Conventional Activated Sludge (CAS) is the predominant wastewater treatment technology globally. One key requirement of this technology is the ability to effectively separate the liquid and solids fractions. Floating or bulking sludge, at least temporarily, has affected the treatment capacity and performance of many of these facilities. World Water Works’ inDENSE™ technology solves this problem.
In the operation of the CAS process, the treated wastewater is separated from the biomass after having passed through the biological reactor basins. In the secondary clarifiers, the activated sludge solids separate via gravity and settle to the bottom while the treated water is discharged through the effluent weir structure. To maintain the process, a large portion of the sludge is returned to the biological reactor basins as Return Activated Sludge (RAS). This maintains the proper Food to Mass (F/M) ratio and Solids Retention Time (SRT) to assure proper biological performance. The remainder of the sludge is removed from the process as Waste Activated Sludge (WAS) and is disposed of via digesting, dewatering, and/or otherwise handled.
Filamentous and other undesirable bacteria, with poor settling properties, can become more abundant and outcompete other more desirable bacteria negatively impacting settling. Poor settlability prevents the appropriate operation of the overall CAS system leading to possible permit violations. One test method used to understand and track flocculation characteristics is the Settling Volume Index (SVI) – the higher the number, the poorer the performance. The graph shown shows SVI’s for year 1 without inDENSE and then with it in Year 2 and 3. Furthermore, by preferentially selecting for the more dense bacteria, organisms such as GAO and PAO’s are naturally selected for. This provides the opportunity to achieve BIO-P in the existing system for chemical free phosphorus removal.
Systems are available on a rental basis to reduce risk and achieve results near-term.