To meet the low phosphorus limit (0.1 mg/l) for the Tualatin River our Rock Creek and Durham facilities both participate in a unique public/private partnership with Ostara Nutrient Recovery Technologies. Ostara has developed a technology to simplify the treatment process by directly removing phosphorus and ammonia from wastewater that would otherwise have to be retreated. This proprietary technology, called the PEARL™ process, diverts the phosphorus and other nutrients to a reactor that converts them into a premium, slow-release, environmentally friendly commercial fertilizer product called Crystal Green®. The facilities produce more than 450 tons a year of fertilizer that is sold to the nursery and turf industry in Oregon's Willamette Valley and beyond. Crystal Green® is also a key component in Clean Water Grow®, our retail all-purpose fertilizer. This innovation saves energy and maintenance costs and increase capacity at the treatment facilities. Learn more about the Ostara process.
Clean Water Services' four wastewater treatment facilities recycle more than 31 dry tons of safe, nutrient-rich organic material from the 60 million gallons of wastewater we clean each day. This recycling process results in the production of biosolids. In fact, the more we succeed in cleaning our water, the more biosolids we can produce and recycle for beneficial use.
The solids that settle out during primary and secondary treatment, are routed to digesters—large cylindrical tanks kept mixed and heated to body temperature. The solids are treated for about a month, undergoing anaerobic digestion, that is digestion by bacteria that need no air. In their metabolism, methane gases are given off which you will often see burning in a torch-like device in any wastewater plant.
The nutrient-rich biosolids are dewatered and recycled onto local farms and rangeland in Eastern Oregon as a soil amendment.