Currently, Edmonton, ON, Canada sells compost for extra cash. The compost includes sewage sludge from its wastewater settling ponds. Now, the fertilizer opportunities can expand, as phosphorous is being pulled out of the ponds as well.
Phosphorous, a catalyst for algae growth in rivers and lakes, is now being monitored by the province—there is a limit to the amount of phosphorous that can remain in the treated water the city pours into the river.
Abdul Mohammed, plant superintendent at the Gold Bar wastewater treatment plant, said that, until now, the phosphorous pulled out of the plant was returned to the Clover Bar settling ponds. This meant that, eventually, much of it would return to the treatment plant.
The concern about this is the substance’s adhesive qualities, which often cause it to clog pipes in a layer called struvite. This clogging inflicts $100,000 in pipe-cleaning costs on the city per year, which significantly increases the plant’s operational costs.
Luckily, Ostara Nutrient Recovery Technologies, Inc. has found a way to combat these problems with a reactor that removes phosphorous and ammonia from the wastewater.
The reactor’s May installation has allowed Mohammed to see an 80 to 90% removal of phosphorous from the water, which exceeds the company’s expectations of a minimum 75% removal.
The $2 to $4 million revenue the plant will receive for the fertilizer made from the phosphorous means that the plant should be able to make up for the reactor’s costs within three to five years. It will also likely cause the plant to purchase more reactors to treat the remaining 80% of the city’s wastewater, Mohammed said.
