Test: Activated Sludge Process - Civil Engineering (CE) MCQ

Highly concentrated micro-organisms are used to degrade organics and remove nutrients from wastewater to produce a high quality effluent that is activated sludge process.

Activated sludge process:

• The essential features of the activated sludge process are an aeration stage, solids-liquid separation following aeration, and a sludge recycle system.
• Wastewater after primary treatment enters an aeration tank where the organic matter is brought into intimate contact with the sludge from the secondary clarifier.
• It requires less space, does not produce obnoxious odor, and requires less time for wastewater treatment.
• It requires skilled supervision

Followings are the classification of secondary treatment units:

To maintain the aerobic conditions and to keep the activated sludge suspended, a continuous and well-timed supply of oxygen is required. Flocs of bacteria, which are suspended and mixed with wastewater is used for the process.

The bacteria use the organic pollutants to grow and transform it to energy, water, carbon-dioxide and new cell material. The bacterium is present in the form of flocs which are suspended and mixed with wastewater.

An SBR essentially combines the aeration basin and the secondary clarifier of a traditional activated sludge system into a single basin. While the system is in aeration mode, air is supplied by the aeration system and influent enters the basin.

SBR stands for a Sequential batch reactor. An SBR essentially combines the aeration basin and the secondary clarifier of a traditional activated sludge system into a single basin.

SBR operates as a batch process. Because sequential batch reactors operate as a batch process, the level of the basin starts out low and the basin fills over several hours as influent enters.

When the filling/ aeration phase is complete, the aeration system shuts off and the basin begins to function as a secondary clarifier. Suspended solids and micro-organisms settle to the bottom of the tank and clarified water is left near the surface.