These fertilizer pellets were created at the F. Wayne Hill Water Resources Center, as part of the process to extract phosphorus from wastewater before it is released into Lake Lanier.
As a farmer will tell you, sometimes the best fertilizer comes from manure.
Likewise, Gwinnett’s sewage treatment process will soon include a step that will make one byproduct of wastewater into a high-quality fertilizer.
Commissioners approved a $16.6 million project to recover nutrients during the treatment process at the F. Wayne Hill Water Resources Center in Buford.
The plant faces one of the most stringent phosphorus limits in the United States, as part of the county’s permit to allow the release of the treated wastewater into Lake Lanier, metro Atlanta’s largest drinking water supplier and a recreational mecca.
While phosphorus could be detrimental to the lake because it could algae to bloom and bring taste and odor problems to the drinking water, the process to extricate it from the water causes problems at the plant, said Tyler Richards, a deputy director for the Department of Water Resources.
The Hill plant — the largest of the county’s three wastewater treatment plants — uses biological and chemical processes to reduce the phosphorus, allowing it to be disposed of with the biosolids at the end of the process or be recycled back into the plant.
When bacteria store the phosphorus during the biological process, Richards explained, it can at times be released, joining with magnesium and ammonia to create “struvite,” which coats the pipes and equipment.
“It comes out is slabs, and they have to chip it out,” Richards said of the struvite, which became a major problem for the plant about four years ago, accelerated by the use of magnesium hydroxide for odor control. “It’s very expensive and very inefficient.”
The new project would allow the phosphorus to be stripped out before the struvite plates onto the pipes, saving about $750,000 in annual costs to deal with the byproduct. Plus, officials hope to sell the slow-release fertilizer pellets formed in the nutrient recovery process to Ostera, a fertilizer company, bringing in up to $500,000 a year.
“It’s naturally occurring,” she said. “We’re taking something that is a problem and turning it into a benefit.”
According to projections, the project will pay for itself in 20 years in savings, even if the fertilizer is not sold. It could pay for itself in as few as 12 years if it is sold.
“If we can harvest that and use them for a beneficial use, that would be great,” Richards said, adding that the project will increase the environmental sustainability of the plant. “It’s something I think we need to be doing a lot more of.”