The Edgemont Ranch Metropolitan District was issued new and very strict TIN, TN and TP limits that rendered their lagoon system obsolete. Edgemont Ranch lies in the watershed of the Florida River, a tributary of the Animas River. Downstream of the treatment facility are agricultural irrigation reservoirs that experienced algae blooms. Because lagoon-based systems are vulnerable to cold temperatures, Edgemont Ranch was unable to nitrify for several months of the year in its high-mountain climate, where water temperatures could drop close to freezing. Small upgrades such as covering over the lagoons could not meet stricter effluent standards.
As a remedy, the district looked to the BIOCOS technology, a hybrid activated sludge system designed to deliver more thorough treatment than conventional systems, consisting of two aeration tanks hydraulically connected to an alternating pair of sludge recycling and settling tanks. The design is built with redundancy in mind, enables continuous wastewater processing, and promotes removal of BOD, TSS, TIN and total phosphorus. Mixing and recycling are driven by blower air, significantly reducing energy usage and maintenance while simplifying treatment. Multiple SCADA-driven aeration control loops based on dissolved oxygen, ammonia and ammonia versus NOx allow operators to set concentration thresholds and provide flexibility to meet the new discharge limits.