In many circumstances, it is advantageous to treat wastewater near the source to prevent long distance wastewater conveyance, or for locations where existing centralized systems are at or near treatment capacity. Decentralized wastewater treatment is a common option for industries, commercial facilities, and new residential subdivisions. System effluent quality requirements vary depending on the ultimate effluent discharge point for the system.
Secondary treatment, consisting of cBOD5 and TSS removal, is accomplished in an unsaturated vertical flow SAGR® which is typically preceded by 1 or 2 days of septic tank retention or low pressure sewer system with individual holding tanks. Effluent recirculation in the SAGR® maintains wetted biomass and optimal efficiency.
A horizontal flow SAGR® (Submerged Attached Growth Reactor) is utilized following the secondary treatment process where nitrification is required. The SAGR® nitrification module can be utilized after any secondary treatment processes including aerated unsaturated gravel bed, lagoons, recirculating sand filter, activated sludge plants, trickling filter, or other processes producing secondary effluent.
The SAGR® process generates minimal odors as it operates in fully aerobic conditions. A layer of mulch on the surface prevents freezing within the bed and further prevents odors which in turn reduces setback requirements for the system
With the reactors located below grade the SAGR® process blends in with the surrounding environment making it ideal for applications where an unobtrusive process is desired. Native plants or grass may be planted in the mulch layer on the SAGR® surface to further improve system aesthetics.