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Activated sludge tank at Beckton sewage treatment plant, UK.The white bubbles are due to the diffused air aeration system. The activated sludge process is a type of biological wastewater treatment process for treating sewage or industrial wastewaters using aeration and a biological floc composed of bacteria and protozoa.
Activated sludge model is a generic name for a group of mathematical methods to model activated sludge systems. The research in this area is coordinated by a task group of the International Water Association (IWA). Activated sludge models are used in scientific research to study biological processes in hypothetical systems.
There are many other aerobic biological processes for treatment of wastewaters, for example activated sludge, trickling filters, rotating biological contactors and biofilters. They all have in common the use of oxygen (or air ) and microbial action to reduce the pollutants in wastewaters.
The quantity or “age” of sludge within the tank is closely monitored, as this can have a marked effect on the treatment process. The sludge is allowed to settle until clear water is on the top 20 to 30 percent of the tank contents. The decanting stage most commonly involves the slow lowering of a scoop or “trough” into the basin.
One type of system that combines secondary treatment and settlement is the cyclic activated sludge (CASSBR), or sequencing batch reactor (SBR). Typically, activated sludge is mixed with raw incoming sewage, and then mixed and aerated. The settled sludge is run off and re-aerated before a proportion is returned to the headworks. [19]
Activated sludge tank at Beckton sewage treatment plant, UK. The white bubbles are due to the diffused air aeration system. The activated sludge process is a type of biological wastewater treatment process for treating sewage or industrial wastewaters using aeration and a biological floc composed of bacteria and protozoa.
Extended aeration agitates all incoming waste in the sludge from a single clarifier. The combined sludge starts with a higher concentration of inert solids than typical secondary sludge and the longer mixing time required for digestion of primary solids in addition to dissolved organics produces aged sludge requiring greater mixing energy input per unit of waste oxidized.
Enhanced biological phosphorus removal (EBPR) is a sewage treatment configuration applied to activated sludge systems for the removal of phosphate. [1]The common element in EBPR implementations is the presence of an anaerobic tank (nitrate and oxygen are absent) prior to the aeration tank.