Conventional Activated Sludge (CAS) Systems

The Conventional Activated Sludge (CAS) process remains a foundational and widely adopted biological wastewater treatment method for both municipal and industrial applications.

The firm's expertise spans the entire CAS treatment train, encompassing preliminary, primary, secondary, tertiary, and advanced treatment stages.

Clients are assisted in achieving specific effluent quality targets, including advanced nutrient removal (nitrogen and phosphorus), which is critical for preventing eutrophication and meeting increasingly stricter environmental standards.

Preliminary Treatment: This initial stage involves the physical removal of large solids and grit from the incoming wastewater using screens and grit chambers.

Primary Treatment: Wastewater then flows into primary clarifiers or sedimentation tanks, where the flow rate is slowed to allow settleable solids to be removed.

Secondary Treatment (Activated Sludge Process): This biological treatment occurs in large, rectangular aeration basins. Here, wastewater is mixed with "activated sludge," which consists of hundreds of millions of actively growing single-celled microorganisms (primarily bacteria and protozoa).

Air or oxygen is continuously introduced to support the growth and multiplication of these microorganisms, which consume the organic waste (BOD) in the wastewater, thereby cleaning it.
After aeration, the mixture flows into secondary clarifiers where the biomass settles to the bottom, and treated water rises to the surface. A portion of this settled sludge, rich in active bacteria, is recycled back into the aeration tank to sustain biological activity.

Tertiary Treatment: This stage focuses on further polishing the effluent, often through filtration (e.g., sand filters) to remove very tiny suspended solids, resulting in water that can appear as clean as drinking water.

Advanced Treatment: Beyond tertiary treatment, this stage targets specific contaminants or aims to achieve exceptionally high effluent quality for water reuse. This often involves technologies like advanced oxidation processes or membrane separation.

While CAS is recognized as a reliable and cost-effective method compared to simpler treatment options, it does present challenges such as high initial capital investment and substantial energy demands for aeration.

Services also include troubleshooting and operational assistance, ensuring stable operations, and addressing common issues like poor settling properties, sludge overflow, and foam problems through tailored chemical solutions and process adjustments.

The firm's capability to manage the entire spectrum of CAS treatment, from preliminary to advanced, and to optimize these processes for various effluent quality targets, particularly given the energy demands, demonstrates a sophisticated understanding of process engineering required to enhance even established systems to meet modern, stricter regulatory demands.