Biological Nutrient Removal (BNR) Basins

Large amounts of nitrogen and phosphorus in wastewater effluent can eventually cause eutrophication (nutrient enrichment due to human activities) in surface waters. Excessive eutrophication can cause algae blooms in the summer, low dissolved oxygen levels, fish kills, murky water, and depletion of desirable flora and fauna.

Biological nutrient removal is a treatment process used to remove nitrogen and phosphorus from wastewater before being discharged into the receiving stream. The BNR process depends on the proliferation and type of microorganisms capable of removing nitrogen and phosphorus from the waste stream. Most BNR treatment processes include anaerobic (without oxygen) basins, followed by mixing, aerobic (with oxygen) basins, and solids removal by clarification.

Secondary Clarifiers

Secondary clarifiers are large round settling tanks and the principal mechanisms for continuous separation of the biological floc from the treated liquid waste stream. A portion of the removed solids are returned to the treatment population, while some solids are permanently wasted from the system.

Advanced Water Treatment

The advanced water treatment process can include enhanced phosphorus removal polishing, and cloth filtration units or sand filtration to remove residual suspended solids.

Operations Building

The operations building will include plant administrative offices and a full-scale laboratory capable of testing, analyzing, and reporting the District’s permitted discharge data.

Solids Handling and Solids Storage

Solids removed from the wastewater receive further treatment, using aeration, chemical addition, and dewatering, resulting in the destruction/digestion of organic compounds. Once stabilized, the biosolids are hauled offsite to either a landfill or land application used to enrich nutrient-deficient soil.

Ultraviolet Disinfection (UV)

Final cleansing of wastewater effluent is accomplished by ultraviolet (UV) disinfection. Ultraviolet light penetrates the microorganism cell wall and destroys the cell's ability to reproduce. The main components of a UV disinfection system include lamps, ballasts, and a reactor.