Activated Sludge

1. Description: Activated sludge is a treatment process by which wastewater and biological sludge (microorganisms) are mixed and aerated in a tank called an aerator, in which biological flocs formed in this process they are put in a settling basin, a place from which they are recirculated back to the aerator tank. On activated sludge process, microorganisms are fully mixed with organic matter in wastewater so that it serves as food for their production. It is important to indicate that the mix or agitation is done by mechanical means (superficial aerators, blowers, etc.), which have a double function: to produce a complete mix and add oxygen to the environment so that the process can develop. The basic elements of the facilities for the process of activated sludge are: aeration tank, sedimentation tank, aeration equipment, system for the return of sludge, excess sludge and its disposal system.

2. Ranges of design: please verify with our Engineering Department based on your requirements.

Important factors to consider in the design:

     a. Daily load of BOD5 or organic matter put into the biological tank.

     b. Daily load of total suspended solids.

     c. Cell retention time of q c, d = 20-30.

     d. Mass load applied to relationship Kg BOD₅ / Kg SSVLM d = 0.05 - 1.5.

     e. Volume load Kg BOD5/m³d = 0.16 - 0.40.

     f. SSLM mg/l = 3,000-6,000.

     g. Hydraulic retention hours = 18-36.

     h. Biological decanter tank recirculation coefficient = 1 - 1.5.

     i. Surface load = 1.0 – 1.33 m³/m²h.

     j. Required Oxygen KgO₂/KgDBO5 = 2 to 2.5 Kg.

     k. Oxygen transfer from the diffusers (depending on model and manufacturer).

     l. Water from the effluent coming from the biological treatment by activated sludge can be dumped in riverbeds, canals or reservoirs once they are within the parameters required by law.

3. Applications: Industrial plants

4. Benefits:

     a. Low operation and maintenance cost.