Mavinic and Ostara have received a 2010 Synergy Award for Innovation from the Natural Sciences and Engineering Research Council of Canada.

Phosphate recovery is the key to creating this successful product. The source of this much sought-after commodity is human waste, which is rich in phosphates. The technology developed by Dr. Mavinic's team recovers 85 percent of phosphates that people flush down their toilet.

The technology is proving to be a win-win proposition. Through fertilizer sales, the nutrient recovery system pays for itself in five to seven years. In addition, removing phosphorus helps the sewage treatment plant run more smoothly. Phosphorus forms crystals known as struvite that build up on the inner walls of sewage plant pipes and must be removed regularly to avoid blockage.

As a component of DNA and a key ingredient of fertilizer, phosphorus is essential for all living things. Crops won't grow without it. However, the substance is in limited supply through conventional mining.

Currently only two countries, Morocco and China, have major known reserves of rock phosphate. Without new sources, global food supply will be affected. Dr. Mavinic estimates that recovering the nutrient from domestic sewage could meet about one third of Canada's phosphorus demand.

The partnership between researchers and the private sector was critical to making the technology commercially viable. In 2005, the pilot project created by researchers was developed into a full-scale system by Ostara, called a PEARL reactor. With input from industry partners, the first reactor began operating at Edmonton, Alberta's Gold Bar Wastewater Treatment Plant in May 2007.

Today, phosphorus collected at wastewater treatment plants is being packaged and sold as Crystal Green fertilizer. It is designed for commercial users, such as nurseries, parks and golf courses, that require the slow-release of nutrients.

The technology is gaining popularity. Ostara currently has extractors in Portland, Oregon; Suffolk, Virginia; and York, Pennsylvania. Portland and Edmonton are building facilities to house four more reactors that will treat all of their wastewater. By 2012, Edmonton will be the first Canadian city to fully adopt the recovery technology.

Looking ahead, work is under way to have reactors operating in Madison, Wisconsin, China and the United Kingdom. With this technology, sewage-based fertilizer will be a renewable and sustainable resource throughout the world.