Wastewater Plant Recovers Nutrients, Produces Commercial Fertilizer

Aug 15, 2013

Sustainable Plant

The City of Saskatoon and Ostara Nutrient Recovery Technologies Inc. recently officially opened Canada’s first commercial nutrient recovery facility at the city’s Wastewater Treatment Plant (WWTP). The project is the first commercial plant of its kind in Canada to use Ostara’s Pearl nutrient recovery process to recover phosphorus and nitrogen from the facility’s wastewater stream and transform them into Crystal Green, a slow-release, enhanced-efficiency fertilizer.

The Saskatoon WWTP is a designated Level 4 plant, which is the highest level of certification. As such, all aspects of the wastewater treatment process are closely monitored 24 hours a day, seven days a week, by highly trained plant operators. The treatment process is continuously analyzed through electronic controls, monitoring devices and computers to ensure the plant is operating effectively. An on-site laboratory performs approximately 30,000 analyses annually to ensure continuous quality control and to record the plant’s performance.

By removing potentially polluting nutrients from the treatment facility’s wastewater stream, Ostara’s technology helps the city meet nutrient discharge limits and overcome operational issues caused by the unintentional build-up of struvite scale in plant equipment.

Struvite is a concrete-like mineral deposit that chokes process equipment, increases operating and maintenance costs, and undermines plant reliability. The formation of struvite is a common challenge in plants that practice biological nutrient removal and anaerobic digestion.

In Saskatoon, the sludge is handled at a bio-solid facility that is 12 kilometers from the treatment plant where it is stored. The struvite problems are exacerbated as the sludge must travel this distance through pipes from the treatment plant to this facility, and then pump decant water back to the treatment plant. Keeping the pipes clear of struvite is a significant operational challenge, especially in the winter. Chemical additives can sometimes be used to mitigate struvite problems, however they are costly and result in a higher volume of sludge waste requiring disposal.

The Ostara system will help the city overcome these challenges by recovering 75 percent of the phosphorus and 10 percent of the nitrogen from the wastewater stream before they accumulate in the equipment.

Read the full article at www.sustainableplant.com

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